contents book of abstract.pdf · nicolas sisourat . srobonne université, france . plenary talk:...

Contents

Plenary Talks………………………………………………………3

Invited & Oral Talks

I - Fundamental Physics at Extremes…………………………………31

II - Pulsed Power and Application……………………………………81

III - Laser and Particle Beam Fusion, Magnetic Driven Fusion……123

IV - Laser Plasma Interaction………………………………………177

Poster Presentations

I - Fundamental Physics at Extremes………………………………229

II - Pulsed Power and Application…………………………………265

III - Laser and Particle Beam Fusion, Magnetic Driven Fusion……315

IV - Laser Plasma Interaction………………………………………365

Satellite workshop on Fluid Interface Instability at Extremes………377

Satellite workshop on Laser and Plasma Instabilities……………..…393

Satellite workshop on Laser Fusion and Science…………………..…401

Satellite workshop on Advanced Diagnostics Technique for HEDP…411

Plenary Talks

May 6th-11th, 2018 Book of Abstract Qingdao, China ICMRE2018

Plenary Talk

Monday May 7th

8:10~8:20 Opening ceremony

1 8:20~9:05 Shaoping Zhu Science and Technology on Plasma

Physics Laboratory, China

Plenary Talk: Status and Progress of Science

Challenge Project

2 9:05~9:50 Kazuo A.

Tanaka

Extreme Light Infrastructure-NP,

Romania Plenary Talk: ELI-NP Status and Plan

9:50~10:30 Group photo & Coffee Break

3 10:30~11:15 Ho-Kwang Mao

Center for High Pressure Science

and Technology Advanced

Research, China

Plenary Talk: Probing Dense Matter with Extreme

Radiations

4 11:15~12:00 Victor Malka Centre National de Larecherche

Scientifique, France

Plenary Talk: Manipulating relativistic electrons

with lasers

Tuesday May 8th

5 8:00~8:45 Michael

Campbell

Laboratory for Laser Energetics,

University of Rochester, USA

Plenary Talk: Laser-Plasma Interaction Physics and

Direct Drive:Challenges,and Path Forward

6 8:45~9:30 Wanguo Zheng Laser Fusion Research Center,

CAEP, China

Plenary Talk: Status of SG-III Laser Facility for

Inertial Confinement Fusion


Plenary Talk

7 9:30~10:15 Thomas

Mattsson Sandia National Laboratory, USA Plenary Talk: The Z Fundamental Science Program

10:15~10:30 Coffee Break

8 10:30~11:15 Weiping Xie Institute of Fluid Physics, CAEP,

China

Plenary Talk: Electromagnetically Driven Research

in IFP-Progresses and Perspectives

9 11:15~12:00 Sergey Lebedev Imperial College London, UK Plenary Talk: Z-pinch Driven Experiments with

Supersonic Magnetized Plasma Flows

Wednesday May 9th

10 8:00~8:45 Zhengming

Sheng

Shanghai Jiao Tong University,

China

Plenary Talk: Plasma Photonics for Applications

from Laser Particle Acceleration to Laser Fusion

11 8:45~9:30 Vladimir

Fortov

Joint Institute for High

Temperature, Russian Academy of

Science, Russia

Plenary Talk: Quasi-adiabatic Multi-shock

Compression of Strongly Coupled Plasmas:

Nonideality and Degeneracy

12 9:30~10:15 Hongwei Zhao Institute of Mordern Physics, CAS,

China

Plenary Talk: Intense Heavy-ion Beam for High

Energy Density Physics:Opportunities and

Challenges


13 10:30~11:15 Jing Chen Institute of Applied Physics and

Computational Mathematics, China

Plenary Talk: Quantum Interference Effect in

Atomic Double Ionization in Intense Laser Field

14 11:15~12:00 Nicolas Sisourat Srobonne Université, France Plenary Talk: Superexchange Interatomic

Coulombic Decay


Plenary Talk

Thursday May 10th

15 8:30~9:15 Dimitri Batani Univeristy of Bordeaux, France Plenary Talk: Physics of Shock Ignition Approach

to ICF

16 9:15~10:00 Qian Yue Tsinghua University, China Plenary Talk: Recent Status and Prospects of CJPL

and Dark Matter Experiments in China


17 10:15~11:00 Praveen

Ramaprabhu

The University of North Carolina at

Charlotte, USA

Plenary Talk: The Lives and Times of Ejecta from

Shocked Metals

18 11:00~11:45 Ke Lan Institute of Applied Physics and


Plenary Talk: Theoretical Study and Octahedral

Spherical Hohlraum Experimental Campaign on the

SG-III


Plenary Talk

Status and Progress of Science Challenge Project

Shaoping Zhu

1. Institute of Applied Physics and Computational Mathematics, P.O.Box 8009, Beijing 100088

2. Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China

Academy of Engineering Physics

3. Graduate School, China Academy of Engineering Physics

Science Challenge Project (SCP), which is started in 2016, is a national research

project of China on fundamental scientific issues. High energy density science (HEDS)

is one of seven fields supported by SCP. In this presentation, I will introduce the status

and progress of HEDS-SCP, and show several research highlights. HEDS-SCP is

organized by Science and Technology on Plasma Physics Laboratory, Laser Fusion

Research Center (LFRC). Three laser facilities, Xing-Guang III，PW laser and Shen-

Guang III prototype, which are operated in LFRC, have been opened for cooperative

researches. In this talk, I will briefly introduce the performance of these three facilities.


Plenary Talk

ELI-NP Status and Plan

Kazuo A. Tanaka

ELI-NP/IFIN-HH, 30 Reractorului Str., PO Box MG6, Magurele-Bucharest, 077125

Romania,

*Email: [email protected]

Introduction

Since chirped pulse amplification scheme[1] has changed the game in high energy

density physics, the available laser intensity has kept increasing, can reach 1023 W/cm2 or

even higher, and can deliver radiation higher than the previously used in nuclear facilities.

In order to make use of this capability in full depth, ELI-NP has been funded to come up

with both high intensity laser and high briliance gamma beam systems through the

European Light Infrastructure (ELI) project for the state of the art and beyond.

High Power Laser System (HPLS)

The high power laser system (HPLS) consists of OPCPA, Ti Sapphire

configuration at the central wavelength 820 nm with 60 nm bandwidth, the output energy

250J, the pulse width 25 fsec, the contrast ratio1013 with 50 cm beam diameter. This may

enable to create a focused laser intensity 1022-1023 W/cm2 on target. 3 PW performance

test is planned in Apr. 2018.

Gamma Beam System (GBS)

The output of gamma-ray beams comes up with continuously tunable energy in

the range from 200 keV to 19.5 MeV. The production of quasi-monochromatic gamma

beams is based on the Inverse Compton Scattering (ICS) process of green laser light

pulses off relativistic electron bunches up to 700 MeV. The resulting GBS is based on a

high-quality electron-photon collider with luminosity at the level of about 2 x 1035 cm–2

s–1, that is almost one order of magnitude better than what was achieved at LHC in CERN

[2].

Planned Experiments

The commissioning phase may be expected to start as early as in 2018. A number

of experiments has been proposed for the Day 1 phase and has been recommended by

the International Scientific Advisory Board (ISAB). For example gamma ray conversion

efficiency, high energy electron acceleration, and non-linear QED [3] are being prepared

for the HPLS. First-phase experiments for the GBS involve studies of the distribution of

the E1 strength in the region of the Pigmy Dipole Resonance (PDR) and the Giant Dipole

Reso-nance (GDR). Delbruck Scattering is also considerd. These experiments will take

advantage of the narrow-bandwidth pencil-size beams at ELI-NP, which provide the

possibility for studies low-abundance targets, e.g. NRF studies in the actinide nuclei.

Call for further proposal will be announced from ELI-DC [4] organization.

Acknowledgement

This project work has been cooperated with the entire staffs, groups and

management of ELI-NP. The efficient and speedy installation of HPLS by Thales is

mailto:[email protected]


Plenary Talk

commended. Excellent technical and scientific suggestions have been made by ISAB

chaired by Prof T Tajima, UC Irvine. Work supported by the Extreme Light

Infrastructure Nuclear Physics (ELI-NP) Phase II, a project co-financed by the

Romanian Government and the European Union through the European Regional

Development Fund and the Competitiveness Operational Programme (1/07.07.2016,

COP, ID 1334).

References

[1] D Strickland and G Mourou, “Compression of amplified chirped optical pulses”,

Opt. Commun. 56, 219 (1985).

[2] D. Balabanski, R. Popescu, D. Stutman, K.A. Tanaka, O. Tesileanu, C.A. Ur, D.

Ursescu and N.V. Zamfir, “New

light in nuclear physics: The extreme light infrastructure”, European Phys. Lett.,

17, 28001 (2017).

[3] N.V. Zamfir et al., Romanian Reports in Physics, Vol. 68, Supplement I & II,

2016.

[4] ELI-DC: https://eli-laser.eu/

https://eli-laser.eu/


Plenary Talk

Probing Dense Matter with Extreme Radiations

Ho-Kwang Mao

Center for High Pressure Science and Technology Advanced Research, China

Geophysical Laboratory, Carnegie Institution of Science, U.S.A.

Pressure densifies matter and profoundly alters all of their states and properties;

radiation interacts with matter to reveal the altered states and properties. The symbiotic

development of ultrahigh-pressure diamond-anvil cells DAC, to compress samples to

sustainable multi-megabar static pressures; and extreme radiations of electromagnetic

waves from infrared, visible, ultraviolet to high-energy x-rays and particle radiations such

as neutrons, to penetrate the DAC to probe sample materials in-situ, has enabled the

exploration of rich and comprehensive high-pressure (HP) science. Currently the

synchrotron based x-ray techniques are by far the most powerful, versatile, and successful

probes. X-ray free electron laser is complementary to synchrotron x-ray but unable to

perform the function of synchrotron in the foreseeable future.

These HP synchrotron studies include: HP x-ray emission spectroscopy, which

provides information on the filled electronic states of HP samples; HP x-ray Raman

spectroscopy, which probes the HP chemical bonding changes of light elements; HP

electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic

phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and

their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes

shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP

nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-

resolved Mössbauer information; HP x-ray photon correlation spectroscopy, which

determines the melting point and viscosity of fluid; HP x-ray diffraction, which determines

the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline,

and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric,

elastic and rheological information.

Integrating these tools with hydrostatic or uniaxial pressure media, laser and

resistive heating, and cryogenic cooling, has enabled investigations of the structural,

vibrational, electronic, and magnetic properties of materials over a wide range of pressure-

temperature conditions. As a result, the impact of pressure is well established in the key

multidisciplinary fields of physics, chemistry, Earth and materials sciences.


Plenary Talk

Manipulating relativistic electrons with lasers

Victor Malka

CNRS & Weizmann Institute, France


Laser Plasma Accelerators (LPA) rely on the electrons motion control with intense

laser pulses [1]. The manipulation of such relativistic electrons with lasers allows a fine

mapping of the longitudinal and radial components of giant electric fields with values that

can exceed hundred of GV/m [2]. This crucial control permits to optimize laser plasma

accelerators for generating ultra-short and ultra-bright energetic particle or radiation beams.

To illustrate the beauty of laser plasma accelerators I will show, how by changing

the density profile of the gas target, one can improve the quality of the electron beam, its

stability [3] and its energy gain [4], and how by playing with the radial field one can reduce

its divergence [5].

I’ll then show how by controlling the quiver motion of relativistic electrons intense

and bright X-rays beam are produced in a compact and elegant way [6-8]. Finally I’ll show

some examples of applications.

Keywords: high power lasers, accelerators, X-ray beams, electron beams

Reference

[1] V. Malka, Europhysics Letters, 115 (2016) 54001

[2] V. Malka et al., Science 22, 298, Nov. (2002)

[3] E. Guillaume et al., Phys. Rev. Lett. 115, 155002 (2015)

[4] C. Thaury Scientific Report, 10.1038, srep16310, Nov. 9 (2015)

[5] C. Thaury et al., Nature Comm. 6, 6860 (2015)

[6] K. Ta Phuoc et al., Nature Photonics 6, 308-311 (2012)

[7] S. Corde et al., Review of Modern Phys. 85 (2013)

[8] I. Andriyash et al., Nature Comm. 5, 4736 (2014)


Plenary Talk

Laser-Plasma Interaction Physics and Direct

Drive:Challenges,and Path Forward

E.M. Campbell1,*, Dustin Froula1, John Palestro1, R.K Follet1, J.F. Myatt2, J.G. Shaw1, J. Bates3,

J.L. Weaver3, R.H.Lehmberg3, S.P. Obenschain3, M. Rosenberg1, John Marozas1

1. Laboratory for Laser Energetics, University of Rochester,

2. University of Alberta, USA

3. Naval Research Laboratory, USA


Laser Direct Drive is one of three viable Inertial Confinement Fusion approaches

to achieve ignition and gain. In order to determine the laser and target parameters needed

to achieve this demanding goal, a detailed and quantitative understanding of laser –plasma

interaction physics is required. Processes such as Cross-beam energy transport (seeded

Stimulated Brillouin Scattering), Stimulated Raman Scattering and the two plasmon Decay

instability can reduce target absorption and ablation pressure, impact the control of drive

uniformity and preheat the fuel raising the target adiabat. Understanding the complexity

introduced by multi-beam interactions, the impact of the laser irradiation conditions and

the scaling with plasma corona conditions are critical issues. In this presentation, the

ongoing research and future plans for laser-plasma interaction physics for direct drive will

be presented.


Plenary Talk

Status of SG-III Laser Facility for Inertial Confinement Fusion

Wanguo Zheng

Laser Fusion Research Center, CAEP, China


SG-III is the largest laser driver for ICF researches in China, which has 48

beamlines and can deliver 180kJ ultraviolet laser energy in 3ns. In order to meet the

requirements of precise physics experiments, some new functions need to be added to

SG-III and some intrinsic laser performances need upgrade. With these function

extensions and performance upgrade, hybrid drive and Indirect drive Inertial

Confinement Fusion using capsules filled with Deuterium-Tritium fuel to achieve

thermo-nuclear fusion have been studied. Both cylindrical hohlraum with 2 LEHs and

spherical hohlraum (SH) with 6 LEHs ICF experiments can be investigated on SG-III.

In this presentation, the ongoing research and future plans for SG-III laser facility

and laser-plasma interaction physics will be presented.

Keywords: Inertial confinement fusion; High power laser; Hydrodynamic Instabilities,

cylindrical implosions


Plenary Talk

The Z Fundamental Science Program

Thomas Mattsson

Sandia National Laboratories, USA


Over the last few years, our ability to drive matter to unprecedented pressure /

temperature states has produced significant new insights across many fields, including

material science, planetary science, astrophysics, fusion science, radiation science, and

plasma physics. Sandia’s Z facility is the premier facility in the world in the area of pulsed-

power science and has unique capabilities to deliver high-precision data at extreme

conditions. In this talk, I will present results from the Z Fundamental Science Program in

the area of planetary science and astrophysics, for example the direct observation of an

abrupt insulator-to-metal transition in dense liquid deuterium; the entropy in the shock state

of iron; the opacity of iron at conditions relevant to the convection-radiation boundary in

the sun; and properties of photo-ionized plasmas relevant to accretion disks surrounding

black holes. Sandia National Laboratories is a multi-mission laboratory managed and

operated by National Technology and Engineering Solutions of Sandia LLC, a wholly

owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's

National Nuclear Security Administration under contract DE-NA0003525.


Plenary Talk

Electromagnetically Driven Research in IFP-Progresses and

Perspectives

WeipingXie*,Lin Chen, Shengyi Song, Jianqiang Yuan, Qizhi Sun, Xianbin Huang, Hongtao Li,

Wenkang Zou, Yong He, Meng Wang, Shuping Feng,Jianjun Deng

Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAEP, China


As an institute with multi-discipline at China Academy of Engineering Physics

(CAEP), the Institute of Fluid Physics (IFP) has involved in electromagnetically driven

research (EDR) for several decades. The EDR in IFP includes high power pulse generation,

loading technologies and physical experiments related to hydrodynamics and high energy

density physics. The earliest history of EDR in IFP dated from the mid of 1960s, when the

suggestion of conducting experimental investigation on fusion using the explosive

magnetic generator was proposed by Academician WANG Ganchang. After 1980s, the

needs for x-ray radiography, radiation effect simulation, hydrodynamic and inertial

confinement fusion (ICF) studies led to speeding development in this area. Especially after

2000, several platforms with MA current capability were developed, which provided new

extreme conditions for EDR. In this presentation, the progresses in platform development

and physical achievements of the past years will be reviewed, and the perspectives in EDR

for the near future will also be presented.


Plenary Talk

Z-pinch Driven Experiments with Supersonic Magnetized

Plasma Flows

Sergey Lebedev

Imperial College, UK

*Email: s.lebedev:imperial.ac.uk

Magnetic fields play an important role in many High Energy Density (HED)

plasmas, but an understanding of their effects on the behavior of these plasmas is still

limited. A controllable introduction of the dynamically significant magnetic fields in the

HED plasma experiments is a challenging problem – the small resistivity of the high

temperature plasmas often prevents the penetration of an externally created magnetic field

into the plasma on the time-scale of an experiment. The use of plasma flows generated by

pulsed power facilities provides a natural platform for designing experimental

configurations which allow well diagnosed studies of the magnetized HED plasmas. The

plasma in this case is created and accelerated by the JxB force of the Mega-Ampere level

currents, forming plasma flows with embedded, frozen-in magnetic fields. In this talk we

will review several recent experiments performed at the MAGPIE pulsed power facility at

Imperial College, aimed at the studies of magnetic reconnection in colliding high beta

plasmas [2, 3] and the structure and stability of magnetized shocks [4]. The relatively large

spatial and temporal scales characterizing this experimental platform, together with an

excellent diagnostic access, allow detailed characterization of the key plasma parameters

[5] for quantitative comparison of the experimental results with numerical simulations.

Keywords: Z-pinch; magnetic reconnection; high energy density plasma

Reference

1. B. Remington, R.P. Drake, D.D. Ryutov, Rev. Mod. Phys., 78, 755 (2006).

2. L.G. Suttle, J.D. Hare, S.V. Lebedev et al., Phys. Rev. Letters, 116, 225001 (2016).

3. J.D. Hare, L.G. Suttle, S.V. Lebedev et al., Phys. Rev. Letters, 118, 085001 (2017).

4. G. C. Burdiak, S. V. Lebedev, S. N. Bland et al., Phys. Plasmas, 24, 072713 (2017).

5. G.F. Swadling, S.V. Lebedev, G.N. Hall et al., Rev. Sci. Instrum. 85, 11E502 (2014).


Plenary Talk

Plasma Photonics for Applications from Laser Particle

Acceleration to Laser Fusion

Zheng-Ming Sheng1,2,3,4, Min Chen2,3, Su-Ming Weng2,3, and J. Zhang2,3,5

1 SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK

2 Key Laboratory for Laser Plasmas (MoE), School of Physics and Astronomy, Shanghai Jiao

Tong University, Shanghai 200240, China

3 Collaborative Innovation Centre of IFSA, Shanghai Jiao Tong University, China

4 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, China

5 Chinese Academy of Sciences, Beijing, China

As a unique nonlinear optical media, plasma is not subject to a damage limit by

high power lasers. Therefore it can find wide applications in the manipulation of high

power lasers, such as, guiding of laser pulses by a plasma channel for laser-driven particle

acceleration [1], amplification of laser pulses to extreme high power in plasma media [2],

shaping laser pulses by plasma mirror or lens [3,4], and compression of laser pulses by

plasma gratings [5], beam smoothing in plasma for fusion applications [6], etc. In this talk,

we present our recent progress in this topic. Firstly, X-rays produced from laser wakefield

accelerators (LWFA) via betatron radiation and nonlinear Thomson scattering are

promising for broad applications. To further improve the controllability of betatron

radiation including its brilliance, polarisation, and energy spectrum, plasma channels are

found to an effective optical element by controlling laser injection into the plasma channels

[7]. Secondly, for future TeV collider, multiple stages are found to be essential, but

extremely challenging [8]. In our new scheme of cascade acceleration based upon LWFA,

a curved plasma channel is proposed with a gradual curvature radius combined with a long

straight plasma channel to guide the secondary driving laser and the electron beams,

respectively. The stable excitation of the secondary laser wakefield and the smooth

injection of the electron beams into the wake of the secondary laser are achieved

simultaneously [9]. Thirdly, we propose a scheme to covert linearly polarised high power

lasers into circularly-polarised lasers by use of the Faraday effect with high magnetic fields

[10]. This could be particularly interesting to manipulate high power lasers at 10PW or

above to replace conventional quarter-wave plates, which submit to limited damage

threshold and size. Circularly polarised high power lasers are critical for laser ion

acceleration [11]. Finally, we introduce an ultrafast, plasma-based optical modulator [12],

which can directly modulate high power lasers with intensity up to 1016 W cm-2 level to

produce an extremely broad spectrum with a fractional bandwidth over 100%. Such optical

modulators may enable a new type of high power lasers, so called broadband decoupled

lasers for the control of laser parametric instabilities [13], critical for laser fusion.

References


Plenary Talk

[1] For example, P. Sprangle et al., Phys. Rev. Lett. 69, 2200 (1992).

[2] For example, R. Trines et al., Nat. Phys. 7, 87 (2011); G. Vieux et al., New J. Phys. 13,

063042 (2011).

[3] For example, C. Thaury, et al., Nat. Phys. 3, 424 (2007).

[4] H. Y. Wang, C. Lin, Z. M. Sheng et al., Phys. Rev. Lett. 107, 265002 (2011).

[5] Z.M. Sheng et al., Appl. Phys. B 77, 673 (2003); H.C. Wu et al., Phys. Plasmas 12,

113103 (2005); H.C. Wu et al., Appl. Phys. Lett. 87, 201502 (2005); L.L. Yu et al., J. Opt.

Soc. Am. B 26, 2095 (2009).

[6] H. Hora, Laser & Part. Beams 24, 455 (2006); S. Hüller and A. Porzio, ibid 28, 463

(2010).

[7] M. Chen et al., Light: Sci. & Appl. 5, e16015 (2016); J. Luo et al., Sci. Rep. 6:29101

(2016).

[8] S. Steinke et al., Nature 530, 190–193 (2016).

[9] J. Luo et al., Phys. Rev. Lett. 120, 154801 (2018).

[10] S. M. Weng et al., Optica 4, 1086-1091 (2017).

[11] S. M. Weng et al., Sci. Report 6:22150 (2016).

[12] L.L. Yu et al., Nat. Comm. 7, 11893 (2016).

[13] Y. Zhao et al., Phys. Plasmas 24, 112102 (2017); Y. Zhao et al., Matt. Rad. Extr. 2,190

(2017).


Plenary Talk

Quasi-adiabatic Multi-shock Compression of Strongly Coupled

Plasmas: Nonideality and Degeneracy

Vladimir Fortov

Joint Institute for High Temperatures RAS, Moscow, Russia

A series of experiments with quasi-isentropic compression of plasma was carried

out to generate strongly coupled plasma of deuterium and helium at extremely high

pressures and densities. Two-stage spherical explosively driven devices were used in these

experiments. High symmetry initiation of spherical high explosive charges provides a high

symmetry of collapsing spherical steel shell which allows to achieve a high degree of

spherical symmetry of the compressed plasma. Record high parameters of strongly coupled

deuterium plasma were obtained in the experimentspressures up to 11 TPa and density up

to 10 g/cc. Helium plasma was compressed ~ 200 times up to density of 8 g/cc and

pressures of P ~ 5 TPa. Multi-channel pulsed X-Ray registrations consisting of three

betatrons and a multi-channel optic-electronic system were used for obtaining X-Ray

images. The physical properties of helium and deuterium plasma at the extremely high

pressures, temperatures and densities are discussed with the use of simplified plasma

physical models. The plasma phase transition was experimentally detected. The different

theoretical models of plasma phase transitions in these conditions are discussed in

comparison with shock wave experiments. Exclusively important role of quantum

degeneracy effects as well as of strong nonideality effects is analysed on the basis of the

experimental data obtained.


Plenary Talk

Intense Heavy-ion Beam for High Energy Density

Physics:Opportunities and Challenges

Hongwei Zhao

Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China

Intense heavy ion beam could be a complementary approach for study of high

energy density (HED) physics. Perspective and advantage for HED physics driven by

heavy ion beam will be reviewed firstly. High Intensity heavy Ion Accelerator Facility

(HIAF) is going to be built in China, which may provide a new opportunity for study of

HED physics driven by heavy ion beam. HIAF will be able to deliver high intensity and

high energy pulsed heavy ion beams, such as, 238Ubeam with energy 0.8-3 GeV/A and

pulsed beam intensity 2×1012ppp, which may correspond 0.5-1 MJ beam energy per pulse.

To reach this scientific goal, HIAF is designed with a superconducting heavy ion linac as

an injector and two synchrotron rings as boosters, which will be constructed through two

phases. To realize the world highest pulsed heavy ion beam intensity by HIAF, there will

be a lot of physics and technical challenges. So a few key technology R&D have been

conducted, for instance, an superconducting ECR ion source named as SECRAL, one of

the world’s best performing ECR ion sources, has so far produced a good number of CW

(Continuous Wave) intensity records of highly-charged heavy ion beams, the world’s first

45 GHz ECR ion source based on Nb3Sn superconducting magnet is being built, and the

world’s first 10-25 MeV CW proton superconducting linac was built and beam

commissioning was successfully conducted to demonstrate intense ion beam stable

acceleration. The key technology R&D for high intensity ion beam production and

acceleration have laid a good foundation for HIAF facility and also for future study of HED

physics driven by intense heavy ion beam.


Plenary Talk

Quantum Interference Effect in Atomic Double Ionization in

Intense Laser Field Jing Chen

Institute of Applied Physics and Computational Mathematics, China


In previous studies on atomic non-sequential double ionization (NSDI) process in

intense infrared laser field, quantum interference effect has eluded experimental

observation and the NSDI can be well understood from a semiclassical perspective. Recent

progress in experimental technique makes it possible to measure the process more

accurately and reveal new effect related to quantum interference effect in the NSDI process.

In this talk, we report some of our recent work on the quantum interference effect in atomic

double ionization process.

We theoretically study electron correlation resulting from non-sequential double

ionization (NSDI) of argon in a low-intensity laser field with wavelength of 800 nm using

an S-matrix theory. We show that the experimentally observed transition from back-to-

back to side-by-side emission with increasing laser intensity can be attributed to quantum

interference between the contributions of different intermediate excited states of the singly

charged argon ion in the RESI (recollision-excitation with subsequent ionization) process

[1,2]. Furthermore, we perform coincidence measurements of the momenta of the doubly

charged ion and the two electrons arising from NSDI of xenon subject to midinfrared laser

pulses at 2400 nm. It is found that the intensity dependence of the asymmetry parameter

between the yields in the 2nd and 4th quadrants and those in the 1st and 3rd quadrants of

the electron-momentum-correlation distributions (i.e., asymmetry between side-by-side

and back-to-back emission) exhibits a peculiar fast oscillatory structure, which is beyond

the scope of the semiclassical picture. Our theoretical analysis using the S-matrix theory

indicates that this oscillation can be attributed to interference between the contributions of

different excited states in the RESI channel. Our work provides solid evidence that

quantum interference plays a pivotal role in the NSDI process [2].

Moreover, we show that the doubly differential cross sections (DDCSs) of the target

ions, e.g., Ar+ and Xe+, can be accurately extracted from the 2-dimensional photoelectron

momentum distributions measured in the NSDI process of the corresponding atoms. The

extracted DDCSs exhibit interference structures strongly dependent on both the target and

the laser intensity, in good agreement with calculated DDCSs from the scattering of free

electron on the corresponding ions. Based on this work, we propose a novel laser-induced

inelastic diffraction (LIID) scheme which may be extended to molecular systems and

provides a promising approach for the imaging of the gas-phase molecular dynamics

induced by a strong laser field with unprecedented spatial and temporal resolution [3].

References

[1] X. Hao, et.al., Phys. Rev. Lett. 112, 073001 (2014).

[2] Y. Liu, et.al., Phys. Rev. Lett. 101, 053001 (2008).


Plenary Talk

[3] W. Quan, et al., Phys. Rev. A96, 032511 (2017).

[4] W. Quan, et al., Phys. Rev. Lett. 119, 243203 (2017).


Plenary Talk

Superexchange Interatomic Coulombic Decay

Tsveta Miteva1, Sevan Kazandjian1, Premysl Kolorenc2, Petra Votavova2, and Nicolas Sisourat1

1. Sorbonne Université, CNRS, UMR 7614, Laboratoire de Chimie Physique Matiere et

Rayonnement, F-75005 Paris, France

2. Charles University, Faculty of Mathematics and Physics, Institute of Theoretical Physics,

V Holesovickach 2, 180 00 Prague, Czech Republic


Interatomic Coulombic Decay (ICD) is an ultrafast energy transfer process. Via

ICD, an excited atom can transfer its excess energy to a neighboring atom which is thus

ionized. The rates of ICD depend on the distance between the interacting species. If the

coupling between the monomers is weak, which is the case for large interatomic distances,

the process can be viewed as an exchange of a virtual photon between the interacting

species. In this so-called virtual photon exchange mechanism the decay rates display a 1/R6

dependence on the distance R between the monomers. We recently reported that the ICD

rates are substantially enhanced in the presence of an ICD inactive atom, i.e. an atom whose

ionization potential is greater than the excess energy of the excited species. This

enhancement occurs due to coupling of the resonance state to intermediate virtual states of

the bridge atom. During the talk, I will present the Fano-Stieltjes method we employed for

computing the ICD rates. Accuracy of the method will be shortly discussed. Finally, some

examples illustrating this novel mechanism will be reported.

Keywords: Non-radiative electronic processes; Fano resonances; Interatomic Coulombic

Decay


Plenary Talk

Physics of Shock Ignition Approach to ICF

Dimitri Batani

University of Bordeaux, CELIA, France


Very large laser facilities are currently used to study the process of inertial

confinement (ICF) fusion and the possibility of igniting thermonuclear targets. These

include the NIF (National Ignition Facility) at the Lawrence Livermore National

Laboratory in the US, the LMJ (Laser Megajoule) at the CEA site of Le Barp near

Bordeaux, or the Shenguang-III laser facility in China.

Nevertheless, despite un-doubtful and huge progresses, the goal of achieving

ignition has not been reached yet.

The talk will introduce the recent progress in ICF, highlight the main problems

towards ignition, and finally addressing the recent “Shock Ignition” approach to ICF,

which provides a promising pathway ahead.

This approach relies on the separation of the compression and ignition phases.

Compression is realized with laser beams of several ns duration at “conventional” intensity

(a few times 1014 W/cm2). Ignition will be instead triggered by using a sub-ns high

intensity laser spike (up to 1016 W/cm2) which irradiates the target at the end of phase,

generating a very strong spherical shock converging in the center and proving the

temperature increase needed to trigger fusion reaction.

The implosion phase takes place with relatively thick targets and at relatively low

velocity, thereby minimizing the impact of hydrodynamic instabilities (Rayleigh-Taylor).

As for the final phase, it is crucial to be able of generating very strong shocks (at least 300

Mbar at the ablation surface).

In order to assess the feasibility of shock ignition we are trying to answer several

physical questions like

- the impact of parametric instabilities (SRS, SBS, TPD) in this interaction regime

- the generation of hot electrons and their effects on hydrodynamics

- the capability of really producing such strong shocks

- the possibility of driving uniform implosions in direct drive by minimizing the

impact of laser non-uniformities.

Several experiments have been and are conducted to answer these questions not

only in the US but also in Europe. The talk will show such undergoing experimental efforts

and future perspectives. The experimental effort includes the development of advanced


Plenary Talk

plasma diagnostics in particular the PETAL+ project devoted to diagnostics for the

LMJ/PETAL laser facility.

Keywords: Inertial fusion; Shock ignition; Plasma diagnostics


Plenary Talk

Recent Status and Prospects of CJPL and Dark Matter

Experiments in China

Qian Yue

Department of Engineering Physics, Tsinghua University, Beijing, China

China Jinping underground laboratory (CJPL) is the deepest laboratory and an ideal

site for rare-event experiments such as dark matter, neutrinoless double beta decay, solar

neutrino experiment and so on. It is located in the Jinping Mountain, Sichuan Province,

southwest China, with an overburden of about 2400m. The laboratory is operated by

Tsinghua University and Yalong River Hydropower Development Company, LTD. This

paper will give an overview of conditions, status and future plan of the laboratory. Main

experiments and scientific activities carried out at CJPL will also be presented. The

experimental programs for direct detection of dark matter at CJPL will also be introduced.


Plenary Talk

The Lives and Times of Ejecta from Shocked Metals

Praveen. Ramaprabhu

University of North Carolina at Charlotte, NC, USA

The phenomenon of mass ejection into vacuum from a shocked metallic free

surface can have a deleterious effect on the implosion phase of the Inertial Confinement

Fusion (ICF) process. Often, the ejecta take the form of a cloud of particles that are the

result of microjetting sourced from imperfections on the metallic free surface. Similarly,

stellar ejections are central to the process of mass and energy distribution associated with

supernovae detonations. Significant progress has been achieved in the understanding of

ejecta dynamics by treating the process as a limiting case of the baroclinically-driven

Richtmyer-Meshkov (RM) Instability.In this picture, rounded bubbles excavate mass that

is then driven in to the metallic spikes which are long and tenuous. In contrast to bubbles,

spikes become ballistic and evolve with a terminal velocity in the absence of any drag in

the lighter fluid. This conceptual picture is complicated by several practical considerations

including breakup of spikes due to surface tension, yield strength of the metal, formation

and propagation of material defects within the metal and cavitation. Thus, the problem

involves a wide range of physical phenomena, occurring often under extreme conditions

of material behavior. However, over the last few years, concerted efforts involving

experiments, detailed simulations and theoretical modeling have led to significant

breakthroughs in our understanding of metallic ejecta formation. I will review these recent

advances in this talk.


Plenary Talk

Theoretical Study and Octahedral Spherical Hohlraum

Experimental Campaign on the SG-III

Ke Lan

Institute of Applied Physics and Computational Mathematics, Beijing 100094, P.

R. China

After we gave the configuration, the concept and the design of octahedral spherical

hohlraum in 2013, we further compared the robustness of the octahedral spherical

hohlraum with that of the cylindrical hohlraum and the rugby hohlraum, proposed a novel

octahedral spherical hohlraum with cylindrical Laser Entrance Holes (LEH) and LEH

shields, and gave a design triangle for determining the geometrical sizes of octahedral

spherical hohlraum for ignition target design. Also, a 3D multi-group radiation

hydrodynamic code is under developing. To investigate the spherical hohlraum by using

experiments, we have designed and accomplished a series experiments in the Spherical

Hohlraum Campaign (SHC) on the SG laser facilities since 2014 and obtained repeatable

results which greatly support the octahedral spherical hohlraums. As a result of our

theoretical and experimental study, the octahedral spherical hohlraum has advantages in a

natural and robust high symmetry without supplementary technology, a high energy

coupling efficiency, and a low LPI.

Key words: Inertial fusion, Indirect drive, Octahedral spherical hohlraum, Natural and

robust high symmetry, Spherical hohlraum campaign


I - Fundamental Physics at Extremes


Invited & Oral Talks Fundamental Physics at Extremes

Monday May 7th

I-1: Fundamental

physics at

extremes

14:00-

14:25

Masakatsu

Murakami Osaka University, Japan

invited talk: Generation of Ultrahigh Field

by Micro-bubble Coulomb Implosion

14:25-

14:50

Haifeng Liu

(刘海风)

Institute of Applied Physics and Computational

Mathematics, China

invited talk: Progress on the Wide Range

Equation of State of Hydrogen and Its

Isotopes

14:50-

15:05

Yongli Ping

(平永利) Beijing Normal University, China

Asymmetric Magnetic Reconnection

Driven by Two Femtosecond Lasers

15:05-

15:20

Yong Hou (侯

勇)

National University of Defense Technology,

China

Multi-charge-state Molecular Dynamics

and Self-diffusion Coefficient in the Warm

Dense Matter Regime

15:20-

15:35

Jiangtao Li

(李江涛)

National Key Laboratory of Shock Wave and

Detonation Physics, Institute of Fluid Physics,

CAEP, China

The Equation of State of Nitrogen in the

Dissociation Regime

15:35-

15:50

Xiaofeng Li

(李晓鋒) Shanghai Jiao Tong University, China

A Nano-structured Device toward High-

contrast Intense Short-pulse Laser

15:50-

16:10 Coffee Break

I-2: Fundamental

physics at

extremes

16:10-

16:35

Xiaochuan

Pan University of Chicago, USA

invited talk: An Optimization-based

Method for Solving Non-linear Data

Model in Multi-energy CT

16:35-

17:00

Sergey

Rykovanov Helmholtz Institute Jena, Germany

invited talk: Tunable Polarization X- and

Gamma-ray Source Based on a Plasma

Undulator

17:00-

17:15

Jianxing Li

(栗建兴) Xi'an Jiaotong University, China

Single-shot Carrier-envelope Phase

Determination of Long Superintense Laser

Pulses

17:15-

17:30

Bo Zhang (张

博)

Science and Technology on Plasma Physics

Laboratory, China

Multi-photon effects of nonlinear Compton

scattering in ultra intense fields

17:30-

17:45

Bo Han (韩

波) Beijing Normal University, China

Contributions of Atomic Processes to the

Emission of He-alpha Triplet



17:45-

18:00 Mu Li (李牧) Institute of Fluid Physics, CAEP, China

Continuous Sound Velocity Measurements

along the Shock Hugoniot of Quartz

Tuesday May 8th

I-3: Fundamental

physics at

extremes

14:00-

14:25

Ravindra

Samtaney

King Abdullah University of Science and

Technology

invited talk: Instability of a Non-thermal

Interface in Converging Geometry with a

Two-fluid Plasma Model

14:25-

14:50

Zhi Zeng (曾

雉) Institute of Solid Physics, CAS, China

invited talk: Theoretical Investigation of

Iron Spin Crossover Pressure in Fe-bearing

MgO

14:50-

15:05 Jun Li (李俊)

INational Key Laboratory of Shock Wave and

Detonation Physics, nstitute of Fluid Physics,

CAEP, China

Investigation on Some Key Problems of

the Dynamic-/static-melting Curve

Discrepancy in the VB Group Elements

15:05-

15:20 Qian Ma

National University of Defense Technology,

China

Directly Calculated Electrical Conductivity

of Hot Dense Hydrogen from Molecular

Dynamics Simulation beyond Kubo-

Greenwood Formula

15:20-

15:35

Genbai Chu

(储根柏)


Laboratory, China

High Energy X-ray Radiography of Laser

Shock Metal Dynamic Fragmentation

Using High Intensity Short Pulse Laser

15:35-

15:50

Zhiyu He(贺

芝宇) Shanghai Institute of Laser Plasma, CAEP, China

Study on Shock Temperature

Measurements of Laser-driven Materials

15:50-

16:10 Coffee Break

I-4: Fundamental

physics at

extremes

16:10-

16:35 Per Jönsson Malmö University, Sweden

invited talk: Fully Relativistic Atomic

Structure Calculations with Applications to

Nuclear- and Astrophysics

16:35-

17:00

Huayun Geng

(耿华运) Institute of Fluid Physics, CAEP, China

invited talk: Anomalous Mechanics in

Simple Group VB Metals at High

Pressures and Temperatures



17:00-

17:15

Meng Lv (吕

蒙) Sichuan University, China

Intensity Induced X-ray Transparency in

Aluminum and Silicon

17:15-

17:30

Xing Liu(刘

兴) Peking University, China

Ab inito Molecular Dynamics for

Hydrocarbon up to 10 million Kelvin

17:30-

17:45

Yindong

Huang

National Institute of Defense Technology

Innovation, China

Air-Plasma Characterization at THz

Frequency Range

17:45-

18:00 Guicun Ma

Institute of Applied Physics and Computational

Mathematics, China

The High Pressure Equation of State of

Polystyrene

Wednesday May 9th

I-5: Fundamental

physics at

extremes

14:00-

14:25 Qiang Zhang City University of Hong Kong, China

invited talk: Shock Induced Unstable

Interfacial Mixing in Compressible Fluids

14:25-

14:50

Hyun-Kyung

Chung

Gwangju Institute of Science and Technology,

Korea

invited talk: Atomic processes in dense

plasmas created by X-ray Free Electron

Lasers

14:50-

15:05

Yuanjie

Huang (黄元

杰)

Institute of Fluid Physics, CAEP, China Shock Waves Preparing Nanocrystalline

Bismuth and c-BN Nanoparticles

15:05-

15:20

Hua Shu (舒

桦) Shanghai Institute of Laser Plasma, CAEP, China

Hugoniot Measurement on Statically Pre-

Compressed Water

15:20-

15:35

Ziyu Chen(陈

自宇) Institute of Fluid Physics, CAEP, China

Spectral Control of High Harmonics From

Relativistic Plasmas Using Bicircular

Fields

Thursday May 10th



I-6: Fundamental

physics at

extremes

14:00-

14:25 Predrag Krstic Stony Brook University, USA

invited talk: Synthesis of Boron-Nitride

Nano-Structures in High-Temperature,

High-Pressure Plasmas

14:25-

14:50 Martin Schanz Helmholtzzentrum GSI-Darmstadt, Germany

invited talk: PRIOR-II - A new Proton

Radiography Facility for FAIR

14:50-

15:15

DuckYoung

Kim

Center for High Pressure Science and

Technology Advanced Research, China

invited talk: Novel Oxidation State of

Iron, Peroxide FeO2:Understanding

Physical Properties and Implication to

Geoscience

15:15-

15:30

Chang Gao(高

畅) Peking University, China

Validity Boundary of Orbital-free

Molecular Dynamics Method

15:30-

15:45

Yang Zhao

(赵阳) Laser Fusion Research Center, CAEP, China

The Experimental Study of Thermal

Relaxation in Shocked Aluminum by K-

Shell Photoabsorption Edge

15:45-

16:00

Chengjun Li

(李成军)

National Key Laboratory of Shock Wave and

Detonation Physics, Institute of Fluid Physics,

CAEP, China

Refractive Index Measurements of Atomic,

Molecular and Mixed Gases at High

Pressure up to 60 MPa

16:00-

16:15 Coffee Break

I-7: Fundamental

physics at

extremes

16:15-

16:40

Sergey A.

Pikuz Joint Institute for High Temperature, Russia

invited talk: Applications of High-

resolution X-ray Spectroscopy

16:40-

17:05

Xiuguang

Huang(黄秀

光)

Shanghai Institute of Laser Plasma, CAEP, China

invited talk: Absolute Equation of State

Measurement of Aluminum by Laser

Driving Two-stage Flyer Plate Method

17:05-

17:20 Zhiguo Li Institute of Fluid Physics, CAEP, China

Multi-shock Compressions of Dense

Cryogenic Hydrogen-helium Mixtures up

to 60 GPa through the Molecular-to-atomic

Transition Regime

17:20-

17:35

Baoxian Tian

(田宝贤) China Institute of Atomic Energy Science, China

Shock Waves of the High Velocity Flyer

Driven by Long-Pulse Laser



17:35-

17:50

Wei Hong (洪

伟)


Laboratory, China

Yield Enhancement of Short-Pulse-Laser

Driven Neutron Source by Laser Cleaning

Technique

17:50-

18:05

Guo Jia (贾

果) Shanghai Institute of Laser Plasma, CAEP, China

High Precision Equation of State of Iron at

Pressure up to 2.4 TPa by Laser-Driven

Shocks



Generation of ultrahigh field by micro-bubble Coulomb

implosion

Masakatsu Murakami

Osaka University, Japan

Breaking the 100-MeV barrier for proton acceleration will help elucidate

fundamental physics and advance practical applications from inertial confinement fusion

to tumour therapy. Herein we propose a novel concept of Coulomb implosions. A Coulomb

implosion combines micro-bubbles and ultraintense laser pulses of 10^20 – 10^22 W/cm2

to generate ultrahigh fields and relativistic protons. The bubble wall protons undergo

volumetric acceleration toward the centre due to the spherically symmetric Coulomb force

and the innermost protons accumulate at the centre with a density comparable to the interior

of a white dwarf. Then an unprecedentedly high electric field is formed, which produces

an energetic proton flash. Three-dimensional particle simulations confirm the robustness

of Coulomb-imploded bubbles, which behave as nano-pulsars with repeated implosions

and explosions to emit protons. Current technologies should be sufficient to experimentally

verify concept of Coulomb implosions.

Keywords: proton acceleration, nanotarget, spherical geometry



Progress on the wide range equation of state of hydrogen and

its isotopes

Haifeng Liu, Gongmu Zhang, Qili Zhang, Qiong Li

Institute of Applied Physics and Computational Mathematics, Beijing, China


Hydrogen (H), being the most abundant element in nature, is interest in the

astrophysics, ICF. The continuous studies on the wide range equations of state of hydrogen,

from experiments, theory, and computation for one century, have been progress and lots of

data are obtained. What is the accuracy of these EOS and How to choose EOS in special

application is still open question .In this paper, we review all these work, especially the last

twenty years. The quantify comparison are shown and the suggestion are gave by including

the modify chemical model, the modern computational techniques such as density

functional theory and quantum Monte Carlo calculations in IAPCM. We conclude that the

EOS from ab initio are not yet capable of sufficient accuracy to supplant other EOS

modeling options for the wide range thermodynamic state and the sem-empirical model

consist of several modes and high precision experiment will play pivotal roles in the

physical engineer model.This work is Supported by Science Challenge Project，No.

TZ2016001.

Keywords: equation of state , hydrogen



Asymmetric Magnetic Reconnection Driven by Two

Femtosecond Lasers

Yongli Ping*,J.Y.Zhong

Department of Astronomy, Beijing Normal University 100875, China


Symmetric magnetic reconnection driven by two femtosecond lasers is investigated,

but the asymmetric magnetic reconnection is more common in astronomy, space and lab

plasma physics. Thus, we have studied the asymmetric magnetic reconnection driven by

two femtosecond lasers with different intensity, which lead to the asymmetric magnetic

field and plasma density for magnetic reconnection. Moreover, the magnetic reconnection

driven by femtosencond lasers is insensitive for different background plasma temperature.

Keywords: magnetic reconnection, femtosecond laser, PIC simulation



Multi-charge-state Molecular Dynamics and Self-diffusion

Coefficient in the Warm Dense Matter Regime

Yong Hou*, Yongsheng Fu, Dongdong Kang, Cheng Gao, Fengtao Jin, Jianmin Yuan

National University of Defense Technology, China


Warm dense matter (WDM) is the kind of intermediate state between condensed

matter and idealplasma. In this regime, the physical properties are crucial for modeling

astrophysical objects andinertial confinement fusion experiments. Now, in the framework

of density functional theory, manyapproaches are presented to calculate the WDM

properties. However, the fine structure of theabsorption or emission spectroscopy of WDM

need detailed treatment of the multi charge states. Fromcalculating atomic structure,

detailed configuration accounting, unresolved transition array, supertransition array, and

detailed term accounting model could be used to describe different energy levelsand ionic

charge states in hot and rarefied plasmas, but in dense matter ion-ion coupling is very

strong,these methods have not included ion-ion correlation effects on the electron structure

and ioniccharge-state distribution.

We present the multi-ion molecular dynamics simulation and apply to calculate the

self-diffusioncoefficients of different charge-state ions in the warm dense matter regime.

Firstly, the method is usedto self-consistently calculate electron structures of different

charge-state ions in the ionic sphere, wherethe ion-sphere radii are determined by the

plasma density and their charges. And then the ionic fractionis obtained by solving the

Saha equation, which has included the interactions of different charge-stateions in the

system and ion-ion pair potentials are computed by the modified Gordon-Kim method in

theframework of the temperature-dependent density functional theory on the basis of the

electronstructures. Lastly, we perform the multi-ion molecular dynamics to calculate ionic

self-diffusioncoefficients through the velocity correlation function according to the Green-

Kubo relation. Throughcomparing with the results of the average atom model, it is shown

that different statistical processeswill influence the ionic diffusion coefficient in the warm

dense regime.

Keywords: multi-charge-state, molecular dynamics, self-diffusion coefficient



The Equation of State of Nitrogen in the Dissociation Regime

Jiangtao Li*, Qifeng Chen, Yunjun Gu, Zhijian Fu

National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics,

China Academy of Engineering Physics, China


As a prototype of diatomic molecules, the main component of the air, one of the

main products of explosives, and an important constitutional element in a number of hard

materials, the equation of state of nitrogen deserves much attention. The diatomic

molecular structure of nitrogen will deteriorate with the increase of pressure and

temperature, forming a state of amorphous in the low temperature (< ~ 5000 K) and of

partially dissociated fluid in the high temperature (> ~ 5000 K). It is in this regime that a

number of interesting phenomena were observed such as the so-called shock induced

cooling. In this talk, new theoretical results and experimental evidence will be provided

addressing the controversy of shock induced cooling and some theoretical predictions on

the plasma phase of nitrogen will be discussed.



A Nano-structured Device toward High-contrast Intense Short-

pulse Laser

Xiaofeng Li1, Shigeo Kawata2, Qing Kong3, Suming Weng1, Min Chen1, Zhengming Sheng1

1. Key laboratory for Laser Plasmas ( MoE), School of Physics and Astronomy, Shanghai

Jiao Tong University, Shanghai 200240, China

2. Utsunomiya University, Japan

3. Institute of Modern Physics, Fudan University, China


A nanostructured target is proposed to enhance an intense-laser contrast: when a

laser prepulseirradiates a nanostructured solid target surface, the prepulse is absorbed

effectively by thenanostructured surface. The nanostructure size should be less than the

laser wavelength. After the prepulse absorption, the front part of the main pulse destroys

the microstructure and makes thesur face a flat plasma mirror. The body of the main pulse

is reflected almost perfectly. Compared with conventional plasma mirrors, the

nanostructured surface is effective for the absorption of the intense laser prepulse, whose

intensity is higher than 1014 W/cm2. The nanostructured laser cleaner improves the laser

pulse contrast by about a hundredfold. The nanostructured laser cleaner works well for

next-generation intense lasers.

Keywords: nanostructured surface, high-contrast laser



An optimization-based method for solving non-linear data

model in multi-energy CT

Xiaochuan Pan

Professor of Radiology and Medical Physics, University of Chicago, USA

X-ray computed tomography (CT) is an imaging technique that has found widely

spread applications in medicine, materials sciences, and other fields. There is renewed

interest in research on and application of dual- and multi-energy (or photon-counting) CT

because it is believed to possess a potentially high degree of utility for various medical and

other applications. In multi-energy CT, accurate image reconstruction remains challenging

because its appropriate data model is highly non-linear. We have recently developed non-

convex optimization-based image reconstruction (OBIR) method to directly solving

adequately the non-linear data model in multi-energy CT, which is discussed in the

presentation. We first discuss the derivation of the OBIR method, and then demonstrate its

effectiveness for image reconstruction in the standard multi-energy CT. Subsequently, we

carried out a study that reveals that the OBIR method can be exploited for enabling dual-

energy CT with partial scanning configurations yet involving no or minimum hardware

modification to standard CT, thus lowering hardware cost, enhancing scanning flexibility,

and reducing imaging dose/time. Numerical studies were conducted to demonstrate image

reconstruction enabled for partial scanning configurations of practical significance with

varying scanning angular range and/or X-ray illumination coverage in dual-energy CT

imaging.



Tunable polarization X- and gamma-ray source based on a

plasma undulator

Sergey Rykovanov1,*, Jingwei Wang2, BifengLei1, Vasily Kharin1, Matt Zepf1

1. Helmholtz Institute Jena

2. Shanghai Institute of Optics and fine Mechanics, Chinese Academy of Sciences


In this contribution recent theoretical and numerical studies of plasma undulators

and wigglers will be presented. Plasma undulator can be generated by a laser pulse(s)

undergoing centroid oscillations in an underdense plasma channel. Electrons injected in

such an undulator will experience two kinds of oscillations, the betatron oscillation and the

centroid oscillation. These two oscillations could become resonant when the initial

conditions are matched, which greatly enhances the amplitude of the electron oscillation.

The energy of the radiation can then extend up to the gamma-ray range, which provides a

flexible and compact laser-driven plasma-based gamma-ray source. In a plasma undulator

excited by a mixture of high-order laser modes, we find that the electron betatron

oscillation can be completely eliminated by choosing appropriate laser intensities of the

modes, leading to a few percent radiation bandwidth. The strength of the undulator can

reach unity, the undulator period can be less than a millimeter, and the total number of

undulator periods can be significantly increased by phase locking and staging. In the fully

beam loaded regime, the electron current in the undulator can reach 0.3 kA, making such

an undulator a potential candidate towards a table-top FEL. Energy and polarization

tunability of such a plasma undulator will be discussed.

Keywords: relativistic laser plasma, gamma-ray sources, X-ray sources, undulators,

synchrotron radiation



Single-shot Carrier-envelope Phase Determination of Long

Superintense Laser Pulses

Jianxing Li

Xi'an Jiaotong University, China


The impact of the carrier-envelope phase (CEP) of an intense multi-cycle laser

pulse on the radiation of an electron beam during nonlinear Compton scattering is

investigated. We have identified a CEP effect specific to the ultrarelativistic regime. When

the electron beam counterpropagates with the laser pulse, pronounced high-energy X-ray

double peaks emerge near the backward direction relative to the initial electron motion.

This is achieved in the relativistic interaction domain, where both the electron energy is

required to be lower than for the electron reflection condition at the laser peak and the

stochasticity effects in the photon emission to be weak. The asymmetry parameter of the

double peaks in the angular radiation distribution is shown to serve as a sensitive measure

for the CEP of up to 10-cycle long laser pulses and can be applied for the characterization

of extremely strong laser pulses in present and near future laser facilities.

Keywords: Radiation, Petawatt lasers, Carrier-envelope phase, relativistic electrons,

quantum regime



Multi-photon effects of nonlinear Compton scattering

in ultra intense fields

Bo Zhang

Science and Technology on Plasma Physics Laboratory, China


On 10PW and 100PW scale laser facilities under construction or plan around the

world, laser intensity is expected to reach 1024W/cm2 or even higher. At such intensity,

NCS and NBW are dominate processes in laser plasma interactions. However, present main

string understanding of these two quantum processes are based on several classical and

semi-quantum ideas: forward emission, recoil reaction and sepctrum cutoff. The essence

of such approximation is, theinfluence of the total energy-momentum of laser photons

involved in the scattering is ignored. In this research, we first show why these three ideas

and present main string understanding on NCS and NBW would become invalid when laser

intensity ~ 1024W/cm2. Then we deduced new features of NCS at such intensity including

fixed emission angle, non-vanishing deflection angle and disappearance of spectrum cutoff.

Simulations show that corresponding signals are significant on 10PW and stronger lasers.

Keywords: strong field QED, laser-plasma interaction, ultra intense laser



Contributions of Atomic Processes to the Emission of He-alpha

Triplet

Bo Han1,*, Jiayong Zhong1, Feilu Wang2, Gang Zhao2

1. Department of Astronomy, Beijing Normal University, China

2. National Astronomical Observatories, China


We present detail study of contributions of atomic processes to the emission of He-

α triplet lines in NLTE plasmas. He-α triplet lines have quite different radiative decay rates,

whose differences are as large as 108, but their intensities are similar in observations. In

this paper, we solve this problem. Accurate populating and depopulating rates of 1s2l levels

are calculated in experimentally and astrophysically NLTE conditions. Therefore, the

detail contributions of atomic processes are weighed systematically.

Keywords: atomic dataline, identificationmethods, analytical methods, laboratory



Continuous Sound Velocity Measurements along the Shock

Hugoniot of Quartz

Mu Li1,2,*, Shuai Zhang2, Hongping Zhang1, Gongmu Zhang3, Feng Wang4

Jianheng Zhao1, Chengwei Sun1, Raymond Jeanloz2

1. Institute of Fluid Physics, China Academy of Engineering Physics, China

2. Earth and Planetary Science, University of California, Berkeley, CA 94720, USA

3. Institute of Applied Physics and Computational Mathematics, Beijing, China

4. Laser Fusion Research Center, China Academy of Engineering Physics, China


We report continuous measurements of the sound velocity along the principal

Hugoniot of -quartz between 0.25 and 1.45 TPa, as determined from lateral release waves

intersecting the shock front as a function of time in decaying-shock experiments. The

measured sound velocities are lower than predictions from prior models based on the

properties of stishovite at densities below ~7 g/cm3, but agree with DFT-MD calculations

and an empirical wide-regime equation of state (WEOS) presented here. The Grüneisen

parameter calculated from the sound velocity decreases from ~1.3 at 0.25 TPa to 0.66 at

1.45 TPa. In combination with evidence for increased (configurational) specific heat and

decreased bulk modulus, the value of suggest a high thermal expansion coefficient at

~0.25-0.65TPa, where SiO2 is thought to be a bonded liquid. From our measurements,

dissociation of the molecular bonds occurs at ~0.65-1.0 TPa, consistent with estimates by

other methods. At higher densities, the sound velocity is close to predictions from previous

models, and the Grüneisen parameter approaches the ideal gas value.



Instability of a non-thermal interface in converging geometry

with a two-fluid plasma model

Ravi Samtaney1,*, Yuan Li1, Daryl Bond2, Vincent Wheatley2, Dale I. Pullin3

1. King Abdullah University of Science and Technology,

2. University of Queensland

3. California Institute of Technology


Shock-driven instabilities such as the Richtmyer-Meshkov instability (RMI) arises

in fluids when an interface is impulsively accelerated, usually by a shock wave. This

instability is observed in nature (e.g. astrophysics in which a supernova blast wave

accelerates surrounding interstellar medium) although RMI has been mostly motivated by

inertial confinement fusion (ICF) in which it plays a rather detrimental role. Previous linear

and nonlinear investigations, within the framework of single-fluid magnetohydrodynamics

(MHD), have revealed that the RMI is suppressed in the presence of a magnetic field.

However, the single-fluid MHD model of a plasma does not account for charge separation,

finite plasma length scales and self-consistently generated electromagnetic fields. We

propose to employ a two-fluid plasma model that includes the set Euler equations for the

ions, another set of Euler equations for the electrons and a complete set of Maxwell’s

equations to evolve the electric and magnetic fields. The coupling between ions and

electrons is achieved via electromagnetic terms. Two length scales: the Debye length (dD)

and Larmor radius (dL) arise in the non-dimensional equations. We present our results from

nonlinear simulations of RMI in planar and convergent geometries in using the two-fluid

plasma model for thermal and non-thermal interfaces for different values of dDand dL. For

the case of zero initial seed magnetic fields, we discuss the self-consistent generation of

magnetic fields and the role played by the Biermann battery term in the dynamics. For the

cases of an initial seed magnetic field, we compare and contrast the growth of the RMI

between the single- and two-fluid models.

Acknowledgement: This research is partly supported by the KAUST Office of Sponsored

Research under Award URF/1/2162-01.

Keywords: Richtmyer-Meshkov Instability, Two-fluid Plasma, Self-generated Magnetic

Field



Theoretical Investigation of iron spin crossover pressure in Fe-

bearing MgO

Kaishuai Yang*, Xianlong Wang Jie Zhang, Ya Cheng, Chuanguo Zhang, Zhi Zeng*

Institute of Solid State Physics, Chinese Academy of Sciences, China


The ferropericlase (Fp), MgO containing ~20 mol% FeO, is the second abundant

mineral in the lower mantle (LM). Within the LM pressure range, Fe in Fp will undergo a

spin transition, from high-spin sate to low-spin state, which can notably affect Fp properties.

It is important to clarify the pressure range, where these spin-transition induced changes

occurring, for understanding the LM properties sufficiently. However, even under room-

temperature (T), experimental reported spin-transition pressure ranges show large

controversy, while theoretical predicted room-T values including only T effects but not

contribution from Fe distribution by assuming ideally periodic Fe substitution in small

supercells (~100 atom) are generally less than half of experimental reports. Moreover,

existing evidences show that Fe-distribution may play an important role in determining the

spin-transition pressure ranges, since spin-transition pressure strongly depends on Fe

concentration and local distributions. However, to date, Fe distribution features in MgO as

functions of iron concentration and temperature are still missing. By performing Based on

the first-principles calculations together with the updated framework, the combination of

the cluster expansion approach and the Monte Carlo method, it has been properly described

the Fe distribution feature in Fe-bearing MgO as functions of T (300 K – 1,800 K) and Fe

concentration (3.125 mol% – 50 mol%) in the supercell containing 93,312 atoms. The

results show that at ~900 K, Fe substituted in MgO will experience an inhomogeneous to

homogeneous transition, and homogeneous Fe substitution acquiring normal-distribution

feature can induce broad spin-transition pressure range comparable to experimental

observations. Together with the T effects, it is predicted that Fe spin-transition will occur

in a very broad spin-transition pressure range in LM environments, where a continuous and

smooth Fp property changes induced by Fe spin-transition can be expected.

Keywords: high pressure, Spin crossover pressure, Fe-bearing MgO, First-principles

calculation



Investigation on Some Key Problems of the Dynamic-/static-

melting Curve Discrepancy in the VB Group Elements

Jun Li*, Huayun Geng, Ke Jin, Ye Tan, Tao Xue, Qiang He, Yixian Wang, Shikai Xiang, Qiang

Wu, Chengda Dai


China Engieering Academic Physics,China


There is still a long-standing open question about an apparent discrepancy in the

dynamic-/static- melting curves of some transition metals. Within these metals, vanadium

is spectacular due to the huge discrepancy of its melting temperatures between DAC and

SW data. In current work, we predict its intriguing solid-solid phase transformations and

not find experimental evidence for a second solid-solid phase transition up to shock melting.

Although the huge discrepancy of the solid-liquid phase boundary from different

experiments is undoubted, our current knowledge about the physical mechanism of these

behaviors is still deficient and incomplete. In further work, we propose to explore and

investigate the structural changes and solid-liquid transformation of vanadium under shock

compression with ultrafast dynamic X-ray diffraction technique. We will attempt to probe

the solid-liquid transformation pathways and the kinetics of shocked vanadium, and to

search for other conjectured phase transition occurring between the reported DAC melting

and SW melting curve.

Keywords: melting curve, transition metal, pressure-temperature phase diagram



Directly Calculated Electrical Conductivity of Hot Dense

Hydrogen from Molecular Dynamics Simulation beyond

Kubo-Greenwood Formula

QianMa*,JiayuDai,ZengxiuZhao

National University of Defense Technology, Changsha,China


Electrical conductivity of hot dense hydrogen is directly calculated by molecular

dynamics simulation with reduced electron force field method, in which the electrons are

represented as Gaussian wavepackets with fixed sizes. Here, the temperature is higher than

electron Fermi temperature (T> 300~eV, density = 40~g/cc). The present method can

avoid the Coulomb catastrophe and give the limit of electrical conductivity based on the

Coulomb interaction. We investigate the effect of ion-electron coupled movements, which

is lost in static method such as density functional theory based Kubo-Greenwood

framework. It is found that the ionic dynamics, which contributes to the dynamical

electrical microfield and electron-ion collisions, will reduce the conductivity significantly

compared with the fixed ion configuration calculations.

Keywords: warm and hot dense matter, electron dynamics, electrical conductivity



High Energy X-ray Radiography of Laser Shock Metal

Dynamic Fragmentation Using High Intensity Short Pulse

Laser

Genbai Chu



Dynamic fragmentation from shock loaded high-Z metal is an issue of considerable

importance for both basic and applied science. The areal density and mass-velocity

distribution are crucial factors for understanding such issue. Experimental methods such as

pulsed X-ray radiography and proton radiography have been performed to obtain the

information for such factors, but they are restricted to the accuaracy and spatial resolution

of ~100 µm. In this work, we present high quality radiography of dynamic fragmentation

from laser shock loaded tin, with a good two-demensional (2D) spatial resolution. Dynamic

fragmentation is generated via the intense nanosecond laser loaded tin. High energy X-ray

sourced comes from the interaction of intense picosecond pulse with Au micro-wire targer,

which is attached to low-Z substrate material. High 2D resolution of 15um has been

achieved by the point-project radiography. Dynamic fragmentation has been clearly shown,

and the signal-to-noise ratio is sufficiently high for single shot experiment. The unique

technique shows potential application for high energy density physics.

Keywords: High energy X-radiograohy, dynamic fragmentation, laser shock loading



Study on Shock Temperature Measurements of Laser-driven

Materials

Zhiyu He

Shanghai Institute of Laser Plasma, China Engieering Academic Physics, China


The equation of state (EOS) of materials at ultra high pressure and temperature is

of great importance to inertial confinement fusion (ICF) , astrophysics and fundamental

material studies. Shock waves induced by high-energy laser has been one of the most

significant means to study EOS of materials at ultra high pressure (especially above TPa).

Typically were the experiments relying on the measurement of the shock velocity and

particle velocity behind the shock front to produce a quantitative relationship between

density, pressure and internal energy in materials. However, the thermal-state variables of

these materials were difficult to measure and disputable. As a fundamental parameter to

thermodynamics, temperature is an important constraint to EOS model and must be

measured separately from density and pressure. A series of experiments was carried out to

measure the temperature in shocked materials including silica, deuterium, water, aluminum,

tantalum and iron at extreme conditions using streaked optical pyrometry (SOP) on

Shenguang-II laser facility. The shock velocity and optical reflectivity of the shock front

were observed by velocity interferometer system for any reflector (VISAR) simultaneously.

The temperature of transparent materials was measured through the emission from shock

front while the temperature opaque materials such as metal was calculated using a modified

model with measured color temperature. The results were compared with theoretical and

experimental data of previous studies.

Keywords: shock temperature, equation of state, laser-driven



Fully Relativistic Atomic Structure Calculations with

Applications to Nuclear- and Astrophysics

Per Jönsson

Materials Science and Applied Mathematics, Malmö University, Sweden


There is an ever increasing demand for accurate atomic data due to advancements

in experimental techniques and investments in large scale research facilities. In

astrophysics data for the complex Lanthanides are required to interpret ejecta from neutron

star mergers and associated r-processes [1]. Accurate atomic data are also required in

fusion plasma physics and in other emerging areas such as laser spectroscopy on isotope

separators, X-ray lithography, and lighting research. The needs include accurate transition

energies, fine- and hyperfine structures, mass- and field shifts as well as parameters related

to interaction with external electric and magnetic fields. Also there is a constant need for

transition rates of different multipolarities between excited states. Data are needed for a

wide range of elements and ionization stages. To meet the demands for accurate atomic

data the COMPutational Atomic Structure (COMPAS) group has been formed. The group

is involved in developing state of the art computer codes for atomic structure calculations

in the non-relativistic scheme with relativistic corrections in the Breit-Pauli approximation

as well as in the fully relativistic domain [2]. Here we describe new developments of the

GRASP2K relativistic atomic structure code [3]. We present results for a number of

systems and properties to illustrate the potential and restriction of modern computational

atomic structure. Among the properties are transition rates, hyperfine- and magnetically

induced rates, energy structure, and isotope shifts. We also discuss current code

developments and plans for future work. The codes developed by the COMPAS group,

along with detailed user manuals, are freely available at

http://ddwap.mah.se/tsjoek/compas/ .

References

[1] M. Tanaka et al. The Astrophysical Journal, Volume 852, Issue 2, article id. 109, (2018).

[2] C. Froese Fischer, M. Godefroid, T. Brage, P. Jönsson and G. Gaigalas, Journal of

Physics B, 49, 182004 (2016).

[3] P. Jönsson, G. Gaigalas, J. Bieron, C. Froese Fischer, and I.P. Grant, Comput. Phys.

Commun.184, 2197 (2013).



Anomalous Mechanics in Simple Group VB Metals at High

Pressures and Temperatures

Huayun Geng

Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of

Engineering Physics, China


Dynamic loading or impact modifies material’s properties and response in a

profound and complex manner. One important parameter that characterizes this drastic

alteration is strain rate, which generates defects and dislocations, merges or splits grains,

and drives the motion of dislocations and grain boundaries. Fast and strong enough impact

also could initiate shock wave. It not only increases the pressure, but also dissipates the

input energy through the medium in a form of heat. The ensuing high-pressure high-

temperature thermodynamic state in turn alters the material’s fundamental properties via

the equation of state, as well as the mechanical elasticity. For simple metals, it is usually

assumed that this tuning is simple, and can be modelled easily if without structure transition.

In this talk, however, I will demonstrate that for the group IV metals, which includes V,

Nb, and Ta that in a symmetrical BCC structure, a rather irregular behavior has been

predicted and observed. The anomaly is the strongest in vanadium, and leads to a transition

into rhombohedral phases (RH). But at finite temperatures, a novel transition of these RHs

back to BCC phase is also predicted. This reentrant transition is found not driven by

phonons, instead by the electronic entropy, which is totally unexpected. Parallel to this

exotic transformation, we find a peculiar and strong increase of the shear modulus C44

with temperature. It is counter-intuitive in a sense that it suggests an unusual hardening

mechanism by temperature. In contrast, there is no any structure transition in both Nb and

Ta, but they also manifest similar anomalies, with Ta is the weakest one. In particular, we

predict a strong anomalous softening of C44 and C' in Nb from 20 to150 GPa and a second

softening for C44 from 275 to 400 GPa. What interesting here is that the physics behind

these two softening is completely different, with the former directly relating to an

underlying rhombohedral distortion whereas the latter being a result of electronic

topological transition. Similar to vanadium, our investigation indicates that all of these

anomalies are sensitively modified by thermo-electrons, which has never been aware of

before. With increasing temperature, all anomalies are gradually reduced, and the metal

finally returns back to a normal BCC metal. This tremendous modification of pressure and

temperature on the fundamental elasticity will inevitably change the impact behavior of

these simple group IV metals, which is an intriguing topic for future experimental studies.

Keywords: Transition metal, High pressure and high temperature, Elasticity, Shear

softening, Electronic structure



Intensity Induced X-ray Transparency in Aluminum and

Silicon

Meng Lv

College of Nuclear Science and Engineering, Sichuan University, China


Ultra-intense X-ray pulse could make matter transparent to X-ray. In this study, we

proposed a model based on inner (or deep inner) shell ionization when intense X-ray (i.e.

XFEL) interacts with matte. We simulated the X-ray transparency effect for Aluminum

and Silicon with both soft and hard X-ray. This ultra-fast physics process is also important

in the formation of Warm Dense Matter with X-ray.

Keywords: X-ray intensity, transparency,Aluminum,Silicon



Ab inito Molecular Dynamics for Hydrocarbon up to 10

million Kelvin

Xing Liu

Center for applied physics and technology, Peking University, China


Using first-principles molecular dynamics, we implement a series of research on

the equation of states, the ion structure evolution, in a wide range in densities from 0.5 to

10 times initial states and temperatures from 2000 k to 100,000,000 k, illustrated by

examples of PS (polystyrene), PE (polyethylene), diamond and graphite. At low

temeprature, the noteworthy deviation between PS Hugoniot curves shows remarkable role

of energy E0 in initial configuration after adequate relaxation. The odd depression

occurring at the same area mentioned above proves to be accompanied by system phase-

transition procedure, where the system can be described by molecular fluid theory. The

reconstitution of H2 molecules taking place in both PS and PE predicts similar existence in

other CH-mixed materials in proper conditions. Moreover, we note that it is the ionization

degree of K-shell electrons to determine when the shocked hugoniot folds back at the

density-maximum for all four carbon-related materials, in which process higher density

states require higher temperatures to ionize same electrons off nucleus. Heat capacity along

Hugoniot indicates that phase transition and ionization will make sense in energy allocation.

Keywords: equation of state, hydrocarbon, ion distribution function, heat capacity



Air-Plasma Characterization at THz Frequency range

Yindong Huang1,*, Jianmin Yuan2, Zengxiu Zhao3

1. National Institute of Defense Technology Innovation, China

2. Beijing Comptutional Science Research Center,China Academy of Engineering Physics,

China

3. National University of Defense Technology, China


Air-plasma is a common and convenient way to obtain intense and broad-band

terahertz (THz) wave in laboratory. Strong emission of THz wave is associated with strong

absorption at the samefrequency, due to the same transition process between light and

matter.This means, THz wave can be appliedto characterize the smilar typical frequency

within air-plasma. In this work, we realizethe characterization of the transmitting property

within air-plasma at THz frequency range. Resonant absorption is observed and analysised

to reveal the reaction caused by the seperation betweenelectrons and the left ions. We

believe it is not only a supplementary to the existing theory of THz generation, but also an

alternative for plasma diagnostics.

Keywords: THz wave,plasma,resonance absorption



The High Pressure Equation of State of Polystyrene

Guicun Ma



The equation of state of polystyrence is calculated based on empirical model. we

use Debye solid model and Cowan's liquid model for ion.The electron part is calculated in

Thomas Fermi Model. The result of the Hugoniot is compared with experiments. we get

good agreement between theory and experiments.

Keywords: polystyrene, equation of state



Shock induced unstable interfacial mixing in compressible

fluids

Qiang Zhang

Department of Mathematics, City University of Hong Kong, China

Shock induced interfacial instability between two compressible fluids of different densities

Richtmyer-Meshkov instability. Nonlinear fingering structures develop at the unstable

material interfaces. Experiments and numerical simulations have been the main tools for

studying the fingers at Richtmyer-Meshkov instable interfaces in compressible fluids.

Developing theories that provide accurate predictions for the growth rates and amplitudes

of fingers at the unstable instable interface is a very difficult task. This is due to the

complication of the shock waves and the rarefaction wave present in the compressible fluid

systems and due to the nonlinearity of finger structures at late times. Theoretical studies

usually approximate the fluids as incompressible and the incident shock as an impulsive

force. In this talk, we present closed-form approximate solutions for the growth rates and

amplitudes of fingers at Richtmyer-Meshkov instable interfaces in compressible fluids.

Our theoretical approach is based on analyzing the solutions at early and late times and

asymptotically matching these two solutions. Our theory contains no fitting parameters.

Furthermore, our solutions are applicable to systems with arbitrary Atwood number,

arbitrary incident shock strength and arbitrary fluid compressibility. Our theoretical

predictions for the growth rates and amplitudes of fingers of Richtmyer-Meshkov

instability in compressible fluids are in remarkably good agreement with the results from

experiments and numerical simulations in the literature over the entire periods of

experiments and numerical simulations. Such excellent agreement is achieved for both

reflected shock and reflected rarefaction wave cases. Even for a compressible fluid system

with a Mach number of the incident shock being as high as 15.3, our theoretical predictions

are still in excellent agreement with the data from the numerical simulations.



Atomic processes in dense plasmas created by X-ray Free

Electron Lasers

Hyun-Kyung Chung

Gwangju Institute of Science and Technology, Korea


High energy density physics is one of the "hottest" and most rapidly developing

basic scientific disciplines. It covers many different areas of plasma physics, nonlinear

optics, physics of lasers and charged-particle beams, relativistic physics, condensed-matter

physics, nuclear, atomic and molecular physics, radiative, gas and magnetic

hydrodynamics, astrophysics. The study of the thermodynamic, structural, gas-dynamic,

optical, electro-physical and transport properties of matter under extreme conditions has

become a mainstream research area. In recent years, new regimes of matter under extreme

conditions have been created with large plasma generation devices, such as NIF (National

Ignition Facility), high power short pulse lasers, X-ray free electron lasers (XFEL) and Z

machines. Particularly the XFEL creates a unique state of matter due to the extreme pulse

length of less than nano-seconds, high photon numbers and precise photon energies. The

interaction with XFEL and a solid-density matter proceeds with photoionization, Auger

decays and collisional processes resulting exotic states of transient matter. To understand

the states of matter created by XFEL, it is critical to understand the atomic processes of

collisional and radiative transitions occurring in the matter during the interaction with

XFEL. A collisional-radiative model called SCFLY was developed to understand the states

of matter and spectroscopic measurements from XFEL experiments. In this talk, the CR

model is presented and the applications to various spectroscopic measurements will be

shown to explain the atomic processes in the dense plasmas created by XFEL interacting a

solid-density material.

Keywords: Spectroscopy, X-ray Free Electron Lasers, Atomic Processes, Atomic Kinetics



Shock Waves Preparing Nanocrystalline Bismuth and c-BN

Nanoparticles

Yuanjie Huang1,*, Houwen Chen2, Xuhai Li1, Liang Xu1, Chuanmin Meng1


2. College of Materials Science and Engineering,Chongqing University, China


According to Hall-Petch effect, nanocrystalline metals and cubic boron nitride (c-BN)

nanoparticles usually exhibit enhanced hardness and strength, and a smaller particle size

often leads to a larger hardness and strength. Thus, they are expected to find many

important applications in various fields and the appropriate preparation methods are the

key. In this work, we propose that shock waves can be employed to fabricate

nanocrystalline metal with anomalous melting line by unloading processes and to

synthesize c-BN nano-particles in large amount. We performed the experiments, and

successfully prepared nanocrystalline bismuth of sizes ranging from 30-50 nm and c-BN

nanoparticles of average size 3 nm, the smallest size ever reported. This work may

enlighten one that shock waves may play a more important role in preparation of some

nanomaterials due to its unique features of high temperature,high pressure and short

period.



Hugoniot Measurement on Statically Pre-Compressed Water

Hua Shu

Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, China


Materials can be experimentally characterized to terapascal pressures by sending a

laser-induced shock wave through a sample that is pre-compressed inside a diamond-anvil

cell. Pre-compression expands the capability for initial condition control, allowing access

to thermodynamic states off the principal Hugoniot and provides access to the 10- to 100-

TPa (0.1-1 Gbar) pressure range that is relevant to planetary science. We demonstrate here

a laser-driven shock wave in a water sample, pre-compressed in a diamond anvil cell. The

compression factors of the dynamic and static techniques are multiplied. This approach

allows access to a family of Hugoniot curves which span the P-T phase diagram of fluid

water to high density. According to the loading characteristics of the SG-II high-power

laser, the traditional diamond anvil cell is improved and optimized, and a new diamond

anvil cell target adapt for high power laser loading is developed. In order to adapt for laser

shock ,the diamond window should be thin(100 μm) enough that the shock could propagate

to the sample before the side rarefaction erode too much the shock planarity. With a

thickness of 100 mm over an aperture of 600 μm diameter, a pre-compressed water sample

at 0.5 GPa can be obtained. The water is pre-compressed to 0.5 GPa using the diamond

anvil cell. Hugoniot curve has been partially followed starting from pre-compression at

pressures of 0.5 GPa . Pressure, density, and temperature data for pre-compressed water

were obtained in the pressure range from 150 GPa to 350 Gpa by using laser-driven shock

compression technique. Our P-ρ-T data totally agree with those of the model based on

quantum molecular dynamics(QMD) calculations. These facts indicate that this water

model be used as the standard for modeling interior structures of Neptune, Uranus, and

exoplanets in the liquid phase in the multi-Mbar range and should improve our

understanding of these types of planets.

Keywords: DAC, Hugoniot, laser



Spectral control of high harmonics from relativistic plasmas

using bicircular fields

Ziyu Chen

Institute of Fluid Physics, China Academy of Engineering Physics


High harmonic generation (HHG) from relativistically intense laser irradiating

plasma surfaces is an extreme nonlinear process, which provides a powerful radiation

source in the extreme ultraviolet and X-ray spectral region with attosecond duration. While

many an investigation has been carried out to control the temporal structure of the

harmonics, e.g., to obtain an isolated single attosecond pulse, methods to control the

harmonic spectrum remain limited. Among the reported spectral control schemes, selected

enhancement of HHG can be achieved via modifying the plasma density ramp or target

surface morpha. In this work, we consider controlling the harmonic spectrum by structuring

the laser field. The approach is based on using circularly polarized two-color driving pulses

rotating in opposite directions. Although this bicircular field configuration has shown to be

effective in HHG from gases, applicability of extending this method from gas HHG to

HHG from surface plasmas looks far from straightforward, as the HHG mechanisms

between these two generation scenario are completely different. Here we demonstrate that

bicircular fields can be used to control the spectrum of high harmonics from relativistic

plasmas. Through particle-in-cell simulations, we show that the harmonic spectral features,

such as the appeared harmonic orders and their helicity, are governed by the symmetry of

the laser fields and related conservation laws. By breaking the rotational symmetry of the

laser fields or the interaction geometry, the otherwise symmetry-forbidden frequencies can

show up. By adjusting the relative intensity ratio of the bicircular driving fields, the

harmonic spectral intensity can be modulated. The present results offer a route to spectral

control the HHG from relativistic plasmas and can be useful for designing novel radiation

sources.

Keywords: Relativistic laser plasmas; High harmonic generation; spectral control; two-

color field.



Synthesis of Boron-Nitride Nano-Structures in High-

Temperature, High-Pressure Plasmas

Longtao Han, Predrag Krstić*

Institute for Advanced Computational Science, Stony Brook University, USA


Boron-Nitride (BN) Nanostructures can be synthetized in various forms like

fullerenes, nanocages, nanococoons, nanoflakes and nanotubes, similarly to the carbon

nanostructures. Synthesis of this nanomaterial which has exceptional features is carried out

experimentally by a number of methods, with ultimate goals to reach high-rate production

of impurity and defect free nanostructures. However, complete understanding of the BN

nanosynthesis process at the atomic level has been missing so far.

With use of the Quantum-Classical Molecular Dynamics (QCMD) computer

simulations we were able to synthesize by self-organization of atoms various BN

nanomaterials at high temperatures and pressures, mimicking partially the experiments on

the BNNT nanosynthesis in the plasma environment of the high pressure electric arc and

plasma torch. We observed that hydrogen may have a profound effect in the BN

nanosythesis process, altering the nanosynthesis outcomes that could lead to creation of an

ultra-hard cubic BN material. Based the results of simulation we are able to recommend

the optimal precursors, temperatures and pressures for synthesis of BN material in plasma.

PACS Codes: 05.65.+b; 34.10+x,52.27.Lw; 61.46.+w

Keywords: Nano-synthesis; Plasma-material interactions; Molecular dynamics; Boron-

nitride



PRIOR-II - A new Proton Radiography Facility for FAIR

Martin Schanz

GSI Helmholtzzentrum für Schwerionenforschung GmbH


In 2014 the prototype of the high energy proton microscope facility for FAIR

(PRIOR-I) was commissioned at GSI in Darmstadt, achieving a spatial resolution of 30

microns with 3.6 GeV protons from the SIS-18 synchrotron [1]. However, due to a large

amount of deflected primary protons as well as secondaries created in the target and the

used collimator, the field quality of the first and third PMQ1 lenses of the quadruplet were

significantly degraded [2].

Therefore, detailed investigations led to the ion-optical design of the new PRIOR-

II facility which will be capable of imaging dense objects with protons up to 5 GeV,

providing an even better spatial resolution performance (see Fig. 1). The new design —

based on compact and strong electromagnetic quadrupoles — will facilitate future

experiments in the fields of high energy density physics and also serve as a diagnostics

device for novel medical applications.

The commissioning of the system is foreseen for 2019, first experiments will

include static density reconstruction tests related to the biomedical „PaNTERA“ project [3]

as well as dynamic experiments. For the dynamic commissioning, a light gas gun and a

new pulsed power setup are currently in development together with the Technical

University of Darmstadt and the Goethe University Frankfurt.

1 Permanent Magnet Quadrupoles



Fig. 1: COSY simulation [4] of the new PRIOR-II setup at the APPA beam line at

FAIR. The beam line, consisting of four standard FAIR and four custom quadrupoles has

been optimised for proton radiography with either the PRIOR-II setup or the FFS system

(not visualised in the presented scheme).

Reference

[1]D. Varentsov et al., “Comissioning of the PRIOR proton microscope,” Rev. Sci. Instrum.

87, 023303 1– 8 (2016).

[2]M. Schanz et al., „High Energy Proton Induced Radiation Damage of Rare Earth

Permanent Magnet Quadrupoles“, Rev. Sci. Instrum. 88, 125103 (2017).

[3]M. Prall et al., “High-energy proton imaging for biomedical applications,” Scientific

Reports 6, 27651 EP – (2016).

[4]K. Makino and M. Berz, “COSY INFINITY Version 9,” Nuclear Instruments and

Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and

Associated Equipment 558, 346 – 350 (2006), proceedings of the 8th International

Computational Accelerator Physics Conference.



Novel Oxidation State of Iron, Peroxide FeO2:Understanding

Physical Properties and Implication to Geoscience

DuckYoung Kim

Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai,

China


Discovery of novel oxidationstate of iron, FeO2 under pressure, [1] becomes great

interest ofscientific communities, and especially it suggests a paradigm change to

ourconventional understanding of geoscience [2, 3]. While multiple follow-upresearch

results from geoscience perspectives provides alternating chemicalpaths to synthesize it [4,

5] and substantial evidences of the existence at thedeep lower mantle conditions [6], there

are much room for condensed mattercommunity to tackle it.

In this presentation, I wouldlike to show recent theoretical results of our

collaboration teams combinedwith experimental results to emphasize how condensed

matter theoretical workscan be related and interpreted to the understanding of the Earth. I

will showresults for metal-insulator transition [7], spin transition, and moleculardynamic

simulation.

Reference

[1] Q. Hu*, D. Y.Kim*, W. Yang*, et al., Nature 534 241 (2016)

[2] T. Yagi, Nature 534 183-184 (2016) (News& Views)

[3] G. Graziano, Nat. Rev. Chem. 1 0023 (2017)(research highlight)

[4] H.-k. Mao, et al., Natl. Sci. Rev. nwx109, https://doi.org/10.1093/nsr/nwx109 (2017)

[5] Q. Hu*, D. Y.Kim*, Jin Liu*, et al., Proc. Natl. Acad. Sci. 114 1498(2017)

[6] J. Liu*, Q. Hu*, D. Y. Kim, et al., Nature 551 494 (2017)

[7] B. G. Jang, D.Y. Kim#, J. H. Shim#, Phys. Rev. B 95 075114 (2017)

https://doi.org/10.1093/nsr/nwx109



Validity Boundary of Orbital-free Molecular Dynamics

Method

Chang Gao

Center for Applied Physics and Technology, Peking University, China


With LiD as an example, we show that the applicable region of the orbital-free

molecular dynamics (OFMD) method in a large temperature range is determined by the

thermal ionization process of bound electrons in shell structures. The validity boundary of

the OFMD method is defined roughly by the balance point of the average thermal energy

of an electron and the ionization energy of the lowest localized electronic state. This

theoretical proposition is based on the observation that the deviation of theOFMDmethod

originates from its less accurate description to the charge density in partially ionized shells,

as compared with the results of the extended first-principles molecular dynamics method,

which well reproduces the charge density of shell structures.

Keywords: OFMD; shell structure; validity boundary



The Experimental Study of Thermal Relaxation in Shocked

Aluminum by K-Shell Photoabsorption Edge

Yang Zhao*, Zhiyu Zhang, Bo Qing, Jiamin Yang, Jiyan Zhang, Minxi Wei, Guohong Yang,

Tianming Song, Gang Xiong, Min Lv, Zhimin Hu

Research Center of Laser Fusion, China Academy of Engineering Physics, China

* E-mail: [email protected]

Understanding the properties of highly compressed Warm Dense Matter is

important in the research field of planetary interiors and inertial confinement fusion. Under

the shock compression, the transition from an initial state to a shocked state undergoes a

finite thermal relaxation from ions to electrons. The parameter of collision frequency

between electrons and ions, Ve, is a most important physical quantity that governs the

energy transfer between ions and electrons. Celliers gave the first assessment of electron-

ion coupling in compressed matter by the measurement of luminous emissions from

shocked transparent silicon [1]. In our work, a novel method by using X-ray spectrum was

promoted to study the collision frequency and thermal relaxation for shocked aluminum,

an opaque and widely studied material.

At ShenGuang II Laser Facility, the time-resolved K-edge absorption

measurements of the aluminum sample at the states created by X-ray radiation-driven

shock colliding compression were carried out[1,2]. By using the X-ray streaked crystal

spectrometer, the continuous variations of the shifts and broadenings of the K-shell edge

for the shocked sample are obvious. Since the x-ray absorption K-edge slope is a model-

free diagnostics of the electronic temperature in warm dense matter, the rise time of the

electronic temperature was deduced to be about 150ps. By adopting different collision

frequency Ve under the Drude model [4], the hydrodynamic simulation was carried out by

using multi 1D code. By comparing the rise time of the electronic temperature between

experimental and hydrodynamic simulation, the collision frequency could be assessed.

This work might extend the study of thermal relaxation in WDM and be helpful to

the assessment of electron collision frequency experimentally.

Keywords: warm dense matter, Thermal Relaxation, X-ray absorption edge

Reference

[1] P. Celliers, A. Ng, G. Xu et. al., Phys. Rev. Lett. 68, 2305 (1992).

[2] Y. Zhao, J. M. Yang, J. Y. Zhang, et. al., Phys. Rev. Lett. 111, 155003 (2013).

[3] Y. Zhao, Z. Y. Zhang, B. Qing, et. al., Euro. Phys. Lett. 117, 65001 (2017).

[4] R. Ramis, K. Eidmann, J. Meyer-ter-Vehn, et al., Computer Physics Communications

183, 637655 (2012).




Refractive Index Measurements of Atomic, Molecular and

Mixed Gases at High Pressure up to 60 MPa

Chengjun Li*, Qifeng Chen, Yunjun Gu, Jun Tang, Lei Liu, Guojun Li, Zhiguo Li




The Refractive index of initially transparent gases at high pressures is very important

in shock compression experiment for velocity correction, in which the velocity of shock

wave is usually determined via laser interfere methods. In this work, by using optical

frequency domain interferometer (OFDI), we measured the refractive index of atomic

(He, Ne, Ar, Kr), molecular (H2, D2, N2) and mixed gases (H2-D2, H2-Ar, D2-He) up to 60

MPa. The polarizability of different gases were derived from their refractive index

according to Lorentz-Lorenz formula. The measured equation of state (P-V-T) are also

compared with the predictions of Self-consistent Fluid Variation Theory and Peng-

Robinson equation. The mixing rule below 60 MPa were verified by the experimental

results of mixed gases investigated in this work.




Applications of high-resolution X-ray spectroscopy

Sergey A. Pikuz

Joint Institute for High Temperature, Russia

*Email:

Keywords:



Absolute Equation of State Measurement of Aluminum by

Laser Driving Two-stage Flyer Plate Method

Xiuguang Huang , Hua Shu, Junjian Ye, Guo Jia, Zhiheng Fang, Zhiyong Xie,

Jiang Wu, Sizu Fu

Shanghai Institute of Laser Plasma, Shanghai 201800, China


Absolute equation of state (EOS) of aluminum has been studied using laser-driven

two-stage flyer plate method. A ~4 ns high power laser pulse is used to drive a strong shock

in the first 120 to 160 μmthick polyimide flyer plate, and the polyimide flyer plate turns to

a weakly ionized plasma state after unloading from a high-pressure state and expanding

across a 200 to 300 μmlong vacuum gap. Then, the ionized plasma state polyimide flyer

plate piles up against the second 25 μmthick aluminum flyer plate and generates a ramped

loading, pushes the aluminum flyer plate accelerating from 4 km/s to 12 km/s through an

80 to 120μm long vacuum gap and still keeps it in solid state. When the solid state

aluminum flyer plate impacts an aluminum step target, then a nearly-symmetric impact is

realized. A line-imaging optical recording velocity interferometer for any reflector (ORVIS)

is used to measure flying velocity of the aluminum flyer plate and shock velocity in

aluminum step target simultaneously, so an absolute EOS measurement is obtained. In this

work, aluminum absolute EOS data are gained with pressures range from 50 GPa to 200

GPa and which are in agreement with the previously reported data in a comparable pressure

regime with various techniques. This absolute EOS measurement method may be used for

studying a variety of materials.

Keywords: Absolute equation of state, Two-stage flyer plate, Line-imaging optical

recording velocity interferometer for any reflector (ORVIS),Nearly-symmetric impact




Multi-shock Compressions of Dense Cryogenic Hydrogen-

helium Mixtures up to 60 GPa through the Molecular-to-

atomic Transition Regime

Zhiguo Li

Institute of Fluid Physics, China Academy of Engineering Physics, China


Multi-shock compression proves possible to implement much higher compression

of matters in relation to what we have in a single shot. In this work, we performed multi-

shock compression experiments on dense cryogenic H-He mixture via a two-state light-gas

gun. The time-resolved light radiance of shocked H-He mixture was recorded by a multi-

channel optical pyrometer (MCOP). Up to three shock reverberations were clearly

observed from MCOP signal, and the measured equation of state (EOS) data of H-He

mixture reached an unexplored range of pressure up to 60 GPa. The multi-shock EOS data

are used to evaluate some widely used EOS models that for modeling giant planets. The

results show that a linear-mixing ab initio EOS [Astrophys. J. Suppl. S. 215, 21 (2014)] is

in best agreement with the present experimental data. The density functional theory

molecular dynamics (DFT-MD) simulations underestimate the dissociation and therefore

result in a stiff prediction for EOS in the molecular to atomic transition regime. Analysis

of the radial distribution functions revealed that DFT-MD might overestimate the effects

of helium on the bond of hydrogen molecule when hydrogen is mixed with helium.

Keywords: Multi-shock compression, hydrogen-helium mixtures, molecular-to-atomic

transition



Shock Waves of the High Velocity Flyer Driven by Long-Pulse

Laser

Baoxian Tian, Zhao Wang

Department of Nuclear Physics, China Institute of Atomic Energy Science, China


Keywords: shock wave, flyer, long-pulse laser



Yield Enhancement of Short-Pulse-Laser Driven Neutron

Source by Laser Cleaning Technique

Wei Hong*,Sukai He



The acceleration of deuteron is very important in the research of neutron sources

driven by intense short pulse laser. The 7Li(d,n) 8Be reaction has much higher cross

section comparing to the 2D(d,n)3He and 7Li(p,n)7Be reactions, and the neutrons from

this reaction has higher energy and is better in collimation. However, in the typical TNSA

ion acceleration, the deuteron acceleration is strongly suppressed due to the contamination

layer of proton-rich hydrocarbonsand water on the foil target surface. In this work, the

contaminant layer was greatly removed by employing a nano second laser, which is

synchronized with the 25 fs, 1J acceleration laser pulse, resulting much more effective

deuteron acceleration and enhancement of Neutron Yield. The neutron yield is increased

by a factor of six, reaching 1.8×104/pulse. The PIC simulation reproduce the measured

energy spectra for both protons and deuterons. The small size, ultra short pulse duration,

high flux of this neutrons may play important roles in the wide application areas, such as

Fusion power plant materials testing, neutron radiography, contraband detectionneutron

resonance spectroscopy.

Keywords: intense short pulse laser, neutron sources, deuteron acceleration



High Precision Equation of State of Iron at Pressure up to 2.4

TPa by Laser-Driven Shocks

GuoJia



Equation of state (EOS) of Fe at high pressure is of great importance in material

science, geo-science, and planetary physics. By using Shenguang-II high power laser

facility and beam smooth technique, EOS data of Fe up to 2.4 TPa was obtained with

Velocity Interferometer System for Any Reflector (VISAR). To obtain more precise data,

target fabrication technique was optimized to eliminate the preheat effect and the shock

wave velocity was confirmed to be stable, the step thickness was also more uniform and

the reflectivity was improved. Based on the above optimizations, the more precise data

would be helpful to application in material science, geo-physics and astronomy.

Keywords: State equation, high pressure physics, laser direct drive


II - Pulsed Power and Application


Invited & Oral Talks Pulsed Power and Application

Monday May 7th

II-1 Pulsed power

and application

14:00-

14:25 Bucur Novac

Loughborough University,

UK

invited talk: Fast Filamentary Numerical Modelling

Applied to High-Current, Pulsed Power Applications

14:25-

14:50

Xinxin Wang

（王新新） Tsinghua University, China

invited talk: Research on Electrical Explosion of Wire in

Tsinghua University

14:50-

15:05

Liang Sheng

（盛亮）

Northwest Institute of Nuclear

Technology, China

Experimental Study on Electrical Exploding of Wire and

Film Related to Z Pinch at NINT

15:05-

15:20 Ping Wu (吴平) Tsinghua University, China

The Effect Experiment of CCD Imaging System Against

High Power Electromagentic Pulse

15:20-

15:35 Mo Li（李沫）


Technology, China

Study of Tungsten Wire Explosion Symmetry on Negative

Discharge Facility

15:35-

15:50

Lifei Hou （侯

立飞)

Laser Fusion Research

Center, CAEP, China A Novel CVD Diamond X-ray Detector

15:50-

16:10 Coffee Break

II-2 Pulsed power

and application

16:10-

16:35 Kyle Peterson

Sandia National Laboratories,

USA

invited talk: Progress and Plans in Magnetized Liner

Inertial Laser Fusion Research

16:35-

17:00 Delong Xiao

Institute of Applied Physics

and Computational

Mathematics, China

invited talk: Radiation Transfer of Cylindrical Z-pinch

Dynamic Hohlraum and Its Interaction with a Spherical

Target

17:00-

17:15

Shaolong

Zhang(张绍龙)

Institute of Fluid Physics,

CAEP, China

Preliminary Result of Viscous Measurement of Tin on the

PTS Facility

17:15-

17:30 Liuxia Li Tsinghua University, China

First Observation of Shock Wave with Piezoelectric

Gauges by Wire Melting in Underwater Electrical Wire

Explosion

17:30-

17:45

Yuji Wu (吴宇

际)


Center, CAEP, China

Research on a Wide-Angle Diagnostic Method for Shock

Wave Velocity at SG-III Prototype Facility



Tuesday May 8th

II-3 Pulsed power

and application

14:00-

14:25

Edl

Schamiloglu

University of New Mexico,

USA

invited talk: HPM Sources: Magnetrons and Metamaterial

Slow Wave Structures - More in Common Than Not

14:25-

14:50

Peitian Cong

（丛培天）


Technology, China

invited talk:Life Time of the LTD Gas Switch Developed

by NINT

14:50-

15:05

Yunsheng

Jiang(姜云升) Tsinghua University, China

Measurement of EMP Environment Inside Target Chamber

of SG-Ⅲ

15:05-

15:20

Bing Teng（滕

冰） Qingdao University, China

Study on Organic Nonlinear Optical Crystal DAST and Its

Application in Teraherz Generation

15:20-

15:35

Wei Yang(杨

薇)

Institute of Applied Physics

and Computational

Mathematics, China

Spatial and Temporal Characteristics of Focused

Microwave Beam Discharge in Nitrogen

15:35-

15:50

Longfei Niu (牛

龙飞)


Center, CAEP, China

Surface Cleanliness Improvements Based on

Contamination Inspection and Removal Methods in SG-Ⅲ

High Power Laser Facility

15:50-

16:10 Coffee Break

II-4 Pulsed power

and application

16:10-

16:35

Victor F.

Tarasenko

Institute of High Current

Electronics, Russia

invited talk:Spectral and Amplitude-time Characteristics

of Crystals Excited by a Runaway Electron Beam

16:35-

17:00

Meng Wang

（王勐）


CAEP, China invited talk:A Novel Rep-Rate LTD

17:00-

17:15

Fengju Sun（孙

凤举）


Technology, China

Conception Design of 30 MA Fast Linear Transformer

Driver Based on Sharing Shell and Stage-Triggering in

Sequence

17:15-

17:30

Hanbing Jin (金

晗冰) Tsinghua University, China

Study of Electromagnetic Pulse Generation at High Power

Laser Facilities

17:30-

17:45

Guiling

Wang(王贵林)


CAEP, China

Current design and pulse shaping techniques on PTS

facility

17:45-

18:00

Zhiqian Xu(徐

志谦) Tsinghua University, China Theoretical and Experimental Evaluation of Cable SGEMP

Response in the SG-III Laser Facility



Wednesday May 9th

II-5 Dischage,

laser and

diagnostics

14:00-

14:25

Huichun Wu

（武慧春） Zhejiang University, China

invited talk: Generation of Gigawatt Attosecond Pulses

from Relativistic Electron Sheets

14:25-

14:50 Tatiana Pikuz Osaka University, Japan

invited talk:Development of X-ray Phase Contrast

Imaging Method for Investigation of Rayleigh-Taylor

Instabilities in the Context of Laboratory Astrophysics

14:50-

15:05

Zhaoyun Zong

(宗兆玉)


Center, CAEP, China

Research on Spectral Failsafe System of High Power Laser

Using Dual Fiber Bragg Gratings

15:05-

15:20 Kai Deng(邓锴) Tsinghua University, China

Development and Test of a 32keV X-ray Talbot-Lau

Interferometer

15:20-

15:35

Fang Wang (王

芳)


Center, CAEP, China

Fifth Harmonic Generation of Nd:glass Lasers in ADP

Crystals

15:35-

15:50

Deyan Zhu (朱

德燕)


Center, CAEP, China Optimized Design of Separated Final Optics Assembly



Fast Filamentary Numerical Modelling Applied to High-

Current, Pulsed Power Applications

Bucur Novac

Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough

University, United Kingdom


The filamentary technique, also termed network mesh or mesh-matrix method,

allows a fast and straightforward 2D calculation of the time dependence of all the

electromagnetic and mechanical characteristics of most high-current, high-energy pulsed

power systems. The output of a filamentary code contains the current and temperature

distribution inside conductors, the complete map of the magnetic and electric field

distribution, the time variation of inductance and resistance, the force and pressure acting

on conductors as well as their dynamics.

The filamentary method has been successfully applied at Loughborough along the

years in a wide range of pulsed power, high-current applications including: pulsed high-

magnetic field coils, ultrahigh magnetic field generation by single-turn coils and Z-pinch

and θ-pinch electromagnetically-driven implosions, explosively-driven magnetic flux-

compression generators, electromagnetic launchers and the design of different types of

high-voltage air-core and magnetic-core pulsed transformers. After an introduction into the

filamentary technique, most of these applications will be detailed.

Keywords: pulsed power physics and technology, pulse compression, high-voltage

techniques, magnetic flux-compression, explosively-driven generators

Biography:

Professor Bucur M. Novac, Loughborough University

The Plasma and Pulsed Power Group at Loughborough University has 25 Years of

Pulsed Power Achievements. The talk will cover the following aspects:

1. A general Introduction to pulsed power at Loughborough including the research group structure, its international collaborations, main publications, funding, awards and international courses delivered abroad.

2. An overview of the pulsed power technology at Loughborough, including studies of original techniques and components and the integration of large pulsed power systems

3. A detailed presentation of pulse compression systems, including Tesla-transformer powered PFLs and Blumlein PFLs, plasma opening switches, bipolar formers, bespoke high-voltage transformers and other techniques.



4. A brief overview of explosively-driven pulsed power including flux-compression generators technology

5. A presentation of the achievements in the domain of electromagnetic flux-compression, with record magnetic fields generated indoors and 2D modelling of such systems

6. A very brief overview of pulsed power applications in aviation, defense, bio-medical research and food processing.



Research on Electrical Explosion of Wire in Tsinghua

University

Xinxin Wang


Electrical Explosion of Wire (EEW) is performed with a pulsed current flowing

through a metallic wire. As the energy deposited into the wire by Joule heating increases,

the wire undergoes the rapid phase transitions (solid liquid vapor plasma). When

the wire starts vaporization, the wire resistance dramatically rises and then one of the three

discharge modes (cutting-off current, restrike, surface breakdown) occurs, depending on

the wire voltage and the medium (vacuum, gas, liquid) surrounding the wire. In the

different medium, EEW behaves differently and thus has the different applications. In this

paper, we present the experimental results of EEW obtained by Tsinghua University,

including EEW in vacuum for X-pinch and Z-pinch, EEW in gases for the nanopowder

production and EEW in liquid for the generation of shock waves.

An X-pinch is made of two wires that take a shape of “X” and are used as the load

of a pulsed power generator. By the compression from the magnetic filed of the wire current,

the plasma in the crossing of the wires forms an extremely hot and dense point (X-pinch)

that intensively emits the pulsed x-rays. It was found that X-pinch is an ideal x-ray point

source for the phase-contrast radiography (PCR) with a temporal resolution of

subnanosends and a spatial resolution of micrometers. Being different from the

conventional radiography that relies on the x-ray absorption as the sole source of contrast,

PCR uses the phase variations as an additional source of contrast by recording the

interference of the x-rays passing through different parts of the sample. PCR offers an

improved contrast when imaging weakly x-ray absorbing samples and has biologic and

clinic applications. As the first step, we took PCR images of the small insects such as

mosquito and ant. The images clearly show the details inside their bodies that can never be

seen with the conventional x-ray radiography.

In 1997, a breakthrough was made in Z-pinch research in Sandia Laboratories. One

of the two reasons for this breakthrough was thought to be the use of a wire-array as the Z-

pinch load. The wire-array of centimeters in diameter is made of hundreds of fine wires. It

was expected and believed that there exists an ideal EEW in which all wires are

simultaneously and fully exploded into plasma and then merged into a uniform and

cylindrically symmetric plasma shell. However, we found that the real EEW is far from the

idealized one according to the x-ray backlighting image of EEW. Instead of forming a fully

vaporized wire, EEW usually shows a structure of core-corona, i.e., a dense core

surrounded by the corona plasma of low density. The corona plasma of each wire takes a

shape of “bamboo joint”, similar to m = 0 plasma instability. Furthermore, by the action of




the global magnetic field produced by the wire-array current, the well conducting corona

plasma first arrives to the axis of the wire-array and forms the “precursor plasma” that

shows high order (m > 0) plasma instabilities. The core-corona structure as well as its

inducing precursor plasma is harmful to Z-pinch. The reason for producing the core-corona

structure was given as the following. During EEW, the electron emission from the

exploding wire triggers an early flashover along the wire surface, which leads to the most

of the current automatically transferring from the highly resistive wire core to the well

conducting corona plasma and the energy deposition into the core almost stopping.

Therefore, it is important to make the flashover as later as possible, so as to depress the

core-corona structure and to realize the core-free EEW, i.e., the whole wire uniformly

vaporizing and then fully exploding into plasma. It was found that the core-free EEW may

be realized by inserting an insulator as a flashover switch into the cathode. The flashover

switch has two effects on EEW. First, it steepens the voltage pulse applied to the wire and

makes the flashover along the wire surface more difficult. Second, it raises the potential of

the wire relative to the cathode and makes a positive radial magnetic field on the wire

surface that depresses the electron emission from the wire. Here we take EEW of tungsten

wire as an example. For the EEW without the flashover switch, the deposition energy is

only 3.4eV/atom, significantly lower than the vaporization energy of 8.8eV/atom.

Correspondingly, a dense core is visible in the center of the interferogram. On the contrary,

for the EEW with the flashover switch, the deposition energy is 12eV/atom, higher than

the vaporization energy. No residual core can be seen in the interferogram, which confirms

the realization of the core-free EEW.

When EEW is performed in gases at a pressure from 0.1–1 atm, the metallic vapor

is cooled by the collisions with the gas molecules, forming nanopowders from the

condensed vapor. It was found that the particle size depends on the overheating of the wires,

i.e., the ratio of the deposited energy before the explosion to the vaporization energy. The

overheating results from a high rate of energy deposition and the expansion lag of the

heated wires. The evolution of an exploding titanium wire embedded in 10 kPa air was

studied with Mach–Zehnder interferometry. The exploding wire is characterized by a

central dense core as well as the surrounding plasma and a rapidly expanding gas shell.

Based on the fringe shifts, the electron density of the plasma and the increased density in

the gas shell were calculated to be about 1.94

respectively. The expanding speed of the gas shell is about 2.28 km/s. A thermal expansion

lag of the dense vapor core and two-phase vaporization of the wire were observed. Due to

the wire exploding in “under heat” mode, the first phase of the vaporization is by the Joule

heating and the second one by the plasma heating.

When EEW is performed in liquid, the shock waves (SWs) are usually generated

and have more and more applications, such as increasing the production and enhancing the

recovery in oil wells, the target ignition for the inertial confinement fusion and the warm

dense matter. The SWs generated by the EEW in water were investigated under the

experimental condition that the energy-storage capacitor was charged to a relatively low

energy so that the energy deposited into the wire is not large enough to fully vaporize the



whole wire. It was found that the SWs have a poor reproducibility due to the partial

vaporization of the exploding wire. However, a partial vaporization rate as low as 6% is

enough to generate the shock wave. The amplitude of the shock wave is determined by the

vaporized mass of the wire. The more is the vaporized mass, the higher is the shock wave.

It was well accepted that the SWs by EEW in water is attributed to the rapid volume

expansion accompanied by the phase transitions, such as the solid melting, the liquid

vaporization and the plasma formation. In past, the SW by the wire melting could only be

observed with an expensive streak camera that may be not available for most laboratories.

The piezoelectric gauges commonly used for recording the SWs are not allowed to work

near the exploding wire. In this case, the SW by the melting has never been observed with

the piezoelectric gauges for the following reason. After going a short path from the

exploding wire, the SW by the melting will be overtaken by and immersed in the stronger

and faster SW by the vaporization. However, in our carefully designed experiments in

which the discharge is in the mode of the cut-off current, the SW by melting in water was

observed with the piezoelectric gauges for the first time. Two shock waves were recorded

with a piezoelectric gauge located at a position of 100mm from the exploding wire. The

first and weak shock wave was confirmed to be the contribution from the wire melting,

while the second and strong shock wave is the contribution from the wire vaporization. The

process of the shock wave by the vaporization overtaking the shock wave by the melting

was observed.



Experimental study on Electrical Exploding of Wire and Film

Related to Z Pinch at NINT

Liang Sheng

Northwest Institute of Nuclear Technology, China


Electrical exploding of wire and film can be utilized to study plasma formulation,

plasma dynamics, instability evolution and radiation yield, which are of importance to

deepen understanding on Z pinch physics. A serious experiments, including surface

insulated Al/W wire array Z pinch and Al planar film exploding, carried out at

'QiangGuang-I' facility with peak current of 1.2 MA and rise time of 100 ns and LTD driver

with peak current of 80 kA and rise time of 100 ns located at Northwest Institute of Nuclear

Technology (NINT). An integrated diagnostic system, consisting of framing camera, streak

shadowgraphy, laser shadowgraphy, lager interferometry, shadow-schlieren symbiotically

imaging, XRD and current monitor, was fielded on pulse power drivers to diagnose the

performance of the electrical exploding stage. The main conclusion of these experiments

are as follows: (1) Surface insulation can dramatically modulate the waveform of X-ray

radiation of wire array Z pinch, such as it can suppress the multi-peaks radiation for Al

wire array and produce high foot radiation for W wire array. (2) Surface insulation can

suppress the ablation stage and delayed the X-ray radiation, but no observable evidence of

enhancing the radiation yield. (3) In Al film electrical exploding experiments, the dynamics

phenomena between the outside surface and inside surface exhibited considerably

difference due to the different driven force produced by a novel push-out load design. The

expanding velocity of the outside was much faster than that of the inside surface. The

instability on the outside surface unfolded a structure of larger amplitude and smaller

wavelength. (4) The periodical structure of different perturbation wavelengths imposed

different effects on the evolution of instability for Al film plasma. Large wavelength

showed the capability of seeding the instability wavelength, while small wavelength did

not indicated the observable effect. The evolution of instability of surface insulated Al film

seemed to be suppressed compared with that of the standard Al film.

Keywords: wire array; metal film; electrical exploding; Z pinch



The Effect Experiment of CCD Imaging System Against High

Power Electromagentic Pulse

Ping Wu

Tsinghua University, China


Electromagnetic Pulse (EMP) is a known issue for laser facilities, which could lead

to the effects of diagnostic equipment range from signal interference, data corruption to

hardware damage. Plenty of damage and interference cases of diagnostic equipment and

empirical analysis were publicized by LLNL (Lawrence Livermore National Laboratory).

However, the harsh environment inside the target chamber is far more complicated, which

may include γ-ray, neutrons, metallic debris and other potential threat. In order to identified

the effects caused by different environment factor, and make sure the diagnostic equipment

could work properly in this environment and last for as long as possible before requiring

replacement, separated and ideal experience is necessary to study the law of the

interference and destruction effects.

In our experience of high power electromagnetic pulse, CCD imager was chosen as

typical example of diagnostic equipment. Consider of both the simplification and

integrality of imaging system, a system constitutes by commercial CCD imager, AV data

line, capture card and PC was build up as DUT. The incident HPEM field is excited by

double-exponential high-voltage source and broadcasted by UWB(Ultra-wideband)

antennas and GTEM (Gigahertz transverse electromagnetic wave) cell. The imaging

system was turn on in recording mode and partly or completely located in HPEM field with

different orientation during the test, so that the effects of both separated constituent parts

and whole system can be monitored and analyzed.

During the HPEM field test, several malfunction phenomena and a few of

destruction cases were observed. The destruction cases happened in the test of UWB, in

which only the CCD imager and data line were directly faced with the incident field with

the order of 100 kV/m. However, the capture card destruction was observed

notwithstanding being placed inside RF shield box and covered by copper foil. Except for

destruction cases, there are several malfunction and interference phenomena were observed,

which include recording break, color distortion and row pixel flash. The minimum

threshold of these effects with different orientation is about 7kV/m. more detail data of

threshold and post image analysis will be further discussed in this paper.

Keywords: CCD imager; high power electromagnetic field; effect



Study of Tungsten Wire Explosion Symmetry on Negative

Discharge Facility

Mo Li1,2*, Jian Wu2, Yihan Lu2, Xingwen Li2 and Yang Li1,2

1 State Key Laboratory of Intense Pulsed Radiation Simulation and Effect,

Northwest Institute of Nuclear Technology, Xi’an 710024, China

2 State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an

Jiaotong University, No. 28 XianNing West Road, Xi’an, Shaanxi 710049, China


Tungsten wire explosion is very asymmetric when fast current rate and

insulated coatings are both applied on negative discharge facility using a cathode

geometry which is commonly used on mega-ampere facilities. It is inferred, based

on an analytical treatment of the guiding center drift and COMSOL simulations,

that the large negative radial electric field causes early voltage breakdown and

terminates energy deposition into the wire core on the anode side of the wire. After

the anode side is short circuit, the radial electric field along the wire surface on the

cathode side will change its polarity and thus leading to additional energy

deposition into the wire core. This change causes ~10 times larger energy

deposition and ~14 times faster explosion velocity in the cathode side than the

anode side. In order to reduce this asymmetry, a hollow cylindrical cathode

geometry was used to reverse the polarity of radial electric field and was optimized

to use on multi-MA facilities. In this case, fully vaporized PI-coated tungsten wire

with greatly symmetry improvement was achieved with energy deposition of ~8.8

eV/atom.

PACS Codes: 70.10.Wd; 04.20.Vm

Keywords: Inertial confinement fusion; Z-pinches



A Novel CVD Diamond X-ray Detector

Lifei Hou



The absolute measurement of thermal X-ray flux from a hohlraum is essential in

the experiments of indirect-driven inertial confinement fusion. The radiation temperature,

which is one of the key parameters in the indirect-drive ICF scheme, can be inferred from

the measured x-ray flux. At the present time, Much of radiation detection relies on silicon-

based photodiodes or p- i- n diodes. Silicon XUV photodiodes have high sensitivities to

soft x rays, as high as 270 mA/W between 50 eV and 5 keV, and are readily available in

large quantities. Some of the disadvantages of Si photodiodes are their sensitivity to optical

radiation and susceptibility to neutron damage. Another detection device for soft x-ray is

the vacuum x-ray diode (XRD). Although often used for x-ray detection, XRDs have

notoriously poor and spectrally dependent sensitivity. Therefore, sensitive yet spectrally

flat and optically insensitive X-ray detectors are in demand. In addition, the Inertial

Confinement Fusion experiments require that the x-ray detectors should be fast and

sensitive, yet radiation damage resistant.Diamond photoconductive detectors (PCD) have

many advantages over silicon photodiodes. Diamond has faster response due to larger

saturated carrier drift velocity (a factor of 2 greater than Si) and lower dielectric constant,

extremely low leakage current at room temperature, and higher resistance to atomic

displacement (displacement threshold is approximately 43eV, compared with

approximately 20 eV for silicon). The large band gap (5.5 eV) also serves as a built-in filter

against optical radiation[4]. They present a possibility of nearly ideal photoconductive

detectors with outstanding radiation resistance, fast charge collection, and low leakage

current. In addition, some of these materials may be minimally sensitive to 1ω0 and 3ω0

driving lasers at the ICF facility. Therefore, the CVD diamond detector may be the ideal

supplement for silicon-based photodiodes and XRDs.Based on the structure of microstrip

CVD diamond detectors, a new coaxial detector with a single connector has been

manufactured. The detector is designed to measure X-ray power. And the detector contains

a broadband coaxial bias insertion tee and a cylinder CVD diamond. The diameter of the

diamond is 4mm. One end surface of the cylinder is plated on by a piece of gold grid

coating film. And the other end surface is covered by a piece of gold plate electrode. This

grid electrode can ensure x-ray to irradiate on the surface of the diamond. At the same time,

bias voltage can be loaded between two end surfaces of the diamond properly. The time

performance of the x-ray detector has been studied on the short pulse laser equipment. The

experimental results show that the rising time is about 61ps. This study gives the possibility

of CVD diamond x-ray detector improvement in the future.

Keywords: CVD diamond, x-ray detector, grid electrode, time performance



Progress and Plans in Magnetized Liner Inertial Laser Fusion

Research

Kyle Peterson

Sandia National Laboratories, USA


Initial results of magnetized liner inertial fusion (MagLIF) experiments at Sandia

National Laboratories have demonstrated the key principles of magneto-inertial fusion;

fuel pre-heating, pre-magnetization, and compression can work in concert to produce

thermonuclear stagnation conditions. Improvements in our physical understanding of the

plasma conditions has led to more than doubling of our fusion yields which are now within

~50% of pre-shot predictions. We are also working to develop more capable platforms on

Z with increased pre-magnetization, drive current, and fuel pre-heating. This talk will give

an overview of the entire MagLIF research program including recent progress and near

term plans to test scaling and understanding. Additionally, it will cover work done at other

facilities including NIF, OMEGA, and OMEGA-EP to support the science of the approach.

Sandia National Laboratories is a multimission laboratory managed and operated by

National Technology and Engineering Solutions of Sandia, LLC., a wholly owned

subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National

Nuclear Security Administration under contract DE-NA-0003525.



Radiation Transfer of Cylindrical Z-pinch Dynamic Hohlraum

and Its Interaction with a Spherical Target

Delong Xiao*, Ning Ding, Zihuan Dai, Shunkai Sun, Xiaojian Shu



Z-pinch Dynamic hohlraum is a possible selection to drive inertial confinement

fusion. The dynamic hohlraum is formed after the energy thermalization of the Z-pinch

plasma with the converter plasma due to impaction, and a strongly radiating shock wave is

also launched in the thermalization process. Basically, the hohlraum radiation is

determined by the detailed profiles of plasma conditions when the wire-array plasma

impacts onto the CH converter plasma. It is shown that several selections, such as changing

the tungsten/converter mass ratio, the radius ratio, as well as adding a high density thin

layer onto the converter, or decreasing the hohlraum volume, can be used to optimize or

adjust the hohlraum radiation. Recently, series of experiments of Z-pinch dynamic

hohlraums were performed on the PTS facility. The radiating shocks were observed and

the formation of dynamic hohlraums is affirmed. And experimental results also show that

if the radiationtemperatureis increased to about 120eV, the radiationwill quickly transfer

to the center of the converter. In this case, if a capsule is placed at the center of the converter,

it will be driven to implode inward by the hohlraum radiation. However, the cylindrical

shock may directly interact with the capsule at the equator, which will cause several

asymmetrical compression of the capsule and affect the final fusion yield. Our numreical

results show that during the radiation ablation, the high density ablator absorbs the

radiation energy to push and compress the fuel. At the same time, the heated ablator will

expand outward. When the cylindrical shock propagates to the boundary between the

converter and the expanded ablator, the shock can be weakened by the ablation pressure.

If we carefully design load parameters to get a higher ablation pressure, the shock can be

remarkably slowed down. It is therefore possible to provide enough time for fuel

compression driven by hohlraum radiation before the shock reaches the ablator/fuel

boundary.

PACS Codes:52.58.Lq; 52.59.Qy

Keywords: Z-pinch; dynamic hohlraum; dynamic hohlraum driven fusion



Preliminary Result of Viscous Measurement of Tin on the PTS

Facility

Shaolong Zhang*, Zhengwei Zhang, Guilin Wang, Qizhi Sun, Zhaohui Zhang

Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering

Physics, China


The hydrodynamic approximation of shock wave propagation, which does not

consider the strength and viscosity of materials, appears to be appropriate only in the range

of shock stresses of hundreds of GPa and above. For shock wave amplitude of one to tens

of GPa the strength and viscosity properties of certain materials become important. When

shock wave passing through an interface of different materials, disturbances on the

interface will grow rapidly, which is known as the Richtmyer-Meshkov instability. At high

pressure, the viscosity property of the material will affect the disturbances developing

behavior significantly. Mikaelian analytically studied the viscous effect on the R-M

instability induced by shock wave, and he proposed the R-M instability as an alternative to

the Sakharov method to experimentally measure the viscosity of the material. Recently, we

have initiate an experiment based on Mikaelian’s proposal to measure viscosity of tin on

PTS facility. In this report, the design and some primary results will be shown and further

attempt will be discussed.



First Observation of Shock Wave with Piezoelectric Gauges by

Wire Melting in Underwater Electrical Wire Explosion

Liuxia Li*, Dun Qian, Xiaobing Zou, Xinxin Wang



The shock waves (SWs) generated by the underwater electrical wire explosion

(UEWE) have more and more applications. The generation of SWs by UEWE is usually

attributed to the rapid volume expansion accompanied by the phase transitions, such as the

solid melting, the liquid vaporization and the plasma formation. In past, the SW by the wire

melting could only be observed with an expansive streak camera that may be not available

for most laboratories. The piezoelectric gauges commonly used for recorded the SWs are

not allowed to work near the exploding wire. In this case, the SW by the melting has never

been observed with the piezoelectric gauges for the following reason. After going a short

path from the exploding wire, the SW by the melting will be overtaken by and immersed

in the stronger and faster SW by the vaporization. In this paper, the SWs generated by the

UEWE were investigated. The energy-storage capacitor was charged to a relatively lower

energy so that the energy deposited into the wire is not large enough to fully vaporize the

whole wire. The discharge is in the mode of the cut-off current without the plasma

formation. Two shock waves were recorded with a piezoelectric gauge that was located at

a position of 100mm from the exploding wire. The first and weak shock wave was

confirmed to be the contribution from the wire melting, while the second and strong shock

wave is the contribution from the wire vaporization. The process of the shock wave by the

vaporization overtaking the shock wave by the melting was observed.

Keywords: underwater electrical wire explosion, shock wave,shock wave by wire melting



Research on a Wide-Angle Diagnostic Method for Shock Wave

Velocity at SG-III Prototype Facility

Yuji Wu

Laser Fusion Research Center, China Academy of Engineering Physics, China


A wide-angle diagnostic method for shock wave velocity is proposed in this paper.

An ellipsoidal equation deduced for wide-angle diagnosis by using geometrical optical

laws is presented. The combination of an ellipsoidal mirror and a traditional velocity

interferometer system for any reflector (VISAR) forms a wide-angle VISAR. Several

fundamental problems such as assembly, imaging, and interference in the wide-angle

VISAR are discussed, and the method is proven to be feasible based on the results of an

eight-beam laser direct drive experiment at SG-III prototype facility. The diagnostic

method is expected to be usable in a wide variety of experiments, especially those related

to implosion compression, including high-pressure equation of state experiments, materials

characterization experiments, shock characterization for Rayleigh–Taylor experiments,

and shock timing experiments for inertial confinement fusion research.

Keywords: shock wave measurement; implosion compression; optical design; velocimetry;

inertial confinement fusion




HPM Sources: Magnetrons and Metamaterial Slow Wave

Structures - More in Common Than Not

Edl Schamiloglu*, Mihail Fuks, Artem Kuskov, Dmitrii Andreev, Andrew Sandoval

University of New Mexico, USA


The University of New Mexico (UNM) has been studying sources of high power

microwave (HPM) radiation for 30 years. UNM first studied linear Cerenkov devices, like

the backward wave oscillator. UNM‘s contributions during its first decade were i)

understanding the proper validation of virtual prototyping using particle-in-cell (PIC)

codes, ii) demonstrating frequency agility through axial displacement of the slow wave

structure (SWS) in a backward wave oscillator (BWO), and iii) using axial laser

interferometry between the annular electron beam and SWS wall to explain the cause of

pulse shortening in a long pulse BWO. UNM has been researching relativistic magnetrons

since 2001. Our initial contribution was the development of the "transparent cathode" that

increased magnetron beam-to-microwave conversion efficiency and decreased the time for

start of oscillations. Our second contribution was to show that a transparent cathode in a

magnetron with diffraction output (MDO - axial extraction) can achieve 70% beam-to-

microwave efficiency, provided that axial loss current can be suppressed. We

demonstrated how the use of endcaps on a transparent cathode can greatly diminish axial

loss current. We next proposed a permanent magnet solution to a compact MDO where,

for the price of decreased efficiency, a very compact HPM source without the bulky

extraction section can be achieved. We next proposed a full relativistic MDO without a

physical cathode where a virtual cathode can be formed in the interaction region to power

the MDO with efficiency comparable to that of an MDO with a transparent cathode.

Finally, we recently proposed a magnetic mirror field for an MDO using a half-cusp

configuration that can completely eliminate axial loss current. At the same time, since

2012, the University of New Mexico has been researching SWSs using double negative

metamaterials. A biperiodic linear split ring resonator structure provides negative

permeability and its insertion in below cutoff waveguide provides negative permittivity.

Powered by an annular electron beam, this Cerenkov-like device produces high power but

with a more compact radial profile. This presentation summarizes each of these advances

and points out common features between magnetrons and metamaterial SWSs, features that

were once thought to be unique to metamaterial structures.

Keywords: HPM, magnetron, metamaterial, virtual prototyping



Life Time of the LTD Gas Switch Developed by NINT

Peitian Cong*, Tieping Sun, Weixi Luo, Xiaofeng Jiang, Tao Huang, Zhengzhong Zeng, Aici Qiu



Spark gap switch is one of the most important components of many pulsed power

generators. Consisting of many spark gap switches, Linear Transformer Driver (LTD) has

become a very promising pulsed power source for about two decades. In a LTD based

facility, there may be over ten thousands of switches, hence the switch lifetime is of crucial

importance. Unlike the capacitors and the cores, the LTD switches are still in the

developmental stage and are designed and built mainly by various laboratories, thus the

lifetime of different switches may vary. Some typical results of the LTD switches were

ever accomplished by HCEI. In this paper we present recent results of the first full-scale

experiments that were aimed to evaluate the life time of the LTD switches developed by

NINT.

Keywords: LTD; Spark gap; Life time; pulsed power



Measurement of EMP Environment Inside Target Chamber of

SG-Ⅲ

Yunsheng Jiang*, Cui Meng



SG-Ⅲ is the most advanced laser fusion research plant in China. It focuses on the

development of clean energy, research of fusion reaction physics and etc. Because of the

complicated features of the EMP field, the electromagnetic compatibility of the diagnostic

equipment inside the target chamber is difficult. Necessary measurement and

understanding of the EM environment is required for EMC design of the diagnostic

equipment. So the magnetic field inside the target chamber of SG-Ⅲ is investigated in this

paper. And at last, some features are concluded.The magnetic field is measured with B-Dot

sensors which are designed and manufactured by the laboratory of Tsinghua University

Electromagnetic Pulse Environment and Effect. The advantages of the sensors lie on rapid

response, wide bandwidth, simple structure and the abilities to measure high amplitude and

reduce the common-mode noise. The B-Dot sensors used in SG-Ⅲ experiments have two

kinds of bandwidth, which are 1GHz and 300 MHz, separately. Different from the regularly

used B-Dot sensors, the sensors used here are also designed to be anti-radiation. HDPE

material is used to reduce the effect of ionization radiation, including X-ray, gamma ray,

and neutron. And the material will not distort the EM field which is to be measured.

Because the B-Dot sensors can only measure the single direction polarized magnetic field,

the sensors are arranged to measure the field of horizontal and vertical direction.The

magnetic field monitored in some experiments have several features that can be concluded

as follows.

The magnetic field strength mainly devotes to the vertical direction. Statistics

shows that the field strength of vertical direction can approach 5 to 8 A/m, while the field

strength of horizontal direction is 2 to 4 A/m. And from the frequency spectrum, the power

of the magnetic field mainly concentrates on the frequencies below 200 MHz. But the field

of higher frequency still exists, which can approach about 900 MHz to 1 GHz. And the

components in 300 MHz to 500MHz exist widely. As a consequence, the measurement

provides preliminary understanding of the EM field inside target chamber of SG-Ⅲ. It also

provides experimental basis for EMC design of the diagnostic equipment inside the

chamber.

Keywords: measurement; EMP environment; B-Dot sensor; EMC



Study on Organic Nonlinear Optical Crystal DAST and Its

Application in Teraherz Generation

Bing Teng（滕冰）

College of Physics, Qingdao University, Qingdao, 266071, China

*Email:

The excellent nonlinearity and electro-optic properties, as well as the low dielectric

constant, make organic DAST crystal as an ideal material for construction of terahertz

(THz) radiation sources and detectors. However, due to the complicated issues of solution

growth method which using methanol as solvent; too many factors can affect the growth

procedure of DAST crystals. It is very difficult to achieve the stable growth of centimeter-

sized high-quality crystals, which hinders the research and application development of THz

technology based on DAST crystals

In our work, high purity raw materials for DAST crystal growth were synthesized. The

influence factors of THz radiation and main challenges in the process of growing high

quality and large size DAST crystal have been analyzed comprehensively. New crystal

growing apparatus was designed and fabricated. Bulk single crystal were grown with

dimensions of 25×22×2 mm3 using the slope nucleation coupled with seed crystal method

in our present work on systematic analyzing the advantages and disadvantages of

spontaneous nucleation method. In addition, some new derivative crystals of DAST were

grown and explored, which showed good applied prospect.



Spatial and Temporal Characteristics of Focused Microwave

Beam Discharge in Nitrogen

Wei Yang*, Qianhong Zhou, Zhiwei Dong



Microwave generated plasmas show potential applications including material

processing, communication technology, and plasma propulsion. Here we report a

simulation study on low pressure (100~500 Pa) nitrogen discharge plasma and its afterglow

generated by focused microwave beams (frequency 9.4 GHz X band, pulse width 2.5 μs,

and peak electric field 1.2 kV/cm) with a detailed comparison to experiments. A one-

dimensional (1D) fluid model is based on the wave equation for the microwave field

propagating through the gas breakdown plasma, the continuity equations for electron, ion

and neutral particle densities, and the energy balance equations for mean electron

temperature, nitrogen vibrational and translational temperature. These equations are

numerically solved in a self-consistent manner with a simplified plasma chemistry set, in

which the reaction rates involving electrons are calculated from the electron energy

distribution function (EEDF) using two-term expansion method. The spatial and temporal

characteristics of the focused microwave breakdown in nitrogen are demonstrated, which

include the amplitude of the microwave electric field, the densities and temperatures of the

plasma components. The temporal evolution of the plasma electron density agrees

reasonably well to that measured from microwave interferometer. The spatial-temporal

distributions of metastable states are discussed on the plasma chemistry and the character

of mean electron temperature. The spatially integrated N2(C3) density shows similar trends

with the measured temporal intensity of optical emission spectroscopy (OES), except a

time delay 100~300 ns. The decay of plasma electron density and electron temperature in

the afterglow was also demonstrated. The quantitative discrepancies are explained in light

of the limitations of the 1D model with two-term expansion of EEDF. The theoretical

model is found to describe the gas breakdown plasma generated by focused microwave

beams at least semi-quantitatively, and may readily expand to air breakdown plasma by

110 GHz W-band microwaves at a power level of several Mega-Watts.This study is

partially supported by the National Natural Science Foundation of China (Grant No.

11505015).

Keywords: high power microwave, gas discharge plasma

References

W. Yang, Q. Zhou, and Z. Dong, J. Appl. Phys. 123, 013301 (2018).

W. Yang, Q. Zhou, and Z. Dong, Phys. Plasmas 24, 013111(2017).



W. Yang, Q. Zhou, and Z. Dong, J. Appl. Phys. 120, 083302 (2016).

W. Yang, Q. Zhou, and Z. Dong, AIP Adv. 6, 055209 (2016).

Surface Cleanliness Improvements Based on Contamination

Inspection and Removal Methods in SG-Ⅲ High Power Laser

Facility

Longfei Niu*, Hao Liu, Xinxiang Miao, Haibing Lv, Xiaodong Yuan, Hai Zhou, Yilan Jiang,

Caizhen Yao, Guorui Zhou



The High Power Laser Facility (HPLF) is a large-scale and complex optical system,

contains large number of mirrors which would be easily damaged due to the existence of

surface contamination. In this paper, the background and progress of cleaning control

techniques in SG-Ⅲ HPLF will be discussed, mainly including the contamination

inspection and removal methods for maintaining the surface cleanliness of optical

components. As a result, the successfully application of the cleaning techniques will lead

to the long-term stable running of the HPLF.

Keywords: The High Power Laser Facility, Surface cleanliness, Optical components,

Contamination



Spectral and Amplitude-time Characteristics of Crystals

Excited by a Runaway Electron Beam

Victor F. Tarasenko1,2,*, Alexander G. Burachenko, Evgenii Kh. Baksht1, Dmitry V.

Beloplotov1,Dmitry A. Sorokin1

1. Laboratory of Optical Radiation of the Institute of High Current Electronics, Russia

2. National Research Tomsk Polytechnic University, Russia


Runaway electrons (RAEs) can adversely affect plasma heating in controlled

thermonuclear research systems [1-9]. Although this fact is well-known from theory, no

reliable detectors of such electrons are available [1,2]. Recent research on tokamaks has

focused much attention on RAEs [3-6] as fast electrons add to the loss of energy and to the

evaporation of vacuum chamber walls. Different types of devices are developed to detect

high-energy electrons, and most widely used in tokamaks are Cherenkov-type detectors [7-

9]. Such detectors, as a rule, comprise a diamond which is shielded with a metal film

against plasma and from which visible and UV radiation produced by RAEs is recorded

with a photomultiplier tube connected to the detector via a quartz fiber. The design of

Cherenkov-type detectors is constantly improved, allowing one to obtain more reliable data

on the generation of RAEs during plasma heating. Unfortunately, no paper is available

comparing the parameters of Cherenkov radiation and cathodoluminescence excited in

diamonds by RAEs or presenting RAE energy spectra.

Cherenkov radiation, which is well known from theory [10] and experiments, can

be emitted by liquids, gases, and solids when charged particles, e.g., electrons, move in

them with velocities higher than the phase velocity of light, and its intensity can increase

up to a certain limit both with decreasing wavelength λ and with increasing kinetic electron

energy ε. This type of radiation arises at a certain energy threshold εthr which depends on

the refractive index n and decreases with increasing n. For diamond, εthr is ~50 keV. This

crystal is used for recording Cherenkov radiation due to its UV transparency up to 223 nm,

high heat conductivity and heat resistance, and high electrical conductivity on electron

beam excitation.

Some papers [11] report that in natural and synthetic diamonds as well as in other

crystals, the radiation at 200– 800 nm excited by a pulsed electron beam of energy from

several tens to several hundreds of kiloelectronvolts is mainly due to cathodoluminescence;

in particular, this is observed for a subnanosecond electron beam known as a supershort

avalanche electron beam (SAEB) [12]. Note that in RAEexcited polymethyl methacrylate,

Cherenkov radiation escapes detection [13].

In the report we present research data on the cathodoluminescence,

photoluminescence, and Cherenkov radiation at 200–800 nm excited in crystals with



different refractive indices by a subnanosecond runaway electron beam and by

KrClexcilamp radiation with a peak wavelength of 222 nm. The data include spectral and

amplitude-time characteristics measured with a resolution of up to ~100 ps for natural and

synthetic diamonds of type IIa, sapphire, CsI, ZnS, CaF2, ZrO2, Ga2O3, CaCO3, CdS, and

ZnSe.

Cherenkov radiation at electron energies of tens to hundreds of kiloelectron-volts

was detected in natural and synthetic diamonds, ZnS, ZrO2, Ga2O3, sapphire, and CsI only

in UV range of spectra, see [14]. The research data, including spectral and amplitude-time

characteristics measured at 200–800 nm with subnanosecond resolution, show that

runaway electron detectors should be designed with regard to cathodoluminescence and

additional bands arising in crystals on repetitive pulsed excitation. The cathodo- and

photoluminescence should be accounted for in Cherenkovtype detectors of runaway

electrons. It is expected that the research data will help to create and calibrate reliable

highenergy electron detectors for tokamak systems.

The work was supported by the grant from the Russian Science Foundation, project

# 18-19-00184.

Keywords: runaway electron, tokamak, cathodoluminescence, photoluminescence,

Cherenkov radiation

References

[1] R. Jayakumar, H. H. Fleischmann, and S. J. Zweben, Phys. Lett. A. 172, 447 (1993).

[2] M. N. Rosenbluth and S. V. Putvinski, Nucl. Fusion. 37, 1355 (1997).

[3] E. M. Hollmann, M. E. Austin, J. A. Boedo, N. H. Brooks, N. Commaux, N. W.

Eidietis, ... and A. Loarte, Nuclear Fusion. 53, 083004 (2013).

[4] M. R. Ghanbari, M. Ghoranneviss, A. S. Elahi, S. Mohammadi, and R. Arvin, J. Fusion

Energ. 35, 180 (2016).

[5] Z. H. Jiang, X. H. Wang, Z. Y. Chen, D. W. Huang, X. F. Sun, T. Xu, and G. Zhuang,

Nucl. Fusion. 56, 092012 (2016).

[6] P. Aleynikov and B. N. Breizman, Nucl. Fusion. 57, 046009 (2017).

[7] V. V. Plyusnin, L. Jakubowski, J. Zebrowski, H. Fernandes, C. Silva, K. Malinowski,

P. Duarte, M. Rabinsky, and M. J. Sadowski, Rev. Sci. Instrum. 79, 10F505 (2008).

[8] L. Jakubowski, M. J. Sadowski, J. Zebrowski, M. Rabinsky, K. Malinowski, R.

Mirowski, P. Lotte, L. Gunn, J. Y. Pascal, G. Colledany, V. Basiuk, M. Goniche, and M.

Lipa, Rev. Sci. Instrum. 81, 013504 (2010).

[9] L. Jakubowski, M. J. Sadowski, J. Zebrowski, M. Rabinsky, M. J. Jakubowski, K.

Malinowski, R. Mirowski, P. Lotte, M. Goniche, L. Gunn, G. Colledani, J. Y. Pascal, and

V. Basiuk, Rev. Sci. Instrum. 84, 016107 (2013).

[10] L. D. Landau, J. S. Bell, M. J. Kearsley, L. P. Pitaevskii, E. M. Lifshitz, and J. B.

Sykes, Electrodynamics of Continuous Media (Pergamon Press Ltd., 1984).

[11] V. I. Solomonov, S. G. Mikhailov, Pulse cathodoluminescence and its application for

analysis of condensed matter. (Ural Branch of RAS, Ekaterinburg, 2003) (In Russian).



[12] E. Kh. Baksht, A. G. Burachenko, and V. F. Tarasenko, Tech. Phys. Lett. 36, 1020

(2010). [13] V. F. Tarasenko, E. Kh. Baksht, A. G. Burachenko, D. V. Beloplotov, and A.

V. Kozyrev, IEEE Trans. Plasma Sci. 45, 76 (2017). [14] D. A. Sorokin, A. G. Burachenko,

D. V. Beloplotov, V. F. Tarasenko, E. K. Baksht, E. I. Lipatov, and M. I. Lomaev.

Luminescence of crystals excited by a runaway electron beam and by excilamp radiation

with a peak wavelength of 222 nm. Journal of Applied Physics. 122, 154902 (2017).



A Novel Rep-Rate LTD

Wang Meng*, Zhang Le, Zhou Liangji, Chen Lin, Zhao Yue, Tian Qing, Wei Bing, Qing Yanling,

Jiang Jihao, Xie Weiping, Deng Jianjun


Physics, China


A novel rep-rate LTD module was developed in Institute of Fluid Physics. The LTD

module consists of 50 individual four-stage Marx generators with a induction cavity, which

integrated the technique advantages of tradition Marx generator and LTD. New designed

20kA gas switches and 100nF capacitors were adopted. The lifetime of switch and

capacitor can reach over 170 thousand shots with reasonably controlling of working

parameters. The coaxial Marx generator overpassed 20 thousand continuously test in like

manner. The module can output 900kA current with risetime about 120ns on matched load

about 0.14Ω, with about 0.06Hz rep-rate continuous working mode. This novel LTD can

be an attractive candidate as prime-power sources for future rep-rate and long-life pulsed

power accelerators.



Conception Design of 30 MA Fast Linear Transformer Driver

Based on Sharing Shell and Stage-Triggering in Sequence

SUN Feng-ju, QIU Ai-ci, Wei Hao, JIANG Xiao-feng, WANG Zhi-guo,Wang Liangpin

State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of

Nuclear Technology, P.O. Box 69-10, 710024, Xi'an, China

*Email: [email protected]; [email protected]

Fast Z pinches have extensive applications on radiation effects, inertial confined

fusion, dynamic material properties, astrophysics, etc. Such as ZR, many pioneered

achievements have been obtained, and in the near term ZR will be refurbished to 32MA

through modifying Laser Trigger Gas Switch to 6.7MV, horizontal tri-plate water

transmission line, vacuum insulation stacks (VIS) and double post-hole convolute

(DPHC) and the charging voltage of Marx of 95kV, and will be operated at least till to

2025. On December 6-7, 2017 in China, the 38th Xiangshan Science conference on the

Frontier scientific problems and key technologies on fast Z-pinches was conducted. The

academicians and specialists attending the proceeding consider unanimously that the state

of art of fast Z pinch in China exists a big gap in driver’s current comparing to the

advanced level in world and it is urgent to construct a pulsed driver with the current of

34MA in vacuum insulation stack based on new technologies.

This paper presents the conception design of Fast Linear Transformer Driver

(FLTD) with the current of 34MA in VIS. The innovative properties of the driver are that

many FLTD modules in parallel share common metal shells so as to the charging cables,

triggering cables and gas lines being shared, every stage consists of one triggering brick

and 23 discharging bricks, and every FLTD modules realizes triggering in special

sequence by only one external triggering pulse and stage-connection trigger method. The

driver comprises of 48 FLTD modules, 32 stages in series for every FLTD module, and

every stage consisting of one triggering brick with two 50nF plastic capacitor and one

multi-gap gas switch of low triggering voltage thresholds and 23 5GW bricks with two

100nF plastic capacitor and one field distortion gas switch. SF6 or the new environmental

friendship gases (such as C4F7N, C5F10O) are used in the primary common shell and

de-ion water are used in the secondary to impedance matched. The configuration of the

driver divides two layers, one layer consists of 24 FLTD modules which the output of

every FLTD module connects to coaxial water line with the length of 7 meters and then

24 coaxial water lines converge to monolithic water radial transmission line of the

diameter of about 5.1 meters, and the power is transferred to the vacuum insulation stacks

(VIS) of the diameter of 1.65 meters and the structure from VIS to Z pinch load is the

similar to ZR. The paper gives the three-dimensional structure, equivalent circuit model,

electrical parameters and the simulation results when the load is wire array. Suppose that

the inductance from the VIS to Z pinch load is 18nH and the charging voltage of 80kV,




the FLTD module triggering in ideal sequence and the loss resistance of 0.6 MITL

vacuum impedance, the simulated results as follow: the current of 34MA and the voltage

of 4.5MV in VIS position, the peak current of 30MA and the rise time of 110ns in Z

pinch load.

Key words: fast Z pinch; Fast linear transformer driver; Switches triggering in

synchronization; sharing common cavity; triggering sequences.

This work was supported by the National Natural Science Funds of China under Grants

51790521 and 51790523



Study of Electromagnetic Pulse Generation at High Power

Laser Facilities

Hanbing Jin*, Cui Meng

Department of Engineering Physics, Tsinghua University, China


Intensive electromagnetic pulses (EMP) can be generated when a high power laser

strikes a target. The transient electromagnetic field can have an intensity up to several

hundred kilovolt per meter with a broad frequency up to gigahertz, which may interfere or

even damage electronic equipment. With the development of high power laser facilities

(SG-III, NIF, LMJ/PETAL, et al.), the challenges in terms of EMP become even more

serious. Researchers have been making effort to reveal the characteristics and mechanisms

of EMP for effective shielding and better physical insight in laser plasma.It‘s widely

accepted that hot electrons which eject from the target play an important role. EMP can be

related to transient current of escaped electrons or target polarization. In this paper, EMP

related to electrons emission is studied and the numerical simulation is investigated. The

generation of EMP in laser-target interaction is a complex process of multi-physics and

multi-scale. Considering main physical effects, the whole process is divided into three

stages for analysis and simulation.First hot electrons generated in the interaction of a laser

pulse with a target are calculated by a two dimension PIC code 2D-LPIC. The simulation

results shows that the hot electrons accelerated by the laser (with the intensity at 2×1018

W/cm2 and the duration at 50 fs) have a maximum energy up to 5 MeV. The energy

distribution of hot electrons is approximately Maxwell distribution with the effective

temperature 236 keV.Then hot electrons diffuse and collide on the target surface. A small

part electrons are energetic enough to overcome the charge separation potential on the

target surface, escape from the target and propagate to the chamber. According to the

dynamics model of target charging established by the research team at the French Atomic

Energy Commission (CEA), the total ejection charge calculated is 13 nC, that is, about 8.5

× 1011 electrons fully escape from the target.Finally EMP radiated by the electrons that

escape the target and flow in the vacuum chamber is simulated using the PIC method

together with the time-bias FDTD method to restrain high frequency noise. A 2D cylinder

chamber model where escaped electrons are ejected from the chamber center is constructed.

The peak value of the electric field is about 8 kV/m and the frequencies are mainly

distributed in the range of MHz to 1GHz, which are consistent with the measurement

results.Numerous experiments have found that the target size significantly affects EMP.

The target size effect is explored and compared with the experiment results in TITAN

facility. The simulation results are consistent with the TITAN measurements in the order

of magnitude. The larger the target, the stronger the EMP. Taking into account that our



computational model is a simplified two-dimensional cylinder, the overall agreement is

reasonable.

Keywords: electromagnetic pulse, high power laser, hot electrons, particle-in-cell



Current design and pulse shaping techniques on PTS facility

Wang Guilin*, Zhang Zhaohui, Zou Wenkang, Guo Fan, Jia Yuesong, Zhang Zhengwei, Sun

Qizhi, Ji Ce, Feng Shuping, Wang Meng


Physics, China

Email: [email protected]

Primary Test Stand (PTS) facility is a pulsed power machine capable of delivering

currents to loads of 4~8 MA over times of 300-750 ns. It consists of 24 modules connected

in parallel and divided into two layers, all the 24 Marx generators are triggered by 12

individual lasers. As current flows in the opposite direction electrode plates. Because the

stress-wave loading path depends on the current pulse, we can control the loading history

on sample by shaping the current waveform. Based on the experimental physics aims as

isentropic compression and hyper-velocity flyer launch, load current design method will

be introduced. Combined with the circuit simulation code which include ICE Load model,

current shaping scheme were determined. Obtained experimental load current agrees with

simulation results pretty well, which produced isentropic compression to the copper

electrodes to 2 megabar pressure, launched aluminum flyer plates to 21 km/s also. The

experiment results confirmed the improvements of current design and pulse shaping

techniques at PTS, more of dynamic material experiments were going to performance on

the stand.



Theoretical and Experimental Evaluation of Cable

SGEMP Response in the SG-III Laser Facility

Zhiqian Xu



Researchers have found severe electromagnetic interference (EMI) on the

diagnostics applied in high-power laser facilities, even with good electromagnetic

compatibility (EMC) design. Coaxial cables are essential for the signal transmission of

electronic equipment and could be an important source of EMI. Although the metal

shielding layer could effectively protect the cable from EMI, X-rays could penetrate into

the conductor to excite or induce a large number of electrons, resulting in a current response,

which is named as system-generated electromagnetic pulse (SGEMP) interference. The

cable SGEMP response could superimpose on the real signal and cause severe impact on

experiments. After the laser shooting, a harsh X-ray environment would be generated in

the target chamber of the SG-III laser facility. Therefore, evaluation of cable SGEMP

response in the SG-III facility is highly needed.

In this paper, a layered cable model was developed to simplify the complex physical

progress. Based on the model, numerical simulations were processed with the Monte Carlo

and finite-difference time-domain (FDTD) methods to accomplish a systematical

investigation. X-rays in the calculation were selected to be 10 keV in average energy, 4.2

J/cm2 in total fluence, and 1 ns in pulse width, which was close to the expected working

environment in the SG-III facility. Some measurement experiments on the single shielded

and double shielded cables were also conducted in the SG-III laser facility. After the

irradiation of a laser with an energy of 1.8 kJ to a golden sphere target, pulsed current

responses are observed.In light of the waveform, the simulation results demonstrate good

consistent with the experimental measurements, despite that the theoretical and

experimental peak current value are 1.26 A and 8.67 mA separately because of the

difference of the X-ray fluence. Finally, the effects of some important parameters on the

cable SGEMP response were studied, including the X-ray fluence, the X-ray energy and

the thickness of the shielding layer. The accuracy and validity of our simulation is

supported by the experimental observations, and the time domain waveform of the current

response obtained by in this paper provides strong support for the anti-radiation

reinforcement design of the cable used in the SG-III facility.

Keywords: SG-III facility; X-rays; cable SGEMP; finite-difference time-domai



Generation of Gigawatt Attosecond Pulses from Relativistic

Electron Sheets

Huichun Wu*, Ke Hu

Institute for Fusion Theory and Simulation (IFTS) and Department of Physics, Zhejiang

University, China


Nowadays, attosecond science mainly uses attosecond (as) pulses generated by

High-harmonic generation from ionized gas. These attosecond pulses have a low power or

intensity and limit the development of as pump probe and nonlinear physics. Here we

discuss that as pulses can also be obtained from relativistic electron sheets (RES) and these

pulses possess the merits of high energy and high power. We first develop the scheme for

producing a better RES and then show two schemes for as pulse generation.

RESs are normally produced by irradiating nanofoils with a powerful laser beam.

However, the generated RES is not good enough since its large transverse momentum. To

avoid this defect, we propose a double layer-target scheme. After the laser pushes one

electron sheet from the first foil, we put the second thicker foil to block and completely

reflect the pulse. The RES interacts with the reflected laser and its transverse momentum

becomes zero. Its energy can be 1-50 MeV and the energy spread is less than 0.1%. From

such an RES, as X-ray radiation can be obtained by means of coherent Thomson scattering

(CTS). When a laser is normally reflected from the sheet, its peak energy and central

frequency will be upshifted by a Doppler factor, which can be as large as several hundred.

We analytically and numerically demonstrate that the reflected pulse has a duration less

than 10 as and a power larger than 10 GW. Besides, when the incident laser is in the few-

cycle regime, two new effects, amplitude enhancement and frequency downshift, can boost

the conversion efficiency even higher by over 100 times.

In the CTS scheme, we also find that under suitable conditions, the scattered signal

can have a saddlelike temporal profile, where the lower frequencies are found mostly in

the center region of this saddlelike profile. By filtering out the latter, we can obtain two

few-as pulses separated by a tunable subfemtosecond interval. Such a pulse pair can be

useful for an attosecond pump probe at an unprecedented time resolution.

In the second scheme of as pulse generation, an intense few-cycle laser pulse is

obliquely incident onto two parallel foil targets. All electrons are blown out from the first

thin foil, forming an uniform RES. A second layer, placed some distance behind, reflects

the drive beam but lets electrons pass through. The reflected beam kicks the RES and

provide it with a transverse momentum. This transverse motion leads to a half-cycle wave

emission. Analytic calculations and PIC simulations show that its intensity is 1019 W/cm-2,



the duration is about 50 as. We highlight that the efficiency is as high as 10-4, much higher

than HHG from gas targets.

In conclusion, gigawatt attosecond pulses can be produced from relativistic electron

sheets by coherent Thomson scattering or half-cycle wave emission. Such sources

overcome the shortcomings of the state-of-art HHG source and can be utilized in many

studies in attosecond science.

Keywords: ultrafast nonlinear optics, attosecond pulse, relativistic electron sheet



Development of X-ray Phase Contrast Imaging Method for

Investigation of Rayleigh-Taylor Instabilities in the Context of

Laboratory Astrophysics

Tatiana Pikuz

*Email:[email protected]

Investigations of properties of the matter under extreme conditions are a state-of-

the-art of nowadays physics and technological applications. During the past decade, several

physical fundamental problems have been pointed out in this field. Particular significant

problems arise for shock physics, which are of prime importance for various domains such

as astrophysics, inertial confinement fusion, planetology and technological and advanced

material creation. In particular, one of the crucial problem is the seeding of the Rayleigh-

Taylor instabilities (RTI) in a laser-matter interaction, which causes growth of any initial

perturbation. High spatial resolution x-ray micro-imaging of such conditions is nowadays

one of the key challenges that will bring new insight in this topic of study.We developed

an x-ray phase contrast imaging method for investigating dynamic evolution of matter in

extreme conditions in the spectral range of 4 - 10 keV. This method is based on a coupling

of XFEL beam or optical laser produced plasma radiation as a probe with an innovative

high-resolution, large-dynamic-range lithium fluoride (LiF) crystal imaging detector.

Modeling of transmission function for monochromatic coherent x-ray radiation passing

through ripple targets commonly used for observing the evolution of RTI will be discussed.

Enhanced phase contrast images of RTI obtained with unprecedented high 2-3 μm spatial

resolution during test-experiments at the SACLA XFEL (Japan) and LULI2000 laser

facility (France) will be presented. Obtained results will bring an important impact for the

perfection of methods intended for investigating matter under high pressure dynamic

physics.

Keywords: : matter in extreme conditions, Rayleigh-Taylor Instabilities, phase contrast

imaging, LiF imaging detector



Research on Spectral Failsafe System of High Power Laser

Using Dual Fiber Bragg Gratings

Zhaoyu Zong1,*, Dangpeng Xu1, Xiaocheng Tian1, Dandan Zhou1, Mengqiu Fan1, Rui Zhang1, Na

Zhu1, Lianghua Xie1, Hongxun Li1



The phase modulated (PM) failsafe system that could interrupt the amplification

following a failure of accidentally seeding the chain with a non-PM pulse is needed for

high energy laser facilities to avoid optical damage. Herein, we demonstrated a reliable

spectral failsafe system which could indicate the presence or absence of adequate PM light.

And the requirement is met by combining dual fiber Bragg gratings detection with high

speed electronics at the output of the fiber front end. The TTL failsafe trigger signal is

generated when the spectral power operating at the peak sideband is larger than the

spectral power remains concentrated. The spectral failsafe system has the power to

distinguish adequate PM pulse from inadequate PM pulse as necessary, and the overall

system responding to change is approximately 25 ns, which is sufficiently short to safely

stop a shot if the PM should fault. Furthermore, the spectral failsafe system shows great

robustness in pulse width, pulse energy and the central frequency drifting of DFB fiber

seed laser in experiments and now is installed in the fiber front end of high energy laser

Facility in China.




Development and test of a 32 kev X-ray Talbot-Lau

interferometer

Kai Deng1,2,*, Jing Li2, Xianbin Huang2, Weiping Xie2

1. Department of Engineering Physics, Tsinghua University,China

2. Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of



A Talbot-Lau interferometer is an x-ray imaging instruments which uses several

(three or less) gratings to separate different x-ray contrast and to make the contrast

detectable. Images of absorption contrast, differential phase contrast and scattering (or

dark-field) contrast can be acquired by stepping one of the gratings to a few certain

positions within one grating period (typically several um). In this paper, we will report a

32 keV Talbot-Lau x-ray interferometer that are recently been build and present typical

multi-contrast images for low-z plastic and biological samples.




Fifth Harmonic Generation of Nd:glass Lasers in ADP

Crystals

Fang Wang, Fuquan Li, Wei Han, Xuewei Deng*,Wei Zhou, Yuancheng Wang, Xiaoxia

Huang, Jingqing Su, Qihua Zhu


Deep-ultraviolet (DUV) coherent light sources near 200nm are extensively required for

science, medical, and industrial applications. Specially, in the context of high energy density

physics, deep UV lasers are desirable for probing beam of diagnostics such as Thomson scattering

since the better penetration of the dense plasma. Moreover, with higher frequency probe laser, the

background due to plasma emission can be reduced and the absorption, refraction and dispersion

of the probe laser in the plasma can be suppressed. It is well known that the fifth harmonic

generation (5thHG) of Nd:glass lasers is an effective way to acquire coherent DUV radiation near

200nm. Nevertheless, in most available materials with high ultraviolet transmission, the large

dispersion in short wavelengths can hardly be compensated by their birefringence, resulting in the

phase-matching condition of 5thHG process cannot be satisfied. In previously reported works, beta-

barium borate (BBO) and cesium lithium borate (CLBO) crystals are commonly used to generate

the fifth harmonic. Nevertheless, for high energy 5ω radiation application, the BBO crystal suffers

from large walk-off angle and limited size, while the CLBO crystal is restricted for its easily

hygroscopic and creaking. The ammonium dihydrogen phosphate (ADP) crystal maybe a good

choice for efficient 5thHG of Nd:glass lasers. It is available in large sizes, and exhibits relatively

high damage resistance and nonlinearity with acceptable transmission down to about 200nm. Here

we introduce the 5thHG experiments of Nd:glass laser in ADP crystals, including the temperature

and angular tuning characteristics on conversion efficiency, as well as the nonlinear loss

mechanisms during the conversion process.



Optimized Design of Separated Final Optics Assembly

DeyanZhu*, Ping Li, ZhitaoPeng, FuquanLi, Yong Xiang, FuquanLi, Bin Feng


It is important to keep away from the ghost reflection point for the design of

separated final optics assembly (FOA). The separated FOA with high-power has too

much optics and complicated ghost reflection distribution lead to the difficult design of

FOA. By use the Zemax software and Ghost software designed by ourselves, we

analyzed the ghost reflection distribution of the FOA, established the model to analyze

the distance of two optics after lens and the angle of optics, used the model to design two

arrangements for the separated FOA, contrasted the two designresult and got the final

design of separated FOA.

Keywords:Separated final optics assembly; reflection ghost analysis;optical design;

high-power laser facility


III - Laser and Particle Beam Fusion,

Magnetic Driven Fusion


Invited & Oral Talks Laser and Particle Beam Fusion, Magnetic Driven Fusion

Monday May 7th

III-1: Laser and

particle beam

fusion, magnetic

driven fusion

14:00-

14:25 Sean Regan

Laboratory for Laser Energetics,

University of Rochester, USA

invited talk: The U.S. National Direct-

Drive Inertial Confinement Fusion Program

14:25-

14:50 Stefano Atzeni Univeristy of Rome, Italy

invited talk: Hydrodynamic Studies of

Shock Ignition Targets

14:50-

15:15

Alexander

Golubev

Institute of Theoretical and Experimental

Physics named by A.I.Alikhanov of

National Research Center “Kurchatov

Institute”

invited talk: High Energy Density Physics

at FAIR

15:15-

15:30 Liang Guo (郭亮)

Laser Fusion Research Center, CAEP,

China

Experimental Study on the Energetics of

Uranium Planar Targets Drove by Lasers

15:30-

15:45 Hui Cao (曹辉)

Institute of Applied Physics and


Design of Octahedral Spherical Hohlraum

for CH Rev5 Ignition Capsule

15:45-

16:00

Bolun Chen (陈伯

伦)


China

Experimental Progress on Pulse Shaped

Implosion Performance at 40TW drive on

SG-III Facility

16:00-

16:15 Coffee Break

III-2: Laser and

particle beam

fusion, magnetic

driven fusion

16:15-

16:40

Hongbo Cai(蔡洪

波)



invited talk: Study of the Kinetic

Effects in Indirect-Drive Inertial

Confinement Fusion Hohlraums

16:40-

17:05 Shigeo Kawata Utsunomiya University, Japan

invited talk: Robust Heavy Ion Inertial

Fusion

17:05-

17:30

Zhimin Hu (胡智

民)


China

invited talk: Mixing Effect Investigation

with Xenon-Doped Capsule Implosion

Experiments

17:30-

17:45

Shuai Zhang(张

帅) Peking University, China

Weakly Nonlinear Analysis of RTI with BP

Effect Evolving on Converging Finite-

thickness Cylindrical Shell

17:45-

18:00

Yongsheng Li (李

永升)



The Formation of “Bubble-Bubble”

Structure of Imploding ICF Target Shells



18:00-

18:15

Shaoyong Tu (涂

绍勇)


China

Experimental Study on Hydrodynamics

Instability in Radiation-Driven Cylindrical

Implosions on SG-III Laser Facilities

Tuesday May 8th

III-3: Laser and

particle beam

fusion, magnetic

driven fusion

14:00-

14:25 Claude Deutsch Université Paris-Sud, France

invited talk: Correlated Ion Stopping in

Ultra-dense Plasmas of ICF Concern

14:25-

14:50

Yongtao Zhao (赵

永涛) Xi'an Jiaotong University, China

invited talk: Stopping and Wakefield

Modulation of Ion Beam in Plasma

14:50-

15:15 Hideaki Habara Osaka University, Japan

invited talk: Visualization of Energy

Transport in the Imploded Plasma for Super-

penetration Fast Ignition

15:15-

15:30 Bin He（何斌）



Electron-ion Energy Partition for Alpha

Particle Moving in Fusion DT Plasmas

Mixed with Hot Au and Be

15:30-

15:45

Tao Gong（龚

韬）


China

Quantitative analysis of the K-alpha

emission from a Cu doped CD shell target

15:45-

16:00

Kaihong Fang (方

开洪) Lanzhou University, China

Environmental Abnormal Screening Effects

on Light-Nuclei Sub-barrier Nuclear Fusion

16:00-

16:15 Coffee Break

III-4: Laser and

particle beam

fusion, magnetic

driven fusion

16:15-

16:40 Chikang Li

Massachusetts Institute of Technology,

USA

invited talk: Exploring the Multi-ion-fluid

Effects in ICF Implosions

16:40-

17:05

Zhurong Cao (曹

柱荣)


China

invited talk: Development of Spatial-,

Temporal-, and Spectral-Resolved X-ray

Diagnostic Instruments for ICF Experiments

on SG Laser Facility in China

17:05-

17:30 Hideo Nagatomo Osaka University, Japan

invited talk: Radiation Hydrodynamic

Simulation with Nonlocal Electron Thermal

Conduction Model in Strong Magnetic Field



17:30-

17:45

Jingwei Wang (王

精伟)

Shanghai Institute of Optics and Fine

Mechanics, CAS, China

High Quality X-ray/Gamma-ray Radiation

from a Plasma Undulator

17:45-

18:00 Jian Wu（吴坚） Xi'an Jiaotong University, China

Initial Plasmas of Thick Cylindrical Liner

Obtained by End-on Laser Interferometry

18:00-

18:15 Xing Wang(王兴)

Xi'an Institute of Optics and Precision

Mechanics, CAS, China

The Development of High Performance

Streak Cameras in XIOPM

Wednesday May 9th

III-5: Laser and

particle beam

fusion, magnetic

driven fusion

14:00-

14:25

Dieter H. H.

Hoffmann

Technische Universitat Darmstadt,

Germany

invited talk: Activation of structural

material of intense beam accelerators due to

beam loss

14:25-

14:50 Jochen Linke

Forschungszentrum Jülich GmbH,

Institut für Energie und Klimaforschung,

Germany

invited talk: Challenges for Plasma-Facing

Components in Nuclear Fusion

14:50-

15:15

Wanli Shang (尚

万里)


China

invited talk: The Properties of Hot-spot

Emission in a Warm Plastic-shell Implosion

on OMEGA

15:15-

15:30

Guanqiong

Wang(王冠琼)



Numerical Study of the Striation Formation

During the Early Phases of the Cylindrical

Foil Implosions on the PTS Facility

15:30-

15:45

Yunsong Dong (董

云松)


China

Efficient Nanosecond X-ray Sources from

Laser-irradiated Metallic Targets with Low

Initial Density

15:45-

16:00 Xing Zhang(张兴)


China

A Bright Pulsed Fusion Neutron Source by

the Laser-Driven Spherically Convergent

Plasma Fusion

Thursday May 10th

http://www.fz-juelich.de/portal/EN/Home/home_node.html





III-6: Laser and

particle beam

fusion, magnetic

driven fusion

14:00-

14:25 Jeremy Chittenden Imperial College London, UK

invited talk: Indirect-drive Inertial

Confinement Fusion Simulations at the

Centre for Inertial Fusion Studies

14:25-

14:50 Rafael Ramis Polytechnic University of Madrid, Spain

invited talk: 3D Simulations of Realistic

Laser Driven Spherical Implosions

14:50-

15:15

Yanyun Ma(马燕

云)

National University of Defense

Technology, China

invited talk: Progress on Radiation

Hydrodynamics Simulations of ICF at

NUDT

15:15-

15:30 Lu Zhang (张璐)


China

Use of Foam Gold to Improve Hohlraum’s

Performance

15:30-

15:45 Yanjun Gu ELI-Beamlines, Czechia

Two-dimensional Simulations of Parametric

Instabilities in the context of the Shock

Ignition

15:45-

16:00

Tiankui Zhang (张

天奎)

Science and Technology on Plasma


Design and Preliminary Experiment of Laser

Plasma X-ray Using Source Coded

16:00-

16:15 Coffee Break

III-7: Laser and

particle beam

fusion, magnetic

driven fusion

16:15-

16:40 Javier Honrubia

Polytenchnic University of Madrid,

Spain

invited talk: Three-dimensional Hybrid

Modelling of High Intensity Ion Beam

Propagation in Plasmas

16:40-

17:05

Feng Wang（王

峰）


China

invited talk：Diagnostic Techniques for

ICF on the ShenGuang-III Laser Facility in

China

17:05-

17:30

Cheng Ning（宁

成）



invited talk: The Implementation of

Implicit Moment Particle-in-Cell Simulation

Method in Z-pinch Dynamic Process

Investigation

17:30-

17:45

Fuyuan Wu（吴

福源）


Technology, China

Numerical Studies on the Formation and

Radiation Characteristics of Liner Z-pinch

Dynamic Hohlraum

17:45-

18:00 Chao Tian (田超)

Science and Technology on Plasma


Radiography of Inertial Confinement Fusion

Implosions Using Hard X-rays Generated by

a Short Laser Pulse



The U.S. National Direct-Drive Inertial Confinement Fusion

Program

S. P. Regana, V. N. Goncharova, T. C. Sangstera, E. M. Campbella, R. Bettia, K. S.

Andersona, J. W. Batesc, K. Bauera, T. P. Bernatd, S. D. Bhandarkarb, T. R. Boehlya,

M. J. Boninoa, A. Bosea, D. Caoa, T. Chapmanb, G. W. Collinsa, T. J. B. Collinsa, R.

S. Craxtona, J. A. Delettreza, D. H. Edgella, R. Epsteina, M. Farrelle, C. J. Forresta,

J. A. Frenjef, D. H. Froulaa, M. GatuJohnsonf, C. Gibsone, V. Yu. Glebova, A.

Greenwoode, D. R. Hardinga, M. Hohenbergerb, S. X. Hua, H. Huange, J. Hundd, I.

V. Igumenshcheva, D. W. Jacobs-Perkinsa, R. T. Janezica, M. Karasikc, J. H. Kellya,

T. J. Kesslera, J. P. Knauera, T. Z. Kosca, J. A. Marozasa, F. J. Marshalla, P. W.

McKentya, D. T. Michela, P. Michelb, J. D. Moodyb, J. F. Myatta, A. Nikroob, S. P.

Obenschainc, J. Palastroa, J. L. Peeblesa, R. D. Petrassof, N. Pettaa, P. B. Radhaa,

J. E. Ralphb, M. J. Rosenberga, S. Sampata, A. J. Schmittc, M. J. Schmittg, M.

Schoffe, W. Sekaa, R. Shaha, R. W. Shorta, W. T. Shmaydaa, M. J. Shoup IIIa, A.

Shvydkya, A. A. Solodova, C. Sorcea, C. Stoeckla, W. Sweete, C. Taylora, R. Taylora,

W. Theobalda, D. Turnbulla, J. Ulreicha, M. D. Wittmana, K. M. Wooa, and J. D.

Zuegela

1. Laboratory for Laser Energetics, University of Rochester, USA

2. Lawrence Livermore National Laboratory, USA

3. Naval Research Laboratory, USA

4. Schafer a Belcan company, USA

5. General Atomics, USA

6. Plasma Science and Fusion Center, Massachusetts Institute of Technology, USA

7. Los Alamos National Laboratory, USA


The U.S. National Direct-Drive Inertial Confinement Fusion Program consists of

the 100-Gbar Campaign on the 30-kJ, 351-nm, 60 beam OMEGA Laser System and the

Megajoule Direct-Drive (MJDD) Campaign on the 1.8-MJ, 351-nm, 192-beam National

Ignition Facility (NIF). The main goals of the 100-Gbar Campaign are to demonstrate and

understand the physics for hot-spot conditions and formation relevant for ignition at the

MJ scale, while the MJDD Campaign seeks to understand the laser–plasma interactions,

energy coupling, and laser imprint for ignition-scale direct-drive coronal plasmas. An

overview of the multi-year, systematic effort that is underway for the National Direct-Drive

Inertial Confinement Fusion Program, including laser, target, and diagnostic improvements

that are in progress, as well as recent results from the 100 Gbar Campaign on OMEGA and

MJDD Campaign on the NIF will be presented.

This material is based upon work supported by the Department Of Energy National

Nuclear Security Administration under Award Number DE NA0001944, Lawrence

Livermore National Laboratory under Contract DE-AC52-07NA27344, the University of

Rochester, and the New York State Energy Research and Development Authority. The




support of DOE does not constitute an endorsement by DOE of the views expressed in the

article.

Keywords: Inertial Confinement Fusion, Laser Direct Drive



Hydrodynamic Studies of Shock Ignition Targets

S. Atzeni, L. Antonelli, A. Marocchino, A. Schiavi

Dipartimento SBAI, Università di Roma “La Sapienza”


Shock ignition [1] is a laser direct-drive inertial confinement fusion (ICF) scheme

in which the stages of compression and hot spot formation are partly separated. The fuel is

first imploded at a lower velocity than in conventional ICF, reducing the risks due to

Rayleigh-Taylor instability (RTI). Close to stagnation, an intense laser spike drives a strong

converging shock, which contributes to hot spot formation. Shock ignition shows potential

for ignition and energy gain at laser energy below 1 MJ, and could be tested on the National

Ignition Facility or Laser MegaJoule. Such attractive features have promoted a significant

effort in target modelling and design (reviewed in Ref. [2]). Novel crucial issues related to

intense laser–plasma interaction and shock generation are actively investigated both

experimentally and theoretically, as summarized in Ref. [3].

In this talk, we present an overview of work by our group, concerning

hydrodynamic studies of shock ignition targets. We used analytical models and 1D and 2D

numerical simulations with the goal of designing robust targets. We first considered the

pure-DT and DT-CH targets proposed in the frame of the HiPER project. Using a suitable

metric [4] (analogous to the ITF used in indirect-drive ICF [5]) we evaluated target ignition

margins, and showed how these margins depend on implosion velocity and spike intensity

[6]. We then upscaled the reference targets, and generated gain curves with different safety

factors, by means of 1D simulations. The robustness of the designs has been then evaluated

using 2D hydrodynamic simulations coupled to 3D laser energy deposition. 2D simulations

of non-uniformly irradiated targets, and/or of non-perfectly positioned targets, confirm a

greater robustness for targets with greater safety factor. Further studies are required to

address the development of short-scale hydrodynamic instabilities.

Work supported by Sapienza Project C26A15YTMA, Sapienza 2016 (n. 257584),

Eurofusion Project AWP17-ENR-IFE-CEA-01.

Keywords: laser fusion, shock ignition, hydrodynamic simulation

References

[1] R. Betti, et al., Phys. Rev. Lett. 98,155001 (2007)

[2] S. Atzeni et al. Nucl. Fusion 14, 054008 (2014)

[3] D. Batani et al. Nucl. Fusion 14, 054009 (2014)

[4] P. Y. Chang et al., Phys. Rev. Lett. 104, 135002 (2010)

[5] J.D. Lindl et al., Physics of Plasmas 21, 020501 (2014)



[6] S. Atzeni, A. Marocchino, A. Schiavi, Plasma Phys. Control. Fusion 57, 014022 (2015);

S. Atzeni et al., 43rd EPS Conference on Plasma Physics (Leuven 2016) paper P4.092



High Energy Density Physics at FAIR

Alexander Golubev on behalf of HED@FAIR collaboration

Institute of Theoretical and Experimental Physics named by A.I.Alikhanov of National Research

Center “Kurchatov Institute”


High Energy Density Physics (HEDP), the study of matter under extreme

conditions of temperature and density, is a developing multidisciplinary field that is

expanding the frontiers of many scientific disciplines. HEDP cuts across many traditional

fields of physical science, including astrophysics, cosmology, nuclear physics, plasma

physics, laser science, and material science. HEDP, along with atomic physics, biophysics

and materials research, forms one of the 4 major scientific pillars for the Facility for

Antiproton and Ion Research (FAIR) presently under construction at the GSI site in

Darmstadt. These pillars will utilize the unique capabilities of FAIR to grow and develop

forefront scientific understanding through the first half of this century.

Accessing warm dense matter conditions in the laboratory presently utilizes a

variety of techniques including shock drivers that are laser-driven, Z-pinch-driven or

explosive-driven. These techniques reach pressures in the range of 1-10 Mbars and are

well established. As an alternative, volumetric heating from highly penetrating photon (x-

ray) sources and particle beams (electrons, ions) provide several advantages. This generates,

for example, warm dense matter in local thermodynamical equilibrium and with samples

large enough such that these systems are relatively uniform and evolve on the nanosecond

to microsecond time-scale. The use of heavy-ion beams at FAIR for creating WDM states

offers a unique and complementary approach to the other WDM drivers. Intense heavy-ion

beams are excellent tool to generate uniform large-volume plasma with solid state density.

The energy deposition of ion beams into a non-ionized target is a reasonably well

understood process and direct heating of a well-defined extended volume is achieved by a

rather homogeneous energy deposition. High precision experiments to study the properties

of bulk matter require a detailed knowledge about the exact amount of energy deposited

into the sample as well as the spatial and time distribution of the energy inside the target

volume. This demand is intrinsically fulfilled by the very nature of the interaction processes

of heavy ions with matter themselves. Thus intense ion beams open new opportunities to

investigate the interaction phenomena of heavy ion beams with dense plasma and they

allow to study the hydrodynamic and radiative properties of beam heated matter with high

precision experiments, and improved or complementary techniques. In order to achieve

this ambitious goal it is also necessary to include the development of new diagnostic

techniques and the design of appropriate heavy ion targets.

In the report there will be present the status of the High-Energy-Density Science at

FAIR (HED@FAIR) collaboration, which was founded in 2017, with experimental



program that will be conducted at the dedicated plasma physics beamline in the APPA cave

of FAIR.

Keywords: high energy density in matter, heavy ion beam,plasma physics



Experimental Study on the Energetics of Uranium Planar

Targets Drove by Lasers

Liang Guo1,*, Shanwei Li1, Qi Li1, Feng Wang1, Shaoen Jiang1, Yongkun Ding2




An energetic comparative experiment among two uranium targets (UN, UB2) and pure

gold planar target is implemented on Shenguang III prototype laser facility, to study their

radiation properties and scattering lights based on laser plasma interactions. All the

materials are used as ablation layers with 3 μm thickness. Under a laser intensity above

1.0×1015 W/cm2, the temporal integral spectra show that both the uranium targets suppress

the hard x-ray emission in the photon energies ranging from 2.0 keV to 3.0 keV and obtain

the quasi-Planckian spectral distributions. It is also found that the 3 μm-thick UN (U:N=1:1)

target obtains almost the same peak radiation intensity as the U targets coated with 100

nm-thick UN in previous experiment. These results indicate that the low-Z element brings

underestimated effect on the laser to x-ray conversion efficiency of the uranium, which

may optimize the design and fabrication of uranium targets in ICF.

Ta-doped uranium target acquires the highest peak intensity of the x-ray flux and

relatively-low scattering light fractions compared to the other targets, which lead to the

best laser to x-ray conversion efficiency. These results indicate that Ta-doped uranium has

the potential to generate an intensive and clean x-ray source, which should have many

applications in matter and radiation at extremes.

Keywords: uranium, laser, radiation, LPI



Design of Octahedral Spherical Hohlraum for CH Rev5

Ignition Capsule

Hui Cao*, Yao-Hua Chen, ChuanleiZhai, Chunyang Zheng, and Ke Lan



In this work, we design an octahedral spherical Au hohlraum for CH Rev5 ignition

capsule [S. W. Haan et al., Phys. Plasmas 18, 051001 (2011)] by using the initial design

method and two-dimensional (2D) simulations, and we investigate its laser entrance hole

(LEH) closure and laser-plasma instabilities (LPI) by using a spherical hohlraum with two

different-size LEHs via 2D simulations. The designed spherical hohlraum with RH=5RC

and RL=1.2mm requires an ignition laser pulse of 1.92 MJ in energy and 670 TW in peak

power, where RH, RC and RL are radii of the spherical hohlraum, capsule and LEH,

respectively. From 2D simulations, the closure and opening up of LEH are clearly obtained.

The LEH closure and its rate are strongly connected to the radiation pulse, while the LEH

opening-up and its rate are strongly connected to the laser pulse. The smallest radius of

LEH during closure is 0.6mm before opening up, which leaves enough room for arranging

the laser beams with a radius of 0.5mm in our design. By using a post-process code for LPI,

a relatively high stimulated Brillouin scattering fraction and a very low stimulated Raman

scattering fraction are predicted, which may be due to the neglection of three-dimensional

density gradients of the ablative flow along the laser transportation in 2D simulations. This

work provides the energy and power references for the future ignition laser facility which

uses octahedral spherical hohlraums as ignition targets.

Keywords: inertial confinement fusion, octahedral spherical hohlraum



Experimental Progress on Pulse Shaped Implosion

Performance at 40TW drive on SG-III Facility

Bolun Chen

Laser Fusion Research Centre, China Academy of Engineering Physics, China


The ShenGuang III laser facility was completed in 2015 which has 48 beams with

wavelength λ=0.35 μm, at peak power 40-60TW. From 2016 pulse shaped implosion

experiment was carried out on SGIII facility with gas filled cylindrical hohlraum.

Implosion performance with DD filled capsule was investigated by varying the trough

width. Almost all the implosion tuning platforms were implemented and several technical

and engineering problems were emerged. Many efforts were engaged in the improvement

of the capsule also the assembling arts of the hohlraum last year. In the experiment, 2D

backlit imaging technique was used for the measurement of the driven symmetry. Both of

the backlit imploded thin shell and thick shell methods were performed. Symmetry tuning

was demonstrated by varying the fraction of the power on the inner versus outer beams.

The ratio of shell shape P2/P0 asymmetry to the cone fraction is coincided with the view-

factor simulation. The pulse shaped implosion was also demonstrated after the symmetry

tuning by varying the power of picket pulse. The highest neutron yield 8.8×109 was

obtained corresponding to nearly 30% YoC. Two kinds of the shell thickness were

performed and a cliff of the yield is appeared which is very sensitive with the strength of

the first shock and the shock timing. Treated as the substituted target of the cryogenic

capsule, a good comprehension on the consequence of the recently experiments will be

helpful for the cryogenic capsule implosion experiments which would be carried out in the

next two years on SG-III facility.

Keywords: pulse reshaped, implosion, symmetry tuning



Study of the kinetic effects in indirect-drive inertial

confinement fusion hohlraums

H.B. Cai1,3,4, L.Q. Shan2, W.S. Zhang5, F. Zhang2, W.M. Zhou2,4, Y.Q. Gu2,4, S.Y. Zou1,3, Y.K.

Ding1,3, B.H. Zhang2,4, S.P. Zhu1,2,5, and X.T. He1,3,4

1)Institute of Applied Physics and Computational Mathematics, Beijing, 100094, China

2)Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, CAEP,

Mianyang, 621900, China

3) HEDPS, Center for Applied Physics and Technology, Peking University, Beijing, 100871,

China

4) IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240,

China

5)Graduate School, China Academy of Engineering Physics, P.O.Box 2101, Beijing 100088,

China

In vacuum hohlraums (or NVH), the high-Z plasma expands from the hohlraum

wall and collides with the blow-off from the capsule (or the low-density fill-gas). Such

collision produces conditions in which kinetic effects may dominate since the ion-ion mean

free paths are larger than the size of the interaction region. In the present work, we present

the first experimental evidence supported by simulations of kinetic effects launched in the

interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona

plasma of the compressed pellet on the Shenguang-III prototype laser facility. In our design,

solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron

yield is quenched, DD fusion yield from the corona plasma provides a direct measure of

the kinetic effects inside the hohlraum. Anomalous large energy spread of DD neutron

signal (~282 keV) and anomalous scaling of the neutron yield with the thickness of carbon-

deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these

results can be attributed to kinetic shocks arisen in the hohlraum wall/ablator

interpenetration region, which result in efficient acceleration of the deuterons (~28.8 J,

0.45% of the total input laser energy). These studies provide novel insight into the

interactions and dynamics of vacuum hohlraum and near-vacuum hohlraum.

References

[1] W.S. Zhang, Hongbo Cai* et al., "Anomalous neutron yield in indirect-drive inertial-

confinement-fusion due to the formation of collisionless shocks in the corona", Nucl. Fusion

57,066012 (2017).

[2] W.S. Zhang, Hongbo Cai* et al., " The formation and dissipation of electrostatic shock

waves: The role of ion-ion acoustic instabilities", Plasma Physics and Controlled Fusion, 60,

055001 (2018).



[3] L.Q. Shan, Hongbo Cai* et al., " Experimental evidence of kinetic effects in indirect-drive

inertial confinement fusion hohlraums", Phys. Rev. Lett., accepted and in press.



Robust Heavy Ion Inertial Fusion

S. Kawata1, 2, *, T. Karino1, H. Katoh1, R. Sato1, A. I. Ogoyski3

1. Graduate School of Engineering, Utsunomiya University, Japan

2. CORE (Center for Optical Research and Education), Utsunomiya University, Japan

3. Department of Physics, Technical University of Varna, Varna,Bulgaria


In this paper on heavy ion inertial fusion (HIF) [MRE, 1 (2016) 89], the state-of-

the-art scientific results are presented and discussed on the fuel target physics, the

uniformity of the HIF target implosion, the smoothing mechanisms of the target implosion

non-uniformity and the robust target implosion. The HIB has remarkable preferable

features to release the fusion energy in inertial fusion: in particle accelerators HIBs are

generated with a high driver efficiency of ~ 30-40%, and the HIB ions deposit their energy

inside of materials. Therefore, a requirement for the fusion target energy gain is relatively

low, that would be ~50-70 to operate a HIF fusion reactor with the standard energy output

of 1GW of electricity. The HIF reactor operation frequency would be ~10~15 Hz or so.

Several-MJ HIBs illuminate a fusion fuel target, and the fuel target is imploded to about a

thousand times of the solid density. Then the DT fuel is ignited and burned. The HIB ion

deposition range is defined by the HIB ions stopping length, which would be ~0.5 mm or

so depending on the material. Therefore, a relatively large density-scale length appears in

the fuel target material. One of the critical issues in inertial fusion would be a spherically

uniform target compression, which would be degraded by a non-uniform implosion. The

implosion non-uniformity would be introduced by the Rayleigh-Taylor (R-T) instability,

and the large density-gradient-scale length helps to reduce the R-T growth rate. On the

other hand, the large-scale length of the HIB ions stopping range suggests that the

temperature at the energy deposition layer in a HIF target does not reach a very-high

temperature: normally the about 300eV or so is realized in the energy absorption region,

and that a direct-drive target would be appropriate in HIF. In addition, the HIB accelerators

are operated repetitively and stably. The precise control of the HIB axis manipulation is

also realized in the HIF accelerator, and the HIB wobbling motion gives another tool to

smooth the HIB illumination non-uniformity.

In the present paper the robustness of the dynamic instability mitigation

mechanism is demonstrated in a DT fuel target implosion by wobbling HIBs. The results

show that the mechanism of the dynamic instability mitigation is rather robust against

changes in the phase, the amplitude and the wavelength of the wobbling perturbation

applied. In general, instability would emerge from the perturbation of the physical quantity.

Normally the perturbation phase is unknown so that the instability growth rate is discussed.

However, if the perturbation phase is known, the instability growth can be controlled by a

superposition of perturbations imposed actively: if the perturbation is induced by, for

example, a driving beam axis oscillation or wobbling, the perturbation phase could be

controlled and the instability growth is mitigated by the superposition of the growing



perturbations. In this paper, we realize the superposition of the perturbation by the

wobbling HIBs illumination onto a DT fuel target in heavy ion inertial fusion (HIF). Our

numerical fluid implosion simulations present that the implosion non-uniformity is

mitigated successfully by the wobbling HIBs illumination in HIF.

Keywords: Heavy ion inertial fusion, fuel target implosion, dynamic stabilization of

instability, uniform implosion, wobbling heavy ion beam



Mixing Effect Investigation with Xenon-Doped Capsule

Implosion Experiments

Zhimin Hu



In the field of inertial confinement fusion (ICF) research, high-Z elements could

mix into the fusion fuel, i.e., hydrogen isotopes, due to hydrodynamic instability growth.

The performance of the ICF implosions could be significantly degraded by the mixed high-

Z material. Implosion mix effect could be investigated by pre-doping heavier elements in

hydrogen isotope capsule. In this talk, we present xenon-doped implosion experiments,

which were conducted at the Shenguang-III laser facility. The doping-fraction of xenon

was set as 0%, 0.1% and 0.5% by atom. The temperature and density of electrons are

diagnosed by measuring the K-shell emission spectra of the highly-ionized trace element

of argon. The size of hot spot was recorded by a time-integrated x-ray pin-hole camera.

The neutron yields were detected by both plastic scintillator and In-activation detectors,

and the ion temperature was measured by neutron time of flight spectrometer. Strong fusion

yield degradation has been found with the increasing doping fraction of xenon. The

experimental results will be compared with rigorous hydrodynamic simulations

Keywords: Implosion mixing, neutron yield degradation



Weakly Nonlinear Analysis of RTI with BP Effect Evolving on

Converging Finite-thickness Cylindrical Shell

Shuai Zhang

Peking University, China


In classical inertial confinement fusion(ICF), Rayleigh-Taylor instability is seemed

as a key factor which reduce the energy transfer efficiency and cause the failure of ICF. A

three-orders theoretical model based on weakly nonlinear(WN) theory have been

developed for a converging concentric cylindrical shell which filled with incompressible

and inviscid fluid. This model can numerically solve the amplitude of first-order, second-

order and third-order perturbation. The profiles of cylindrical shell in acceleration and

coasting phase for different mode numbers with amplitude and velocity ripple are shown

and qualitatively accordant with those given by experiment.

Keywords: RTI,BP effect



The Formation of “Bubble-Bubble” Structure of Imploding

ICF Target Shells

Yongsheng Li*, Wenhua Ye, Weiyan Zhang, et al.

Institute of Applied Physics and Computational Mathematics, Beijing ,China


During the capsule shells’ processes of Inertial Confinement Fusion (ICF) ignition

targets, the low-/mid- mode perturbations of the shells are very detrimental to

capsules‘ nuclear performance, not only due to the distortion of hot spots but also to the

formation of local thin shell which could break up and result in mixing of ablator materials

into hot spot. As one of the important contributions to thin-shell, this work investigates the

formation mechanism of “bubble-bubble” structure during the shellsacceleration phase,

showing that the Bell-Plesset effect of compressible fluid may play an important role.

Keywords: Inertial Confinement Fusion, Ignition, Thin-shell, Bubble-bubble structure



Experimental Study on Hydrodynamics Instability in

Radiation-Driven Cylindrical Implosions on SG-III Laser

Facilities

Shaoyong Tu



The perturbation increases with absence of the acceleration field in a convergent

geometry, namely the Bell-Plesset effects. During an implosion, convergence reduces the

threshold for nonlinear saturation, the growth rate, and the threshold for mode coupling,

compared with planar geometry. This is different from that in planar geometry.

The experiments have been developed to study the hydrodynamics instability in

cylindrical geometry on SG-III laser facilities. Laser beams inject into hohlraum to

generate radiation source which drive the cylinders to implode. A clear x-ray radiography

of the perturbation is obtained along the cylinder axis. The hydrodynamics instability data

obtained during the implosion compression stage can be used to verify the reliability of

two-dimensional numerical simulation, and to support the design of target in the inertial

confinement fusion ignition experiments. The experimental platform for cylindrical

hydrodynamics instability can also be used to study the explosion mechanism of supernova

in laboratory astrophysics.

Keywords: Hydrodynamics Instability,indirect-drive,convergent cylindrical geometry



Correlated Ion Stopping in Ultra-dense Plasmas of ICF

Concern

Claude Deutsch

LPGP, Université Paris-Sud, UMR CNRS-8578,91405-Orsay,France

Correlated ion stopping of ion debris resulting from intense cluster ion beams(CIB)

envisioned for high energy acceleration in particule driven inertial confinement fusion(ICF)

is thorougly investigated.Sudden impact ionization of Si and C clusters is considered

altogether with multiple scattering on target ions,and also the progressive Coulomb

explosion, A special attention is given to the crucial and initial high velocity regime treated

in an analytic plasmon-pole approximation for any degeneracy of target electrons. The

instantaneous topology of correlated ion debris appears as a leading parameter in the

stopping analysis. Optimum scaling relations connecting CIB velocity,target electron

density and spatial extension of the ion debris cloud are evidenced for maximazing CIB

stopping in given targets. Possible scenarii of direct as well as indirect CIB-driven ICF are

finally presented.



Stopping and Wakefield Modulation of Ion Beam in Plasma

Yongtao Zhao1,*, Jieru Ren1, Dieter Hoffmann1, Wei Liu1, Zhongfeng Xu1, JianxingLi1, Rui

Cheng2, Xianming Zhou2, Weimin Zhou3, Zongqing Zhao3, Leifeng Cao3, Younian Wang4

1. Xi'an Jiaotong University, China

2. Institute of Modern Physics, Chinese Academy of Sciences, China


4. Dalian University of Technology, China


Stopping and tranportion of ion beam in plasma is one of key fundmental issues in

the field of fusion science and application. Here we would like to report our recent activities

on ion-beam and plasma interaction, mainly including the following aspects,1. stopping of

ion beam with energy in order of 100MeV in theta-pinch plasma or dense-ionized-matter

created by Haulroam-X-ray heating of a foam.The experiments were carried out at GSI-

Darmstadt.2. Stopping of laser-acceletated proton and C-ions in MeV region in dense-

ionized-matter, the experiment was carried out at the XG facility in Mianyang, China.3.

Stopping and transportation of ~100keV/u proton and He ions in gas discharging plasma.4.

Wakefield self-modulation of ion beam in plasma, and its infulence to ion-stopping and

application to focus and compress intense heavy-ion-beam for HEDP research.

Keywords: ion beam, wakefield modulation, stopping power, high energy density physics



Visualization of Energy Transport in the Imploded Plasma for

Super-penetration Fast Ignition

Hideaki Habara



"Super-penetration" fast ignition is the relativistic laser penetration into the

overdense plasma beyond the classical critical density, and is therefore one of the attractive

options of fast ignition [1]. When the laser power exceeds the critical power of relativistic

self-focusing, the laser beam is focused during the propagation in coronal, underdense

plasma. The enhancement of focused laser intensity allows further penetration of overdense

plasma due to relativistic induced transparency effect. Once the pulse front successfully

propagates into the region, following part of the laser pulse can easily propagate its energy

into the dense region via laser hole boring. In our previous work, the intense laser always

creates a single plasma channel into overdense plasma and energetic electrons with very

small beam divergence of 10-20º on the laser axis.In this presentation, I would like to show

the energy transport inside the imploded plasma. Our group performed an integrated

experiment using Cu doped (1 at.%) plastic ball target in order to obtain the stable

implosion for getting higher areal density with low core temperature, which is suitable for

fast ignition, at Gekko XII and LFEX laser system in Institute of Laser Engineering, Osaka

University. By adding the optimum thickness plastic coating on the ball target, we

successfully eliminate Cu Ka emissions generated during the implosion process by

superthermal electrons and show the emission only by the fast electrons. In the results, the

size of emission is nearly equivalent with the core (~50μm) at the maximum compression

timing. Based on Jarrott‘s estimation [2], the energy coupling on the core is estimated as

around 0.3% of LFEX energy in our experimental conditions, with too low (0.05g/cm2)

areal density of the plasma and too high (10MeV) average kinetic energy of fast electrons

compered with the ideal heating conditions. In order to improve the coupling efficiency,

we demonstrated the enhancement of magnetic collimation of fast electrons by utilizing

the self-generated magnetic field via the resistive gradient between embed metal cylinder

in the imploded plasma. The results indicate almost 3 times enhancement of Cu Ka

emission, corresponding to about 1% of coupling efficiency. If we can use the ignition

scale plasma (nearly 10 times higher than the current experiment) and reduce the electron

slope temperature, one can expect the practical coupling efficiency (>10%). From these

observations, this scheme could be fruitful in the application to full-scale fast ignition.

Keywords: Fast Ignition, Ultra intense laser, Fast electrons

Reference

[1] M. Tabak et al., Phys. Plasmas 1 (1994) 1626.

[2] L.C. Jarrott et al., Physics of Plasmas 24 (2017) 102710.



Electron-ion Energy Partition for Alpha Particle Moving in

Fusion DT Plasmas Mixed with Hot Au and Be

Bin He*, Jian-Guo Wang



The heating of DT ion by alpha particle is crucial to the realization of the nuclear

fusion and it has been studied for many years. Besides DT mate-rial, some other materials

such as Be and Au are often used in the design of fusion targets [1] or fusion device of fast

ignition driven by ions. During the implosion process these materials would mix with DT

fuel inevitably. How the mixed material influence the heating of DT ion is still unknown

to us, which is the motivation of the present work, where the case for Au or Be mixture is

considered.

For this problem the electron-ion energy parti-tion for alpha particle in DT Plasmas

should be studied first. The related investigation has been made with the mechanism for

the excitation of the ionic acoustic wave to discuss the problem in ICF dense plasma [2].

In recent time this prob-lem was discussed in BPS model [3] in a com-plex form when both

the coulomb binary colli-sion and the ionic acoustic wave excitation were considered. In

the first part of the present work the mechanism of the field fluctuation [4] is in-troduced

to discuss the problem in DT plasmas. It is naturally found that the heating of the plas-ma

is stopped when the projectile energy is slowed down to the plasma temperature Te, which

is more reasonable than the models men-tioned above. Based on this the electron-ion en-

ergy partition in DT plasmas is obtained, which is compared with different models with

their dif-ferences explained.

Au ion is almost in fully ionized state for Te≥5keV according to the average atom

model [5]. Near the end of alpha particle range the en-ergy exchange between alpha particle

and the Au ion becomes important, which will influence the heating of DT ion in the mixed

plasmas due to the highly charged state of Au ion. Reasonable result of the problem is

obtained by us according to the binary collision mechanism with the Au ion potential

obtained from the average atom model. It is found that the well-known binary collision

model with constant Coulomb loga-rithm [6] as well as the revised model by Ferrar-iis and

Arista [7] is not suitable in this case alt-hough they work well in DT plasmas. The reason

for this is found and how to improve this in Coulomb potential is obtained, which is useful

for rapid and reliable calculation.

Basing on the above work electron-ion energy partition for alpha particle in the

mixed DT+Au and DT+Be plasmas are studied in the case of solid Au or Be density with

a huge range of plasma temperature and DT density for different percentage of Au or Be.



The preliminary results show that the heating of DT ion will be strongly affected by the

mixed highly charged Au ion for the temperature beyond 10keV and the percent-age of Au

beyond 5%. Similar results are also found for mixed Be plasmas, and the difference with

mixed Au is discussed. The relevant results will be presented in detail in the conference.

Acknowledgement: This work was supported by the National Key R & D

Programm of China under Grant Nos. 2017YFA0402300 and 2017YFA0403200, National

Natural Science Foundation of China (Grants Nos. 11574034, 11575032, U1530142,

11474031), and the Science Challenge Project under Grant No. JCKY201612A501.

Reference

[1] A. Macchi et al., 2013 Rev. Mod. Phys. 85, 751; R.C. Kirkpartick et al., 1975 Nuclear

Fusion 15, 333

[2] J. D’avanzo et al., 1995 Nuclear Fusion 35 210

[3] Lowell S. Brown et al 2012 Phys. Rev. E 86, 016406

[4] W.D Kraeft and B. Strege 1988 Physica A 149,313

[5] Balazs F. Rozsnayai 1972 Phys. Rev. A. 5 1137

[6] S.T. Butler and M.J. Buckingham 1962 Phys. Rev.126 1

[7] L. de Ferrariis and N. R. Arista 1984 Phys. Rev. A 29, 2145



Observation of Transport and Energy Deposition of Fast

Electrons in a Compressed Core Plasma

Tao Gong

Department of Experimental Physics, Laser Fusion Research Center, China


Efficiently coupling the energy of a heating laser beam to the pre-compressed fuel

core is of great importance for fast ignition. In electron fast ignition, this energy coupling

efficiency is primarily dependent on the transport and energy deposition of the fast

electrons produced by the heating laser. To study the fast electron transport and energy

deposition, we performed a set of integrated experiments in the super-penetration concept

on the GEKKO-LFEX laser facility. By doping the target with a Cu tracer, the fast electron

transport in a compressed core plasma was directly observed for the first time through the

stimulated Cu K-alpha emission. With the measured Cu K-alpha photons, the energy

deposited by the fast electrons in the core region was estimated, which corresponded to a

laser-to-core coupling efficiency of ~0.6%. Possible reasons for this low coupling

efficiency were analyzed. The findings in this work laid the groundwork for future

optimized experiments.

Keywords: Fast ignition, super-penetration, fast electrons, transport, energy deposition,

coupling efficiency



Environmental Abnormal Screening Effects on Light-Nuclei

Sub-barrier Nuclear Fusion

Fang Kaihong1,*, Zhang Qian1, Chen Bingjun1, Wang Qiang1, Wang Tieshan1,Jirohta Kasagi2

1. School of Nuclear Science and Technology, Lanzhou University, China

2. Research Center for Electron Photon Science, Tohoku University, Japan


Light-nuclei fusion reactions occurred in sub-Coulomb barrier energy region,

playing an important role infusion energy utilization, astrophysical application and nuclear

weapons designs, their reaction cross sections and the environmental effects should be

experimentally measured precisely. The ‘abnormal’ screening effect on fusion-reaction

rate in metallic environment under a sub-barrier energy region has been reported by

several laboratories [1-3], but the screening mechanism is not fully understood yet.

As a systematic research work, we have performed: a). The d-D reactions

occurred in more than 30 kinds of hosts in 2-20 keV region; b). The p/d-7/6Li reactions

occurred in solid/liquid Li/LiNO3 and LiF targets in 25-100 keV region; c). The p/d-9Be

reactions in metallic Be target in 18-100 keV region. The experiments were performed at

a low-energy high-current ion beam generator at Research Center for Electron Photon

Science of Tohoku University.

The results [4-7] show:

a). Most metallic environments provide ‘abnormal’ screening energies;

b). Phase (solid/liquid) of hosts affects on the reaction rate;

c). Temperature of host would affect the reaction rate also;

d). Species of beam (ion/molecular) lead to a different reaction rate.

Keywords: Light-nuclei fusion; Sub-Coulomb barrier; Cross Section; Screening Effect.

Reference

[1] F. Raiola, et al., Eur. Phys. J. A 19, 283.

[2] J. Kasagi, Surf. Coat. Tech. 201, 8574.

[3] K. Czerski,et al.,Europhys. Lett. 54 449.

[4] T. S. Wang, et al., J. Phys. G: Nucl. Part. Phys. 35,068001

[5] Fang Kaihong, et al., Phys. Rev. C 94, 054602.

[6] Fang Kaihong,et al., Europhys. Lett. 109, 22002.

[7] Fang Kaihong, et al., J. Phys. Soc. Jap. 80, 084201.



Exploring the Multi-ion-fluid Effects in ICF Implosions

C. K. Li1, H. Sio1, J. A. Frenje1, M. Gatu Johnson1, R. D. Petrasso1, F. H. Séguin1,

L. Chacon2, N. M. Hoffman2, P. A. Amendt3, S. C. Wilks3, S. Atzeni4,

R. Betti5

1Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

2Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

3Lawrence Livermore National Laboratory, Livermore, California 94550, USA

4Università di Roma “La Sapienza”, Via A Scarpa, 14–16, I-00161 Roma, Italy

5University of Rochester, Rochester, New York 14623, USA


The multi-ion-fluid effects, which have been overlooked in the conventional single-

spices-averaged hydrodynamic codes for inertial-confinement fusion (ICF) implosions, are

attracting increasing attentions. It has been realized that such effects could largely be

responsible for some disagreement between experimental results and numerical

simulations. Observations include: increasing yield degradation as the implosion becomes

more kinetic; thermal decoupling between ion species; anomalous yield scaling for

different fuel mixtures; ion diffusion; and fuel stratification. The common theme in early

experiments is that the results are based on time-integrated nuclear observables that are

affected by an accumulation of effects throughout the implosion, which complicate the

interpretation of the data. To quantitatively explore the dynamics of kinetic/multi-ion

effects in the fuel and their impact on the implosion performance, we have conducted a

series of ICF implosions at OMEGA with time-resolved measurements of multiple nuclear-

burn histories. These experiments provide new insight into the multi-ion fluid effects in the

strong ICF kinetic regime and their important implication to the ongoing experiments at

the National Ignition Facility. This work was supported in part by the US DOE, LLE,

LLNL, and DOE NNSA SSGF.

Keywords:ICF implosion, multi-ion fluid effects, time-resolved nuclear diagnostics



Development of Spatial-, Temporal-, and Spectral-Resolved X-

ray Diagnostic Instruments for ICF Experiments on SG Laser

Facility in China

Zhurong Cao



In the field of indirect-drive inertial-confinement-fusion, temporal and spatial

diagnosis of X-ray is very important to the imploded process researches and the simulate

procedure verifications. According to the temporal, spatial and spectral characteristics of

x-ray radiation, many x-ray imaging diagnosis devices were successfully developed. Along

with the development of ICF research, especially the SG-III facilities establishment, our x-

ray imaging diagnosis capability has been increasingly powerful. Some of the novel

diagnosis equipments even do have more excellent characteristics than that kind of

diagnosis equipments abroad.

Keywords: X-ray diagnostic instruments; inertial confinement fusion



Radiation Hydrodynamic Simulation with Nonlocal Electron

Thermal Conduction Model in Strong Magnetic Field

Hideo Nagatomo

Institute of Laser Engineering, Osaka University, Japan


In the laser plasma simulations, modeling the electron heat conduction is one of difficult

problems. Especially if laser intensity exceeds 1015 W/cm2 the hot electrons is produced

and classical heat conduction model cannot be applied. Numerical simulation for these

conditions non-local electron transport model is necessary. Recently, we have installed B-

SNB model [1] to a 2-D radiation hydrodynamic simulation code [2], where effect of

external magnetic field to the hot electron is considered. In this presentation, B-SNB model

is explained briefly and numerical example is shown.

Keywords: radiation hydrodynamic simulation, nonlocal electron transport, laser plasma

Reference

[1] Ph. D. Nicolai et al, Phys. Plasmas 13 032701 (2007).

[2] H. Nagatomoet al., NUCLEAR FUSION 55, 093028 (2015)



High Quality X-ray/Gamma-ray Radiation from a Plasma

Undulator

Jingwei Wang

Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, China


In this talk, I will introduce the concept of a plasma undulator induced by the

centroid oscillation of a laser pulse(s). Electrons injected in such an undulator will

experience two kinds of oscillations, the betatron oscillation and the centroid oscillation.

These two oscillations could become resonant when the initial conditions are matched,

which greatly enhances the amplitude of the electron oscillation. The energy of the

radiation can then extend up to the gamma-ray range, which provides a flexible and

compact laser-driven plasma-based gamma-ray source. In a plasma undulator exited by

high-order laser modes, we find that the electron betatron oscillation can be completely

eliminated by choosing appropriate laser intensities of the modes, leading to a few percent

radiation bandwidth. The strength of the undulator can reach unity, the undulator period

can be less than a millimeter, and the total number of undulator periods can be significantly

increased by phase locking and staging. In the fully beam loaded regime, the electron

current in the undulator can reach 0.3 kA, making such an undulator a potential candidate

towards a table-top FEL.

Keywords: laser plasma, plasma undulator, X-ray, FEL

Reference

[1] J. W. Wang et al., Scientific Reports 7, 16884 (2017).

[2] S. G. Rykovanov, J. W. Wang et al.,Physical Review Accelerators and Beams 19 (9),

090703 (2016).

[3] B. Lei, J. W. Wang*et al., submitted.



Initial Plasmas of Thick Cylindrical Liner Obtained by End-on

Laser Interferometry

Jian Wu

School of Electrical Engineering, Xi'an Jiaotong University, China


MagLIF is a new fusion concept using a thick cylindrical liner Z-pinch implosion

to reach thermonuclear fusion. The process of initial plasma formation of thick liner (2mm

in diameter, 0.1mm thickness) is investigated on the 0.3MA, ~250ns pulsed power machine

"Qin-1". To observe the initial plasmas formed both in the inner region and on the outer

surface of the liner, an end-on laser interferometer is setup on "Qin-1" facility. Firstly,

current is distributed on the outer surface of the liner due to the eddy current effect. Then

the surface materials vaporize and ionize because of ohmic heating and the current and

magnetic field penetrate inside. Plasma generated at the inner surface is observed. Through

the interferometry and shadowgraph diagnostic system, the electron density distribution is

obtained. A bright spot at the center area where the plasma collide is observed, which may

be from strong self-emission.

Keywords: Inertial confinement fusion; MAGLIF; end-on laser interferometry



The Development of High Performance Streak Cameras in

XIOPM

Xing Wang*, Jinshou Tian

Xi'an Institute of Optics and Precision Mechanic,, China


We present our recent developments of high performance streak cameras in XIOPM.

The temporal resolutions of these streak cameras are from nanosecond to femtosecond.

The highest temporal resolution we have achieved was 450 fs, which is the best value for

practical applications in China. The maximum synchroscan frequency is 300 MHz. To our

knowledge, this is the highest level in the world. The dynamic range is 10000:1@100 ps

temporal resolution. The static and dynamic spatial resolutions of the streak cameras are

higher than 25 lp/mm and 10 lp/mm @CTF=10% respectively. The photocathode

sensitivity is more than 100 μA/1m. The streak cameras have been used in diagnosis of the

X-rays in laser plasma, measurement of the laser-induced fluorescence lifetimes, analysis

of the pulsed laser and so on. In addition, XIOPM also developed three types of compact

streak cameras. The dimensions of the subcompact streak tube is just Ф60 mm x 110 mm.

Apart from the small size and light weight, the compact streak tubes also have large

effective photocathode area, 100 times higher luminous gain than the conventional streak

tubes, which makes them suitable for 3D imaging.

Keywords: streak camera, temporal resolution, dynamic range



Accelerator driven high energy density science

-activation of structural components of high intensity

accelerators

D.H.H. Hoffmann1,2,*, Yongtao Zhao1,3, Peter Katrick4

1. Xi’An Jiaotong University, School of Science, Xi’An, China

2. National Research Nuclear University “MEPhI“, Moscow, Russia

3. Institute of Modern Physics, CAS, Lanzhou, China

4. Helmholtzzentrum GSI-Darmstadt, Germany


High intensity particle accelerators like FAIR at GSI Darmstadt and the proposed

HIAF facility in China are a new tools to induce High Energy Density states in matter. We

will address a topic that has until now not been investigated in detail but is paramount to

the operation of high intensity accelerators as drivers for inertial fusion or high energy

density physics experiments. This is theinvestigation of activation processes of structural

components of heavy ion accelerators due to beam loss during operation. This is a crucial

issue to optimize the choice of construction materials and maintenance procedures.

Significant optimization of the operation schedule can be achieved if the accumulated

residual activity is properly controlled and predicted. Radiation may cause changes of the

functional properties of the construction materials, which possibly leads to shortening of

their lifetime. Replacing of the activated accelerator components is affected by dose-rate

restrictions for the “hands-on” maintenance. Handling and final disposal of the accelerator

parts after several years of usage is also an important issue directly related to the activation.

Physics (HEDP) with intense heavy ion beams as a tool to induce extreme states of

matter. The development of this field connects intimately to the advances in accelerator

physics and technology. At Xi’An Jiaotong University we are starting a group that will

build a low energy, high current ion beam facility for basic beam plasma interaction physics

and will make use of existing machines at the Gesellschaft für Schwerionenforschung

(GSI-Darmstadt), the Institute of Theoretical and Experimental Physics in Moscow (ITEP-

Moscow), and the Institute of Modern Physics (IMP-Lanzhou).

China NSFC grants: U1532263, 11505248, 11375034, 11205225, 11275241, and

11275238



Challenges for Plasma-Facing Components in Nuclear Fusion

Jochen Linke*, Juan Du, Thorsten Loewenhoff, Gerald Pintsuk, Benjamin Spilker,

Isabel Steudel, Marius Wirtz

Forschungszentrum Jülich GmbH, Institut für Energie und Klimaforschung, Germany

*corresponding author, present address: Auf Vogelsang 48, 52066 Aachen, Germany


The plasma facing wall of future thermonuclear fusion reactors with magnetic

confinement such as ITER or DEMO has to withstand harsh loading scenarios. These

processes are associated with quasi-stationary thermal loads up to 20 MW/m2 combined

with short, extremely strong thermal transients up to the GW/m2-range during Edge

Localized Modes (ELMs). In addition, irradiation effects resulting from the plasma species

and the 14 MeV neutrons have strong impact on the integrity of the wall armour materials.

Therefore, also synergistic effects resulting from simultaneous thermal, plasma and

neutron wall loads are evaluated in complex experiments. Under reactor-relevant

conditions, thermally induced defects such as cracking and melting of the plasma facing

material (PFM), thermal fatigue damage of the joints between PFM and the heat sink,

hydrogen-induced blistering, helium-generated formation of nano-sized tendrils, and

neutron induced degradation of the wall armour via reduction of the thermal conductivity,

embrittlement, transmutation and activation are the most serious damaging mechanisms.

Today tungsten is considered as the most reliable material for high heat flux

components in future fusion reactors due to its high melting point (3410°C) and a thermal

conductivity of approx. 160 Wm-1K-1. For ITER or other large-scale confinement

experiments alternative solutions based on beryllium and carbon-fibre composites are

promising material candidates. A major drawback for the application of beryllium as

plasma facing material is the relatively low melting point (1287°C). In D-T-burning fusion

reactors with carbon walls tritium-containing hydrocarbon deposits are formed on all in-

vessel components. This will finally result in an inacceptable T-inventory in the fusion

reactor. Depending on the selected fibre type and architecture, carbon-fibre reinforced

graphite can be manufactured with thermal conductivities equal to or even better than

copper (up to ≈ 400 Wm-1K-1). However, such an excellent thermal conductivity will

degrade rapidly under the influence of energetic neutrons.



The Properties of Hot-spot Emission in a Warm Plastic-shell

Implosion on OMEGA

Wanli Shang



A warm plastic-shell implosion was performed on the OMEGA laser system. The

measured coronaplasma evolution and shell trajectory in the acceleration phase are

reasonably simulated by theone-dimensional LILAC simulation including the nonlocal and

cross-beam energy transfer models.The results from analytical thin-shell model reproduce

the time-dependent shell radius by LILACsimulation, and also the hot-spot x-ray

emissivity profile at stagnation predicted by Spect3D. Inthe Spect3D simulations within a

clean implosion, a "U"-shaped hot-spot radius evolution canbe observed, and an "M"-

shaped hot-spot radius evolution is presented with the Kirkpatrick-Baezmicroscope

response (the photon energy is from 4 to 8 keV). However, a fading away hot-spot

radiusevolution was measured in OMEGA warm plastic-shell implosion because of

mixings. The distancefrom the measured hot-spot radius evolution shape to the "U/M"

shape could be a new criterion foran experimental implosion performance. To recover the

measured hot-spot x-ray emissivity profileat stagnation, a non-isobaric hot-spot model is

built, and the normalized hot-spot temperature,density, and pressure profiles (normalized

to the corresponding target-center values) are obtained.

Keywords: Direct drive, implosion



Numerical Study of the Striation Formation During the Early

Phases of the Cylindrical Foil Implosions on the PTS Facility

Guanqiong Wang*, Yang Zhang, Xiaoguang Wang, Delong Xiao, Ning Ding,

Shunkai Sun, Xiaojian Shu



Dense Z-pinch can produce an intense shot-pulse x-ray source and shows the

potential of driving inertial confinement fusion. The implosion quality is a key issue on

producing high temperature radiation to drive fusion, which may shows remarkable

difference for different kind of load. Recent experiments on the implosions of 15 mm long

and 2 μm thickness aluminum liners having a diameter of either 12.8 or 20.0 mm were

performed on the Primary Test Stadium (PTS) facility.

The striations can be observed as alternating dark and light transverse stripes

utilizing the extreme ultraviolet (XUV) imaging and the laser shadowgraph in the

experiments. The stratified structures with wave vectors parallel to the flow of current were

formed early in the implosion i.e., at the stage where the load is almost at rest. Analysis of

the experimental results suggests that the most probable physical mechanism responsible

for the stratification is the electrothermal instability (ETI) that occurs as a consequence the

inhomogeneity of Joule heating due to the characteristic relation between the resistivity

and the temperature.

By using a two-dimensional MHD code (ZUES2D) we also investigate the role of

electrothermal instabilities in the striation formation. It is found that both the inner surface

and the outer surface are heated simultaneously because the wall thickness is much less

than the skin depth, electrothermal instabilities characterized by the temperature

perturbations immediately grow once the current pulse starts, and the density perturbations

occur and increase after the liner melts. In 2D simulations the stratified structures can be

seen obviously in both density and temperature contours. the simulation results agree

qualitatively with experiments. It is also interesting to note that ETI provides a significant

seed to subsequent magneto-Rayleigh-Taylor(MRT) instability growth since the direction

of ETI wavevector is similar to MRT.

Keywords: Z-pinch; Electrothermal instability; Magnetohydrodynamics



Efficient Nanosecond X-ray Sources from Laser-irradiated

Metallic Targets with Low Initial Density

Yunsong Dong, Jiamin Yang, Shaoyong Tu, Wanli Shang, Lu Zhang, Tianming Song,

Chengwu Huang, Tuo Zhu, Wenhai Zhang, Zhichao Li, Xiayu Zhan, Huabing Du, Feng

Wang, Shaoen Jiang


X-ray sources from laser-produced metallic plasmais very significant for various

applications. In the soft x-ray region, the conversion efficiency increases with the atomic

number and gold is usually irradiated with nanosecond intense laser as the hohlraum wall

for heating source. In the multi-keV energy region, nanosecond x-ray emissions can be

used as backlighter and obtained by laser-irradiated intermediate-Z metals from titanium

to germanium. Low initial density has been proposed to both enhance the conversion

efficiency of the Au target in the soft x-ray region and the intermidiate-Z metallic target in

the multi-keV region. The enhancement is theoretically caused by the increase of the laser

absorption and the reduction of ion kinetic energy for the low initial density. Here we

explore the dependence of the initial density on the x-ray radiators generated by

nanosecond laser-produced plasma. The x-ray emissions from multi-eV to multi-keV of

~0.36g/cm3 gold with micro-nano structure is demonstrated experimentally with about 21%

relative enhancement compared with the solid gold target, consistent with simulation

results. For intermidiate-Z metallic target, the simulation shows that the optimal initial

density is only several mg/cm3 at which the laser-produced plasma is dominantly under-

dense and the laser ionization wave is supersonic. A promising target geometry with micro-

nano structure has been designed for the enhanced multi-keV x-ray source and

corresponding experiment on the Shenguang-III laser facility is underway.

Keywords: X-ray source, micro-nano structure, enhancement



A Bright Pulsed Fusion Neutron Source by the Laser-Driven

Spherically Convergent Plasma Fusion

Xing Zhang, Ji Yan, Zhongjing Chen, Wei Jiang, Bolun Chen, Tianxuan Huang, Feng Wang,

Jiamin Yang , Shao’en Jiang, Guoli Ren, Zhengfeng Fan, Jie Liu

Laser Fusion Research Center, CAEP, 621900 Mianyang, China

Institute of Applied Physics and Computational Mathematics, 100088 Beijing,China

For generation of a bright, robust pulsed fusion neutron source, a scheme of laser

driven spherically convergent plasma fusion (SCPF) was proposed (Phys. Rev. Lett. 118,

165001). And it was demonstrated by the experiments on Shenguang-III prototype

facility. AD-D neutron yield of 3×109 was obtained with driven laser of 6kJin 8 laser

beams and 1ns pulse. Different with the ICF implosion, the SCPF scheme uses thelaser

beams of ns pulseduration to uniformly irradiate the inner surface of a CD wall

sphericalhohlraum.The high-speed deuteron involved plasma flows converge and merge

in the center of the hohlraum. A high temperature (Ti~7keV) and large volume (several

hundred μm) plasma core is formed and can continue for more than 1ns. We proposed

apredicted neutron yieldscaling law as Yn∝(EL/Rh1.2τ0.2)2.5, in which EL is the laser

power, τ is the laser pulse duration and Rh is the hohlraum radius.

An experiment on Shenguang-III prototype facility with laser energy variation was

carried out, and the scaling law with laser energy was test. The CD wall hohlraum

diameter was 1.7mm and the laser pulse duration was 1ns. Recently, an experiment with

variation of the laser pulse duration (0.5ns, 1ns, 2ns and 3ns) was implemented on

Shenguang-II upgrade facility. The highest D-D neutron yield of 5.6×109 in 2ns laser

pulse was obtained. The CD wall hohlraum diameter was increased to 2mm. It shew that

increase of laser pulse duration could enhance the fusion neutron yield under the present

laser power intensity. The hot plasma core living time and expanding speed were also

measured by X-ray emission radiography. The experiments with 100kJ laser energy and

2-3ns laser pulse duration on Shenguang-III laser facility is in plan. It is expected that the

D-D neutron yield can be as high as 1012 with 180kJ/3ns laser. And the equivalent D-T

neutron yield can be over 1014.

Keywords: Spherically Convergent Plasma Fusion, High Yield Fusion Neutron Source



Indirect-drive Inertial Confinement Fusion Simulations at the

Centre for Inertial Fusion Studies

J.P. Chittenden, B. D. Appelbe, K. McGlinchey, C. Walsh, J. Tong and A. Crilly

Centre for Inertial Fusion Studies, Imperial College, United Kingdom


We present a summary of the research of the Centre for Inertial Fusion Studies in

relation to simulations of Indirect-drive Inertial Confinement Fusion experiments. Results

are presented from simulations of High-Foot and High Density Carbon capsule implosions

on the National Ignition Facility. These simulations make use of the ‘Chimera’ 3D

radiation hydrodynamics code which incorporates multi-group radiation transport,

extended MHD and Monte-Carlo alpha particle packages. Simulations are post-processed

with novel synthetic diagnostic tools which construct detailed neutron spectra along with

images of the primary and scattered neutrons and gamma rays. These tools are used to

establish characteristic diagnostic signatures of different forms of capsule engineering

features and radiation drive asymmetries. Detailed 3D radiation hydrodynamics

simulations are used to explore the effect of drive asymmetry and the capsule support tent

on fusion performance in High-Foot capsules as well as the effect of the fill tube at

deceleration in HDC capsules. The process of ignition and propagating burn in highly

perturbed, inhomogeneous hotspots and dense fuel is examined using the 3D Monte-Carlo

alpha particle model both for present day experiments and through extrapolation, to

possible future experiments with higher laser energies. The contribution of self-generated

magnetic fields (arising from the Biermann battery effect) to hotspot thermal insulation is

explored using extended MHD models which incorporate the full Braginskii transport. The

increase in fusion performance anticipated with externally applied fields is also explored.

Preliminary results from magnetised alpha particle burn calculations are used to explore

how applied fields can influence the laser energy required to progress along an ignition

cliff.

Keywords: Inertial Fusion: MHD, Ignition, Neutron Diagnostics, Simulation.



3D Simulations of Realistic Laser Driven Spherical Implosions

Rafael Ramis

Polytechnic University of Madrid, Spain


The effects of laser imperfections on the implosion of spherical capsules are

analyzed. In realistic laser systems, beam misalignment, profile inhomogeneities, inter-

beam power unbalance, and synchronization errors are always present. The analysis is

based on hydrodynamic numerical simulations of laser driven thin shell capsule implosions.

In this work, we employ the 3D version of the computer code MULTI, which includes one

temperature hydrodynamics with unstructured Lagrangian grids, flux limited electron heat

transport, and ray tracing with inverse bremsstrahlung absorption. Although neither

radiation transport nor nuclear reactions are included in the current version of the code,

synthetic x-ray and neutron emission images are generated by post-processing the

hydrodynamic results. Also, several technical issues concerning the numerical preservation

of the symmetry are considered. In particular, ray tracing algorithms induce numerical

noise that can be eventually amplified by hydrodynamic instabilities, giving place to

spurious distortions. In this respect, the appropriate choice of the number of beamlets and

their distribution in space and time is discussed.

Keywords: Inertial confinement fusion; Computational Fluid Dynamics; Implosion

Symmetry; Direct Drive



Progress on Radiation Hydrodynamics Simulations of ICF at

NUDT

Y. Y. Ma1,2,*, X. H. Yang1, Y. Z. Ge1, B. B. Xu1, F. Y. Wu1 and Z. H. Li3

1. College of Liberal Arts and Sciences, National University of Defense Technology, China

2. IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, China

3. Institute of Nuclear Physics and Chemistry, China Academy of Engineering, China


Some recent progress on radiation hydrodynamics simulations at National

University of Defense Technology (NUDT) has been made. Some new code modules

have been developed to improve the applications of the code MULTI. A reflection and

refraction module was added into the Multi-2D for the simulations of inertial

confinement fusion (ICF) driven by laser. Some modules were also added into the Multi-

2D for the simulations of inertial confinement fusion (ICF) driven by Z-pinch. Physical

models describing the formation of Z-pinch dynamic hohlraums were established. The

magneto-hydrodynamic models were implemented as packages for the open-source code

MULTI-IFE (1D) and MULTI-2D, which were initially designed for the simulations of

inertial confinement fusion driven by laser or heavy ion.

Z-pinch dynamic hohlraumis one of the competitive ways to drive inertial

confinement fusion due to the excellent properties, such as high radiation conversion

efficiency, low cost of X-ray energy and larger fusion energy gain. In order to increase

the radiation conversion efficiency and improve the radiation uniformity in the dynamic

hohlraum and suppress the fluid instability at the process of capsule implosion，the

related factors affecting radiation temperature in dynamic hohlraum were analyzed, and

the reasons of radiation non-uniformity around the surface of fusion capsule were

discussed, and the fluid instabilities at the inner and outer surfaces of ablator were

explored through both theoretical analysis and radiation hydrodynamics simulations.

Reference

[1] Xu Binbin, Ma Yanyun, et al. Plasma Physics and Controlled Fusion, 59 (10),

105012, 2017.

[2] Xu Binbin, Ma Yanyun, et al. Laser and Particle Beams, 35, 366 ~372, 2017.

[5] Fuyuan Wu, Rafael Ramis, et al., Journal of Computer Physics, 357, 2017.




Use of Foam Gold to Improve Hohlraum’s Performance

Lu Zhang1, Longyu Kuang1, Zhiwei Lin1, Longfei Jing1, Hang Li1,

Shaoen Jiang1, and Yongkun Ding2

1. Research Center of Laser Fusion, China Academy of Engineering Physics, China



Current hohlraums have three main challenges: (i) wall motion; (ii) drive spectrum;

(iii) LPI. Our previous studies demonstrate that foam gold planar target with 0.3 g/cc

density could improve x-ray reemission flux (Nucl. Fusion, 56, 036006) and reduce wall

motion (Phys. Plasmas, 22, 110703).

In this talk, we present the foam gold cylindrical hohlraum experiments carried on SG-

III prototype laser facility for the first time. The measured emission fronts of ~420 eV and

~2.5 keV in the foam gold hohlraum move 25% and 35% slower than those in the solid

gold hohlraum, respectively. These results indicate that the wall motion in the foam gold

hohlraum with 0.4g/cc density is reduced with respect to that in the solid gold

hohlraum.Furthermore, the x-ray flux in the foam gold hohlraum at 45°polar angle is 5.5%

higher. The drive spectrum is also optimized as follows. The fraction of x-ray between 0.7

keV and 1.6 keV in the foam gold hohlraum is about 5% higher than that in the solid gold

hohlraum, whereas the M-band fraction is about 5.5% smaller.Theseconclusions present

the opportunity to improve hohlraum’s performance on wall motion and drive spectrum by

constructing hohlraum walls with low density foam gold.

Keywords: gold foam, hohlraum, wall motion, spectrum



Two-dimensional Simulations of Parametric Instabilities in the

Context of the Shock Ignition

YANJUN GU1,*, Ondrej Klimo1, Philippe Nicolai2, Vladimir Tikhonchuk2, Stefan Weber1

1. ELI-Beamlines, Institute of Physics, The Czech Academy of Sciences, Czechia

2. University of Bordeaux, France


Shock ignition (SI) is an approach to direct-drive Inertial Confinement Fusion (ICF)

which separates the stages of compression and hot spot formation. It is an attractive topic

due to the significant reduction of the driving energy requirements and the improvement

on hydrodynamic stability. By abruptly raising the laser intensity by one or two orders of

magnitude, SI is achieved with a strong shock launched at the end of implosion phase.

Laser-plasma interaction and hot electron generation play a crucial role in the context of

the shock-ignition. However, the interactions at this stage are strongly nonlinear and the

physics of laser spike absorption is important, which is still not clear in the SI scenario.

In this paper, we present the results of the large-scale two-dimensional kinetic

simulations studying laser interacting with a relatively long and hot plasma corona. The

Particle-in-cell (PIC) simulations are based on the relativistic electromagnetic code

EPOCH with the initial conditions obtained from the hydrodynamics simulations. The

simulations show a large fraction of laser energy is transferred into hot electrons with

temperature higher than hundreds keV and strong Stimulated Raman Scattering (SRS) is

accompanied by cavitation at quarter critical density and density profile modification. It is

observed that the SRS becomes stronger and shifts to the less dense plasma in front of the

quarter critical density region. The competition among different plasma instabilities makes

the oscillation in the electron distribution function. Secondary parametric instabilities are

observed with the fractional harmonics in the reflected frequency spectrum. The processes

of laser beam filamentation and two-plasmon decay are also discussed.

Keywords: laser plasma interaction, stimulated Raman scattering, hot electrons, particle-

in-cell simulations



Design and Preliminary Experiment of Laser Plasma X-ray

Using Source Coded

Tiankui Zhang

Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China

Academy of Engineering Physics, China


In order to carry out research on shock wave measurement, inertial confinement

fusion capsule diagnostic, equation of state measurement and Rayleigh-Taylor instability

diagnostic, it needs to develop backlight radiography with high temporal and spatial

resolution. Laser plasma x-ray source possess many advantages, such as short-pulse, high

brightness, and tunable photon energy. However, the radiography spatial resolution is

limited by source size. In spite of the spatial resolution of the 10 microns can be achieved

by microstructural targets, the signal-to-noise ratio is poor because of low yield, and it is

difficult to improve spatial resolution even more. A new laser plasma X-ray source

backlight radiography technique based on coded source technique is present here. To tackle

the difficulty of non-uniform spatial distribution in process of design of source coded, the

adaptable source coded mask and the inversion algorithm with strong robustness are

studied. The preliminary experiment of source coded radiography using laser plasma x-ray

source is also carried out.

Keywords: laser, X-ray,radiography



Three-dimensional Hybrid Modelling of High Intensity Ion

Beam Propagation in Plasmas

Javier Honrubia1,*, Weiquan Wang1,2

1. School of Aerospace Engineering, Polytechnic University of Madrid, Spain

2. College of Science, National University of Defense Technology, China


The study of ion beam-plasma interaction is a growing field of research as the

beams areappealing for their potential applications in a broad range of research fields.

Targets can bestrongly heated in picosecond time scales by using laser-driven high-energy

ions, enablingfundamental studies on high energy density matter [1], ion fast ignition (IFI)

[2] and others. Mostof the ion beam-plasma interaction models used so far rely on strong

assumptions such asperfectly focused beams that interact with the plasma via Coulomb

collisions only. Even for thesimplest acceleration scheme, ions emerge with a relatively

high divergence angle (≈10-15º) andthe beam intensities may be high enough to generate

resistive fields. Only recently, anomalousinteractions between the beam and the target due

to those fields have been reported [3]. Inaddition, there are substantial differences between

the stopping power models available,particularly at low energies.

We have developed a 2-D/3-D ion beam interaction model with matter including

beam divergence, self-generated resistive fields and a stopping power model validated

experimentally [4,5]. Beam divergence studies are motivated by the important divergences

found in PIC simulations even for the re-entrant cones typically used in IFI. The divergence

effects on proton beam ignition threshold were presented in [6]. The ion beam interaction

model is aimed for studying resistive field generation and its consequences on ion beam

propagation and energy deposition. For very intense beams with current densities of

1011Acm-2or higher propagating in resistive targets such as aluminum (resistivity at 10 eV

10-6Ωm), ion energy loss by ohmic heating is not negligible and resistive fields may

affect substantially the beam propagation.

Two and three-dimensional simulations of intense ion beam interaction with

plasmas will be presented, highlighting the importance of resistive fields and beam

divergence. The sensitivity of the ion energy deposition to the stopping power model will

be also presented. Examples of high energy density matter generation and ion-driven fast

ignition of fusion targets will be shown.

Keywords: Intense ion beams, ion beam-plasma interaction, plasma simulation




Diagnostic Techniques for ICF on the ShenGuang-III

Laser Facility in China

Feng Wang


Shenguang-III (SG-III) laser facility, developed by laser fusion research center

(LFRC), is designed to provide the experimental capabilities to study the inertial

confinement fusion (ICF) physics in China. The disintegrate experiments of inertial

confinement fusion physics could be carried out at SG-III laser facility. Over 80 diagnostics

have been installed at SG-III laser facility, including the optical diagnostics, the x-ray

imaging diagnostics, the x-ray spectrum diagnostics, the fusion product diagnostics, the

general diagnostics assistant systems, and the central control and data acquisition systems.

In this presentation, we will introduce some new diagnostic techniques. These new

diagnostic concepts and techniques which had been developed, included the full aperture

backscattering system (FABS), near backscattering system (NBS), three dimensional

velocity interferometer system for any reflector (3D-VISAR), optical Thomson scattering

system (OTS), X-ray transition bandpass system (XTDS), eight channel Kirkpatrick-Baez

mirror, spherical bent crystal system (SBS), spatial resolution flux diagnostic system

(SRFD). The diagnostics platforms play important roles in the ICF experiments at SG-III

laser facility.

Keywords: Inertial confinement fusion; High power laser; diagnostics technique



The Implementation of Implicit Moment Particle-in-Cell

Simulation Method in Z-pinch Dynamic Process Investigation

Cheng Ning1, Xiaoqiang Zhang1, Wei Jiang2

1. Institute of Applied Physics and Computational Mathematics, China

2. Institute of Physics, Huazhong University of Science and Technology, China


The main idea of implicit moment method (IMM) is to obtain the advanced

electromagnetic filed values by solving the Maxwell‘s equations with the advanced source

terms, which are estimated through the Taylor expansion of current density and charge

density. The charged partilces are then pushed forward under the advanced electromagnetic

field. This particle-in-cell (PIC) simulation method has a well characteristic of energy

conservation and can effectively avoid the numerically self-heating phenomenon exhibited

in the explicit particle-in-cell simulation. And it is an important theoretical method in the

studies of intensively magnetized plasmas in large spacial scale. Compared to the related

literature, we improve the metodes to calculate the current density and charge density, and

in turn the computational accuracies of the densities and electromagnetic field have been

increased. Different weight function is used in the interpolations of electric and magnetic

fields during moving the particles, and the numerical errors caused by the traditional

average and interpolation processes are obviously reduced. The corresponding program

has been developed and the IMM PIC simulation method is applied in the Z-pinch dynamic

process investigation for the first time. The Z-pinch of a rarefied deuterium plasma shell

driven by a low current has been simulated in one-dimensional cylindrical coordinate. The

microscopic physical informations, such as velocities and positions of the particles and the

electromagnetic field, of Z-pinch, are obtained by tracking the particles, and the

macroscopic physical images and the spatio-temporal evolutions of all physical quantities

of Z-pinch can be calculated by statistically averaging on the microscopic physical

quantities. The reasonability of results and the well characteristic of energy conservation

in the calculation demonstrate that the proposed implementation method for implicit

moment PIC simulation is theoretically accurate and numerically reliable.

Keywords: Electromagnetic particle simulation; Implicit moment method; Z-pinch



Numerical Studies on the Formation and Radiation

Characteristics of Liner Z-pinch Dynamic Hohlraum

Fuyuan Wu

College of Art and Science, National University of Defense Technology, China


Z-pinch dynamic hohlraum can effectively convert electrical energy into hohlraum

radiation energy, imploding a fuel-filled pellet to fusion conditions. For the moment, most

current Z-pinch dynamic hohlraums are composed of nested wire arrays and a single plastic

foam. However, this configuration has some drawbacks. For example, the collision of inner

and outer array plasma will emit x-rays with radiation temperature more than 50 eV,

driving a shock moving towards the foam center before the array plasma collides with the

plastic foam (Fig. 1a), which may destroy the spherical implosion of pellet. Recently,

Xianjue Peng et al. propose a Z-pinch dynamic hohlraum consisted of a single metal and

nested foam convertor to replace the traditional wire-array dynamic hohlraum (Fig. 1b). So

that the x-ray emitted by the collision of nested wire array plasma can be avoided, and a

hohlraum with higher radiation temperature can be expected. In this report, we use the 1D

radiation magneto-hydrodynamic code MULTI-IFE to study the formation and radiation

characteristics of the liner dynamic hohlraum with peak drive current of 8 MA, 26 MA and

50 MA. Both the radius and density of metal liner and foam converter are scanned to get

optimized hohlraum radiation pulse. The effects of liner material on the hohlraum

performance are also analyzed in this report.

Fig. 1 Implosion trajectories of nested wire array Z-pinch dynamic hohlraum (a) and

schematic diagram of single liner Z-pinch dynamic hohlraum (b)

Keywords: Z-pinch, Liner, Dynamic hohlraum, Nested foam



Radiography of Inertial Confinement Fusion Implosions Using

Hard X-rays Generated by a Short Laser Pulse

Chao Tian



Short-pulse laser-driven hard X-rays can be used to achieve time-resolved

radiographic images of the dense cold fuel surrounding the hot spot in inertial confinement

fusion. This measurement technique is based on point-projection radiography at photon

energies above 10 keV. The backlighter source is generated by a short pulse beam driving

a metal microwire on a low-Z substrate. Radiographs of CH steps with different thickness

are obtained and they have a spatial and areal density resolution of 10 μm and 0.1 g/cm2,

respectively. Furthermore, we have successfully applied this radiography technique to the

study of the compression of direct-drive and indirect-drive double shell targets on the SGII

upgraded laser facility. Time-resolved radiographic images of indirect-drive targets are

obtained for the first time. 3D nonuniformities of the inner shell are clearly shown.

Keywords: short laser pulse, hard X-rays radiography, double shell target implosion


IV - Laser Plasma Interaction


Invited & Oral Talks Laser Plasma Interaction

Monday May 7th

IV-1: Laser

Plasma

Interaction

14:00-

14:25 Kunioki Mima

The Graduate School for the

Creation of New Photonics

Industries, Japan

invited talk: Laser Driven Ion Acceleration and Neutron

Source

14:25-

14:50 Stefan Weber

Institute of Physics, Czech

Academy of Sciences, Czech

Republic

invited talk: High-Energy Photons and Positrons Produced

in Laser-Plasma Interaction

14:50-

15:15

Vladimir

Tikhonchuk University of Bordeaux, France

invited talk: Generation of Strong Magnetic Fields with

Lasers: from Nano- to Picoseconds

15:15-

15:30

Yuchi Wu (吴

玉迟)

Science and Technology on

Plasma Physics Laboratory,

China

Towards High Energy Micro-CT Based on Micro-spot

High Energy X-ray Source from Laser Wakefield

Accelerator

15:30-

15:45

Zhimeng Zhang

(张智猛)



China

Generation of High-power Few-cycle Lasers via Brillouin-

based Plasma Amplification

15:45-

16:00

Dong Wu (吴

栋)

Shanghai Institute of Optics

and Fine Mechanics, CAS,

china

Bright Gamma-ray Burst by Ultra Strong Laser Solid

Interactions: The Role of Bremsstrahlung and Radiation

Reactions

16:00-

16:15 Coffee Break

IV-2: Laser

Plasma

Interaction

16:15-

16:40 John Marozas

Laboratory for Laser

Energetics, University of

Rochester, USA

invited talk: Wavelength Detuning Cross-Beam Energy

Transfer Mitigation Scheme for Polar Direct Drive on SG-

III

16:40-

17:05

Björn Manuel

Hegelich

University of Texas at Austin,

USA

invited talk: Ultrahigh Intensity Physics at the Center for

Relativistic Laser Science

17:05-

17:30 Yan Yin (银燕)


Technology, China

invited talk: Laser Hole-Boring Acceleration of Two

Diamond-Like Carbon Foils for Copious Positron

Production and Gamma-Rays

17:30-

17:45

Wenpeng Wang

(王文鹏)

Shanghai Institute of Optics

and Fine Mechanics, CAS,

China

Multi-stage Proton Acceleration Controlled by Double

Beam Image Technique



17:45-

18:00

Lihua Cao (曹

莉华)


Computational Mathematics,

China

Fast Electrons and Ka X-ray Produced by Laser

Interactions with Structured Targets

18:00-

18:15

Yue Yang (杨

月)



China

Concept Study of High-spatial-resolution CT with a Laser-

based Hard X-ray Source

Tuesday May 8th

IV-3: Laser

Plasma

Interaction

14:00-

14:25

Yutong Li (李

玉同)

Institute of Physics, CAS,

China

invited talk: Generation and Applications of >mJ

Terahertz Radiation Driven by Relativistic Laser Pulses

14:25-

14:50 Gregory Vieux University of Strathclyde, UK

invited talk: A Laser Amplifier Based on Raman

Amplification in Plasma

14:50-

15:15

Caterina

Riconda LULI invited talk: High Intensity Lasers and Plasma Optics

15:15-

15:30

Weimin Wang

(王伟民)

Shanghai Institute of Physics,

CAS, China

Theoretical and Experimental Studies on THz Radiation via

Two-color Laser Scheme

15:30-

15:45

Jinqing Yu (余

金清) Peking University, China

Ultra-brilliance Isolated Attosecond Gamma-ray Light

Source from Nonlinear Compton Scattering

15:45-

16:00 Lu Li（李路）

Helmholtz Institute Jena,

Germany

Attosecond Control and Temporal Characterization of

Surface High Harmonics Generation

16:00-

16:15 Coffee Break

IV-4: Laser

Plasma

Interaction

16:15-

16:40

Dino A.

Jaroszynski University of Strathclyde, UK

invited talk: Laser-Plasma Optical Elements, Accelerators,

and Radiation Sources: New Tools for Science

16:40-

17:05 Stephan Neff

Facility for Antiproton and Ion

Research, Germany

invited talk: High Energy Density Science at FAIR -

Planned Experiments and Facilities

17:05-

17:20

Feng Zhang (张

锋)



China

Muon Generation, Detection and Acceleration in Laser

Wakefield



17:20-

17:35 Chongjie Mo Peking University, China

First-Principles Calculations of X-ray Thomson Scattering

of Warm Dense Matter

17:35-

17:50

Rong Yang (杨

容)



China

Laser Ray Tracing Simulation on Three-dimensional

Structured Grids

17:50-

18:05

Xiaohui Zhang

(张晓辉) Tsinghua University, China

Electron Acceleration and Betatron Emission from ps Laser

Plasma Interactions

Wednesday May 9th

IV-5: Laser

Plasma

Interaction

14:00-

14:25 Antonio C. Ting University of Maryland, USA

invited talk: Propagation and Modulation of Intense Short

Laser Pulse in Near Critical Density Plasma

14:25-

14:50 Bengt Eliasson University of Strathclyde, UK

invited talk: Vlasov Simulations of Wave-Wave and

Wave-Particle Interactions in Plasma

14:50-

15:15 Han Wen

University of California, Los

Angeles, USA

Invited talk: Petascale Kinetic Simulations of Laser

Plasma Interactions Relevant to Inertial Fusion —

Controlling Laser Plasma Interactions with Laser

Bandwidth

15:15-

15:30

Yaoyuan Liu

(刘耀远)

University of Science and

Technology of China, China

Analysis of Stimulated Scattering of the Outer Beam in

Experiments on SG-III Facility

15:30-

15:45 Chen Lin (林晨) Peking University, China

A New Method of Measuring Magnetic and Electric Fields

in a Tokamak Using a Laser-accelerated Ion-beam Trace

Probe

15:45-

16:00

Tongpu Yu (余

同普)


Technology, China

Ultra-bright Gamma-ray Emission and Dense Positron

Production with PW Lasers

Thursday May 10th

14:00-

14:25 Robert Bingham

Rutherford Appleton

Laboratory, UK invited talk: Laser plasma parametric Instabilities



IV-6: Laser

Plasma

Interaction

14:25-

14:50 Chuang Ren University of Rochester

Invited talk: Laser-plasma instabilities and hot electron

generation in shock ignition

14:50-

15:15

Zhichao Li (李

志超）

Laser Fusion Research Center,

CAEP, China

invited talk: Exploration of located hohlraum-plasma

evolution using Thomson scattering technique

15:15-

15:30

Yanqing Deng

（邓彦卿）

Shanghai Jiao Tong University,

China

Cavitation Structure Evolution During Ultra-intense Laser

Near-critical Density Plasma Interaction

15:30-

15:45

Chengzhuo

Xiao (肖成卓) Hunan University, China

On the Hot-electron Generation Produced by Two-plasmon

Decay and Stimulated Raman Scattering in Inhomogeneous

15:45-

16:00

Jingxia Gong

(公静霞) Peking University, China

The Propagation of Intense Laser and Particle Acceleration

in Presence of External Magnetic Field

16:00-

16:15 Coffee Break

IV-7: Laser

Plasma

Interaction

16:15-

16:40 Chuansheng Liu University of Maryland, USA

invited talk: Stimulated Raman Scattering: Convective and

Absolute instabilities

16:40-

17:05

Dong Yang (杨

冬)


CAEP, China

invited talk: Laser Plasma Instability in Indirect-Drive

Inertial Confinement Fusion: From Shenguang-II to

Shenguang-III

17:05-

17:20

Liang Hao (郝

亮)



China

Study of the Secondary Laser Plasma Instabilities in ICF

with FLAME Code

17:20-

17:35

Jinlong Jiao (矫

金龙)


Technology, China

Reduction of Crossing Beam Transferred Energy by Ion

Transfer Effect

17:35-

17:50

Qing Wang (王

清) Peking University, China

Stimulated Brillouin Scattering in Inhomogeneous Flowing

Plasmas by Using Vlasov Simulations

17:50-

18:05

Kaiqiang Pan

（潘凯强）


CAEP, China

The Coupling Between a Laser and a Pre-structured Target

with an Arbitrary Structure Period



Laser Driven Ion Acceleration and Laser Neutron Source

Kunioki Mima1,*, A. Yogo2, R. Hanayama1, A. Sunahara3, T. Asahina2, H. Nagatomo2,

H. Kondo1, N.Iwata2, Y.Sentoku2, A. Morace2, H. Nishimura2, Y. Kato1, and S. Nakai1

1. The Graduate School for the Creation of New Photonics Industries, Kurematsu, Japan

2. Institute of Laser Engineering, Osaka University, Osaka, Japan


The laser driven ion acceleration has been widely investigated for various possible

applications, such as laser driven neutron source, ion beam cancer therapy, ion beam

radiography, high energy density science, and so on. The efficient ion acceleration is in

particular important for those applications.

In this talk, we present the project on applications of laser driven ion acceleration

and the neutron source. Because of the short pulse and small source size nature of laser

neutron, the laser driven neutron source is useful for the precise neutron spectroscopy and

high spatial resolution imaging. For these purposes, the efficient laser ion acceleration is

in particular important. we propose that the ion acceleration efficiency is enhanced by the

laser pre-pulse.

When the intense short pulse laser propagates in the pre-plasma formed, ions are

accelerated by the hole boring/collision-less shock wave in the pre-plasma [1]. When those

accelerated ions reach the rear surface of the target, they are re-accelerated by the sheath

field as shown in the figure. This process can be called “Laser two step acceleration”.

According to the LFEX experiments, the conversion efficiency was higher than 5%. This

processes is applied for deuteron acceleration and the efficient neutron generation. Finally,

the prospects of the laser neutron source R&D will be presented.

Fig. Ion phase space distribution

Reference

[1] N.Iwata, et al., Nature Communication, 2018

(MeV)&9.0&2.25&0&

X

0.3$ps




High-energy photons and positrons produced in laser-plasma

interaction

S. Weber on behalf of R6

ELI-Beamlines, Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic


Worldwide there many high-power laser installations under construction (ELI,

APOLLON, SULF etc.), which will allow to generate ultra-high intensities, above 1022

W/cm2. At present investigations are under way to understand the physics effects taking

place if such high light intensities interact with matter. In particular any interaction process

is likely to produce gamma-ray photons and positrons via the Breit-Wheeler effect as well

as accelerate particle to very high energies. In this talk simulation work is presented of

several configurations [1,2,3,4,5] which produce high-energy gamma-photons and

positrons and which have the potential to be reproduced in real experiments at a later stage.

The phenomena observed strongly depend on the physics parameters employed (e.g.

density, mass and laser intensity) as well as the specific geometric configurations of the

interaction process. Also briefly mentioned are some technological issues considered in

P3 [6] to increase the intensities.

References

[1] M. Jirka et al., Scientific Reports 7, 15302 (2017)

[2] M. Vranic et al. , Scientific Reports (submitted) (2017)

[3] E. Gelfer et al, Phys. Rev. Lett. & PPCF (submitted) (2017)

[4] J. Vyskocil et al., PPCF (submitted) (2017)

[5] Y.-J. Gu et al., Phys. Rev. Lett. (submitted) (2018)

[6] S. Weber et al., Matter Rad. Extremes 2, 149 (2017)



Generation of strong magnetic fields with lasers: from nano- to

picoseconds

V. T. Tikhonchuk1,2,*, Ph. Korneev3, J. J. Santos1

1. Centre Lasers Intenses et Applications, University of Bordeaux – CNRS – CEA, France

2. ELI-Beamlines, Institute of Physics, Czech Academy of Sciences, Czech Republic

3. National Research Nuclear University MEPhI, 115409, Moscow, Russian Federation


Recent experiments with high intensity lasers are showing possibilities to generate

strong magnetic fields exceeding a kilotesla level. They are promising new studies of laser

matter interaction in unexplored domain. However, the physical processes leading to

generation of strong quasi-stationary currents exceeding hundreds of kiloamperes are not

sufficiently understood. In this talk we present theoretical models and target setups that can

be used for generation of strong magnetic fields on nanosecond and picosecond time scale

and several examples of their application in experiments.

Magnetic fields of nanosecond duration are generated in a coil connected to a laser-

driven diode, which supplies a quasi-stationary electric current. We present a self-

consistent model explaining generation of a strong magnetic field in such a system, which

accounts for three major effects controlling the current: space charge neutralization in the

diode, plasma magnetization and heating of the coil wire. The model provides the necessary

conditions for transporting strongly super-Alfvenic currents in the system. Its validity is

confirmed by a comparison with experimental data. This capacitor-coil scheme is applied

for improving the relativistic electron beam transport in solid targets and can be used for

other applications in high energy density physics.

Magnetic fields induced by sub-picosecond laser pulses may exist much longer time

than the laser pulse duration. Their origin is in supra-thermal electron ejection from the

target or in generation of hot electron vortices. Without confinement, these magnetic fields

are emitted in a form of high amplitude electromagnetic pulses presenting danger for

diagnostics operation and electronic devices in the experimental chamber. In contrast,

while confined within the target structure, these magnetic fields could be used for

controlling electron and ion acceleration and guiding. We present a theoretical model of

target charging and electromagnetic field generation followed with several examples of its

application in experiments.

This work has been carried out within the framework of the EUROfusion

Consortium and has received funding from the European Union’s Horizon 2020 research

and innovation programme under grant agreement number 633053. The views and opinions

expressed herein do not necessarily reflect those of the European Commission. We also

acknowledge financial support from the French National Research Agency (ANR) in the

frame work of "the investments for the future" Programme IdEx Bordeaux-LAPHIA

(ANR-10-IDEX-03-02).



Towards high energy micro-CT based on micro-spot high

energy x-ray source from laser wakefield accelerator

Yuchi Wu



High energy X-ray radiography plays a very important role in dense matter

inspection. Computer tomography (CT) provides a unique path from classical 2D

radioscopy to 3D imaging. Now, CT technology has become an important not-destructive

testing (NDT) method, and used in many fields such such as medical radiology, industrial

field and scientific researches.

For high energy CT, the systems often use high energy bremsstrahlung radiation

produced by electron beams with typical energy of a few MeV or higher from a

conventional electron linear accelerator. The electron beam focal spot is usually 1-2mm,

making the bremsstrahlung source in the same level, and becomes the bottleneck of the

improvement of the spatial resolution.

With the rapid development of intense laser technology, high quality electron

beams can be reproduced steadily from the interaction of laser pulse with underdense

plasma, which exciting interest as compact next-generation accelerators. Due to the strong

fields both in accelerating and focusing, which is thousands of times the intensity of those

achievable in conventional accelerators, energetic electron beams with low emittance,

small spot size and short duration can be obtained within several millimeter plasma.

Based on the laser wakefield accelerators, we detailed investigates the generation of micro-

spot high energy X-ray source. Under the optimal condition, the spot size can reach less

than 50μm which is almost 20 times less than conventional ways. Using the micro-spot

size, an experimental demonstrate was performed to improve of the spatial resolution in

high energy X-ray CT. Following our experiment result, intense laser provides a large

potential way of high energy micro CT for complex and dense objects NDT with a

resolution less than 100μm.

Keywords: high energy micro-CT, micro-spot high energy x-ray, laser wakefield

accelerator



Generation of high-power few-cycle lasers via Brillouin-based

plasma amplification

Zhi-Meng Zhang



Strong coupling stimulated Brillouin backscattering (sc-SBS) in plasma is

potentially an efficient method of amplifying laser pulses to reach exawatt powers. Here,

we report on a new regime of brillouin-based plasma amplification, producing an amplified

pulse with a duration of 5fs and unfocused intensity of 6×1017W/cm2. The results are

obtained from 2D particle-in-cell simulations, using two circularly polarized pump and

seed pulse with Gaussian transverse profile, both at an intensity of 2.74×1016W/cm2,

counter-propagating in a 0.3nc plasma. The significant compression of amplified seed is

achieved as a result of sc-SBS amplification as well as additional compression by the

interplay between self-phase modulation and negative group delay dispersion. We show

that the amplified seed retains high beam qualities since the filamentation can be prevented

due to the fast compression. This scheme may pave the way for few-cycle laser pulses to

reach exawatt or even zetawatt regime.

Keywords: Brillouin plasma amplification, particle-in-cell, few-cycle laser



Bright gamma-ray burst by ultra strong laser solid

interactions: the role of bremsstrahlung and radiation

reactions

D. Wu1*, S. X. Luan1, J. W. Wang1, W. Yu1, S. Fritzsche2,3, X. T. He4

1. State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine

Mechanics, China

2. Helmholtz Institut Jena, D-07743 Jena, Germany

3. Theoretisch-PhysikalischesInstitut, Friedrich-Schiller-University Jena,Germany

4. Key Laboratory of HEDP of the Ministry of Education, CAPT, and State Key Laboratory

of Nuclear Physics and Technology, Peking University, China


Ultra strong laser radiation, with intensity over 1020 W/cm2 , can be used to produce

ultra brightx/γ ray burst through the interaction with a high-Z solid. The ultra bright x ray

burst can beused to high sensitivity imaging by Thomson scattering. The ultra bright

gamma ray sources canbe used to the transmutation of nuclear waste through the (γ, n)

reactions. In addition, this kind of ultra bright gamma ray sources also provide a possibility

for the future gamma-gammacolliders, which would be of fundamental importance for

basic sciences.

Under moderate irradiations, varying laser beams and the target materials will allow

us totune the energetic electron generation in front of the target and transportation within

the target,which would finally influence the bremsstrahlung x/γ ray sources. While when

laser intensitybecomes higher, such as 1023 W/cm2, the x/γ rays from nonlinear Compton

scattering can becomparable to the bremsstrahlung effects. Furthermore, the radiation

reaction effect would alsobecome nonignorable, which would significantly influence the

energetic electron generation in front of the target and even the following transportations.

In this talk, the characteritics of bright gamma-ray burst by ultra strong laser

interaction with high-Z solid are investigated through particle-in-cell simulations, within

with both bremsstrahlungs and nonlinear Compton scattering have been implemented in

recently. The relative strength of gamma ray production from bremsstrahlungs and

nonlinear Compton scattering have been compared. The threshold under which the

nonlinear Compton scattering becomes dominate is also outlined.

Keywords: Laser solid interaction; Radiation sources



Wavelength Detuning Cross-Beam Energy Transfer

Mitigation Scheme for Polar Direct Drive on SG-III

John Marozas

Laboratory for Laser Energetics, University of Rochester,

250 East River Road, Rochester, NY 14623-1299, USA

Cross-beam energy transfer (CBET) has been shown to significantly reduce the

laser absorption and implosion speed in direct-drive implosion experiments on OMEGA

and at the National Ignition Facility (NIF) and should similarly affect the SG-III Facility.

Mitigating CBET aids in achieving ignition-relevant hot-spot pressures in deuterium–

tritium cryogenic OMEGA implosions, is an essential aspect of NIF polar-direct-drive

(PDD) ignition designs, and simulations predict improvement in designs for SG-III. In

addition, reducing CBET allows for lower, more hydrodynamically stable, in-flight aspect

ratio ignition designs with smaller nonuniformity growth during the acceleration phase.

Detuning the wavelengths of the crossing beams is one of several techniques under

investigation at the University of Rochester to mitigate CBET. This talk will describe these

techniques with an emphasis on wavelength detuning. Recent experiments designed and

predicted using multidimensional hydrodynamic simulations including CBET at the NIF

have exploited the wavelength arrangement of the NIF beam geometry to demonstrate

CBET mitigation through wavelength detuning in PDD implosions.1 Shapes and

trajectories inferred from time-resolved x-ray radiography of the imploding shell,

scattered-light spectra, and hard x-ray spectra generated by suprathermal electrons all

indicate a reduction in CBET. Application of these results to PDD designs proposed for

the SG-III will be presented using current SG-III capabilities and compared to similar

designs for the NIF, as well as symmetric-drive configuration designs on OMEGA.

Upgrades required to the SG-III laser to permit wavelength detuning in an optimal PDD

configuration will be discussed.

This material is based upon work supported by the Department of Energy National

Nuclear Security Administration under Award Number DE-NA0001944, the University of

Rochester, and the New York State Energy Research and Development Authority. The

support of DOE does not constitute an endorsement by DOE of the views expressed in this

article.



Ultrahigh Intensity Physics at the Center for Relativistic Laser

Science

Björn Manuel Hegelich

Center for Relativistic Laser Science, Institute for Basic Science (IBS), South Korea

University of Texas at Austin, USA


At the Center for Relativistic Laser Science (CoReLS) we have recently

commissioned a 4 PW laser system that can focus in various geometries, reaching peak

intensities of up to 1023 W/cm2. We are establishing a broad scientific program centering

on exploring quantum effects at ultrahigh intensities, the development of laser particle and

photon sources and the development of the required ultrahigh intensity laser technology.

I will review the status of the program, describing the laser and experimental system

using examples of recent and currently planned experiments on radiation reactions,

electron and ion acceleration and non-linear Compton scattering and outline future plans

and opportunities for collaborations and joined experiments.



Laser hole-boring acceleration of two diamond-like carbon

foils for copious positron production and gama-rays emission

Jin-Jin Liu1, Tong-Pu Yu1,2, Yan Yin1,3,*, Xing-Long Zhu2, Han-Zhen Li1, Jian-Xun Liu1, De-Bin

Zou1, Li-Xiang Hu1, Fu-Qiu Shao1

1. College of Science, National University of Defense Technology, China

2. Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, China



Laser-hole boring acceleration of two colliding foils for bright gamma-rays

emission and dense positrons production is studied by using full three-dimensional

particle-in-cell simulations. It is shown that, when two counter-propagating elliptically-

polarized lasers irradiate two thin diamondlike carbon foils from both sides, the electrons

in the center area are rapidly accelerated to relativistic velocities by the hole-boring type

radiation pressure acceleration. Due to the strong longitudinal expansion, the foils then

become relativistically transparent so that the lasers are capable of penetrating through the

foils and collide with the energetic electrons from another side, resulting in bright gamma-

ray emission via Compton back-scattering. It is shown that dense electron-positron pairs

are produced via the multi-photon Breit-Wheeler process. This compact dense positron

source may have diverse applications, such as nuclear and particle physics for fundamental

research, laboratory study of astrophysics, medical imaging and material science, etc.

Keywords: laser-plasma interaction, electron-positron pairs, gama-rays emission



Multi-stage Proton Acceleration Controlled by Double Beam

Image Technique

Wenpeng Wang

Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, China


A double beam image (DBI) technique is coupled in the two-stage accelerating

mechanism to simultaneously improve the spectra and maximum energy of the proton

beam. The cascaded shock acceleration mechanism and the cascaded TNSA mechanism

work together to generate a proton beam with a narrow-spectrum center at 5.4 MeV and a

long tail up to 14.4 MeV. Experimental and simulation results show that spatial

collineation, time synchronization, and real-time monitoring are needed for optimum two-

stage proton acceleration and are realized by the DBI technique to a certain extent in our

experiment. This DBI technique can be used to achieve optimum two-stage acceleration in

a feasible manner and will allow precise manipulation of multistage acceleration to

improve the energy and spectra of particle beams.

Keywords: proton acceleration



Fast electrons and Ka X-ray produced by laser interactions

with structured targets

Lihua Cao



Ions or protons, pulsed neutron source, X-ray or Ka source is important in laser-

target interactions. The structured targets are promising for enhancing laser-target coupling

efficiency and the qualities of fast electrons. Some structured targets, such as vacuum

capillary, hollow cone with two opens and nanobrush target, were proposed. The

generation of fast electrons was studied by PIC simulation, the emission of Ka photons was

simulated by Monte Carlo simulation.

The physics of a laser pulse interactions with structured targets will be presented.

The quality of the laser pulse can be greatly improved by a vacuum capillary. A hollow

cone with two opens can be used to focus an intense laser to a tiny and highly localized

spot, accompanied by much enhanced light intensity. A copper nanobrush target was

proposed to achieve brighter Ka X ray. The emission of Ka X ray by a nanobrush target

will be presented. The refluxing effect on the yield of Ka photons will be simulated by

adding the electric fields both at the front and rear surfaces of the target with Monte Carlo

code.

Jincui Zhao, Jianhua Zheng, Lihua Cao et al., Phys. Plasmas 23,022705(2016). J.C.

Zhao, L.H. Cao, J.H. Zheng et al., Laser Part. Beams 35,283 (2017). Lihua Cao et al., Phys.

Plasmas 17, 043103 (2010)；Phys. Plasmas 17, 103106(2010)；Phys. Plasmas 18, 054501

(2011). Lihua Cao et al., Phys. Plasmas, 16, 093109(2009). Lihua Cao et al., Phys. Rev. E

78,036405(2008).

Keywords: Fast electrons, Ka X-ray, structured target



Concept study of high-spatial-resolution CT with a laser-based

hard X-ray source

Yang Yue



With the rapid growth of technological innovation in industrial production, the

standard of facility manufacturing has been becoming increasingly important for many

applications. X-ray computed tomography (CT) is introduced to provide densitometric

images of a cross-sectional plane through an object, thus permitting quantitative physical

characterization of its internal structure. Since the industrial imaging of CT cannot offer

high-resolution inspection due to the large spot size of conventional X-ray source, a novel

CT technology based on the laser-plasma bremsstrahlung source is proposed.

In this work, we prove the feasibility of laser-driven compact hard X-rays to realize

high-spatial-resolution tomographic imaging of dense objects by computational

simulations with a consideration of realistic factors including parameter fluctuations,

statistical noise and absorption efficiency of detector. It is found that an appropriate

configuration enables the tomography of high-density objects(19.35g/cc) with a spatial

resolution better than 100μm and CNR>10, indicating an outstanding CT system

performance. And based on the line patterns and modulation transfer function, the

dependences of imaging quality on detector, source, scanning geometry and projection

parameters are investigated to give the solution to satisfy the performance requirements.

This concept provides a promising technical route to achieve high-resolution high-

perspectivity CT imaging by table-top devices, hopefully to be widely utilized in security

inspection, material discrimination, high-precision product testing, defect detection and

other potential applications.

Keywords: high-spatial-resolution; high-perspectivity; X-ray computed tomography;

laser-driven; bremsstrahlung



Generation and applications of >mJ terahertz radiation driven

by relativistic laser pulses

Yu-Tong Li

Institute of Physics, Chinese Academy of Sciences, China


Recently Terahertz (THz) radiation from laser-produced plasmas has attracted

much interest since plasmas can work at arbitrarily high laser intensity. However, only few

experiments with relativistic laser pulses are reported. We have systematically studied

strong THz radiation from solid targets driven by relativistic laser pulses. In this talk, we

will concentrate on the THz generation due to coherent transition radiation of relativistic

laser-driven electron beams when they pass the solid-vacuum boundary. The experiments

are performed with femtosecond and picosecond laser systems respectively. The THz

energy reaches >10 mJ per shot when driven by picosecond laser pulse, which is record.

With the strong THz pulses, we have demonstrated applications, including single shot

imaging, VO2 phase transition, and luminescence emission from Si. The present THz

transition radiation enables not only a potential tabletop brilliant THz source, but also a

novel noninvasive diagnostic for fast electron generation and transport in laser-plasma

interactions.

Keywords: Terahertz radiation, relativistic laser-foil interactions, Transition radiation,

fast electrons



A laser amplifier based on Raman amplification in plasma

G. Vieux1, E. Brunetti1, S. Cipiccia2, B. Ersfeld1, J. P. Farmer3, M. S. Hur4, N. Lemos5, G. H.

Welsh1, S. M. Wiggins1, X. Yang6, S. R. Yoffe1, J. M. Dias7, D. A. Jaroszynski1

1Department of Physics, Scottish Universities Physics Alliance and University of Strathclyde,

Glasgow, G4 0NG, UK

2Diamond Light Source, Harwell Science and Innovation Campus, Fermi Ave, Didcot, OX11

0DE, UK

3Theoretische Physik I, Heinrich Heine Universität, 40225, Düsseldorf, Germany

4UNIST, Banyeon-ri 100. Ulju-gun, Ulsan, 689-798, South Korea

5Lawrence Livermore National Laboratory, NIF and photon Sciences, 7000, East avenue,

Livermore, CA, 94550, USA

6Department of Physics, Capital Normal University, Key Lab of Terahertz Optoelectronics,

Ministry of Education, and Beijing Advanced Innovation Center for Imaging Technology,

Beijing, 100048, China

7GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa,

Lisbon, Portugal


High power, short pulse lasers have become valuable tools for scientists exploring

a wide range of phenomena and developing new technologies such as ultra-compact

wakefield accelerators1 and compact light sources2 with applications ranging from particle

physics to biology. Multi-petawatt laser systems are currently very expensive because they

are based on the chirped pulse amplification (CPA) technique developed in the 1980’s3 to

avoid damage to optical components. Existing large-scale laser facilities make use of

metre-scale optical components to restrict the laser intensity to below their damage

thresholds. This scaling challenge has led to the suggestion of using stimulated Raman

back-scattering (SRBS) in plasma4 as an alternative amplifying method5, because plasma

can sustain very high fields without breakdown of the medium. Similar to solid-state laser

amplifiers, where energy of a monochromatic pump beam is stored in a crystal and

extracted by CPA, energy transfer in plasma can be achieved through SRBS, but without

requiring a temporally stretched seed pulse. While SRBS has potential to drastically reduce

the size and cost of laser systems and reach, in theory, exawatt powers, its feasibility has

only been partially demonstrated in several proof-of-principle experiments, with energy

transfer efficiencies below 10%.



In this talk, we present an overview of the work that has been carried out by the Strathclyde

University group on Raman amplification of short laser pulses6. In particular, we will

discuss the use of the pump frequency chirp to control the amplification process. We will

also review the current challenges of increasing the energy transfer efficiency of this

emerging technology. Finally, we will present an application where we have used Raman

backscattering to locally measure the plasma density7.

References

[1] Tajima, T.; Dawson, J., Phys. Rev. Lett. 43:267, 1979.

[2] Jaroszynski, D. A.; Vieux, G., AIP Conf. Proc. 647:902, 2002.

[3] Strickland, D; Mourou, G., Opt. comm. 56:219, 1985.

[4] Kruer, W., The Physics of Laser Plasma Interaction, Addison-Wesley, Reading, MA,

1988.

[5] Shvets, G.; Fisch, N. J.; Pukhov, A.; Meyer ter Vehn, J., Phys. Rev. Lett. 22:4879,

1998.

[6] Vieux, G. et al., New J. Phys. 13:063042, 2011; Yang, X. et al., Sci. Rep. 5:13333,

2015;

Vieux, G. et al., Sci. Rep. 7:2399, 2017.

[7] Vieux, G. et al., Appl. Phys. Lett. 103:121106, 2013.



High Intensity Lasers and plasma Optics

C. Riconda1,*, J.-R. Marquès2,L. Lancia2, T. Gangolf2,3, M. Blecher3, S. Bolanos2, J. Fuchs2, O.

Willi3,F. Amiranoff1, R. L. Berger4, M. Chiaramello1, S. Weber5

1. LULI, Sorbonne Université, CNRS, Ecole Polytechnique, CEA, Paris, France

2. LULI,CNRS, Ecole Polytechnique, CEA, Université Paris-Saclay, Sorbonne Université,

Palaiseau,France

3. ILPP, Heinrich-Heine Universität Düsseldorf, Germany

4. Lawrence Livermore National Laboratory, Livermore, California 94550, USA

5. Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague, Czech Republic

The use of plasmas provides a way to overcome the damage threshold of classical

solid-state based optical materials which is the main limitation encountered in producing

intense and energetic laser pulses. In particular one can use plasmas to directly amplify

ultra-short laser pulses to high intensities via the three wave coupling equations for

parametric processes. In particular the strong coupling regime of Brillouin (sc-SBS)

scattering is of interest for controlled backscattering in the case of plasma-based

amplification to produce short and intense laser pulses. Recent progresses in this domain

are presented: this includes the role of the global phase in the spatio-temporal evolution of

the 3-wave coupled equations for backscattering that allows to describe the coupling

dynamics and the various stages of amplification from the initial growth to the so-called

self-similar regime. This study also allows to assess the role of the chirp of the laser beams

and of the plasma density profile in the amplification process, and shows how to optimize

or quench the coupling mechanism. It is also found that the directionality of the energy

transfer is imposed by the phase relation at the leading edge of the pulse. This actually

ensures continued energy transfer even if the intensity of the seed pulse is already higher

than the pump pulse intensity.

Recent experimental results are finally presented: optimal interaction conditions

that have allowed to obtain an unprecedented energy transfer in excess of 1.7 J, from a

1.7 ps-9 J pump beam to a 700 fs seed beam of the same wavelength in the sc-SBS

scheme. Numerical simulations confirm that amplification takes place in the first stages

of the interaction as soon as the self-similar regime has been reached and that the pump is

efficiently depleted for the experimental conditions.



Theoretical and experimental studies on THz Radiation via

two-color laser scheme

Wei-Min Wang

Institute of Physics, Chinese Academy of Sciences, China


Strong broadband terahertz (THz) radiation sources are in high demand in THz

spectroscopy and THz-field matter interactions. The widely studied two-color laser scheme

[1] can provide such THz sources with field strengths up to multi MV/cm [2]. In this

scheme, the frequency ratio of the two laser pulses is fixed at w2/w1 =1:2. Recently,

whether this scheme can be extended to other frequency ratios has become a hot issue [3-

5]. Among them, our two theoretic reports [3,5] have predicted that THz radiation can still

be generated with some new frequency ratios w2/w1 =1:4, 2:3, etc.

We present the first experimental demonstration [6] of efficient THz generation

with these new frequency ratios. We scan the w1-laser wavelength with the w2-laser

wavelength fixed and observe that the THz energies have three resonant-like peaks located

near w2/w1= 1:4, 1:2, and 2:3, where the energies at these peaks are at the same order. We

observe the THz polarization can be adjusted by rotating the longer-wavelength laser

polarization and the polarization adjustment becomes inefficient by rotating the

polarization of the other laser with shorter wavelength. This phenomenon agrees with a

fourth-power law of the laser wavelength, which is derived by us.

Our investigation [6] also provides a new dimension to explore the THz-generation

mechanism. Our experimental results contradict with multi-wave mixing theory, which is

one of two main models to explain the THz-generation mechanism under two-color laser

excitation. This theory predicts that THz yield obeys different scaling laws with different

frequency ratios, but we observe similar scaling. On the other hand, this observation agrees

with the other model: plasma-current or gas-ionization model [7-9].

Keywords: THz Radiation, laser plamsa interactions

Reference

[1]J. Cook and R. M. Hochstrasser, Opt. Lett. 25, 1210 (2000).

[2]M. Clerici, M. Peccianti, B. E. Schmidt et al., Phys. Rev. Lett. 110, 253901 (2013).

[3]W.-M. Wang, Y.-T. Li, Z.-M. Sheng, X. Lu, J. Zhang, Phys. Rev. E 87, 033108 (2013).

[4]V. Kostin, I. Laryushin, A. Silaev, N. Vvedenskii, Phys. Rev. Lett. 117, 035003 (2016).

[5]W.M. Wang, Z.M. Sheng, Y.T. Li, Y. Zhang, J. Zhang, Phys. Rev. A 96, 023844 (2017).

[6]L.-L. Zhang, W.-M. Wang, T. Wu et al., Phys. Rev. Lett. 119, 235001 (2017).

[7]K. Y. Kim, J. H. Glownia, A. J. Taylor, and G. Rodriguez, Opt. Express 15, 4577 (2007).

[8]W.-M. Wang, Z.-M. Sheng, H.-C. Wu et al., Opt. Express 16, 16999 (2008).



[9]W.-M. Wang, P. Gibbon, Z.-M. Sheng, Y.-T. Li, Phys.Rev. Lett. 114, 253901 (2015).



Ultra-brilliance isolated attosecond gamma-ray light source

from nonlinear Compton scattering

Jinqing Yu



In this work, we propose a novel method to generate high charge (~1nC) attosecond

(<200 attosecond) electron bunch by the near-threshold self-injection mechanism in

wakefield acceleration with current-generation laser, and demonstrate the ability to

generate an ultra-brilliance (> 2 ×1024 photons s-1 mm-2 mrad-2 0.1%BW) attosecond

(<200 attosecond) gamma-ray (Emax > 3 MeV) pulse via nonlinear Compton scattering.

To the best of our knowledge, this is the first method to generate attosecond gamma-ray

photon source using current-generation laser. This gamma-ray source is the shortest

gamma-ray photon source even compared with the results (>800 attosecond) generated

with next-generation laser, and the highest brilliance (orders higher than the results,

reported) photon source in MeV range. This method can be widely applicated for

experimental generation of 100 keV to several MeV high brilliance attosecond gamma-ray

sources with certain ~100 TW laser facilities, will benefit ultra-high resolutions

radiography application and some basic science.

Keywords: isolated attosecond gamma-ray; attosecond electron bunch; self-focusing;

nonlinear Compton scattering



Attosecond control and temporal characterization of surface

high harmonics generation

Li, Lu

*Email:

Keywords:



Laser-plasma optical elements, accelerators, and radiation

sources: new tools for science

Dino Jaroszynski

University of Strathclyde, Glasgow, Scotland, UK

The talk will review progress at the University of Strathclyde, Scotland, in

developing laser-plasma-based optical elements, accelerators and radiation sources, and

their applications. These next-generation, ultra-compact devices have a niche potential for

some applications, and could become widespread because of their lower cost and

compactness, when compared with conventional technologies. Laser-driven radiation

sources and accelerators can be three or four orders of magnitude smaller than conventional

devices. The use of plasma as a robust optical medium, and for the generator of ultra-high

electrostatic fields leads to unique radiation parameters, including ultra-short pulse

duration, ultra-high intensity, high brightness etc. We present experiments where the

duration of electron bunches from a laser wakefield accelerator (LWFA) has been deduced

from the spectra of coherent transition radiation, which shows that bunches of one

femtosecond can be produced. This is surprisingly short, and two orders of magnitude

shorter than from conventional accelerators. We show that 100 attosecond pulses should

be possible, which would lead to peak currents in excess of 10 kA, even for modest charges.

The measured energy spreads of less than 1% at ~100 MeV shows that they should be

suitable for driving a free-electron laser (FEL). Though still a challenge, the development

of a FEL based on the LWFA should be feasible.

However, laser-plasma structures have some interesting intrinsic properties that can

be taken advantage of. They can have extremely large fields, in excess of 100 GV/m, which

can also drive transverse “betatron” motion of electrons. This gives rise to wiggler-like

femtosecond duration pulses of X-ray radiation. We show that instabilities arising from the

ponderomotive force leads to coherence build up, which could lead to the replacement of

long magnetic undulators by plasma undulators, as in the ion channel laser. We will discuss

experiments where we have observed femtosecond duration pulses of incoherent gamma-

ray betatron radiation with photon energies up to 7 MeV. The inferred peak brilliances are

similar to third generation synchrotron sources, but in a photon energy range that is not

usually accessible. We will also discuss how intense coherent THz radiation is produced

from a plasma dipole, and coherent transition radiation emitted as 10-50 nC bunches of

electrons emitted from the LWFA pass through thin metal foils or on the plasma-vacuum

boundary. We also discuss how plasma structures can be produced using colliding laser

pulses to generate plasma echelons that can be used manipulate, amplify and compress

light.



High Energy Density Science at FAIR - Planned experiments

and facilities

Stephan Neff

Facility for Antiproton and Ion Research, Germany


At the site of the Gesellschaft fuer Schwerionenforschung (GSI) in Darmstadt, the

Facility for Antiproton and Ion Research (FAIR) is currently under construction. FAIR will

offer unique high-intensity heavy ion beams and high-intensity proton beams for

experiments covering many fields of research.The research activities in the field of high

energy density (HED) physics and warm dense matter (WDM) research are carried out by

the High Energy Density Science at FAIR (HED@FAIR) collaboration. In the planned

experiments, the heavy-ion beams can be used to heat or compress macroscopic, mm-sized

samples (HIHEX and LAPLAS experimental schemes). Another possibility is to use high-

intensity proton beams to study dense samples with proton microscopy (PRIOR).In my

presentation, I will give an overview of the planned experiments and of the experimental

facilities that will be available for HED and WDM research. In addition, I will also present

the opportunities for HED and WDM experiments at GSI in the time until the start of FAIR.

Keywords: HED, HED@FAIR, PRIOR, LAPLAS, HIHEX, Proton microscopy



Muon generation, detection and acceleration in laser wakefield

Feng Zhang



Muons produced by short pulse laser can serve as a new type of muon source having

potential advantages of high intensity, small source emittance, short pulse duration, and

low cost. To validate it in experiments, a suitable muon diagnostics system is needed since

high muon flux generated by short pulse laser shot is always accompanied by high radiation

background, which is quite different from cases in general muon researches. A detection

system is proposed to distinguish muon signals from radiation background by measuring

the muon lifetime. It is based on the scintillator detector with water and lead shields, in

which water is used to adjust energies of muons stopped in the scintillator and lead to

against radiation background. A Geant4 simulation on the performance of the detection

system shows that efficiency up to 52% could be arrived for low energy muons around 200

MeV and this efficiency decreases to 14% for high energy muon energy above 1000 MeV.

The simulation also shows that the muon lifetime can be derived properly by measuring

attenuation of the scintilla light of electrons from muon decays inside the scintillator

detector. Furthermore, muons produced by the Bethe-Heitler process from laser wakefield

accelerated electrons interacting with high Z materials have velocities close to the laser

wakefield. It is possible to accelerate those muons with laser wakefield directly. Therefore

for the first time we propose an all-optical "Generator and Booster" scheme to accelerate

the produced muons by another laser wakefield to supply a prompt, compact, low cost and

controllable muon source in laser laboratories. The trapping and acceleration of muons are

analyzed by one-dimensional analytic model and verified by two-dimensional particle-in-

cell (PIC) simulation. It is shown that muons can be trapped in a broad energy range and

accelerated to higher energy than that of electrons for longer dephasing length. We further

extrapolate the dependence of the maximum acceleration energy of muons with the laser

wakefield relativistic factor γ and the relevant initial energy E0. It is shown that a maximum

energy up to 15.2 GeV is promising withγ= 46 and E0 = 1.45 GeV on the existing short

pulse laser facilities.

Keywords: Muon source, Laser wakefield



First-Principles Calculations of X-ray Thomson Scattering of

Warm Dense Matter

Chongjie Mo



Through the perturbation formula of time-dependent density functional theory

(TDDFT) broadly employed in the calculation of solids, we provide a first-principles

calculation of the electronic dynamic structure factor in warm dense region.

The calculated results are directly used to compare with the experimental X-ray

Thomson scattering spectrum of warm dense matter, and most of them are consistent well

with the measurements.<br>The deviations between our results and the previous

measurements may well reveal the unique electronic properties of warm dense matter

different from solids, which can be further illustrated by future experiments.

Keywords: X-ray Thomson Scattering, Warm Dense Matter, First-Principles



Laser Ray Tracing Simulation on Three-dimensional

structured grids

Rong Yang



An algorithmic is presented for laser beam evolution on three-dimensional

structured grids composed of hexahedra. The geometrical-optics approximation to the

electromagnetic wave equation is used to follow propagation of a collection of discrete

rays used to represent the beams. Ray trajectories are obtained by solving the ray equation

of motion, in which the electron number density is shown to play the role of an effective

potential. The spatial variation of the electron density within a computational mesh cell is

modeled with a linear approximation. It is constructed by Gauss formula along a new

defined equivalent face for arbitrary non-planar surface. Furthermore, the basic algorithmic

for three-dimensional laser ray tracing is briefly described. The trajectory passing through

different grids from arbitrary direction could be calculated. The program is coupled with

the radiation hydrodynamics code. Numerical experiments are presented to verify the

applicability and accuracy of the new algorithm. Test examples shows the results have

better precision and adaptability. Several examples show that it performs well on three

dimensional ICF application simulation.

Keywords: laser ray tracing, three-dimensional structured grids



Electron acceleration and betatron emission from ps laser

plasma interactions

Xiao-Hui Zhang1,*, Ke-Gong Dong1, Bin Zhu1, Yu-Qiu Gu1, Da-Zhang Li2,Li-Ming Chen2

1. Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center

2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese

Academy of Sciences, China


Betatron radiation from laser plasma acceleration has been used to characterize the

laser wakefield acceleration progress and image biology objects. It has been proposed to

used high power ps laser to produce betatron radiation for high energy density diagnosis.

As there are many electrons involved using ps laser, it supposed to produce much more

photons than using fs laser. We conducted the first experiment in China to produce betatron

radiation on a ps laser facility—the ps beamline of the XGIII laser facility in LFRC. As

much as 30nC electrons with energy more than 5MeV were detected with image plate

stacks in the experiment. The electron beams had a quasi-maxwellian spectrum and

extended to 120MeV. We demonstrated that both DLA and SM-LWFA worked in the

acceleration progress. The spectrum of the betatron radiation was characterized by metal

foils. We also used the radiation to image the optical resolution test board. The resolution

was better than 120 µm, limited by the experimental setup.

Keywords: betatron radiation, ps laser



Propagation and Modulation of Intense Short Laser Pulse in

Near Critical Density Plasma

A. Ting1,*, B. Hafizi2, T. Antonsen1, Y.H. Chen2, C. Miao1, L. Johnson2, D. Gordon2

1. Institute for Research in Electronics & Applied Physics, University of Maryland, USA

2. Plasma Physics Division, Naval Research Laboratory, USA


Near critical density plasma are being used in many applications such as laser ion

acceleration where the slowing down of the laser pulse affects the propagation and interaction of

the intense laser pulse with the plasma. The perturbation on the plasma density is generally

achieved through the ponderomotive force of the intense laser field and the resultant plasma

wakefield provides the large longitudinal electric field for the acceleration of particles such as

electrons and ions. This wakefield generation traditionally has been characterized into two regimes,

the laser wakefield acceleration (LWFA) and the self-modulated laser wakefield acceleration (SM-

LWFA).The distinction is simply the ratio of the laser pulse length to the plasma period, where it

is ~ 1 for LWFA and >>1 for SM-LWFA. With the advance of femtosecond intense laser

technology, laser pulse lengths have been short enough such that for most sub-critical plasma

conditions, the LWFA condition can always be achieved. When near critical density plasma is

employed, even for the tens of femtosecond laser pulses, the plasma period will become almost as

short as the period of the carrier wave of the laser such that the SM-LWFA condition inevitably

will occur. Similar condition no doubt will also occur when laser pulses interact with solid surfaces

and the rapidly expanding plasma from the solid surface will go through a density gradient region

where near critical density condition holds.

There exists, therefore, an interesting regime where the laser pulse can potentially be

modulated very near the laser frequency with large amplitude wakefields being generated. The

group velocity of the laser pulse in near critical density plasma can be substantially lower than the

vacuum speed of light, leading to much lower phase velocities for the associated wakefields. Any

trapped particles, most likely the lighter electrons, would accelerate to lower maximum energies

before dephasing occurs. Large quantities of electrons would be trapped and a large current of

relatively low energy electrons would be swept up from the background plasma. The large but low

energy electron current moves forward with the laser pulse and can be a useful source of high

current short pulse electron beams. Many issues need to be studied to realize this outcome, among

which include, the modulation of a laser pulse at frequencies close to the carrier frequency where

spectral components could be travelling at vastly differing speeds due to severe dispersion

conditions. Density gradients encountered by the laser pulse as it enters the plasma would introduce

varying modulation frequencies as the laser pulse propagates, and thus disrupt synchronism and

amplification of the modulation in the laser pulse. Nonlinear self-focusing of the laser also would

be varying in a plasma with density gradient. In addition, intense short laser pulses also undergo

substantial dispersive pulse length modification due to their large bandwidths. We are studying

both analytically and numerically these propagation issues to investigate the modulation of intense

laser pulse by near critical density plasma with density gradients. Results show that the modulation




can be developed despite the high density, plasma gradient, self-focusing, and dispersion.

Dependences of the modulation on these propagation conditions will be shown and discussed.



Vlasov simulations of wave-wave and wave-particle

interactions in plasma

B. Eliasson

SUPA, Department of Physics, University of Strathclyde, Glasgow, United Kingdom

Vlasov simulations are attractive due to the low numerical noise, in particular in

studies of mildly nonlinear wave-wave and wave-particle interactions, or when the low-

density tail of the momentum (or velocity) distribution function has to be resolved

accurately. Examples include the Raman instability, investigations of nonlinear kinetic

structures (Bernstein-Greene-Kruskal-like modes), and the coupling to electron Bernstein

modes in magnetized plasma [1,2]. Lower-dimensional Vlasov simulations can show good

convergence and thus become an attractive complement to particle-in-cell simulations. The

conservation of transverse canonical momentum is conveniently used to reduce the number

of momentum dimensions in Vlasov simulations of relativistic laser-plasma interactions

[3], and in more general cases fluid moments can be taken in transverse directions and fully

kinetic modelling kept along dominant directions. We will present Vlasov simulations of

relativistic laser-plasma interactions [2,4], the interaction with electron and ion holes in

plasmas [5], and parametric interactions with electron Bernstein waves in magnetized

plasmas [6].

Reference

[1] B. Eliasson, Transp. Theor. Stat. Phys.39(5&7), 387-465 (2010).

[2] B. Eliasson, C. S. Liu, P. K. Shukla and N. Kumar, PhysicaScripta73, 632-638

(2006).

[3] B. Eliasson, C. S. Liu, X. Shao, R. Z. Sagdeev, and P. K. Shukla, New J. Phys.11,

073006 (2009).

[4] P. K. Shukla and B. Eliasson, Phys. Rev. Lett.94, 065002 (2005).

[5] B. Eliasson and P. K. Shukla, Phys. Rev. Lett.93(4), 045001, (2004); ibid. 92(9),

095006 (2004).

[6] D. C. Speirs, B. Eliasson, and L. K. S. Daldorff, J. Geophys. Res. - Space Phys.122,

10638 (2017).



Petascale kinetic simulations of laser plasma interactions

relevant to inertial fusion — controlling laser plasma

interactions with laser bandwidth

Han Wen

University of California, Los Angles, USA


Large scale (> 10 million cpu hours) particle-in-cell (PIC) simulations have been

performed with parameters relevant to initial confinement fusion (ICF). In three (and two)

dimensions, we have studied the interplay between hight frequency hybrid instability

(HFHI) and side scattered stimulated Raman scattering (SRS) near quarter-critical densities.

Furthermore, we are performing very large scale simulations with increasing realism,

including laser speckles and temporal beam smoothing such as induced spatial incoherence

(ISI) and smoothing by spatial dispersion (SSD), and Spike Train of Uneven Duration and

Delay (STUD pulses). Simulation results show that SRS can be greatly reduced with laser

bandwidth comparable to the temporal growth rate of the instability.

The kinetic effects have been found to be important for SRS at low plasma densities.

Future works will also be discussed.




Analysis of stimulated scattering of the outer beam in

experiments on SG-III facility

Yaoyuan Liu1,2,*, Dong Yang2, Jian Zheng1,4, Tao Gong1, Liang Hao3, XinLi3, Zhichao Li2, Tao

Xu2, Weiyi Zha2, Xiaoshi Peng2, Guangyue Hu1,Yongkun Ding3

1. Department of Modern Physics, University of Science and Technology of China, China





In the indirect-drive inertial confinement fusion (ICF), it is complex and difficult

to control the driven asymmetries in the traditional cylindrical hohlraum with two laser

entrance holes (LEHs), due to the laser-plasma interactions of inner beams, such as the

simulated Raman scattering (SRS) and cross-beam energy transfer (CBET). Recently, the

three-axis cylindrical hohlraum with six LEHs and single cone laser beams is put forward,

in which the stimulated Brillouin scattering (SBS) is dominant. To understand the

processes when one cone beams exist only, the experiments were performed on

Shenguang-III (SG-III) facility. The traditional cylindrical hohlraum without capsules was

employed, with the existence of LEH in one side and none in the other side. The spectra of

SRS and SBS were observed by the full-aperture backscatter systems (FABS). The results

with different laser intensity and LEHs are shown in this presentation. To deal with the

spectra of SBS and SRS, we develop a steady-state stimulated scattering program for one

dimensional configuration, S4P-1D. The temporal plasma parameters are given by the two-

dimensional radiation hydrodynamic code LARED-JC. The volume noise sources

(attributed by both the bremsstrahlung and Thomson scattering), inverse bremsstrahlung

absorption, boundary noise and pump depletion are included in our model. The time-

resolved spectra of simulations and experiments show similar features for the hohlraum

with or without LEH. At the time with high level reflectivity, it is indicated that the SBS

grows fastest in the high density regions of gold bubble and amplifies convectively in the

CH plasma, through the intensity versus the distance along laser. And SRS grows mainly

in the CH regions. Both for SBS and SRS, the noise sources are dominant by the Thomson

scattering. The transient reflectivity of SBS has a rapid increase at the rising edge of main

pulse in experiments, which is caused by the shock wave ablating from the polyimide

window from our analysis. This work shows a practicable method to comprehend the

scattering spectra of outer beams in SG-III facility, which is helpful for the design of the

next generation of ignition facility.

Keywords: stimulated Raman scattering, stimulated Brillouin scattering, outer beam,

laser-plasma interactions, SG-III facility



A new method of measuring magnetic and electric fields in a

Tokamak using a laser-accelerated ion-beam trace probe

Chen Lin Xiaoyi Yang Yihang Chen Long Wang Tianchao Xu MInjian Wu Chijie Xiao

SKL of Nuclear Physics and Technology,Peking University, China


A compact laser plasma accelerator (CLAPA) has been built at Peking University.

Proton beams with 3-15 MeV and good stability have been demonstrated. Compared with

the mono-energetic ion beam accelerated by traditional electrostatic accelerator, the laser-

driven ion beam has three properties: large energy spread, short pulse lengths, and multiple

charge states, which considered as hindrances to its application. Here we proposed a new

method to diagnose both Bpand Erin a tokamak device at the same time, which is named

Laser-accelerated Ion-beam Trace Probe (LITP). LITP takes advantage of all three

properties of laser driven ion beam mentioned above, providing the 1D/ 2D images of both

Bpand Erwith precious time and spatial resolution. A PKU Plasma Test (PPT) device has

also been constructed to simulate one segment of the tokamak plasma. The preliminary

CLAPA-and-PPT joint experiment results agree well with the theoretical calculation. LITP

is not only the first practical application of laser ion acceleration technology in magnetic

confinement fusion, but also is great significance for future combustion plasma diagnosis

and experimental research.

Keywords: Laser driven ion acceleration, plasma diagnosis, magnetic confinement fusion



Ultra-bright gamma-ray emission and dense positron

production with PW lasers

Tongpu Yu

National University of Defense Technology


Matter can be transferred into energy and the opposite transformation is also possible

by use of high-power lasers. A laser pulse in plasma can convert its energy into gamma-

rays and then electron-positron pairs via the multi-photon Breit-Wheeler process. The mass

production of electron-positron pairs is presently attracting immense research interest due

to their potential applications in various fields. Until now, the obtained positron beams in

laser-plasma experiments have so far been either with <1017 cm-3 or a small energy

<100sMeV with a limited laser energy conversion efficiency <0.02%.

In this work, we address these critical issues. Here we propose an all-optical scheme

for ultra-bright gamma-ray emission and dense positron production with lasers at intensity

of 1022-23 W·cm-2. By irradiating two colliding elliptically-polarized lasers onto two

diamondlike carbon foils, electrons in the focal region of one foil are rapidly accelerated

by the laser radiation pressure and interact with the other intense laser pulse which

penetrates through the second foil due to relativistically induced foil transparency. This

symmetric configuration enables efficient gamma-photon emission with unprecedented

brightness of 1025 photons /s/mm2/mrad2/0.1%BW at 15 MeV and intensity of 5×1023

W·cm-2. A GeV positron beam with density of 2.5×1022 cm-3 and flux of 1.6×1010/shot is

achieved. Collective effects of the pair plasma may be also triggered, which allows a few

nonlinear QED effects to be tested experimentally with the upcoming 10 PW lasers in the

foreseeable future. To the best of our knowledge, it the first time to report such high-

brightness ultra-short gamma-ray emission and dense positron production in full 3D

configuration of laser-foil interaction.

Keywords: high power lasers; electron-positron pair; near-critical-density plasma;

radiation pressure acceleration;nonlinear Compton scattering

Reference

[1] X. L. Zhu, T. P. Yu, Z. M. Sheng, et al., Nat. Commun. 7, 13686 (2016)

[2] H. Z. Li, T. P. Yu, J. J. Liu, et al, Sci. Rep. 7, 17312 (2017)

[3] H. Z. Li, T. P. Yu, L. X. Hu, et al, Opt. Express 25, 21583-21593 (2017).



Laser plasma parametric Instabilities

R Bingham1,2,*, R Trines1, H Schmitz1, A Cairns3, E Los4, R Fonseca5, J Vieira6, L Silva6.

1. Rutherford Appleton Laboratory, Harwell, Didcot, UK

2. Department of Physics, University of Strathclyde, Glasgow, UK

3. School of Mathematics and Statistics, University of St Andrews, UK

4. University of Manchester, Manchester, UK

5. DCTI/ISCTE Lisbon University Institute, Portugal

6. GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de

Lisboa, Lisbon, Portugal

There is renewed interest in parametric instabilities of intense lasers in inertial

fusion and laser pulse amplification. In both direct and indirect drive inertial fusion it is

well known that cross beam energy transfer, a Brillouin scattering process, can be helpful

in transferring energy between laser beams in indirect drive. It can also be detrimental in

inertial fusion by scattering beams away, reducing the energy delivered to the pellet. The

parametric instabilities such as stimulated Raman and Brillouin scattering are two schemes

being investigated as possible schemes for the amplification and compression of laser

pulses in plasmas. Other parametric instabilities will also be discussed such as two plasmon

decay, the oscillating two stream, and the parametric decay instability and there role in

inertial fusion. The role of the filamentation instability in laser plasma wakefield

accelerators and inertial fusion will also be presented. I will present new studies of the role

these parametric processes play in these different areas of laser plasma coupling.



Laser-plasma instabilities and hot electron generation in shock

ignition

Chuang Ren

*Email:

Keywords:



Exploration of located hohlraum-plasma evolution using

Thomson scattering technique

Zhichao Li1,*, Hang Zhao1, Dong Yang1, Yongkun Ding2, Tao Gong1, Xiaohua Jiang1,

YonggangLiu1, Feng Wang1, Shenye Liu1, Jiamin Yang1, Shaoen Jiang1, Baohan Zhang1

Xin Li1, Hongbo Cai1, Shiyang Zou1, Changshu Wu1, Wudi Zheng1,

Peijun Gu1,Shaoping Zhu1, Jian Zheng3



3. University of Science and Technology of China, China


Laser-driven X-ray hohlraums are important in many areas of high energy density

physics (HEDP). The hohlraum is a highly dynamic and complex environment due to the

development of concurrent processes such as laser plasma interaction (LPI), particle and

radiation transport. Modeling this environment requires advanced knowledge of nonlocal

thermal equilibrium atomic physics and nonlocal electron transport. Thomson scattering

has played an important role in the exploration of the hohlraum physics by providing

accurate plasma condition with high temporal/spatial resolution. In recent years, several

optical Thomson-scattering diagnostics have been designed and implemented in China’s

Shenguang laser facilities, along with the experimental campaigns for charactering the

complex hohlraum plasmas.

The Thomson scattering diagnostic uses an additional 263nm laser as the probe beam

on Shenguang-III prototype laser facility, which capable of delivering a maximum 351nm

laser energy of ∼10 kJ with 8 laser beams. A delicately designed hohlraum is used to create

a quasi-two-dimensional condition by irradiating a laser ring on the hohlraum waist. High-

quality ion feature spectra have been obtained with these gas-filled hohlraums. The plasma

evolution and kinetic behavior at different regions inside the hohlraum are explored

through comparing the post-processed Thomson-scattering spectra based on rad-hydro

simulation with the experiment. Another Thomson scattering diagnostic is set up on

Shenguang-III laser facility, one of the largest laser facilities in the world whose output of

351nm laser energy with 48 laser beams can be 180kJ. The hohlraum environment is more

difficult to model because of more complicated laser geometry and much higher energy

density. Typical ion feature spectra of the collective Thomson-scattering are obtained. The

result is analyzed by a newly developed method which includes several models such as the

resolution of the diagnostic system, the optical background from bremsstrahlung emission

of the plasmas and the Thomson-scattering of the 351nm heater beams. Detailed analysis

evalutated the influences of the gradientof theplasmas and the evolution of internal electron

density. This diagnostic is believed to make significant contributions to understanding the

physics inside the hohlraum and benchmarking radiation-hydrodynamic simulations.

Keywords: Thomson scattering, hohlraum, plasma evolution



Cavitation structure evolution during ultra-intense laser near-

critical density plasma interaction

Yanqing Deng1, 2, *, Dongning Yue1, 2， Muhammad Noaman-ul-Haq 1, 2, Yaojun Li 1, 2, Xu Zhao 1,

2, Xulei Ge1, 2， Wenqing Wei1, 2, Jian Gao1, 2,Yuan Fang1, 2, Min Chen1, 2，Feng Liu1, 2, Xiaohui

Yuan1, 2

1、Key Laboratory for Laser Plasmas (Ministry of Education) Department of Physics

and Astronomy

2、Collaborative Innovation Center of IFSA（CICIFSA）Shanghai Jiao Tong

University


With the development of ultra-intense laser, increasingly importance has been

attached to the ion or radiation source based on laser plasma interaction (LPI), especially

since the gas target with near-critical densities (NCD) is available in recent years. An

efficient coupling between a laser pulse and a plasma takes place at NCD, which could

further induce many novel nonlinear phenomena like: plasma instability and nonlinear

coherent structures, electric vortex and electro-magnetic solitons.

We performed our preliminary ultra-intense laser NCD plasma interaction at

Shanghai Jiao Tong University using a 200 TW ultra-short Ti: Sapphire laser system.

Time-resolved diagnosis of plasma structure and spatial evolution was obtained by

applying the optic probe (shadowgraph and interferometry). Two characteristic structures

were observed: A single plasma cavity and filaments (as shown in Fig.1), which are

different with the plasma channel in laser wake-field acceleration (LWFA). The cavitation

occurs at the beginning of the interaction and reach the quasi-stable state (500 μm in

longitudinal direction and 300 μm in transverse direction) in 2~3 ps which could maintain

almost 30 ps before breaking. The filaments emerge when cavity is quasi-stable and fast

expand to around 300 μm longitudinal size at half-light speed then reach its own quasi-

stable. Structure dependence of gas type, density, laser focus position and pulse duration

were investigated in the experiment. A comprehensive research about the structure would

provide a further understanding of laser transport in NCD gas and the energy coupling




dynamics, which has a promising potential application for ion acceleration and radiation

research.

Fig.1 Typical shadowgraph of cavity and filaments structure



On the hot-electron generation produced by two-plasmon

decay and stimulated Raman scattering in inhomogeneous

plasmas

C. Z. Xiao1, ∗, Z. J. Liu2, 3, C. Y. Zheng2, 3, 4, H. B. Zhuo5, Y. Yin5, X. T. He 2, 3, 4

1. School of Physics and Electronics, Hunan University, Changsha, China


3. HEDPS, Center for Applied Physics and Technology, Peking University, China

4. Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, China

5. College of Science, National University of Defense Technology, Changsha, China


Hot-electron generation in inhomogeneous plasmas are of great significance in

inertial confinement fusion such as direct-drive scheme, shock ignition, and hybrid drive

scheme. We propose a model based on the wave-particle interaction to estimate hot

electrons produced by plasma waves, especially by stimulated Raman scattering (SRS) and

two-plasmon decay (TPD). It is found that suppression occurs when SRS is dominant over

TPD near the quartercritical density. In two-dimensional particle-in-cell simulations, we

observe such transition from TPD dominant regime to SRS dominant regime at ignition

conditions. The consequence of the transition is the decrease in hot-electron fraction, which

has already been observed in direct-drive and shock ignition experiments but obtains

clearly physical interpretation for the first time. Once the threshold for convective SRS is

surpassed, convective rather than absolute instability nature is dominant and convective

SRS strongly suppresses TPD resulting in suppressing of hot-electron generation and

increasing of reflectivities, and the maximum hot-electron fraction is just located at the

threshold with the value of 2%. Influences of dimensional effects on the simulation model

are also discussed.

Keywords: hot electrons, two-plasmon decay, stimulated Raman scattering




The propagation of intense laser and particle acceleration in

presence of external magnetic field

J. X. Gong*, L. H. Cao, X. T. He

Center for Applied Physics and Technology, Peking University, Beijing, China


Laser plasma accelerator has attracted plenty of interest for its remarkable advantages.

Electron acceleration and proton acceleration are two main items in it. For our work, the

propagation of left-hand (LH-) and right-hand (RH-) circularly polarized (CP) lasers and

the accompanying acceleration of fast electrons and protons (accelerated by target normal

sheath field) in a magnetized cone-target with pre-formed plasmas are investigated. In this

work, the strength of external magnetic field is comparable to that of the incident laser.

Theoretical analyses indicate that the cut-off density of LH-CP laser is larger than that

without an external magnetic field. When the external magnetic field normalized by the

laser magnetic field is larger than the relativistic factor, the RH-CP laser will keep on

propagating till the laser energy is depleted. The theoretical predictions are confirmed by

two dimensional (2D) particle-in-cell (PIC) simulations. Simulation results show that in

the presence of an external longitudinal magnetic field, the energies and yields of fast

electrons and protons are both greatly enhanced for RH-CP laser. Besides, the coupling

efficiency of laser energy to energetic electrons for RH-CP laser is much higher than that

from LH-CP and without an external magnetic field. The divergency of electrons and

protons are suppressed remarkably by the external magnetic field. Furthermore, for RH-

CP laser, detailed simulation results perform an enhancement of incident laser absorption

and the maximum proton energy with increasing external magnetic field.

References

[1] M. Tabak, J. Hammer, M. E. Glinsky, et al., Phys. Plasmas 1, 1626 (1994).

[2] F. F. Chen, Introduction to Plasma Physics and Controlled Fusion, Vol 1: Plasma

Physics, 2nd ed. (Plenum Press, 1984).

[3] J. X. Gong,L. H. Cao,K. Q. Pan,C. Z. Xiao,D. Wuand X. T. He, Phys. Plasmas 24,

033103 (2017).



Stimulated Raman Scattering: Convective and Absolute

instabilities

Chuansheng Liu

*Email:

Keywords:



Laser Plasma Instability in Indirect-Drive Inertial

Confinement Fusion: From Shenguang-II to Shenguang-III

Dong Yang1,3,*, Liang Hao2, Zhichao Li1, Xin Li2, Tao Xu1, Yaoyuan Liu1,3, Sanwei Li1, Weiyi

Zha1, Xiaoshi Peng1, Chunyang Zheng2, Zhanjun Liu2, Yulong Li1, Liang Guo1, Hang Zhao1, Jian

Zheng3, Xiaohua Jiang1, Feng Wang1, Shenye Liu1, Jiamin Yang1, Shaoen Jiang1, Yongkun Ding1

and Baohan Zhang1





The goal of laser plasma instability (LPI) study in the indirect-drive inertial

confinement (ICF) fusion is to minimize its uncertainty during the coupling of laser energy

to capsule. Because the quantitative interpretation of LPI reflectivity has always been a

major challenge, continuous experimental efforts on laser-plasma couplings are conducted

in different irradiation and plasma condition on Shenguang laser facilities. These works

focus on two major issues. First is suppressing the scattered light at acceptable levels to

enable the exploration of high energy density physics on the existing laser facility, which

is always achieved by optimizing the target design and beam smoothing. Second is

assessing the LPI risk in the future laser fusion scheme on the next generation of laser

facility in which the LPI gain was insufficient to have noticeable effects on energetics or

symmetry. It is achieved by deliberately producing a large scale plasma and high laser

intensity consistent with future ignition target design. The 10 kJ level (3w laser output

energy) Shenguang-III prototype is the first case we have to seriously control the LPI.

Vacuum hohlraum shots shown 20-40% SBS levels and large shot-to-shot fluctuations.

This scattered light was mitigated by keeping the laser intensity below 5×1014 W/cm2 with

phase plates. Shenguang-III is built to operate at an energy of 180 kJ using 48 UV lasers.

Initial 100kJ scale experiments using gas-filled hohlraums exhibits evident beam-to-beam

backscatter difference even in the same cone. The focal spot as well as the SRS spectra of

multiple beams are studied to elucidate whether the beam condition or the plasma condition

might be distinct between different laser beams of the same cone. The SRS spectra suggest

the beam-to-beam backscatter difference often correlates with the plasma condition in

some shots. Thus a gas-filled hohlraum with one side LEH truncated is employed to study

the beam propagation in large, hot and well-defined plasmas. The SRS and SBS backscatter

is studied when the A6S2/A6S4 beam intensity is from 5×1014 W/cm2 to 1.5×1015 W/cm2

while keeping other heaters beams energy constant. The beneficial effects of beam

smoothing, the competition of instabilities in large-scale plasmas, the influence of LEH

size are also explored in combination with a rad-hydro and LPI simulation.

Keywords: LPI, scatter light, SRS, SBS, hohlraum



Study of the secondary laser plasma instabilities in ICF with

FLAME code

Liang Hao



Laser plasma instability (LPI) is an important issue in ICF. As known, the primary

instabilities such as SRS, SBS, TPD are important nonlinear processes in both direct and

indirect drive. Besides these primary instabilities, daughter waves in primary instability

can work as a pump wave and stimulate some kinds of secondary instabilities. In this work,

we study the coupling between the secondary LPIs and the primary LPIs with non-envelope

fluid code FLAME in different ignition regimes. In direct drive regime, Langmuir wave of

absolute SRS near 1/4nc induces cascade Langmuir decay instability (LDI), which saturate

the growth of absolute SRS. The forward ion-acoustic wave in LDI can work as a seed of

SBS, which results in strong pump depletion and strong burst process. The scattered light

of absolute SRS propagate backward and stimulates the re-scatter of SRS near the 1/16nc,

where the amplitude of secondary Langmuir wave is large and the strong ponderomotive

force of the secondary Langmuir wave results in cavity around 1/16nc. In indirect regime,

the scattered light of convective SRS also have chance to stimulate the re-scatter of SRS at

certain low density region. This re-scatter process limits the amplified level of scattered

light in primary convective SRS and convert part of its energy into the secondary scattered

light and secondary Langmuir wave, which have the higher collisional damping rates. This

part of energy is deposited in the low density region through the daughter waves in re-

scatter and has less contribution in X-ray conversion. This effect might be a reason of the

"energy deficit" observed in experiments on NIF facility.

Keywords: ICF LPI SRS SBS LDI Re-scatter



Reduction of Crossing Beam Transferred Energy by Ion

Transfer Effect

Jinlong Jiao

National University of Defence Technology, China


Crossing beam energy transfer (CBET) is an important effect that must take into

account in laser driven inertial confinement fusion (ICF). It will change the energy

distribution during laser beams crossing each other. The laser beams energy redistribution

will affect the implosion symmetry significantly. The understanding of CBET can help us

to modify and improve the simulation code used in ICF. However, the results of numerical

simulation that it accepts liner gain of CBET have large deviation with experiments. The

ion stochastic heating effect can explain a part of experiments, but not of all. This indicates

that there are other effects affecting CBET. Here we report a new effect, ion transfer effect,

by large-scale two-dimension particle-in-cell simulations. Research shows that this effect

can reduce the transferred energy in CBET compared with liner gain.

Keywords: crossing beam energy transfer, inertial confinement fusion



Stimulated Brillouin scattering in inhomogeneous flowing

plasma by using Vlasov simulations

Qing Wang*, Chunyan Zheng, Zhanjun Liu, Qingsong Feng, Liuhua Cao, Xiantu He

Peking Univeristy, China


Stimulated Brillouin scattering (SBS) has been studied in detail in a homogeneous

medium, where the regimes of convective and absolute instabilities have been identified.

However, the saturation mechanism of SBS is still an ambiguous problem, which

motivated the analysis of ion nonlinearities, such as ion wave harmonic generation, ion

wave decay and ion trapping. Theoretical studies of ion nonlinearities have been mainly

limited to an idealized model of a homogeneous plasma, whereas combined effects of ion

nonlinearity and plasma inhomogeneity were never addressed by using Vlasov simulations.

Although both the ion nonlinearity and the plasma inhomogeneity separately reduce the

SBS reflectivity, their combination may result in a qualitatively new effect known as the

autoresonance phenomenon. As a result the resonance region is enlarged and the scattered

electromagnetic wave is more strongly amplified.

Keywords: SBS, inhomogeneous flowing, ion nonlinearity



The coupling between a laser and a pre-structured target with

an arbitrary structure period

Kaiqiang Pan



With the help of theoretical analysis and two-dimensional (2D) particle-in-cell (PIC)

simulations, we investigate the coupling between a laser and a pre-structured target with

an arbitrary structure period. The simulation results show that new electromagnetic waves

containing high order harmonics will be generated and the propagation directions of these

newly generated electromagnetic waves can be controlled by the structure period. The

controlling can be well explained by the coupling mechanism between the laser and the

pre-structured target. The simulation results also show that when the newly generated

electromagnetic waves are propagating along the target surface, the quasi-static magnetic

field on the surface will be lowered, which is caused by the decrease of the surface current.

However, it is also shown that, even if the surface current is decreased, the structure period

has little influence on the electron heating.

Keywords: Laser-plasma interaction, micro-structure, radiation generation, plasma optical

grating


I - Fundamental Physics at Extremes


Poster Presentation Fundamental Physics at Extremes

Laser – Driven Proton Acceleration using Nano Spherical

Cannon

Murakami Masakatsu*, Okada Minoru



In the past decade, proton acceleration has received a lot of attention in many

branches of physics such as medical application, proton-driven ICF. Here in we provide a

new mechanism of proton acceleration, named Nano-Spherical Cannon (NSC). The

mechanism is as follows: A spherical shell of nano-scale made of high-z materials has a

hall on its surface. A hydrogen cluster in them embedded inside. Being irradiated by

ultraintense ultrashort laser pulse, the bulk of electrons are blown off. The proton cluster

are ejected out of the hall to be collimated to form a proton beam. We have conducted

particle simulation to calculate the NSC dynamics. Salient features of NSC are discussed

in detail.

Keywords: proton acceleration, nanotarget, spherical geometry



Development of MD-PIC Hybrid Code for Coulomb Implosion

Masakatsu Murakami*, Akito Inoue



In many numerical studies for laser-ion accceleration, Particle-in-cell (PIC)

simuration have been used. However, to investigate the dynamics of nano-scaled targets,

which are in the same order of Debye length or even smaller, PIC simulations are

inappropriate. We have therefore developed a MD-PIC hybrid code with cylindrical and/or

sperical coordinates, with which a novel scheme for proton acceleration-Coulomb

Implosion has been studied. It has thus become possible for the first time to investigatae

such ultra high field plasma phisics attained by Coulomb Implosions.

Keywords: proton acceleration, code development, MD scheme



Laser driven magnetic reconnection in low beta plasmas

Jiayong Zhong

Department of Astronomy,Beijing Normal University, China


The Sun is not so quiet as it looks. Solar flares, coronal mass ejections and the solar

wind strongly influence interplanetary and terrestrial space by virtue of shock waves, hard

electromagnetic radiation and accelerated particles. It is very important to understand space

weather and develop effective tools for space weather simulation and prediction to protect

the performance and reliability of space borne and ground-based technological systems. It

is believed that the coupling between the solar wind and the magnetosphere is mediated

and controlled by the magnetic fields in the solar wind through the process of magnetic

reconnection, which is considered to be an important mechanism of explosively

transferring energy from magnetic fields to plasma flows and heat. In addition to

(expensive) spacecraft, we show that the plasma reconnection process can also be studied

by appropriately scaled lab experiments, in which large-scale space plasmas are scaled to

(relatively low cost) small lab plasmas; these experiments also offer significant and flexible

control over the conditions of reconnection.

One novel plasma device for magnetic reconnection is demonstrated by Shenguang

II and Gekko XII lasers irradiating a double capacitor-coils target. Optical probing reveals

a high velocity, accumulated plasma plume at the region of magnetic reconnection outflow.

The background electron density and magnetic field are measured around 1018 cm-3 and

50-60 Tesla with Nomarski interferometry and Faraday effect, respectively. Compared

with high beta magnetic reconnection experiments driven by Biermann battery effect, the

present beta is much lower than one, which largely extends the parameter regime of laser

driven magnetic reconnection and shows potential applications in astrophysical plasmas.

Keywords: magnetic reconnection



Electron-induced degradation of J-V characteristics of GaInP

top cell and GaAs middle cell by electroluminescence

measurements

Junling Wang

College of Nuclear Science and Technology, Beijing Normal University, China


Electroluminescence (EL) measurements were carried out to investigate the

irradiation effects of 1.0 MeV electrons on the current density-voltage (J-V) characteristics

of the GaInP top cell and GaAs middle cell of GaInP/GaAs/Ge triple-junction solar cells

at injection current densities ranging from 2.5 mA/cm-2 to 30 mA/cm-2. By utilizing the

optoelectronic reciprocity relation between the EL and external quantum efficiency (EQE),

the dark J-V characteristics of the two subcells were derived, as well as the short circuit

current density and the open circuit voltages. It is shown that the short circuit current

density and the open circuit voltage of the top cell and the middle cell both degrade with

the increasing fluence, but that of the middle cell degrade more than the top cell at the same

fluence. Meanwhile, The current-limitting cell changes from GaInP top cell to the GaAs

middle cell. The GaAs middle cell contributes to more loss in voltage of the 3J solar cell.

Keywords: J-V characteristics; GaInP/GaAs/Ge triple-junction solar cells; Electron

irradiation; Optoelectronic reciprocity relation



Accurate calculations of energy structures and radiation rates

of L-shell ions of astrophysics interest

K. Wang1,*, R. Si2, P. Jönsson3, C. Y. Chen2, J. Yan4

1. Hebei Key Lab of Optic-electronic Information and Materials, The College of Physics

Science and Technology, Hebei University, China

2. Shanghai EBIT Lab, Institute of Modern Physics, Department of Nuclear Science and

Technology, Fudan University, China

3. Materials Science and Applied Mathematics, Malmö University, Sweden



Accurate atomic data for highly charged ions are needed in astrophysics and

plasmaphysics. Iron group elements are important in the study of astrophysical plasmas, as

many of their emission lines are frequently observed from different ionization stages. These

observationsprovide a wealth of data about the plasma characteristics, such as temperature,

density, and chemical composition. Atomic data, including energy levels and transition

data, are required for many ions.

Employing two state-of-the-art methods, multiconfiguration Dirac-Hartree-Fock [1]

and second-order many-body perturbation theory [2], level energies, wavelengths, electric

dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition rates,

oscillator strengths, and line strengths are calculated for the n ≤ 6 states in a numberof L-

shell ions of Iron group elements for astrophysics interest [3-9]. Extensive comparisons

with experiments from the NIST [10] and CHIANTI [11] databases, and other

recentbenchmark calculations, show that the present results are highly accurate: for level

energies, uncertainties are less than 0.1% for most states; for transition rates, accuracies

arebetter than 10% for a majority of transitions.

The excellent description of the energy separations along the isoelectronic

sequencesmakes it possible to point out a number of lines for which the experimental

identificationsare questionable. A complete dataset should be helpful in analyzing new

observationsfrom the sun and other astrophysical sourcesand is also likely to be useful for

modelingand diagnosing a variety of plasmas including astronomical and fusion plasma.

Keywords: energy structures, radiation rates

Reference

[1] C. Froese Fischer, M. Godefroid, et al., J Phys B, 49, 182004 (2016).

[2] M. F. Gu, Astrophys J, 169, 154 (2007).

[3] P. Jönsson, G. Gaigalas, et al., Atoms, 5, 16 (2017).

[4] K. Wang, P. Jönsson, et al., Astrophys J Suppl S, 229, 37 (2017).

[5] R. Si, S. Li, et al., Astrophys J Suppl S, 227, 16 (2016).

[6] K. Wang, Z. B. Chen, et al., Astrophys J Suppl S, 226, 14 (2016).



[7] K. Wang, R. Si, et al., Astrophys J Suppl S, 223, 3 (2016).

[8] K. Wang, X. L. Guo, et al., Astrophys J Suppl S, 218, 16 (2015).

[9] K. Wang, D. F. Li, et al., Astrophys J Suppl S, 215, 26 (2014).

[10] A. Kramida, Yu. Ralchenko, J. Reader, & NIST ASD Team, NIST. Atomic Spectra

Database (ver. 5.3), [Online]. Available: http://physics.nist.gov/asd.

[11] P. R. Yong, K. P. Dere, et al., J Phys B, 49, 74009 (2016).



TDOA Pattern Matching Localization Method

Tao Wang*, Qi Zhang, Bo Yang, Lihang Du, Yapeng Fu

Army Engineering University of PLA, China


A novel localization method combined time difference of arrival (TDOA) data and

pattern matching is proposed in this paper, in which the TDOA sequence is regarded as a

pattern of spatial point mapping to the localization array. So, the TDOA pattern matrix of

spatial points is first established based on the one-to-one correspondent relationship

between the patterns and spatial points. Then, a matching algorithm is given to find the

target point by matching the measured TDOA data with each pattern in the matrix. For

cases with more array elements, the principal component analysis (PCA) is applied to

reduce dimensions of the TDOA pattern matrix, while the localization accuracy is still

ensured. Compared to the traditional TDOA location technology, the proposed TDOA

pattern matching localization method (TDOA-PMLM) no longer involves the solution of

the nonlinear equations. To verify the performance of the TDOA-PMLM, simulations are

conducted with different error levels. The results show that the TDOA-PMLM keeps strong

robustness before performance breaks away from the Cramer-Rao lower bound.

Keywords: TDOA, Pattern Matching, PCA, Localization



Influence of plasma density gradient on high-order harmonic

generation from relativistic plasma surfaces

Jian Gao1,2,*,Feng Liu1,2 , Boyuan Li1,2 , Dongning Yue1,2 , Xulei Ge1,2,3, Su Yang1,2,Yanqing

Deng1,2 , Yuan Fang1,2, Wenqing Wei1,2, Xiaohui Yuan1,2, Min Chen1,2, Zhengming Sheng1,2,4,Jie

Zhang1,2,5

1. Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics

and Astronomy, Shanghai Jiao Tong University, China

2. Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University

3. State Key Laboratory of Surface Physics and Department of Physics, Fudan University

4. SUPA, Department of Physics, University of Strathclyde, UK

5. Chinese Academy of Sciences, Beijing, China

* E-mail:[email protected]

Generationof light pulses with shorter duration for diagnosing and controlling the

ultrafast processes in microcosmhas been a subject of strong scientific interest. In

contrast with the high-order harmonic generation (HHG) from laser-gas interactions,

whose driven laser intensities are limited by ionization threshold at about1015 W/cm2 [1] ,

the HHG from solid targets has no limitation on laser intensities. There are two well

recognized mechanisms of HHG from plasma surfaces, coherent wake emission (CWE) [2] and relativistically oscillating mirror (ROM) [3, 4].

In addition to the laser intensities, the plasma density gradientalso plays a crucial

role in the harmonic generation process. We use the 200 TW laser system (800 nm, 25 fs)

at the Laboratory for Laser Plasmas in Shanghai Jiao Tong University to investigate the

influence of plasma density scale length L on HHG. The laser temporal contrast was

improved to ~10-10 at 10 ps prior to the main peak by a single plasma mirror (PM)

system.

The pulse with peak intensity of 3.5×1019 W/cm2 was focused onto the polished

fused silica targets at 40.8° and the HHG spectra are measured by a flat field

spectrometer. The results show that the harmonics can only be generated when the PM is

used [Fig. 1(a)]. The harmonic with the maximum 46th order is obtained [Fig. 1(b)]. We

also introduce a pre-pulse with the relative intensity of 10-2 to the main pulse. The L

could be continuously tuned by adjusting the delay between the pre-pulse and the main

pulse. With increasing the L, the intensities of harmonics first increase and then drop.

When the L is 0.3λ, the intensities of harmonics are optimum (Fig. 2).




Fig. 1(a) No harmonics can be obtained when the PM is not used. (b) The harmonic spectrum

with the maximum 46th order is generated.

Fig. 2A pre-pulse is introduced to tune the scale length. When the L is 0.3λ, the intensities of

harmonics are optimum.

Keywords: high harmonics, density gradient, plasma surfaces

References

1 J. L. Krause, K. J. Schafer, and K. C. Kulander, Phys. Rev. Lett. 68, 3535 (1992).

2 F. Quéré, C. Thaury, P. Monot, S. Dobosz, and Ph. Martin, Phys. Rev. Lett. 96,

125004 (2006).

3 S. V. Bulanov, N. M. Naumova, F. Pegoraro,Phys. Plasmas. 1, 745 (1994).

4 T. Baeva, S. Gordienko, and A. Pukhov,Phys. Rev. E. 74, 046404 (2006).



Demonstration of the EM wave measurement in the laser

plasma probed by a single electron bunch

Shengguang Liu*, Pengfei Zhu, Xiaohui Yuan

Shanghai Jiao Tong University, China


Laser fusion research confronts fatal challenges in the whole world today, which

means a lot of plasma instabilities are out of human understandings. We developed a device

and a special method to measure the EM field in the plasma by a single electron bunch.

One measurement covers the whole-time window of the plasma process driven by 4ns laser

pulse. An electron source can generate a single electron bunch with 100keV energy and

10ns bunch width. A laser pulse with 1J energy and 532nm wavelength hits on the edge of

a silver target, the target nearby the hitting spot becomes into plasma. At the very beginning

of plasma generation, the head of the electron bunch begins to enter the plasma. EM wave

in plasma push the electrons transversely. A high voltage pulse at a good time is used to

deflect the electron linearly in the transverse direction to avoid the different electrons

overlap on the CCD camera downstream. By analysis the deflection distance of the

different electron, we succeed to get the electronic field of the plasma during the whole

plasma process.

Keywords: EM wave measurement， plasma instability， electron bunch



An improved ion-sphere model for the ionization of ion

embedded in dense plasma

Xiangdong Li

State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics & Fine

Mechanics, China


Improved ion-sphere model is set up to simulate the ionization process for ions

embedded in dense plasma. Full quantum mechanics calculations show that great

improvement have been made for the K-edge energy of different charge-states in the solid

dense and warm aluminum plasma. The improved model confirms that to take the bound

electrons and the free electrons inside the ion-sphere as a whole and to properly treat the

state of the ionized electron with the energy zero is very important for the ionization

process of an ion in dense plasma. The discrepancies exist between theory and experiment

indicate that the introduction of free electron distribution with higher polarization is a way

to improve the consistency between theory and experiment.

Keywords: Ionization, K-edge, ion-sphere model, dense plasma



Theoretical study of the oscillator strengths of the transitions

between the 3s21S0, 3s3p3Po0, 1, 2

1Po1states for Mg-like ions

Tingxian Zhang1, 2, 3, Jiguang Li2,*, Per Jӧnsson4,Chengbin Li1, Tingyun Shi1

1. Wuhan Institute of Physics and Mathematics, 430071, Wuhan, China


3. The University of Chinese Academy of Sciences, 100088, Beijing, China

4. Group for Materials Science and Applied Mathematics, Malmö University, Sweden

The transitions in the Mg-like ions, such as Si III, S V, Ar VII, etc. were observed

in the spectra of solar, astrophysical and laboratory plasmas [1]. The theoretical parameters

of the transitions in Mg-like ions, such as transition energies, oscillator strengths are

required to analyze the spectra from the plasmas and diagnose its state, since the

experimental data are incomprehensive. Previous theoretical studies indicate that the

properties of the transitions in Mg-like ions are sensitive to many factors [2-5], for instance,

the electron correlations for low-Z ions, and the Breit interactions and QED corrections for

those ions with high Z.

We have investigated the effects of the electron correlations on the transition

properties of the Mg-like ions systematically.The uncertainties of calculated results can be

controlled to within a small number if the CC correlation and part of higher-order

correlation are included in the computational models.Based on the above discovery, in this

work we reevaluate the oscillator strengths of the transitions between the 3s21S0, 3s3p 3Po0,

1, 21Po

1 states for Mg-like ions along the isoelectronic sequence using the multi-

configuration Dirac-Hartree-Fock method [6].Figure 1 shows the contributions of the CC2s

correlation and part of the higher-order correlation to the oscillator strengths (in Babushkin

gauge) of the 3s21S0 – 3s3p 3,1Po1 transitions.It indicates that the effects of the CC2s

correlation on the oscillator strengths of the transitions in the Mg-like ions are non-

negligible, especially for the low-Z ions.

Fig. 1 The contributions of the CC2s and part of the higher-order correlations to the

oscillator strengths (in Babushkin gauge) of the 3s21S0 – 3s3p 3,1Po1 transitions for the Mg-

like ions with 𝑍 = 14 ~ 20.



Keywords: Multi-configuration Dirac-Hartree-Fock method , electron correlation effects,

oscillator strengths, Mg-like ions

Reference

[1] P. R. Young et al, J. Phys. B: At. Mol. Opt. Phys. 49 074009 (2016)

[2] Y. Zou, et al, J. Phys. B: At. Mol. Opt. Phys. 34 915 (2001)

[3] Y. Zou, et al, Phys. Rev. A 62, 062505 (2000)

[4] H. Kang, et al, J. Phys. B: At. Mol. Opt. Phys. 43 095003 (2010)

[5] S. Gustafsson, et al, Atoms 5 5010003 (2017)

[6] I. P. Grant, Relativistic quantum theory of atom and molecules (Springer, New York,

2007)



Study on the algorithm of 14MeV fast neutron radiography

Chang-Bing Lu1,*, SongWang2,Ming-XiGu1,Lei Zhang1, Jin-NanYin1

1. Key Laboratory of Nuclear Data, China Institute of Atomic Energy, China

2. The Chinese People’s liberation army 92609 troops, China


Fast neutron radiography (FNR) is an effective non-destructive testing technique.

Due to the scattering effect and low detection efficiency, the detection limit of FNR under

certain conditions could not be determined so far. In order to obtain the minimum

discernible thickness by FNR, we studied the contrast sensitivity of FNR of lead samples

both theoretically and experimentally. Then we clarified the relationship between the pixel

value and the irradiation time, sample materials and thicknesses. The experiment of a 4-

cm-thick lead sample verified our theoretical expression of the system‘s contrast sensitivity.

Keywords: Fast neutron radiography, Contrast sensitivity, Experimental research



The point explosion with radiation transport

Zhiwei Lin* , Lu Zhang, Longyu Kuang, Shaoen Jiang



Some amount of energy is released instantaneously at the origin to generate

simultaneously a spherical radiative heat wave and a spherical shock wave in the point

explosion with radiation transport, which is a complicated problem due to the competition

between these two waves.

The point explosion problem possesses self-similar solutions when only

hydrodynamic motion or only heat conduction is considered, which are Sedov solution and

Barenblatt solution respectively. The point explosion problem wherein both physical

mechanisms of hydrodynamic motion and heat conduction are included has been studied

by P. Reinicke (Phys. Fluids A 3 (1991) 1807) and A.I. Shestakov (Phys. Fluids 11 (1999)

1091).

In this talk we numerically investigate the point explosion problem wherein both

physical mechanisms of hydrodynamic motion and radiation transport are taken into

account. The radiation transport equation in one dimensional spherical geometry has to be

solved for this problem since the ambient medium is optically thin with respect to the

initially extremely high temperature at the origin. The numerical results reveal a high

compression of medium and a bi-peak structure of density, which are further theoretically

analyzed at the end.

Keywords: point explosion, radiation hydrodynamics, heat wave, shock wave



X-ray Spectral Measurements of a Highly Ionized Non-Local-

Thermodynamic-Equilibrium Laser-Produced Au Plasma

Bo Qing



The charge state distribution of a highly ionized non-local thermodynamic

equilibrium Au plasma is determined, with independent temperature and density

measurements. Through laser-irradiationof a CH-tamped gold micro-disk, the Au plasma

reaches temperature of about 2.3 keV and ionizes into the M-shell. The electron

temperature is measured by the isoelectronic line ratios of K-shellemission from helium-

like ions of doped Ti and Cr. The density is determined from time-gated x-ray imaging the

extent of Au sample expansion. The charge state distribution is obtained fromanalysis of

emission strengths of Au 5f-3d transition arrays in the energy range 3,200-3,600eV. The

Au plasma has an average density of ne=1.9×1021 cm-3 and an average charge state of

<Z>=49.2.

Keywords: non-LTE Au plasma, charge state distribution



Study on the movement of gold bubble plasma in hohlraum

SanweiLi1,*, Liang Guo1, Xin Li2, Zhurong Cao1, Shenye Liu1, Shaoen Jiang1,

Yongkun Ding2, Baohan Zhang1




Recent experiments on Shengguang III laser facility have explored gas filled

hohlraums to create plasma condition that is close to the ignition status. An x-ray framing

camera is used to acquire the time-resolved movement images of the gold bubbles. The

experimental results are simulated with a phenomenological model very well,

demonstrating its validity and rationality.

Keywords: ICF, hohlraum, bubble plasma, phenomenological model



Charged paricle activation analysis for characterization of

laser-accelerated protons

He Shukai



Laser-driven proton acceleration using ultra-high intensity laser has been

extensively studied. The most commonly used detectors for measuring laser-driven proton

are Tomspon parabola ion energy analyser(TP) and filtered nuclear track detectors, such

as radiochromic films(RCF). TP uses a parallel magneto-electric field to distinguish ions.

This conventional technique can precisely identify the ion species as well as their energy

spectra, but the strong electromagnetic field produced by the laser plasma interaction can

affect its work, and it has no spatial resolution. RCF can give the spatial integration

spectrum of proton, but easy to saturate, and can not be reused. This paper presents a

method based on traditional charged particle activation analysis and gamma-gamma

coincidence measurement to measure the spectrum of protons accelerated by ultra intense

lasers. In this method, a copper plate stack is placed in proton emission direction. Collision

with MeV proton converts 63Cu in the copper plates to radionuclide 63Zn, whose decay

can be easily observed and measured. Proton spectrum is then recovered from 63Zn decay

counts from layers in the copper stack. Layout of diagnostics and the method to solve

proton spectrum is discussed in detail and a self consistency test is given. This spectrum

analysis method is applied in a laser-driven proton acceleration experiment carried out on

XG-III laser facility. Our method shows that protons up to 18 MeV are obtained, the spatial

integrated spectrum and a laser-proton conversion efficiency of 1.07% are given. In

conclusion, this method has some advantages as an laser-driven ion diagnostics tool, it has

no saturation problem and is not affected by strong electromagnetic fields. The basic

principle of charged particle activation analysis is nuclear reaction, it can be extended to

measure other charged particle beams besides proton such as deuterons, helium ions

produced by ultra-high intensity laser depending on the nuclear reaction cross section.

Keywords: charged particle activation analysis, laser-driven proton acceleration,

coincidence measurement, unfold spectrum



Attosecond X-ray generation driven by the relativistic laser

pulse based on the semi-analytical selfconsistent theory

Shaoyi Wang



A semi-analytical theory of the interaction between a relativistic laser pulse and the

overdense plasma to generate an attosecond X-ray source is presented. The physical

parameters such as plasma oscillation trajectory, surface electric field and magnetic field

can be given by this model, and the high-order harmonic spectrum is also calculated

accurately from the solution of the plasma surface oscillations, the obtained result is

consistent with the result from the PIC simulation program. Our results show that the

radiation of the attosecond X-ray source is dependent on the plasma surface oscillation. By

using a few-cycle laser field, the smooth high-order harmonics can be obtained, which

leads to a single attosecond pulse with high signal-to-noise ratio.In a word, our calculation

results show that the time evolution progress of plasma surface can be controlled by

changing the carrier envelope phase of the few-cycle laser pulse, and then the radiation

progress of the high-order harmonics can be influenced as result of a single attosecond X-

ray pulse.

Keywords: self-consistent theory, high-order harmonic, single attosecond pulse



Experiment research on dynamic response of Copper Film at

high strain rate by chirped pulse spectral interferometry

WeiFan*,Tao Xi



Femtosecond laser pulses irradiate metallic materials inducing ultrahigh strain rates

is an important experimental approach for studying the material behavior under extreme

conditions. Femtosecond laser-generated shock waves in metal films have the rise times of

several picoseconds, the corresponding diagnostic technique is required to work with

higher time resolution, which makes the experimental measurements difficult. Chirped

pulse spectral interferometry (CPSI) takes a power of ultrafast time resolution and

continuous measurement, thus it provides a diagnostic technique for studying the ultrashort

shock wave. In this article, we carried out an experiment on femtosecond laser driven shock

wave in copper films and the measurement by CPSI. Laser pulses of 25 fs duration at the

central wavelength 800 nm were used, the tested samples were copper films of 502±5 nm

in thickness fabricated by electron beam sputtering deposition onto cover slip substrate of

180μm in thickness, pump beam was focused onto front surface of the copper film through

the transparent substrate and this laser intensity was 2.3×1013 W/cm2. Chirped pulse

spectral interferometry was used to detect movement of the free rear surfaces of the copper

films with temporal and spatial resolution. In the spectral interferometry, linearly chirped

pulse was required and obtained by stretching the femtosecond laser pulse with a pair of

gratings, and the relation between frequency and time of the chirped pulse was accurately

measured using asymmetric spectral interference method, which was required for the

experimental data interpretation. Since CPSI is a single shot diagnostic technique, we got

displacement and velocity history of the free rear surface with picosecond time resolution

in a single measurement. From the results, the average shock velocity was calculated to be

5.6±0.2 km/s and the shock wave rise time was determined to be 6.9 ps. According to the

shock wave relations, impact pressure and strain rate in the copper film were 57.1±8.8 GPa

and 8×109 s-1 respectively, the strain rate is so high that it is hard to achieve by long-pulse

laser driven or other loading approaches. Additionally, experimental results also showed

that the free rear surface underwent alternately acceleration and deceleration, which

indicated spallation in the copper target. It is obvious that chirped pulse spectral

interferometry is a reliable approach for studying ultrashort shock waves in metal films.

Keywords: chirped pulse, spectral interference, time-resolved, shock wave



Compact all-optical Thomson scattering source based on shock

wave injection and cascaded laser wakefield accelerator

Fang Tan

Department of high energy density physics, Laser Fusion Research Center, China Academy of



Through add on a knife edge to a double exits gas jet, we experimentally

constructed a steep shock wave as the electron injector in the structred gas density profile,

leading to the stable quasi-monoenergetic e-beams with central energy in the range of 90-

160MeV. Then using a plasma mirror placed at the end of the jet to reflect the driving laser,

the laser pulse could be scattered by the e-beam and stable quasi-monochromatic hard X-

rays were experimentally obtained. Further measurements on this X-ray source show that

the radiation spectra have a cut-off energy of 500keV. The resolving power of this source

can archive 12 micron.

Keywords: Thomson scattering source,wakefield acceleration,shock wave

injection,plasma mirror



Development of multi-keV X-ray sources at the Shenguang-III

prototype facility

Gang Xiong, Bo Qing, Yang Zhao, Zhimin Hu, Yunsong Dong, Minxi Wei, Tianming Song, Min

Lv, Zhiyu Zhang, Guohong Yang, Jiyan Zhang, Jiamin Yang, Shaoen Jiang



High laser-to-X-ray conversion efficiency(XCE) multi-keV sources are important

for various research applications in inertial confinement fusion and high energy density

physics, such as imaging and radiography, X-ray absorption measurements, testing of

materials exposed to X-ray radiation, and so on. Although different characteristics of the

X-ray source are required for different applications, improvement of the XCE is common

and crucial. A traditional way for creation an keV X-ray source is laser irradiation with a

thick solid planar target. However, the high-density plasma generated from the solid planar

target prevents the laser absorption and limits the XRCE. An underdense plasma with

electron density below 0.25 nc provides a way to significantly increase the XCE. The

underdense plasma allows efficient laser absorption, supersonic heat-front propagation,

volumetric sample heating, and finally greater XCE.

Recently, the multi-keV X-ray sources have been tested using the underdense

plasma mechanism at the Shenguang-III(SG-III) prototype laser facility. Thin-wall

cylindrical cavities are the main targets in the present work. The cylindrical cavities are

700-800 μm diameter, 500-800 μm tall. The main wall materials are Ti, V and Ni. CH tubes

of 30μm thick are used to enclose these thin metal cavities, confine the expansion plasmas,

and allow the transmission of the X-ray through the encloser. The SG-III prototype facility

deposited about 6.4 kJ of 3ω laser into the cavity in a 1ns square pulse. The absolute x-ray

fluxes with energy higher and lower than 4keV were measured by several calibrated HXRD

and FXRD at different angles, respectively. The time evolution of the X-ray images in the

two energy region were recorded through X-ray framing camera to have an insight into the

different X-ray emission behavior. Time integrated spectra in the K-shell range were

recorded by crystal spectrometers. The X-ray conversion efficiency in the present spectral

range was determined to be about 2-3 times higher than the traditional solid planer sample.

Keywords: X-ray souce, multi-keV, conversion efficiency



Detection efficiency calibraion of CsI(TI) scintillator with

2000eV-2800eV soft X-Ray energy emitting

Wang Jing



CsI(Tl) scintillator is a key part for the transition from X-ray to visible light in X-

ray detectors, its transition efficiency is crucial importance in X-ray diagnosis for inertial

confined fusion. X-rays could deposit energies into the CsI(Tl) scintillator and visiable

lights are emitted. The transition efficiency of CsI(Tl) scintillator with different thickness

was calibrated on the beamline 4B7A at Beijing Synchrotron Radiation Facility in the

energy range between 2,000eV and 2,800eV. Energy deposition and energy response with

the stimulation of X-ray was studied. The whole system includes emitting X-ray、standard

detector,shutter,CsI(Tl) scintillator,black box and SI1000 CCD. Emitting X-ray is

normalized with curve fitting. SI1000 CCD is used to recieve the visible light which the

counts were kept in the linearity range of CCD. The experiment gets the detector current,

CCD counts, the ratio of CCD counts and emitting X-ray counts in the energy region from

2,000eV to 2,800eV. The results show the energy response increase with the increase of

the thickness of CsI(Tl) scintillator. This method investigation has provided valid proofs

for the preparation of the forthcoming experimental study.

Keywords: Inertial confinement fusion; CsI(TI) Scintillator; Soft X-Ray; Calibration;

Detection efficiency



The Calculations of the profile of β line in argon Ar XVII ions

B. Duan*, Z.Q. Wu, J. Yan, Y. Wu, J.G. Wang



Under electron temperature Te=2Ti=1 keV(Tiion temperature) and electron

densityNe=6×1023cm-3, and the ion number ratio of deuterium and tritium to argon is

3600:1, plasma electrons are considered within impact theory and the ions in the quasi-

static approximation, we obtain the numerical calculations of the profile of β line in argon

Ar XVII ions ( 13n ).

Keywords: line profile, impact theory, quasi-static approximation



Many-particle correlation effects on the electron screened

potential of non-ideal plasmas

Fuyang Zhou*, Yong Wu

Institute of Applied Physics and Computational Mathematics,Beijing, China


A plasma becomes strongly coupled when Coulomb coupling parameter, that is the

ratio of the interparticle Coulomb potential and kinetic energy, greater than unity.The

strongly coupling exists comprehensively in different non-ideal plasma environments, such

the plasmas produced during inertial confinement fusion [1], dense astrophysical

environments [2], and colloidal or dusty plasmas ofhighly charged macroscopic particles

[3]. Equilibration in these systems is of particular interest due to that it involves the

establishment of spatial correlations between particles.

The purpose of present work is to explore the electron screenedpotential between

charged particles in strongly coupled plasmas. Electron screening is among the most

fundamental properties of plasmas, since it determines the effective interactions of charged

particles which impact all properties of a plasma. A description of a plasma in terms of

screened Coulomb potentialsplays an importantrole where straightforward first-principle

calculations are not possible. For example, reaching the mesoscopic scales of

nonequilibrium transport for dense plasmas can necessitate millions to billions of particles

[4]. However, the underlying theories of screenedpotential break down in strongly coupled

systems which display strong correlations between particles.

Here, we useboth theoretical models and molecule dynamic (MD)simulationsto

study the electron screening in ultra-cold natural plasmas(UNPs), which are of fundamental

interest as a platform for the study of strongly coupled matter. UNPs canbe produced from

a laser-cooled atomic cloud confined in amagneto-optical trapand are much easier to be

controlled in laboratory conditions than hot, dense strongly coupled plasmas [5,6]. The MD

simulations are capable of describing the electron screening with a nearly exact description

of the classical many-body system. By comparing the results of MD simulations and

effective potential theories, the many-particle correlation effects on electron screening in

strongly coupledplasmas are investigated.

Keywords: Strongly coupled plasma, electron screening

References

[1] M. Nantel, G. Ma, S. Gu, et al. Phys. Rev. Lett. 80, 4442 (1998)

[2] H. M. van Horn, Science252, 384 (1991)

[3]G. E. Morfill, H. M. Thomas, U. Konopka, M. Zuzic, Phys. Plasmas6, 1769 (1999)

[4] C. Hollenstein, Plasma Phys. Controlled Fusion42, R93 (2000)



[5] T. C. Killian, T. Pattard, T. Pohl et al.Phys. Rep. 449, 77 (2007)

[6] J. W. Gao, Y. Wu, Z. P. Zhong, et al. Phys. Plasmas23, 123508 (2016)



State-selective electron transfer in low and intermediate energy

He++ He collisions

J.W. Gao1,2,∗, Y. Wu1, J. G. Wang1, N. Sisourat2,†, A. Dubois2,‡

1. Institute of Applied Physics and Computational Mathematics, 100088, Beijing, China.

2. Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Chimie Physique Matière

et Rayonnement, 75005, Paris, France.

∗Corresponding author: [email protected]

†Corresponding author: [email protected]

‡Corresponding author: [email protected]

Experimentally, He++He collisions have received a great deal of interest for several

decades up to very recently(see Ref. 1 and references therein), because helium is

particularly well suited for experimental purposes. From thetheoretical point of views, the

He+ + He collisions, although there are only three electrons involved, are

sufficientlycomplex to give rise to the main types of inelastic reactions observed in ion-

atom collisions. Despite the fact thata number of theoretical efforts have been pursued to

understand and model the He+ + He collision system (seeRef. 2 and references therein). In

the intermediate impact energy region, to study such a three-electron collisionsystem is

still a challenge due to the strong coupling of various channels and electronic correlations,

where theperturbation theory or the calculations simplified by using a model potential with

only one- (or two-) activeelectronare inadequate. Consequently, non-perturbative full-

electron (three-electron) semi-classical or quantumapproaches are still required.

In the conference, we shall present results for ground-state electron transfer (GT),

excitation-state electrontransfer (ET) and electron transfer excitation (TE) processes

occurring during the collisions of He++He:

He+(1s) +He(1s2) → He(1s2) +He+(1s) (GT)

→ He∗(1snl) +He+(1s)(ET)(1)

→ He(1s2) +He∗+(nl) (TE)

The cross sections are calculated by using a three-active-electron semiclassical

atomic-orbital close-coupling(SCAOCC) method [3-5] for a wide energy domain 1-225

keV/u. Our calculations shown in Fig. 1 for stateselectivecross sections (left) and the GT

angular-differential cross sections (right) at E=25 keV/u are in very goodagreement with

previous experimental measurements [1]. A detailed interpretation for the prominent

oscillatoryenergy dependence structure in the TE cross sections and the distinct angular



dependenceoscillatory structureobserved in angular-differential cross sections of GT as

well as other processes will also be presented during theconference.

Fig. 1: Comparison between the present state-selective (left) and angular-differential (right)

cross sections withexperimental and theoretical results of [1].

Keywords: Atomic and molecular collisions; Charge-transfer collisions

References

[1] D. L. Guo, X. Ma, R. T. Zhang, S. F. Zhang, X. L. Zhu, W. T. Feng, Y. Gao, B. Hai,

M. Zhang, H. B. Wang, and Z. K. Huang,

Phys. Rev. A 95, 012707 (2017).

[2] M. Baxter, T. Kirchner, and E. Engel, Phys. Rev. A 96, 032708 (2017).

[3] N. Sisourat, I. Pilskog, and A. Dubois, Phys. Rev. A 84, 052722 (2011).

[4] G. Labaigt, A. Jorge, C. Illescas, K. B eroff, A. Dubois, B. Pons, and M. Chabot, J.

Phys. B 48, 075201 (2015).

[5] J. W. Gao, Y. Wu, N. Sisourat, J. G. Wang, and A. Dubois, Phys. Rev. A 96, 052703

(2017).



Enhancement of radiation pressure acceleration with a strong

magnetic field

Cheng Hao



Laser-driven particle acceleration has become an active area of experimental and

theoretical research due to high acceleration efficiency and low expenses. And radiation

pressure acceleration is one of the most efficient mechanisms of ion acceleration, almost

all the laser energy can be transferred to ions. With a laser pulse ejects into an ultrathin foil,

ions can be accelerated to multi GeV. However, the transverse target expansion caused by

transverse instability such as Rayleigh Taylor-like instability makes the areal density

decrease, which leads to a termination of ion acceleration. This limits the maximum

attainable ion energy.To suppress the transverse expansion, a strong longitudinal magnetic

field has been considered to be used. With a magnetic field constraining

electrons‘ transverse expansion, the transverse instability is inhibited, which markedly

limits ions acceleration, with destruction of target‘s structure and reduction of areal

density.Therefore, a series of two-dimensional particle-in-cell simulations has been used

to study laser -driven ion acceleration with a strong magnetic field. In this regime, the

transverse expansion of electrons has been efficiently suppressed. And the areal density of

electrons and protons can maintain for longer time. Moreover, the cone-like structure of

target is quietly different with ones without a magnetic field. And the proton beam‘s

transverse emittance is greatly improved with an applied strong field. With a more

complete structure and a higher density, protons can be accelerated longer by the charge

separation field, which is proportional to surface density.However, no obvious promotion

of the maximum attainable ion energy is obtained. And in this regime, the transverse

velocity of electron and proton is less than the one without a magnetic field, which means

an applied strong magnetic field make a great impact on the deflection of electron‘s

trajectory resulting in maintenance of protons‘ structure. The following work will

concentrate on enhancement of protons‘ maximum attainable energy. Thus, utilization of

a strong magnetic field may provide a way to restrain transverse instability of the target.

Keywords: radiation pressure acceleration, magnetic field



Quantum molecular dynamics study on the proton exchange,

ionic structures, and transport properties of warm dense

hydrogen-deuterium mixtures

Lei Liu1, 2, Zhi-Guo Li 2, Qi-Feng Chen 2, *,, Xiang-Rong Chen 1, **

1. Institute of Atomic and Molecular Physics, College of Physical Science and Technology,

Sichuan University, China

2. National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of

Fluid Physics, China Academy of Engineering Physics, China


**Email:[email protected]

A comprehensive knowledge of properties such as equation of state (EOS), proton

exchange, dynamic structures, diffusivity, and viscosity of hydrogen-deuterium (H-D)

mixtures with densities from 0.1 g/cm3 to 5 g/cm3 and temperatures from 1 kK to 50 kK

has been presented via quantum molecular dynamics (QMD) simulations. The existing

multi-shock compression EOS provided a unique opportunity to evaluate several

exchange-correlation (XC) functionals, and a XC functional vdW-DF1 with van der Waals

corrections gives reasonable results. Over the considered ρ-T region, the H-D mixture is

composed of varying concentration of H and D atoms, H2, D2, HD diatomic molecules,

and high order cluster, circle and chain structures in terms of the analysis of pair

distribution functions (PDFs) and effective coordination number model. Fraction analysis

of molecules using a weighted integral over PDFs was performed and then generated a

dissociation diagram together with the phase boundary where the proton exchange occurs

(resulting HD molecules). The dissociation diagram shows evidences that HD molecules

form as the H2 and D2 molecules are almost 50% dissociated. The mechanism to form HD

molecules can be interpreted as a process of involving fluctuating dissociation -

recombination of molecules. The QMD calculated diffusivity and viscosity were utilized

to benchmark two popular analytical models: the one component plasma (OCP) and the

Yukawa OCP model. The discussion, as to why and where the differences between QMD

results and (Yukawa) OCP calculations occur was also presented.

Keywords: Warm dense matter (WDM); Quantum molecular dynamics (QMD);

H-D mixtures; Proton exchange; One-component plasma (OCP) model



Study on Si K-edge XANES experiment based on laser-plasma

M-band radiation source

Qingguo Yang, Bozhong Tan*, Dongbing Liu



An X-ray absorption near-edge spectroscopy (XANES) experiment based on the

laser plasma M-band radiation is reported. The M-band radiation is generated by an

intense pulse laser iradiating on high atomic number target. The M-band radiation is

absorbed by a Si membrane and then recorded by a X-ray spectrometer with elliptic

cylinder alpha-quartz crystal. Through comparation with the laser-plasma spectra of Au,

Lu, Yb, Dy, Ta and Co, it show that the M-band radiations from Lu, Yb, Dy are much

brighter than the other materials nearby Si K-edge energy (1839 eV). The M-band

radiations from Lu, Yb, Dy are used to perform Si K-edge XANES experiment, and the

experiment resault is in accordance with the calculation of FEFF9.0.




The simulation study of laser shocked plastic by x-ray

radiography

Liang Sun*, Jianhua Zheng, Xiaoxi Duan, Hao Liu, Yongteng Yuan, Zhebin Wang



The monochromatic X-ray radiography technique could be used in absolute

measurements of the equations of state of low-Z materials in the multi-Mbar regime using

laser-driven shocks by determining the density of shocked materials.This paper report our

experiment consideration and simulation results of laser shocked plastic EOS using X-ray

radiography. Synthetic radiographs which also take into account the finite size of the X-

ray source, are generated using density maps produced by hydrodynamic simulations. The

contrast of radiography is also studied for different properties of backlighters. The results

are helpful for analyzing the data and comparing results for next experiments in SGIII

facility.

Keywords: plastic EOS, laser shocked, X-ray radiography



The in-situ diagnosis of shock-compressed iron

Fan Zhang*, Xiuguang Huang, HuaShu



The study of dynamic reponse characteristics of material is an important academic

field, in which in-situ diagnostic technique using various high energy particle sources plays

a more and more important role, although it's not mature enough with some prombles need

to be resovled. We conducted the experiments about the properties of iron under extreme

conditions(high temperature and pressure) on 'shenguang II' laser facility by means of

several laser beams with some of which are used for generate high energy X-rays for

diagnosis and others for dynamic loading. In the experiments, backlight targets created by

pure polycrystalline iron were driven by several laser beams, generated 6.7 kev X-rays with

a nice monochromaticity, meanwhile, the studied materials were radiated by other laser

beams to reach the states of high temperature and high pressure. A series results have been

obtained in the experiments about the iron materials properties under extreme conditions

by dynamic loading, which can be used in the studies on astronomy and geophysic where

the iron element plays an essential role. In addition, this work also builds a substantial

foundation for the further development of dynamic in-situ diagnostic technology.

Keywords: in-situ diagnosis, laser-driven, iron material


II - Pulsed Power and Application


Poster Presentation Pulsed Power and Application

Ultraviolet frame camera diagnosis in foil liner implosion

experiments

Zhanchang Huang*, Jianlun Yang, Faxin Chen

Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, China


Radiation properties in cylindrical foil liner implosion were investigated

experimentally for the first time at JULONG-I facility in China. The thickness of the

aluminum foil was 2 μm. The diameter and height of the load were 12.8 mm and 15 mm,

respectively. The radiation properties in the early stage in foil liner implosion experiments

were explored via an ultraviolet 6-frame imaging system. The results showed that in the

very early stage there were some vertical striate patterns which should correspond to

current channels. Then some horizontal striate patterns appeared, resulting from

electrothermal instability, which indicated electrothermal instability might act important

role and provide initial perturbation for MRT instability.

Keywords: Z-pinch; UV imaging; dynamic hohlraum; JULONG-I facility

May 6th‐11th, 2018 Book of Abstract Qingdao, China ICMRE2018


X-rays emission in a nonuniform electric field during discharges with tens-hundreds nanosecond rise time

Victor F. Tarasenko1,2,*, Cheng Zhang3, Igor D. Kostyrya1, Tao Shao3, Evgenii Kh. Baksht1, Ping Yan3, Andrey V. Kozyre1,2, Vasily Y. Kozhevnikov1,2

1. Institute of High Current Electronics, Russia 2. National Research Tomsk State University, Russia

3. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China


To date, it is established reliably that generation of runaway electron beams and X-ray radiation at high-voltage nanosecond discharges in dense gases are common phenomena (see, [1, 2] and references there). There are voltage and current pulses of long duration in controlled thermonuclear research systems [3]. In a number of experimental papers, it was shown that runaway electron beam and X-ray radiation are registered when applying a voltage pulse with the microsecond risetime to a gap made in “tip-plane” geometry [4, 5], as well in corona discharge [6, 7]. It was established that an increase in the voltage pulse rise time leads to a substantially decrease of a runaway electron beam amplitude and X-ray radiation intensity. However, such modes of generation of runway electron beams were not studied in detail.

The main objective of the paper is to study effect of the voltage pulse rise time ranged from 15 ns to 1 µs on generation process of X-ray radiation and runaway electron beam in nonuniform electric field at air pressure of 0.1 MPa.

The generation of a supershort avalanche electron beam (SAEB) and X-rays in an inhomogeneous electric field is studied on two pulsers with pulse rise times of 500 (setup #1) and 15 ns (setup #2).

In the setup #1 voltage pulses were supplied to the gasfilled diode from a pulser similar to the SLEP-150 [2,5]. To increase the duration of the voltage pulse front, we removed the peaking spark gap normally installed in the coaxial line of the SLEP-150 pulser. A section of a coaxial high-voltage line was charged using a pulsed transformer, the central conductor of which was connected to the cathode of the gasfilled diode.

In the pulser of setup #2 used one-stage magnetic compression and semiconductor opening switch. The output voltage was varied from 0 to 200 kV with a rise time of about 15 ns and a full width at half maximum (FWHM) of 30–40 ns. In order to investigate runaway behavior of fast electrons produced in nanosecond-pulse gas discharges, measurement of X-ray emission is a useful parameter.

For setups #1 and #2, X-ray emission was detected by an on-line system, which consisted of an X-ray detector with scintillator and photomultiplier tube. The integrated multichannel analyzer in experiments on setup #2 was used. A detailed description of the X-ray measurement and calibration on setup #2 was described in paper [8].

May 6th‐11th, 2018 Book of Abstract Qingdao, China ICMRE2018


The results show that the discharge has various modes, i.e., corona, diffuse, and spark. The discharge mode can be controlled by the air gap length, the point–plane geometry, and voltage pulse parameters. SAEB and X-rays was measured during corona and diffuse discharges. For conditions at which diffuse discharge are realized, calculations of parameters of SAEB and X-ray radiation were performed.

The experiments on setup #1 have shown that there are two regimes of generation of runaway electrons and X-ray emission when voltage pulses with a microsecond front duration are used. At high values of voltage behind the anode that were reached by increasing the cathode size and the electrode gap length, a SAEB with a full width at halfmaximum (FWHM) of up to ~100 ps was detected. At voltages of ~50 kV, the second breakdown regime was revealed in which a runaway electron beam with an FWHM of ~2 ns was detected. In the second regime, a diffuse discharge initially forms in the gap and the spark formation is delayed by a few tens to several hundred nanoseconds. After the formation of a diffuse discharge, the gap voltage decreases more than twofold and X-ray pulses with an FWHM of ~100 ns are recorded.

The experiments on setup #2 show that X-rays are detected in the pulse-periodic mode with repetition rate up to 1000 Hz. X-ray density reaches its mamimum when the discharge behaves diffuse. Anode material significantly affect the X-ray count, indicating the bremsstrahlung X-rays mainly contribute to the detected X-rays.

The work on the experimental setup #1 was supported by grants RFBR # 18-52-53003_ГФЕН_а. The work on the experimental setup #2 was supported by the National Natural Science Foundation of China under Contract #1171101226.

Keywords: X-rays emission, runaway electron, discharges with tens-hundreds nanosecond rise time

References

[1] L. P. Babich, High-Energy Phenomena in Electric Discharges in DenseGases: Theory, Experiment, and Natural Phenomena (ISTC Science andTechnology Series, Vol. 2) (Futurepast, Arlington, VA, 2003). [2] V. F. Tarasenko (Editor), Generation of Runaway Electron Beams andX-rays in High Pressure Gases: Techniques and Measurements, Vol. 1.Processes and Application, Vol. 2 (Nova Science Publishers Inc., NewYork, 2016). [3] E. M. Hollmann, M. E. Austin, J. A. Boedo, N. H. Brooks, N.Commaux, N. W. Eidietis, ... and A. Loarte, Nuclear Fusion. 53, 083004(2013). [4] T. V. Loiko, Sov. Phys. Tech. Phys. 25, 232 (1980). [5] I. D. Kostyrya, V. F. Tarasenko, Plasma Physics Reports. 41, 269(2015). [6] V. S. Bosamykin, V. I. Karelin, A. I. Pavlovskii, and P. B. Repin, Sov.Tech. Phys. Lett. 6, 383 (1980). [7] T. Shao, V. F. Tarasenko, C. Zhang, D. V. Rybka, I. D. Kostyrya, A. V.Kozyrev, P. Yan, V. Y. Kozhevnikov, New Journal of Physics. 13, 113035(2011). [8] C. Zhang, T. Shao, Y. Yu, Z. Niu, P. Yan, and Y. Zhou, Review ofScientific Instruments. 81, 123501 (2010)



Characterisation of plastic scintillators for detection of laser-

accelerated protons

Yaojun Li

Key Laboratory for Laser Plasmas, School of Physics and Astronomy,



Some key experiments about the generation of multi-MeV proton beams from

high-intensity, short-pulse laser interactions, have sought not only to understand the

nature of the acceleration mechanisms, but also to control and optimize proton beam

production. It helps realize future applications, such as proton fast ignition or medical

treatments. Radiochromic film (RCF) stacks, which can image a laser-generated proton

beam with a high degree of spatial and spectral resolution, are often employed when

spatial and spectral information of a proton beam is required. With the development of

new ultra-high intensity, high repetition rate facilities, such as Astra Gemini, new

diagnostics are required capable of acquiring data on a shot-to-shot basis. We have

designed a new scintillator-based ion beam profiler capable of measuring the ion beam

transverse profile. In our experiment, helium target is interacted with one intense laser

beam, stainless steel target is interacted with another intense laser beam to generate

proton for proton photography. The evolution of plasma bubbles in the interaction

process of laser and plasma can be observed clearly by this proton probe. The preliminary

experimental results show that the bubble structure produced by the interaction of laser

and plasma increases first and then decreases with time.

Keywords: laser plasma, proton

References

[1] Kirby, D., Green, S., Palmans, H., Hugtenburg, R., Wojnecki, C., & Parker, D. (2010).

LET dependence of GafChromic films and an ion chamber in low-energy proton dosimetry.

Physics in Medicine and Biology, 55, 417.

[2] Saylor, M., Tamargo, T., McLaughlin, W., Khan, H., Lewis, D., &Schenfele, R. (1988).

A thin film recording medium for use in food irradiation. International Journal of Radiation

Applications and Instrumentation. Part C. Radiation Physics and Chemistry, 31 (4-6), 529-

-536.

[3] Hey, D., Key, M., Mackinnon, A., MacPhee, A., Patel, P., Freeman, R., Van Woerkom,

L. D., & Castaneda, C. M., (2008). Use of GafChromic film to diagnose laser generated

proton beams. Review of Scientific Instruments, 79, 053501.



Measurement of Pulsed X-ray Energy Spectrum Based on

Transmission Measurements

JihuWang

Research Institute of Aeronautical Meteorological and Nuclear Radiation, China


Using the abstract measurement model, truncated singular value decomposition,

Tikhonov regularization, algebraic reconstruction technique, the expectation maximization

algorithm is studied in simulated conditions. The results obtained from different algorithms

are compared and analyzed, and the expectation maximization algorithm gives the best

results. Thus, characteristic features of the expectation maximization algorithm are

emphaticallystudied, including the impact analyses of attenuation sheets and the robustness

analyses of this algorithm. The impact on spectrum reconstruction of attenuation sheets is

studied, using multiple ranges spectrum and the suggestion of selecting attenuation sheets

is given. The robustness of the expectation maximization algorithm is analyzed in different

conditions, including different ranges spectrum, measurement data containing different

noise levels, different pre-spectrums, different energy bins. The results indicate that the

expectation maximization algorithm has strong robustness.

Two different spectrum measurement systems are designed to obtain all attenuation

transmission data of single one pulse. Spectrum measurement system based on CCD

camera imaging is simple, but the sensitivity is low, so it can be applied to measure the

spectrum of high-intensity X-ray sources. However, optical-fiber time-delay spectrum

measurement system based on photomultiplier, is sensitive and suitable for the

measurement of spectrum of low-intensity and narrow-time X-ray sources. A collimator

with multiple collimating apertures, in which the attenuation sheets are placed, is designed.

The impacts on transmission measurements of collimator parameters are studied, using

1MeV photons according to the energy range of target source. The structure of collimator

and used attenuation sheets are chosen. The simulated results show that the interplay of

each attenuation sheets can be neglected and the reconstructed spectrum is accurate under

these conditions.

The validation of spectrum measurement systems and spectrum unfolding

algorithm are performed utilizing X-ray source Philips X'Unique II,

onthebasisofavailableequipments. The results demonstrate that the spectrum derived by the

expectation maximization algorithm is very close to the spectrum measured by HPGe

spectrometer. CCD imaging spectrum measurement system is applied to get the spectrum

of pulsed X-ray source XRS-3 whose spectrum is unknown. The result derived by the

expectation maximization algorithm is more consistent with the prior knowledge. The

optical-fiber time-delay spectrum measurement system is applied to measure the spectrum

of Tesla repetition-rate pulsed X-ray source. The expectation maximization algorithm can

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also get good result. These experiments prove the feasibility of spectrum measurement

systems and the validity of spectrum unfolding algorithm, which lays the groundwork for the

spectrum measurement of target X-ray source.

Keywords: Attenuation Transmission，Pulsed X-ray Energy Spectrum，Expectation

Maximization Algorithm

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Effect of Radial Electric Field on Electrical Explosion of Wires

in Vacuum

NaichengLv*, HuantongShi, Xiaobing Zou, Xinxin Wang

Department of Electrical Engineering, Tsinghua University, China


Wire array Z-pinch is an active frontier in high-energy physics, especially in

controlled nuclear fusion. Z-pinch is considered as a promising approach to the ignition

because of the high capacity of X-ray radiation and high efficiency of energy

transformation. The first stage of wire array Z-pinch is electrical explosion of wires (EEW),

the energy depositon of this stage has great influence on the following implosion process.

Due to the capacitive coupling of the gap switches,'prepulse'often occurs in large pulsed

power facilities. If the wires in an array can be fully vaporized driven by the prepulse, and

expand and merge during the period between prepulse and main pulse, the Magnetic

Rayleigh-Taylor (MRT) instabilities of the following stages can be suppressed and final

X-ray yield increased dramatically. In this paper, to explore the effect of radial electric

field on the explosion of wire array under prepulse, first, COMSOL software was used to

simulate the radial electric field of the dual wire load. The results show that the radial

electric field near the surface of the wires can be changed by the insulation flashover switch,

which was connected to the cathode. Using insulated cathode can change the negative

radial electric field that promotes electron emission into a positive radial electric field that

inhibits electron emission. Furthermore, a small pulsed power platform(PPG-3) was

improved, the parameters as follows: short circuit current 0-4kA; 10%-90% rising time of

current ~20ns. The optical measuring system of PPG-3 includes laser shadowgrah and

Mach-Zehnder interferometry. The electrical measuring system of PPG-3 includes V-dot

probe to measure voltage and Rogowski coil and shunt to measure current. Finally,

experiments were carried on the PPG-3, using 12.5μm dual wire load .We used insulated

cathode of changing the radial electric field and delaying the breakdown along the surface

of the dual wire load. Experimental results show great improvements of deposition energy

of dual wire load. These results clearly demonstrate that using insulation flashover switch

connected the cathode is one of most effective way to change the radial electric field and

improve the deposition energy of dual wire load.

Keywords: Electrical Explosion of Wires; Z-pinch; Surface Breakdown; Specific Energy



The effect of growth temperature on the homogeneity of DKDP

crystal

Han Gao, 1 Bing Teng,1* Shaohua Ji,1* Zongqi Wang,1 Hong Liu,1 Chen Hu,1 Degao Zhong,1

1College of Physics, Qingdao University, Qingdao 266071, China

*Email:

Two deuterated potassium dihydrogen phosphate (DKDP) crystals are grown from 70%

deuterated solutions by point-seed rapid growth method at 63.3-49.6°C and 53.9-39.7°C

temperature range, respectively. The deuteration level of DKDP crystals is measured by

Raman spectroscopy. 5% crystal deuterium content difference is found between crystals

grown from similarly deuterated solutions but with varying growth temperature. With the

increase of the growth temperature, the deuterium segregation difference becomes smaller.

Meanwhile, the UV transmission of the crystal grown in higher temperature range is

obviously higher. Our results indicate that the increase of growth temperature in a proper

range can reduce the deuterium segregation deviation and increase the homogeneity of the

DKDP crystal grown by rapid growth method.



Numerical Analysis of Nonlinear Inductor Effect on

Modulated Characteristics of Gyro-magnetic Nonlinear

Transmission Line

W. Tie1,2，C. Meng1，H. Jin1，Z. Xu1，P. Wu1，Y. Jiang1，J. Wen1，E. Cheng1

1. Department of Engineering Physics, Tsinghua University, China

2. Xi’an Electronic Engneering Research Institute, China

Gyro-magnetic nonlinear transmission line (GNLTL) is a solid state oscillator to

generate high power RF electromagnetic pulse, the center frequency of which can be

adjusted online. In order to cognize the nonlinear inductor effect on modulated pulse of

GNLTL, we established the distributed parameter circuit model of GNLTL, and the

influences of initial inductance, saturated inductance and saturated current on the

oscillation frequency and rise time of modulated pulse were iteratively analyzed. The

analysis results show that the oscillation frequency drops gradually with increase of initial

inductance, and there is the fastest rise time at a certain initial inductance. By contrast, the

saturated inductance has more effect on the oscillation frequency and rise time of

modulated pulse than those of initial inductance. Under the condition of lower saturated

inductance, an oscillation pulse with a faster rise time and a higher centre frequency can

be obtained. In addition, we notice that the oscillation wave is hard to be modulated

whether the saturated current is extremely high or low. In the certain range, the oscillation

frequency increases with decrease of saturated current, accordingly, the rise time of

modulated pulse is much faster.

Keywords: GNLTL; nonlinear inductor; RF pulse; oscillation frequency; rise time



Generating of a rotating drive magnetic field for the alternant

Theta-Z pinch Liner Inertial Fusion concept

Shu-Chao Duan



A time-varying, rotating drive magnetic field is required to implement the alternant

Theta-Z pinch [S.-C. Duan et al, High Power Laser and Particle Beams 30, 020101 (2018)]

or dynamic screw pinch [P. F. Schmit et al, Phys. Rev. Lett. 117, 205001 (2016)]. In view

of this, we performed some three-dimensional electromagnetic simulations of the helically

twisted current-return posts configuration suggested in [P. F. Schmit et al, Phys. Rev. Lett.

117, 205001 (2016)] and other configurations we have considered, to verify whether these

configurations really produce a rotating drive magnetic field and/or the effects of these

configurations. This work is funded completely and directly by the National Natural

Science Foundation of China (Grant No. 11405167).

Keywords: Dynamic Z-pinch; Rotating drive magnetic field; Theta-Z-LIF; Alternant

Theta-Z pinch; Inertial confinement fusion (ICF); Magneto-inertial fusion (MIF).



The realization of long focal depth with a linear varied-area

zone plate

Quanping Fan



We report a linear varied-area zone plate, in which arbitrary long focal depth can

be achieved by properly adjusting the corresponding parameters. Meanwhile, the lateral

focal spot and side lobes can be kept very small. Numeral simulations are carried out to

verify the performance of our zone plate through Fresnel-Kirchhoff diffraction theory, and

the results are in good accord with the experimental verifications. The influences of our

zone plate‘s parameters to the intensity distribution in focal region are discussed in detail.

Comparisons are made with the behaviour of a linear varied-line-space grating, and we find

that the behaviour of our novel zone plate along optical axis is just like a reverse

transformation of the focusing behaviour of a linear varied-line-space grating.

Keywords: long focal depth; zone plate; diffractive optics



Research on Resistance Matching Method to Reduce the

Transient Grounding Resistance of Vertical Grounding Rod

Yapeng Fu*, Lihang Du, Qi Zhang, Cheng Gao

National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical

Engineering,PLA Army Engineering University,China


In this paper, we study reducing the transient grounding resistance (TGR) of

vertical grounding rod by use of matching method. We set single or double matching layer

surround the ground rod and change their sizes and conductivity to get the laws about

reducing the TGR peak and stable value. The finite-difference time-domain (FDTD)

method is adopted for calculating. For the single matching layer, both of the peak and stable

value of the vertical grounding rod TGR reduce, compare with normal case, as matching

layer exists when the conductivity of matching layer is larger than that of ground.

Increasing the conductivity and size of matching layer can reduce the TGR value. For the

double matching layer, the TGR value will reduce even more than single matching layer

case when the conductivity of outer matching layer is larger than that of ground. Moreover,

the TGR value will reduce with the conductivity of outer matching layer increasing when

inner layer and ground conductivity are invariants and with the conductivity of inner

matching layer increasing when outer layer and ground conductivity are invariants.

Keywords: Transient grounding resistance (TGR), grounding, matching method, finite-

difference time-domain (FDTD) method



Circuit simulation of synchronization of double magnetic pulse

compression modules

Jingming Gao*, Song Li, Hanwu Yang

National University of Defense Technology, China


Magnetic pulse compressor is an important method for solid-state high power pulse

modulation; application of multiple such modules to drive a common load benefits for

pulsed power step-up where synchronization is the key issue. Compared to other

synchronization technologies, electromagnetic coupling between the double modules could

be utilized as a passive synchronization method to reduce output jitter caused by some

dynamic factors of magnetic pulse compression modules. The paper carries out a

preliminary circuit simulation via PSpice software to investigate the synchronization

characteristics of double magnetic pulse compression modules. Differences of charging

voltage of the capacitors, triggering time of the primary switches and voltage-second

product of the magnetic switches are analyzed. The results verified the key function of the

coupling windings for improving the synchronization precision.

Keywords: Synchronization, solid-state, high power pulse modulation, magnetic pulse

compression, coupling winding



Anode failure mechanism of GaAs photoconductive

semiconductor switch triggered by laser diode

Yi Shen*, Yi Liu, Wei Wang, Mao Ye, Huang Zhang, Liansheng Xia


Physics, China


This paper presents an experimental study on the failure mechanism of high current

gallium arsenide photoconductive semiconductor switches (GaAs PCSS) triggered by laser

diode. We propose a Blumlein pulse forming line to test the GaAs PCSS. The result shows

that the damage of GaAs PCSS almost occurred on the anode side nearby the electrode

either anode illumination or cathode illumination. Since the highest amplitude of Gunn

oscillating always occurs on the anode. We speculate that the failure of high current GaAs

PCSS is attributed to the Gunn effect according to the statistics about failure factor of GaAs

PCSS. And we use a scanning electron microscope to semi-quantitative analysis of

composition of the erosions micro ball or granules, which the composition are the Gallium

and Arsenium. It further proves our speculation.

Keywords: gallium arsenide, photoconductive semiconductor switch, filamental current,

Gunn effect, failure mechanism



The Role of Conducting Current to Conducting Resistance of

GaAs-PCSS in Nonlinear Mode

Yi Liu*, Liansheng Xia, Yi Shen, Wei Wang, Mao Ye, Jinshui Shi, Linwen Zhang



GaAs-PCSS nonlinear conducting experiment is performed by utilizing high power

laser diode as trigger source. In order to avoid the interference of conducting duration and

bias electric-field to the results, the experimental platform is a Blumlein Line constructed

of solid plate transmission lines with different characteristic resistances. The conducting

current and conducting resistance can be calculated from the detected bias voltage and

output voltage. It is emerging from the experiment results that the conducting resistance

decreases with increasing conducting current in the case of all other parameters remaining

unchanged in nonlinear mode. By primary analysis, higher conducting current leads to

fiercer avalanche effect of carrier, thus smaller conducting resistance reflects in

macroscopic view.

Keywords: Photoconductive semiconductor switch, nonlinear mode, conducting current,

conducting resistance, avalanche effect of carrier.




Experiments on multi-stage continuous acceleration of proton

beam in dielectric wall accelerator

Wei Wang*, Yi Shen, Yi Liu, Mao Ye , Liansheng Xia, Jinshui Shi



A new type of compact linear accelerator, dielectric wall accelerator (DWA), is

under development at the Institute of Fluid Physics (IFP). The machine, aiming at proton

therapy for cancer, promises to increase the average accelerating gradient by at least an

order of magnitude over that of existing linear induction accelerators. The key technologies

of DWA have been researched in the past few years, including high gain gallium arsenide

photoconductive semiconductor switch (GaAs PCSS), composite ceramic plate

transmission line (PTL), and high gradient insulator (HGI). Recently, 5-stage continuous

acceleration of proton beam has been achieved, and the total energy gain is approximately

296 keV, which is the highest energy gain of proton beam with the same accelerating theory

for now.




Research on the power sources decoupling at IFP’s Dielectric

Wall Accelerator

Ye Mao*, Chen Yi, Zhang Huang, Liu Li, Wang Wei, Xia Liansheng



Dielectric wall accelerator (DWA) is a new type of pulsed linear accelerator. Its

working mechanism is regulating the discharge order of different power sources to keep

the accelerating field present near the particles all the time, which is really suitable for

heavy ion acceleration. The Institute of Fluid Physics, China Academy of Engineering

Physics (IFP, CAEP) began the research on DWA since 2011, and had built a sample DWA

for proton acceleration. During the debugging process of the accelerator, it was found that

the coupling between adjacent power sources in the discharge circuit will lead to a sharp

drop of the accelerating voltage on the accelerating cavity, and the energy gain of proton

was much less than expected. In this paper, the research on the coupling between power

sources was studied and a new electrode structure which can suppress the coupling between

power sources was put forward. And three-dimensional electromagnetic simulation

software was used to compute the electric field distribution under the new structure. The

result showed that the new electrode structure successfully blocked the discharge circuit

between adjacent power sources, and the coupling between them was effectively

suppressed, the voltage on a single accelerating cavity was significantly increased. Even

though there will get decelerating electric field presenting near the new electrode structure,

the simulation result showed the magnitude of decelerating electric field was limited, and

the influence to particle energy gain is negligible, particles still can get high gradient

accelerating. The experimental result of the voltage loading on the accelerating structure

also showed the effectiveness of the improved structure.



A high-current ultra-short pulsed vacuum arc ion source

Tao Wang*, Zhen Yang, Pan Dong, Le Zheng, Jie Li, Jidong Long



The vacuum arc discharge is useful for high-current pulsed ion source, which is

widely used in particle beam fusion, ion beam modification. This paper reports on a study

of the ultra-short high-current ion beam source based on vacuum arc discharge technology.

The ion beam was generated from cathode material mainly, and the entire elements were

generated in this ion source. The ion source was operated at 20 kV discharge potential, 1

kA discharge current, under 1 μs pulse width, 10-4 Pa vacuum environment and several

A/cm2 of ion beam current. In this report, we will discuss various physical and technical

issues related to the components of the ion source.




A Low Inductance Current Convergence Configuration for

Large Repetitive Z-pinch Driver

Liang-ji Zhou*, Wenkang Zou, Fan Guo, Meng Wang, Lin Chen


Physics, China


Z-pinch driven fusion-fission hybrid reactor is a promising energy approach for future.

Z –pinch driver for such a energy system should work in a repetitive mode and portions of

the MITL are vaporized every shot. To meet these requirements, a new low inductance

current convergence configuration with two sections is put forward. The first section

consist of six conical MITLs in parallel to minimize the inductance and then the second

section is a RTL (Recyclable Transmission Line) that can be replaced every shot. Initiative

design and simulation results are given.

Keywords: Inertial fusion energy; Z-pinch; Pulsed power driver; Current convergence

configuration; Low inductance




Design of a multi-turn railgun for accelerating heavy vehicle to

high speed

Yong He*, Yongchao Guan, Shengyi Song


Physics, China

*Email: [email protected], [email protected]

A multi-turn railgun is designed to accelerate a relatively heavy launch vehicle of

hundred kilograms for a pulse duration of several seconds, yielding launch speed of several

Mach. The designed multi-turn railgun has length of 500 m to 1000 m, bore of 400 mm to

800 mm, turns of 20 to 50, and propulsive inductance gradient of 0.25 mH/m to 1.6 mH/m.

The distributed and concentrated structure power supply for accelerating the vehicle are

presented and analyzed. The distributed power supply are lined up and fed in the railgun

in proper sequence with different voltages. The concentrated power supply is fed in the

railgun at the tail with high voltage. The merits and drawbacks of the two kinds of

structures are analyzed. Simulations of the electromagnetics and mechanics of the multi-

turn railgun are presented. The acceleration process of the heavy load is simulated. An

initial velocity of the heavy load is powered by a multi-stage coilgun with a bore of 400

mm. The main technique challenges, for example, the contacts between the armature and

rails, the insulation between the different layers of armature, the structural performance of

the armature assembly, and the crossovers that connects the rails, for developing the

designed multi-turn railgun are presented and discussed. Consequently, it should be

possible to construct a launch system to accelerate heavy vehicle to high speed utilizing

multi-turn railgun.

Keywords: Multi-turn railgun, heavy vehicle, distributed power supply, concentrated

power supply





Noncritical phase-matched fourth harmonic generation of

converging beam by DKDP crystal

Xiangxu Chai, Bin Feng, Ping Li, Liquan Wang, Deyan Zhu, Fang Wang, Guanzhong Wang,

Yukun Jing


*E-mail: [email protected]

In the ICF device, DKDP crystal is an optimal choice for converting the Nd:glass

radiation to fourth harmonic laser by noncritical phase matching (NCPM), which performs

as a probe to detect the laser-plasma interaction. To reduce the damage probability of

focusing lens, the DKDP crystal is suggested to be set before the focusing lens and a

converging beam enters the fourth harmonic generation (FHG) crystal. In this paper, we

simulate the process of FHG in the scheme and the dependence of FHG efficiency on the

lens’ F is derived. Besides, DKDP crystal with gradient deuterium is proposed to realize

the NCPM FHG of converging beam. At every position the phase matching is achieved by

adjusting the deuterium level and the FHG efficiency increases as a result. The relation of

the lens’ F with the deuterium gradient is also investigated.



Technique of puniness object extractive based on crystal

birefringence

Yuan Hao-yu1,Wang Wen-feng2,Chen Feng-dong2, LiuGuo-dong2,PengZhi-tao1


2. School of Electrical engineering and Automation,Harbin Institute of Technology, China

Lasing offrequency-tripled by two uniaxial crystals, they are woke on high flux

laserand can be damaged easily. For obtain damage information of uniaxial crystals on

surface, we detected damage point by Optical Damage Online Inspection system. But

because of crystal birefringence, there are two damage sites on image correspondence a

damage site that have same size, same shape and gray-value very close. It could not

delimitation them as independent damage site by image processing techniques of generality

plane optic, reduced measuring accuracy. In view of this situation, we researched a method

based on transfer of axes. First, made the target to seed field growth, delimitationtwo

damage site by method of edge extraction. Secondly, according to theory of crystal

birefringence and geometrical optics, built two systems of axes to delimitation damage site

that we need, and measured its size. At the present time, this technology has been used on

Optical Damage Online Inspection system.

Keywords:uniaxial crystal;birefringence; transfer of axes; edge extraction



Theoretical researches on small-scale self-foucsing of high-

power laser with multi-wavelengths

Zhou Lidan*, JiaHuaiting, HanWei, Wang Fang, Li Fuquan, Feng Bin,Li Ping, Hu Dongxia,

Zheng Kuixing, Su Jingqin, Zhu Qihua


The high-power lasers nonlinear propagation of multi-wavelengths is different

from single-wavelength. In this article, thehigh-power lasers propagation in isotropic

medium with two-wavelengths are theoretically researched. Base on plane wave

perturbationtheory, the small-scale self-focusing theoretical model of multi-wavelengths

high-power lasers is constructed. The theoretical solutionand impacting picture are

obtained in the model.Compared to high-power laser with single-wavelength, the nonlinear

gain coefficientsare higher and the nonlinear gain spatial spectrums are broader. The spatial

distribution of per wavelengths is similar and their peak andvalley are matched completely.

This result will promote the understanding of self-focusing theory and so it can provide the

conditions forthe research of multi-wavelengths load in high-power laser facility.



Process-oriented adaptive optics control method in the multi-

pass amplifiers

Q. Xue*, D. E. Wang, X. L. Zhang, F. Zeng, S. Gao, K. Yao, C. Fan, Y. Yang, X. Zhang, Q. Yuan,

J. P. Zhao, X. D. Xie, W. J. Dai*, D. X. Hu, K. X. Zheng and Q. H. Zhu


*Email address: *[email protected]

In this talk, we propose and demonstrate the process-oriented adaptive optics

wavefront control method, for optimizing the beam quality in the multi-pass amplifiers.

Different from the conventional target-oriented wavefront control approach, the novel

method divides the aberration correction process into several steps, to optimize the

wavefront quality in time during the courses of the beam's transport and amplification. The

experiments validate that the novel approach can effectively prevent the beam quality from

worsening and ensure the successful reality of multi-pass amplification



1J, 1Hz ultra-multi-pass Neodymium glass laser amplifier with

high efficiency and excellent beam quality

Ke Yao, Song Gao, XudongXie, Chen Fan, Jun Tang, Zhenhua Lu, Kuixing Zheng,

Zhitao Peng, JingqingSu


An effective ultra-multi-pass neodymium glass amplifier with high energy was

developed. By means of appropriate depolarization compensation, wavefront distortion

correction and relayed-image methods, the output laser with 1Hz repetition and excellent

beam quality was obtained. Under the condition of 3.2x single-pass small-signal gain and

twelve-pass amplification, output energy of 1J, net gain of 2×104 and energy-extraction

efficiency of 36.2% were realized. The near-field modulation was 1.4 and far-field quality

was 4.1 times of diffraction limit. Furthermore, the energy stability of output laser was

obviously improved by saturation from twelve-pass amplification.



The pulsed waveform shaping in SG-III laser facility

Xiaoxia Huang*, Wei Zhou, Xuewei Deng, Bo Zhang, Yuancheng Wang, Huaiwen Guo


The SG-III laserfacility is a high power laser facility with 48 beams delivering a

precise amount of laser power on the target for inertial confinement fusion

experimental research. For each experimental shot, pulsed waveform varies depending

on the physics of the particular campaign. The precise temporal shape, energy and

timing characteristics of a pulsed waveform target interaction are key components in

meeting the experimental goals. By adopting Laser Performance Operation Simulation

System and Repeat-frequency Pulse Control System built in SG-III laser facility, 48

unique experimental pulsed waveforms can be sculpted autonomously and

efficiently.In this report, we provide an overview of the pulse shaping system, the

pulsed waveform shaping procedure and associated challenges that have been

overcome throughout the evolution of the controls.

Keywords: pulsed waveform shaping, laser performance operation simulation system,

repeat-frequency pulse control system



Research on the shooting accuracy of ICF laser device based

on radiation fluid

Xiaolu Zhang (张晓璐), Zeng Fa, Wang Shenzhen, Zhao Junpu, Xue Qiao, Dai Wanjun*


The shooting accuracy of cluster laser is an important indicator to evaluate the

performance of ICF laser devices. By measuring the distribution of the X-ray generated

from interaction between the third-harmonic beam and the target, the position information

of the third-harmonic beam to the target can be obtained, along with the shooting accuracy.

In the beam transmission process, the fundamental, second-harmonic beams and the third-

harmonic beams approach to the target at the same time generating spurious X-ray. Based

on the radiation fluid, the present paper is to assess the effect of the stray light on the

performance of the shooting accuracy. The intensity distribution and power density of the

fundamental, second-harmonic and third-harmonic beams at the target position were

calculated for the laser device using SG-99 software. The characteristics of X-ray generated

by the different beams radiation are simulated by one-dimensional radiation fluid program

MULTI 1D. The results show that the power density of the fundamental, the second-

harmonic and third-harmonic beams at the target position are, under the condition of typical

shooting precision test (infused fundamental energy of 50J and pulse width is 200ps)

0.28GW / s / cm2, 0.14GW / s / cm2, 99GW / s / cm2, respectively. The X-ray energy

intensity radiated from the interaction between the third-harmonic beam and target is 104

times of that from the fundamental, second-harmonic beam. In the current optical system

configuration conditions of the laser device, the effects of the fundamental and second-

harmonic beams on the target accuracy test can be ignored.

Key words: radiation fluid, shooting accuracy, power density, X-ray energy intensity



Influence of annealing atmospheres on the nanometer-scaled

defects in fused silica defect layer

Lijuan Zhang1, *, Jing Chen1, Yilan Jiang1, Jiandang Liu2, Xiaolong Jiang1, Chuanchao Zhang1,

Haijun Wang1, Xiaoyu Luan1, Bangjiao Ye2, Xiaodong Yuan1, Wei Liao1


2. State Key Laboratory of Particle Detection and Electronics(IHEP & USTC), Department

of Modern Physics, University of Science and Technology of China, China

*E-mail: [email protected]

Laser-induced damage in fused silica optic is responsible for restricting the output of

the high power laser system. Laser damage threshold of fused silica can be influenced by

the microstructure variation of the nanometer-scaled defects. The annealing process is

possible to anneal out the photoluminescence defects. Thus, investigation of defects

variation under different annealing processes is very important in improving laser damage

resistance properties of the fused silica optics. Two positron annihilation spectroscopy

techniques have been used to detect the variation of the vacancy clusters and the structure

voids in fused silica after annealing in an air atmosphere, a vacuum atmosphere and a

hydrogen atmosphere, respectively. Doppler broadening annihilation spectroscopy coupled

to a slow positron beam results indicate that hydrogen atmosphere have an influence on

vacancy defects and vacancy clusters, while having no effect on the large voids. However,

due to the large volume and low diffusion coefficient of the oxygen atom, ambient oxygen

atmosphere only affects the surface of the fused silica (about 300 nm depth). The reduction

of size and concentration of vacancy cluster are also observed by the positron annihilation

lifetime spectroscopy. The experimental results can provide important information for

understanding the laser damage mechanism and improving laser damage resistance

properties of the fused silica optics.

Keywords: Fused silica, Positron annihilation, Thermal annealing



Optimum inductively coupled plasma etching technique for

obtaining subsurface damage free fused silica needed in high

power laser system

Xiaolong Jiang1,*,Zhengkun Liu2,Keqiang Qiu2, Ying Liu2,**

1. Research Center of laser Fusion, China Academy of Engineering Physics, China

2. National Synchrotron Radiation Laboratory, University of Science and Technology of

China, China


** Email: [email protected]

Currently, optical surface finish in fused silica is usually obtained by abrasive-based

polishing methods, during which damage is created in the subsurface of optics due to the

physical force involved at the microscopic scale. In high peak power laser system, subsurface

damage (SSD) is believed to serve as a laser damage precursor when exposed to high power

laser. Therefore, obtaining of SSD-free fused silica substrate has been a goal for the optical

fabrication industry for many years. Inductively coupled plasma etching is a state of art dry

etching technology and is promising to remove SSD layer of fused silica. It is based on

chemical reaction between silicon-based material atom and reactive fluorine radicals

generated by the plasma. Volatile reaction products are generated to remove the material,

which avoids further damage to the processed surface. However, dry etching often causes

the development of roughness on etched surface. Moreover, in this case, open of SSD due to

lateral etching is also an important issue. In this work, we introduce an optimum inductively

plasma etching technique which successfully removes the subsurface damage layer of fused

silica without causing surface roughening or lateral etching of SSD. As one of the commonest

roughening initiators, metal contamination from reactor chamber is prevented by employing

a simple isolation device. Based on this device, a unique low-density pitting damage is

discovered and subsequently eliminated by optimizing the etching parameters. Meanwhile

etching anisotropy also improves a lot, thus preventing the lateral etching of SSD. Using this

proposed technique, SSD layer of fused silica is successfully removed with a surface

roughness of 0.23 nm.

Keywords: Inductively coupled plasma etching; Plasma induced surfacedamage;

Fused silica; Subsurface damage;





Surface Damage Mitigation of Large-Aperture Fused Silica

Optics for High Power Laser

Chuanchao Zhang, Wei Liao, Lijuan Zhang, Xiaolong Jiang, Jing Chen, Haijun Wang,

Xiaoyu Luan, Xiaodong Yuan


For the high power laser systems, one of the challenged issues is laser-induced

surface damages of fused silica optics due to the routine operation above the laser damage

initiation and growth thresholds. The damages will grow exponentially upon subsequent

laser shots, and will result in excessive light scattering and beam modulation, and finally

lead to the failure of fused silica optics. Considerable work has been done to mitigate

growth of damages, and the most commonly used technique is by the CO2 laser treatment

to locally melt or evaporate the damages[1-3]. However, some thermal negative effects, such

as raised rims, re-deposited debris, and residual stress at the mitigated damage sites, may

occur by using the CO2 laser-based mitigation technique, and will lead to problematic

damage re-initiation and growth, and downstream intensification. Therefore, an effective

control of the thermal negative effects to an acceptable level is necessary for the mitigation

of damage sites. It was thought that the mitigation protocol based on pulsed CO2 laser can

effectively minimizes the thermal negative effects[1-2]. In this paper, an investigation of the

pulsed CO2 laser-based mitigation technique was conducted to limit the raised rims, re-

deposited debris, and residual stress left in the surface of optics. The mitigation parameters

of peak power, pulse width, and repetitive frequency were taken into account, and the

thermal negative effects of mitigated damage sites were characterized by microscope and

polarimetry. The results indicated that the pulsed CO2 laser-based mitigation technique can

eliminate the thermal negative effects induced by CO2 laser-based damage mitigation.

References

[1] I. L. Bass, G. M. Guss, and R. P. Hackel, Proc. of SPIE Vol. 5991 59910C (2005)

[2] I. L. Bass, G. M. Guss, M. J. Nostrand, and P. J. Wegner, Proc. of SPIE Vol. 7842

784220 (2010)

[3] T. Doualle, L. Gallais, S. Monneret, S. Bouillet, A. Bourgeade, C. Ameil, L.

Lamaignère, and P. Cormont, Opt. Eng. 56(1), 011022 (2017)



High fidelity Frequency Modulation Pulse Waveform

Centralized Measurement Technology for High Power Laser

Facility

Bo Zhang, Zhitao Peng, Yanwen Xia, Zhihong Sun, Jun Dong, Zongui Lu


A high fidelity waveform centralized measurement technology which has low cost

and good maintainability is developed for high power laser facility. The frequency

modulation pulses were sampled to graded index fibers by several lens arrays and after

fiber transmission the pulses waveforms can be measured by one detector using time

division multiplex method which manage the length of fibers. The experiment shows the

technology have a high fidelity on waveform measurement and avoid FM-AM effect

successfully because the lens array sampling technique and graded index fibers

transmission technique can effectively improve the power coupling ratio and have strong

resistance to angle drift.

Keywords: waveform centralized measurement; time division multiplex; lens array;

graded index fiber



Forward Raman scattering of the seed pulse in strongly

coupled stimulated Brillouin amplification in plasma

Hao Peng


Plasma amplification is a novel way to provide ultra-intense and ultra-short laser,

which detours the damage problem in the traditional solid amplifiers. Laser amplification

via strongly coupled stimulated Brillouin scattering (sc-SBS) in plasma has the advantages

that pump and seed can be at the same frequency and it is not sensitive to the plasma density

inhomogeneity. But it is subject to various deleterious instabilities. Here, specific analyses

on the forward Raman scattering (FRS) of the seed are presented. FRS grows from noises

and deplete the seed energy. It causes strong seed modulations and decoherence. At first,

the mechanism of the FRS couples with sc-SBS and terminates the amplification is

discussed. Then, two possible ways to suppress the FRS during the sc-SBS amplification

are proposed and examined by both theory and simulations.

Keywords: plasma amplifier, strongly coupled stimulated Brillouin scattering, ultra-

intense and ultra-short laser, forward Raman scattering.



The suppression of core-corona structure for aluminum wire

array and its influence on the implosion dynamics under a

current of mega-ampere

Zhang Jinhai1,2, Qiu Aici2, Wang Liangping2, Li Mo2, Sun Tieping2, Cong Peitian2, Li Yang2,

Shengliang2, Wu Hanyu2

1. Department of Engineering Physics, Tsinghua University, China

2. Skate Key Laboratory of Intense Pulsed Radiation Simulation and Effect,Northwest

Institute of Nuclear Technology,China

The core-corona structures, namely the dense wire core in atomic state surrounded by

plasma with high temperature and low density, are widely observed in wire array z-pinch

experiments under a current of mega-ampere for the early breakdown of each metal wire.

The corona plasmas are accelerated toward the array axis by the global J×Bforce. The wire

cores, as well as the plasma streams, both exhibit a characteristic mm scale modulation

along the axis. The wavelength of this modulation just depends on the wire material

according to experiments on many different current-scale generators (~0.5mm for Al and

~0.25mm for W). These modulations are also the initial perturbations of the following array

implosion, which will aggravate the development of plasma instability.

In order to suppress the core-corona structure, two-stage wire array experiments has

been carried out on Qiangguang-I generator (1.3MA,~80ns). Two-stage array consisted of

two parts: the top load wire array and the lower wire inverse array. The adding inverse

array was to be a shut-down switch to ensure the vaporization and uniform expansion of

aluminum wires in load array during the pre-pulse current before current switch and the

implosion of load array during the main pulse current after current switch. The load

aluminum wires with a diameter of 15μm were completely vaporized by adjusting the

parameter of two-stage array and regulating the pre-pulse of the generator. The results

showed that the shutdown time of inverse array depended on wire number. The shutdown

time was 40ns after the start of main current when two aluminum wires were placed in

inverse array, which ensured that there were still enough time during main current for load

array to implode and radiate X-rays. The vaporized wire cores expanded uniformly along

the axis with a smooth boundary and the average wire diameter was 1.8~1.9mm. The

vaporized wire cores were ionized rapidly after the shutdown of inverse array. The

perturbations of plasma instability were firstly observed at the boundary of vaporized core

and developed rapidly after the start of implosion. The average wavelength of these

perturbations was 600~650μm. The precursor plasma was barely observed on the array axis

in optic images. Considering the waveform of X-rays and the main current, the implosion

of the vaporized load array tended to zero-shell model. Nevertheless, there were still some

fractions of plasma being left down at the initial position to lead the second implosion for

the fast development of plasma instability in implosion, which resulted in the double peaks



of X-rays. The suppression methods of the implosion instability will be further studied and

explored in future.

Key words: Core-corona structure, two-stage array, pre-pulse current, vaporization,

implosion of zero-shell model



Polarization smoothing for single beam by a nematic liquid

crystal scrambler

Yuancheng Wang


Polarization smoothing (PS) is a key approach to suppress laser plasma instabilities

(LPI) in inertial confinement fusion (ICF) experiments. Here, we propose a liquid crystal

(LC) PS element to realize single beam smoothing and demonstrate its smoothing effect,

in principle, with a 2 × 2 LC polarization checkerboard, which reduces the laser intensity

variation in the focal spot to 78.4%. LC PS elements, which have potential applications in

high-power ICF laser drivers, have many advantages because they are easy to fabricate,

cost effective, flexible, and large.



Midinfrared extracavity optical parametric oscillator based on

BaGa4Se7 crystal

Minqiang Kang (康民强), Ying Deng, Yan Xiongwei, Zhu Qihua, Zeng Xiaoming, Li Jianbin, Li

Min, Zhang Fan, Xiang Xianjun, Jiang Xinying, Zheng Jiangang, Zhou Kainan, Su Jinqing


We present a high-efficiency and high energy mid-infrared extracavity optical

parametric oscillator (OPO) based on the nonlinear crystal BaGa4Se7 pumped by a diode-

side-pumped Q-switched Nd:YAG laser. The maximum pulse energy of 1.03 mJ at 4.25

μm is obtained with the repetition rate of 10 Hz and pulse width of 12.6 ns when the

pump energy was 13.5 mJ, corresponding to an optical-to-optical conversion efficiency

of 7.6% from 1.064μm to 4.25 μm. To our best knowledge, it is the highest reported

conversion efficiency for the BaGa4Se7 OPO driven by the diode-side-pumped Nd:YAG

laser.

Keyword: Mid-infrared lasers; Nonlinear optics materials; Parametric oscillators and

amplifiers



Simulation of the magnetically driven flyer plate experiment

with an improved magnetic field boundary formula

Ming-xian Kan*, Zhao-hui Zhang, Bo Xiao, Long Yang, Shu-chao Duan,

Gang-hua Wang, Gui-lin Wang



To consistently simulate the magnetically driven flyer plate experiments with a

MHD code by taking the measured current as input, one needs a relation connecting the

measured current and the magnetic field on the loading surface. Lemke's magnetic field

formula gives deep insights into this relation, but yet also leads to visible discrepancy to

experiments if the formula is directly used for flyer plate simulation. In this paper we find

that, by adding to Lemke's formula a new term that reveals the ablation effect of the loading

surface, the simulation can be much improved. With the modified version of Lemke's

formula, the magnetically driven flyer plate experiments performed on PTS facility are

simulated, which shows satisfying agreement with the VISAR velocity measurements.

Therefore, magnetically driven flyer plate velocity is able to correctly simulate directly

from the measured current. The simulated results imply that the improved magnetic field

formula for the loading surface of the flyer plates is correct, and measured current is

accurate.

Keywords: PTS facility, Flyer plates, MDSC2 code, Magnetically driven experiments,

Magnetic field boundary formula



CEP-stabilized, TW-class, 18 fs, 1 kHz, Ti: Sapphire laser

system with an original front-end design

X. Chen1, *. A. Golinelli1, 2, E. Gontier1, B. Bussière1, P.-M. Paul1, 3, O. Tcherbakoff2,

P. d’Oliveira2, J.-F. Hergott2

1. Amplitude laser group – Lisses operations, France

2. LIDYL, CEA, CNRS, Université Paris-Saclay , France

3. Amplitude Laser Group – San Jose operations, San Jose, USA


The last two decades have seen a lot of progress in attosecond science or high field

physics [1-2]. These developments place rising demands on shorter pulse duration as well

as higher peak and average power laser with efficient CEP stabilization.

We present here a Ti: Sa based chirped-pulse-amplified laser chain delivering 15

mJ, 17.8 fs pulses (0.85 TW) at 1 kHz with long-term CEP stability. An original water-

cooled 10 kHz front-end, relying on an innovative double-crystal regenerative amplifier

delivering 700 µJ, 110-nm spectral bandwidth laser pulses [3] is used to seed different

amplification stages. This design helps to optimize the thermal load management inside the

cavity in which a Mazzler [4] is used to counteract amplification gain narrowing. The front-

end output is then split in two, thus seeding simultaneously two amplifiers operating at 1

and 10 kHz respectively. The 1 kHz laser pulses are amplified up to 22 mJ by two amplifier

stages, leading to 15 mJ, 17.8 fs (Figure 1(a)) after a grating-based compressor.

The remaining CEP noise was also measured using a homemade detector and

analogical feedback loop applied on Dazzler [5]. Shot to shot remaining CEP noise is ~370

mrad RMS (Figure 1 (b)) over more than 2 hours, while it is as low as 260 mrad RMS for

the 10-kHz beamline thanks to larger correction bandwidth. Note that the compressor is

installed in the experiment room which is more than 5 meters away from the power

amplifier. To our knowledge, this is one of the best results reported for TW-class Ti:Sa

lasers based on grating stretcher/compressor with large stretching ratio. The innovative

regenerative cavity design shows one of the most promising configurations for future high

intensity CEP stabilized lasers. This work was supported by European Union grant H2020-

MSCA-ITN-MEDEA-641789 and AgenceNationale de la Recherche grant ANR11-

EQPX0005-ATTOLAB.




Figure 1 (a) Measured temporal profile by Wizzler. (b) 1kHz shot-to-shot CEP error measurement

recorded over 30 minutes < 370 mrad RMS.

Keywords: Ultra-fast technology, TW-class laser, Ti: Sapphire (Ti: Sa) laser, thermal load

management, Carrier-Envelope-Phase (CEP) stabilization

Reference

[1] E. Takahashi, P. Lan, O. D. Mucke, Y. Nabekawa and K. Midorikawa, “Attosecond

nonlinear optics using gigawatt-scale isolated

attosecond pulses” Nature Comm. 4, 1 (2013).

[2] K.T. Kim, C. Zhang, T. Ruchon, J. F. Hergott, T. Auguste, D. M. Villeneuve, P.B.

Corkum and F. Quéré, “Photonic streaking of attosecond

pulse trains” Nature Phot. 7, 651 (2013).

[3] A. Golinelli, X. Chen, E. Gontier, B. Bussière, O. Tcherbakoff, M. Natile, P. D’Oliveira,

P.M. Paul and J.-F. Hergott, “Original Ti:Sa 10k

Hz Front-end design delivering 17 fs, 170 mrad CEP stabilized pulses up to 5 W”, Opt.

Lett. 42, 2326 (2017)

[4] A. Trisorio, P.M. Paul, F. Plé, C. Ruchert, C. Vicario and C. P. Hauri, “Ultrabroadband

TW-class Ti:Sapphire laser system with adjustable

central wavelength, bandwidth and multi-color operation” Opt. Exp. 19, 20128 (2011).

[5] C. Feng, J-F. Hergott, P-M Paul, X. Chen, O. Tcherbakoff, M. Comte, O. Gobert, M.

Reduzzi, F. Calegari, C. Manzoni, M. Nisoli and G.

Sansone,”Complete analog control of the carrier-envelope-phase of a high-power laser

amplifier” Opt. Exp. 21, 25248 (2011).



Generating of a rotating drive magnetic field for the alternant

Theta-Z pinch Liner Inertial Fusion concept

Shu-Chao Duan



A time-varying, rotating drive magnetic field is required to implement the alternant

Theta-Z pinch [S.-C. Duan et al, High Power Laser and Particle Beams 30, 020101 (2018)]

or dynamic screw pinch [P. F. Schmit et al, Phys. Rev. Lett. 117, 205001 (2016)]. In view

of this, we performed some three-dimensional electromagnetic simulations of the helically

twisted current-return posts configuration suggested in [P. F. Schmit et al, Phys. Rev. Lett.

117, 205001 (2016)] and other configurations we have considered, to verify whether these

configurations really produce a rotating drive magnetic field and/or the effects of these

configurations. This work is funded completely and directly by the National Natural

Science Foundation of China (Grant No. 11405167).

Keywords: Dynamic Z-pinch; Rotating drive magnetic field; Theta-Z-LIF; Alternant

Theta-Z pinch; Inertial confinement fusion (ICF); Magneto-inertial fusion (MIF).



Ultraviolet frame camera diagnosis in foil liner implosion

experiments

Zhanchang Huang*, Jianlun Yang, Faxin Chen

Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, China


Radiation properties in cylindrical foil liner implosion were investigated

experimentally for the first time at JULONG-I facility in China. The thickness of the

aluminum foil was 2 μm. The diameter and height of the load were 12.8 mm and 15 mm,

respectively. The radiation properties in the early stage in foil liner implosion experiments

were explored via an ultraviolet 6-frame imaging system. The results showed that in the

very early stage there were some vertical striate patterns which should correspond to

current channels. Then some horizontal striate patterns appeared, resulting from

electrothermal instability, which indicated electrothermal instability might act important

role and provide initial perturbation for MRT instability.

Keywords: Z-pinch; UV imaging; dynamic hohlraum; JULONG-I facility



The realization of long focal depth with a linear varied-area

zone plate

Quanping Fan



We report a linear varied-area zone plate, in which arbitrary long focal depth can

be achieved by properly adjusting the corresponding parameters. Meanwhile, the lateral

focal spot and side lobes can be kept very small. Numeral simulations are carried out to

verify the performance of our zone plate through Fresnel-Kirchhoff diffraction theory, and

the results are in good accord with the experimental verifications. The influences of our

zone plate‘s parameters to the intensity distribution in focal region are discussed in detail.

Comparisons are made with the behaviour of a linear varied-line-space grating, and we find

that the behaviour of our novel zone plate along optical axis is just like a reverse

transformation of the focusing behaviour of a linear varied-line-space grating.

Keywords: long focal depth; zone plate; diffractive optics



Effect of optical path difference on coherent polarization beam

combination of ultrashort lasers pulses

Zhang Fan



A theoretical model for the effect of optical path difference on coherent polarization

beam combination of ultrashort laser pulses is established, and the effects of optical path

difference and spectral width on coherent polarization beam combination efficiency of

ultrashort laser pulses are studied. The corresponding control index is put forward, and this

research has certain guiding significance for the design of coherent polarization beam

combination system of ultrashort laser pulses.

Keywords: ultrashort laser pulses, coherent polarization beam combination, optical path

difference



CEP-stabilized, TW-class, 18 fs, 1 kHz, Ti: Sapphire laser

system with an original front-end design

X. Chen1, *. A. Golinelli1, 2, E. Gontier1, B. Bussière1, P.-M. Paul1, 3, O. Tcherbakoff2,

P. d’Oliveira2, J.-F. Hergott2

4. Amplitude laser group – Lisses operations, France

5. LIDYL, CEA, CNRS, Université Paris-Saclay , France

6. Amplitude Laser Group – San Jose operations, San Jose, USA


The last two decades have seen a lot of progress in attosecond science or high field

physics [1-2]. These developments place rising demands on shorter pulse duration as well

as higher peak and average power laser with efficient CEP stabilization.

We present here a Ti: Sa based chirped-pulse-amplified laser chain delivering 15

mJ, 17.8 fs pulses (0.85 TW) at 1 kHz with long-term CEP stability. An original water-

cooled 10 kHz front-end, relying on an innovative double-crystal regenerative amplifier

delivering 700 µJ, 110-nm spectral bandwidth laser pulses [3] is used to seed different

amplification stages. This design helps to optimize the thermal load management inside the

cavity in which a Mazzler [4] is used to counteract amplification gain narrowing. The front-

end output is then split in two, thus seeding simultaneously two amplifiers operating at 1

and 10 kHz respectively. The 1 kHz laser pulses are amplified up to 22 mJ by two amplifier

stages, leading to 15 mJ, 17.8 fs (Figure 1(a)) after a grating-based compressor.

The remaining CEP noise was also measured using a homemade detector and

analogical feedback loop applied on Dazzler [5]. Shot to shot remaining CEP noise is ~370

mrad RMS (Figure 1 (b)) over more than 2 hours, while it is as low as 260 mrad RMS for

the 10-kHz beamline thanks to larger correction bandwidth. Note that the compressor is

installed in the experiment room which is more than 5 meters away from the power

amplifier. To our knowledge, this is one of the best results reported for TW-class Ti:Sa

lasers based on grating stretcher/compressor with large stretching ratio. The innovative

regenerative cavity design shows one of the most promising configurations for future high

intensity CEP stabilized lasers. This work was supported by European Union grant H2020-

MSCA-ITN-MEDEA-641789 and AgenceNationale de la Recherche grant ANR11-

EQPX0005-ATTOLAB.




Figure 1 (a) Measured temporal profile by Wizzler. (b) 1kHz shot-to-shot CEP error measurement

recorded over 30 minutes < 370 mrad RMS.

Keywords: Ultra-fast technology, TW-class laser, Ti: Sapphire (Ti: Sa) laser, thermal load

management, Carrier-Envelope-Phase (CEP) stabilization

Reference

[1] E. Takahashi, P. Lan, O. D. Mucke, Y. Nabekawa and K. Midorikawa, “Attosecond

nonlinear optics using gigawatt-scale isolated

attosecond pulses” Nature Comm. 4, 1 (2013).

[2] K.T. Kim, C. Zhang, T. Ruchon, J. F. Hergott, T. Auguste, D. M. Villeneuve, P.B.

Corkum and F. Quéré, “Photonic streaking of attosecond

pulse trains” Nature Phot. 7, 651 (2013).

[3] A. Golinelli, X. Chen, E. Gontier, B. Bussière, O. Tcherbakoff, M. Natile, P. D’Oliveira,

P.M. Paul and J.-F. Hergott, “Original Ti:Sa 10k

Hz Front-end design delivering 17 fs, 170 mrad CEP stabilized pulses up to 5 W”, Opt.

Lett. 42, 2326 (2017)

[4] A. Trisorio, P.M. Paul, F. Plé, C. Ruchert, C. Vicario and C. P. Hauri, “Ultrabroadband

TW-class Ti:Sapphire laser system with adjustable

central wavelength, bandwidth and multi-color operation” Opt. Exp. 19, 20128 (2011).

[5] C. Feng, J-F. Hergott, P-M Paul, X. Chen, O. Tcherbakoff, M. Comte, O. Gobert, M.

Reduzzi, F. Calegari, C. Manzoni, M. Nisoli and G.

Sansone,”Complete analog control of the carrier-envelope-phase of a high-power laser

amplifier” Opt. Exp. 21, 25248 (2011).



Estimation of the Neutron Generation from Gas Puff Z-pinch

on Qiangguang

Liangping Wang




Modeling and analysis of the depolarization in large laser

facility

Wanqing Huang



The model of the depolarization of beam in large laser facility is built by the tool

of Jones matrix. The model includes the effects of twist of the beam injection, the reflecting

film and the stress or thermal induced birefringence of the optics. Therefore we could

ascertain the parameters of the material, the film and the installation of the optics that have

influence on the polarization of the beam.Based on the model, the depolarization during

the propagation and amplification could be analyzed, also the change of the isolation ratio

and the gain decrease could be calculated .

Keywords: depolarization; birefringence; reflecting film; isolation ratio; gain decrease



Numerical simulation of laser ablation of Stainless steel

Zongshu Mei*, Chengying Shi, Changbing Lu

Xi’an Research Insitute of High-Tech, China


In this paper, the ablation performance of stainless steel under high-power fiber

laser beam is studied. The ablation rate and morphology of rigid body in a wide range of

laser powers is obtained by numerical calculation. The nonlinear relationship between laser

powers, lens optical properties and ablation rate of stainless steel is summarized. The

experimental results verify the accuracy of the model. Meanwhile, the numerical results

show that the laser absorption increases with the increase of power, which is consistent

with the experimental results.

Keywords: ablation, fiber laser, fiber laser, stainless steel


III - Laser and Particle Beam Fusion,

Magnetic Driven Fusion


Poster Presentation Laser and Particle Beam Fusion, Magnetic Driven Fusion

Direct–drive Richtmyer-Meshkov instability experiment with

reshock on the Shenguang-Ⅲ prototype laser facility

YongtengYuan



In inertial confinement fusion, shock waves repeatedly pass through an interface,

the interface growth caused by Richtmyer-Meshkov instability, it tend to destroy the

imploding shell and later hinder the formation of the central hot spot. Moreover, the RM

instability caused by reshock also play a central role in the evolution of many astrophysical

phenomena, such as supernova explosion, high Mach number jets, etc. Therefore, it is

essential to study the RM instability process involving multiple shocks, because of its

significance in both fundamental research and engineering applications. A planar reshock

experiment is conducted on the Shenguang-Ⅲprototype laser facility, the radiographic data

are record by monochromatic X-ray backlighting system with spherical bent crystal. The

initial growth is seen from 3 to 11 ns, the compression due to reshock occurs between 11

and 13ns, and then the re-growth occurs. The experimental results of the mix width across

the aluminum layer are compared with numerical simulations, the comparing results show

that the numerical simulations are in good agreement with the experimental mix width

evolution between the shocking phase and compression phase by reshock, but can not

match the re-growth caused by reshock. It means the numerical simulations only accurately

capture the early time hydrodynamic evolution of a single-mode sample. The reshock

experiment demonstrates the ability to perform quantitative measurements of mix length

in planar geometry, it can help to understand and analyze the hydrodynamic evolution

process caused by multi shocks.

Keywords: reshock, Richtmyer-meshkov instability, monochromatic X-ray backlighting

system



Integrated Implosion Experiments on Shenguang-Ⅲ Laser

Facility

Tianxuan Huang


Series of integrated implosion experiments have been performed on Shenguang-Ⅲ

laser facility since 2015. First, a single-shock platform was developed with cylindrical

hohlraums driven by short square laser pulses. Cone power balance was used to tune the

P2 asymmetry of imploding core emission, which was measured with a gated X-ray

framing camera. With optimized cone fraction, P2 drive asymmetry was diminished to an

acceptable level. As a result, near one-dimensional implosion performance can be

reproduced with yield over clean (YOC) more than 50%. Then, many efforts were made to

develop a 2-shock platform with gas-filled hohlraums driven by shaped laser pulses. Cone

power balance of picket pulses was employed to tune the early-time P2 asymmetry by thin

shell radiography. Sequentially, cone fraction of main pulses was optimized to achieve full

P2 asymmetry by thick shell radiography. However, the performance of 2-shock

implosions was still limited by the long shaped pulse after symmetry tuning, the best of

which was demonstrated with YOC less than 30%. The effect of picket and trough was

examined with adjusted shaped laser pulses. Mix caused by capsule defects and

hydrodynamic instability growth was studied by numerical simulations. By all means, the

roles of shock timing and fuel-shell mix in this implosion degradation must be understood

quantitatively, before a near one-dimensional 2-shock platform is completed, which is a

proof-of-principle test for ignition campaign.

Keywords: implosion, asymmetry, cone fraction, core emission, radiography, YOC



Fluorescence imaging for M-band drive symmetry

measurement in hohlraum

Qi Li



A critical issue for achieving laboratory inertial confinement fusion (ICF) is the

drive symmetry on the capsule in the center of a hohlraum. Improving implosion

performance requires an x-ray irradiation as uniform as possible on the surface of the

capsule. Too large drive asymmetry may lead to hydrodynamic instabilities and lower the

implosion performance. Imaging for hot spot, shock velocity measurement in surrogate

SiO2 foam-target, and "reemission technique" were developed to measure the drive

asymmetry on the capsule. However, all of the previous works dealt with the drive

asymmetry by thermal radiation. The drive asymmetry by high-energy x-ray (i.e., gold M-

band radiation) was not measured independently. M-band radiation, typically 2-4 keV, is

mainly generated at the laser spot regions, and thus has more serious drive asymmetry due

to its spatial emission feature. M-band radiation can penetrate through the capsule, and

therefore, lead to fuel adiabat increasing and hydrodynamic instability perturbation on the

inner shell. Simulation shows that M-band drive asymmetry can lower implosion

performance even in fairly uniform thermal radiation. Thus, symmetric M-band radiation

is also a critical requirement to improve implosion performance. To research the drive

asymmetry due to M-band radiation independently, characteristic x-ray related to M-band

radiation is required. Fortunately,X-ray fluorescence is only induced by highenergy x-ray

photon or electron. Thus, fluorescence based imaging may become a direct approach to the

measurement of M-band drive symmetry. The excitation energy for the K-shell electron of

Si is about 2 keV, much higher than the main portion of the thermal x-ray but lower than

the M-band radiation, so Si was used as the tracer layer for fluorescence imaging in this

work. The experiment obtained clear fluorescence images and the corresponding M-band

P2 asymmetry. Experimental results show that the P2 asymmetry increases with the wall

motion distance, which is consistent with the view-factor simulation.

Keywords: fluorescence imaging, M-band, drive symmetry



Implosion fuel density diagnosis of cone-in-shell target in

indirect-driven fast ignition

Bi Bi(毕碧)1,*, Lianqiang Shan（单连强）1, Lai Wei（魏来）1, Dongxiao Liu（刘东晓）1,

Feng Zhang（张锋）1, Jin Li（李晋）1, Yimeng Yang（杨轶濛）1, Huabing Du(杜华冰) 1,

Weiwu Wang（王为武）1, Chao Tian（田超）1, Zongqinag Yuan（袁宗强）1, Lei Yang（杨

雷）1, Junfeng Wu（吴俊峰）2, Weimin Zhou（周维民）1, Leifeng Cao（曹磊峰）1, Yuqiu Gu

（谷渝秋）1




As an attractive option for inertial fusion, fast ignition separates the laser into two

systems: one for implosion and the other for heating the imploded fuel core. The implosion

system is required to have multiple nanosecond duration laser beams to compress a fuel

shell directly or indirectly to a density as high as 1000 times the solid density. With

adiabatic shaping technique, Omega EP already showed the probability to improve

compression areal density from 60 mg/cm2 to over 300 mg/cm2 in fast ignition target that

consisted of a thin shell whose spherical symmetry is interrupted by a metal cone. Such

density is high enough to stop MeV electrons and deposit energy. A tremendous effort has

been devoted to achieve high compression in China in the past few years. The density and

areal density of the imploded fuel were measured to 30 g/cm3 and 50 mg/cm2 respectively

in experiments carried on Shenguang II (SGII) facility.

In 2015 and 2016, compression experiments and density diagnosis of an indirect-

driven fast ignition target using picosecond-duration backlighting have been carried out on

the Shenguang II upgrade (SGII-U) facility for the first time in China. A picosecond-

duration X ray backlighter has been produced by picosecond-duration laser irradiating

mass-limited target. The mass-limited target is so small that by the refluxing, target heating

of hot electrons, the reabsorption of fluorescent X rays, and the secondary radiation

generation and transport, the target is a homogenous floor, which improving the image

resolution from 12.5 μm to 10 μm. Based on conformed radiation properties, vivid

backlighting radiographies from Kirkpatrick-Baze (KB) microscope showed us the fine

hydrodynamic instability structures and evolving shell deformation. The areal density of

fuel at peak compression was measured exceed of 90 mg/cm2. Further investigations and

attempts to improve implosion performance to a higher density are in progress.

Keywords: Fast ignition; Compression; Short-pulse backlighting; Density diagnosis



Preliminary design of Hybrid Spherically Convergent Plasma

Fusion (SCPF) in SG-III

J. Yan1,*, X. Zhang1, G. Ren2, J. Liu2, et al

1. Laser Fusion Research Center, Chinese Academy of Engineering Physics, China



A high energy coupling efficient and robust laser fusion platform based on SCPF had

been proposed in SG-III PT (6kJ/1ns, PRL 118, 165001(2017)) and SG-II upgrade

(12kJ/2ns) laser facility. A repeatable high temperature (~7keV) and dense (1021~1022/cm3)

DD “hot ball” with the scale length around 1mm had been created. In sum, the highest

neutron yield up to 5×109 and all shots compared with scaling law (1.2 0.2 2.5( / )L hYn E R

)

well. Based on the scaling law, the neutron yield of SCPF might greater than 1012 in SG-

III (180kJ/3ns). In another hand, because of the lower area density of “hot ball” (compare

with traditional ICF hot spot), the burning efficiency is extreme lower than ICF (in our

experiment, the burning efficiency is around 10-7,710

8

fusion

total

N nv

N

).

In this work, we proposed a novel hybrid SCPF scheme and experimental design in

SG-III laser facility to improve the burning efficiency and enhance the neutron yield. In

our scheme, 32 laser beams(named ablated beam) with incident cone angle 49.5 and 55 are

using for traditional SCPF to create an ~1mm “hot ball” in center of CD hohlraum. 1-2ns

later, 16 laser beams (named compressed beam) with incident cone angle 28.5 and 35 are

interaction with “hot ball” directly. While the center of “hot ball” with a density greater

than Nc for 2-3ns ablated beams driven, the compressed beams can enhanced the density

of “hot ball” and improved DD electron temperature. All these effects can increase the

neutron yield for times (shown in fig1 (b)) and the hybrid SCPF design looks like a hopeful

scheme to create high flux neutron source in SG-III laser facility.

Keywords: laser fusion, neutron source



Research on ultrafast X-ray detectors based on optical

detection

Jiukuang Zhu*, Tao Yi, Shaoen Jiang



Research on ultrafast X-ray detectors based on optical detectionJiukuang Zhu, Tao

Yi, Shaoen JiangResearch Center of Laser Fusion, China Academy of Engineering Physics,

Mianyang 621900, ChinaAbstract: X-ray diagnosis is a kind of important methods in

inertial confinement fusion experiments. A class of high-speed detectors, called RadOptic

sensor, measures X-ray radiation by using light. X-ray incident on semiconductor material

produces a change in the optical refractive index which could be sensed by a phase

modulation of an optical probe beam, thereby detect X-ray. Compare with conventional

electronic radiation detectors, RadOptic sensor detect X-ray with light, and the recording

of the probe beam provides the final step in the detection of the initial radiation. Since no

net charge is produced and no charge transport is required, time resolution of RadOptic

detector is of order 1 ps. Moreover the detector perform well in anti-electromagnetic

interference, and there are excellent applications in X-ray ultrafast detection. The phase

shifts depend on changes in the refraction index, which in turn depend on density of

electron-hole pairs created from X-ray inducing electron cascades in material. We choosed

common material GaAs as our subject. We calculated the density of electron-hole in the

GaAs, after which we calculated changes in the index of refraction. There are multiple

approaches to the detection. We designed a kind of Fabry-Perot detector, response curves

of which were measured in experiment and were compared with the calculated results.

Keyword: X-ray detector, optical detection, ultrafast diagnosis, electron cascades

Keywords: X-ray detector, optical detection, ultrafast diagnosis, electron cascades



Simulation Codes for Magnetic Driven Experiments in IFP

Ganghua Wang (王刚华)

*Email:

Keywords:



Population distribution and K-shell radiative properties of

argon plasmas in non-local thermodynamic equilibrium

Xiaoyue Li*, Yongjun Li, Fengtao Jin

Department of Physics, College of Science, National University of Defense Technology, China


Population distribution and K-shell radiative properties of argon plasmas are

investigated theoretically by utilizing a collisional-radiative model. A complete set of

atomic data are obtained in the framework of detailed-level-accounting method. Level

population distributions are obtained by solving rate equation. The physical effects of hot

electrons and external radiative fields in the implosion core can play an important role on

population distributions and K-shell emission spectra. The sensitive of emission lines to

different physical reasons are discussed in details.

Keywords: NLTE, Ar K-shell spectra, Rate equation, population distribution



High-energy-density plasma jet generated by laser-cone

interaction

Yanzhao Ke*, Xiaohu Yang, Yanyun Ma, Binbin Xu

Department of Physics,National University of Defense Technology, China


The generation of high-energy-density(HED) plasma jet from laser ablating thin

cone target is studied theoretically and by numerical simulations. Theoretical analysis and

1D simulations show that a maximum kinetic energy conversion efficiency(CE) of 26%

can be achieved when nearly 80% of the foil is ablated by laser. An HED plasma jet is

generated when intense laser(∼1015W/cm2) irradiating the cone target, inducing a great

enhancement of energy density compared to that of planar target, which is attributed to the

cumulative effect of cone shape and new generation mechanism of jet, i.e., laser directly

accelerating the cone wall onto the axis. The characteristic of jet is influenced by the cone

geometry, i.e., thickness and cone angle. It is found that a cone with a half opening angle

around 70° and the optimized thickness (∼5μm) can induce a jet with high CE and long

duration, whose peak energy density can reach 4×1015erg/cm3. The results can be beneficial

for laser-driven novel neutron sources and other fusion related experiments, where HED

plasma jet can be applied.

Keywords: high-energy-density, plasma jet, laser-cone interaction



Relativistic stopping power for alpha particles and electrons in

hot plasma

Yan-Ning Zhang1, 2,*, Bin He2, Yong-Tao Zhao1

1. Xi'an Jiaotong University, China



The stopping power of particles in plasma is of interest in many aspects of plasma

and fusion science, especially for research about the ion-driven inertia confinement fusion

and fast ignition. Generally, alpha particles with 3.45 MeV per ion interact with a mixture

plasma of deuterium and tritium (D-T) in controlled fusion. When considering the stopping

power, the plasma temperature can be quite hot that the relativistic effect of free electrons’

thermal velocity shouldn’t be ignored. In fast ignition, the incident electrons velocity is

also relativistic in addition to the relativistic effect of plasma. To this end, we calculated

the stopping power for alpha particles and electrons with several MeV in hot plasma of

several hundreds of keV. The relativistic Vlasovequation[1] is applied to investigate the

collective response of the plasma. As for the collision contribution, we followed the method

in Ref.[1] by the relativistic differential cross section. Here we showed the stopping power

of electrons in H plasma and compared the results with others’[1, 2].

FIG.1. Stopping power for 3 - 50MeV electrons in H plasma. The collective energy loss due to

longitudinal excitation, transverse wave and collision without exchange effect is shown

respectively. There is also our calculation compared with others’ for total stopping power.

Keywords: stopping power; relativistic;

Reference

[1] Solodov A A, Betti R. Stopping power and range of energetic electrons in dense plasmas of

fast-ignition fusion targets[J]. Physics of Plasmas, 2008, 15(4): 042707.

[2] Starikov, K. V., and Claude Deutsch. "Stopping of relativistic electrons in a partially

degenerate electron fluid." Physical Review E 71.2 (2005): 026407.

0 10 20 30 40 500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

d

E/d

x(M

eV

/cm

)

Ep(MeV)

Long

Transe

Collision Without Exchange

total

PRE 71,026407 Fig7_a

POP15,042707Eq.(11)

ne=10

23cm

-3

Te=5T

F



Study of Gd-coated Au planar target radiation spectrum

Liling Li



In indirect-drive inertial confinement fusion(ICF), the M-band(2~5keV) X-rays

which are of long mean free path can transmit further, these x-rays can reach the fuel and

preheat it before the arrival of the shock wave. Suppressing the generation and the transport

of the M-band X-rays can reduce the preheat effect. In our study, peak of Gd M-band is at

about 1.5keV. Radiation spectrum of Gd-coated Au planar target has been studied by using

the radiation hydrodynamic code MULTI-1D. The Gd-coated Au planar target can reduce

the Au M-band fraction and improve the radiation spectrum. As Si K-shell absorption edge

is at 1.8keV. Si dopant can significantly suppress the transport of Gd M-band X-rays. So

study of Gd-coated Au planar target radiation spectrum is important.

Keywords: Gd-coated Au, radiation spectrum, preheat



Monte Carlo simulations of electron cascade in microchannel

plates

Jianhua Zheng



X-Ray framing cameras based on microchannel plates (MCPs) are powerful

diagnostic tools for time-resolved imaging in inertial confinement fusion experiments. We

present a Monte Carlo approach to simulate electron cascade in a MCP. In our model,

instead of using probabilistic models based on fit to experimental data to describe the

secondary emission from the channel wall, the whole cascade of electrons in the wall is

followed, which includes such physical processes as elastic scattering with atomic nuclei,

inelastic scattering with atomic electrons, quasi-elastic scattering with phonons and

trapping due to the polaronic effect.

Keywords: inertial confinement fusion, framing camera, microchannel plate, electron

cascade, Monte Carlo simulation



An improved view-factor method inclusion of plasma filling for

angular distribution of radiation temperature from laser-

driven hohlraum

LongfeiJing,a,*, LongyuKuanga, Lu Zhanga, Liling Lia, Hang Lia, Zhiwei

Lina, Jianhua Zhenga, YunbaoHuangb, ShaoenJianga

1. Laser Fusion Research Center, China Academy of Engineering Physics,

China

2. Mechatronics School of Guangdong University of Technology, China


A modified version of the view-factor method is proposed which improves

the accuracy of the description of angular distribution of radiation temperature from

a laser-driven hohlraum in inertial confinement fusion (ICF). An equivalent radiative

surface (ERS) model is advanced to characterize approximately the contribution of

the blow-off the plasma from laser-spots zone (bubble) in the view-factor code

IRAD3D (L.F.Jinget al. Phys. Plasmas 22, 022709 (2015)). The simulation shows

reasonable agreement with experimental measurements performed on Shenguang-Ⅲ

laser facility. The value of the method is that it can be used as an approximate “first

look” at hohlraum energy balance prior to a more detailed radiation hydrodynamic

modeling.

PACS Codes: 52.57.-z; 52.57.Bc; 52.38.-r

Keywords: Indirectly-driven inertial confinement fusion; View factor; IRAD3D;

Distribution of radiation temperature



The measurement of Laser entrance hole of hohlraum on SG-

III facility

Pin Yang*, Zhenghua Yang, Sanwei Li, Li Chen



In inertial confinement fusion (ICF), the indirect drive scheme is to implode the

capsule with x-rays generated by the laser-irradiated high-Z hohlraum. The X-radiation

drive is measured with a low resolution, time-resolved x-ray spectrometer（DANTE）

that views the hohlraum‘s laser entrance hole (LEH) at 42ºto the hohlraum axis. To

convert this to the X-ray drive inside the hohlraum, the area of the measured x-radiation

inside the hohlraum must be known. As the LEH hole goes smaller during hitting process,

it is essential to get the real size of the LEH. The size of the LEH is measured with the time

integrated Static X-ray Imager (SXI) which views the LEH at 16ºto the hohlraum axis. A

soft x-ray image has been developed to the SXI to measure the LEH‘s Clear Aperture in

order to correct the measured radiation of DANTE. The soft X-ray image is measured

using a multilayer mirror plus beryllium filter selects an x-ray band centered at 850 eV,

near the x-ray energy peak of a 300 eV blackbody. The size of LEH before and after hitting

from this channel is clear enough to correct the x-radiation drive.

Keywords: ICF, laser entrance hole, soft X-ray, SXI



Monochromatic spherical bent crystal imaging system for

Shenguan Ⅲ laser facility

Zhenghua Yang



Monochromatic spherical bent crystal imaging system based on physical

requirements is developed for Shenguan-Ⅲ laser facility, and it based on 2023 quartz

crystal. The system image center energy is 4.53keV, and magnification is 19.8, and high

space resolution, high energy resolution and wide field monochromatic X-ray is obtained.

Static image testing of the system has been done, and backlit spectrum has been tested by

flat crystal simultaneously. The highest spatial resolution up to 6 microns of the four period

grid image, and the spectral resolution(Δλ\λ) is 6.609×10-3 according to the width of half

height in spectrum distribution.

Keywords: Spherical bent crystal, monochromatic imaing, Shenguan Ⅲ laser facility



Large-charge quasimonoenergetic electron beams produced by

off-axis colliding laser pulses in underdense plasma

Zhigang Deng



Electrons can be efficiently injected into a plasma wave by colliding two

counterpropagating laser pulses in a laser wakefield acceleration. However, the generation

of a high-quality electron beam with a large charge is difficult in the traditional on-axis

colliding scheme due to the growth of the electron beam duration coming from the increase

of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in

which the collision point is away from the axis of the driver pulse. We show that the

electrons injected from the off-axis region are highly concentered on the tail of the bubble

even for a large trapped charge, thus feeling almost the same accelerating field. As a result,

quasimonoenergetic electron beams with a large charge can be produced. The validity of

this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian

model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the

injection pulse to realize the off-axis colliding injection in three dimensions symmetrically,

which may be useful in simplifying the technicallayout of the real experiment setup.

Keywords: laser wakefield acceleration, off-axis injection



Method of Calibrating High-order Harmonics of Synchrotron

Radiation Based on Filter

Ao Sun



The charged particles with the speed close to light move along the arc path in the

electromagnetic field, then they can generate electromagnetic radiation, which is

synchrotron radiation. Synchrotron radiation is a reliable light source with high accuracy

and exact energy. It can be applied to many other frontier science and technology research,

such as the calibration of the performance of X-ray diode (XRD), that many other light

sources can not carry out. In the process of the XRD‘ calibration, the X-ray needs to be

monoenergetic and requires high purity, but although the source of synchrotron radiation

can provide adjustable wavelength X-ray, due to the splitting beams element of synchrotron

radiation beamlines is generally grating and crystal, the principle of splitting beams based

on grating equation and Bragg equation, so besides of the fundamental component of

monochromatic light which we need, there is high-order harmonics (νn=nν1,n=1,2,3). In

the process of XRD’ calibration, the influence of the second harmonics is bigger (the low

energy area is more sensitive), and the influence of the higher harmonic is smaller. Using

the monochromatic light with high-order harmonics will affect the calibration result,

making the work of calibration meaningless. If we cannot eliminate the influence of high-

order harmonics, we need to calibrate the share of high-order harmonics in corresponding

frequency band of the monochromatic light of synchrotron radiation, so that we can correct

the calibration result of XRD and get better results of practical application. In the previous

harmonic calibration, we use grating-method, which cannot get the ratio of high-order

harmonic fast and direct, so this method would make the progress of calibration slow and

inefficient. Now there is a new calibration method based on filter calibration which is much

more simple and quick, and this method can also verify the result of grating-method. In

this method, we first ignored the third and higher harmonics, considering only the second

harmonics (2E) effect. Through measuring the acceptance of particle number ratio between

the before and after using the filter, with the addition of calibrated filter transmittance

(ηE),η(2E)) and receptor’s response coefficient (S(E),S(2E)), we can calculate the high-

order harmonics of the share in the program using the corresponding data. Then the

program would deduct the influence of high-order harmonics in the XRD calibration.

Finally, we can get the more accurate XRD calibration curve to provide better support for

the accuracy of measurement data in XRD after then.

Keywords: synchrotron radiation, high-order harmonics, XRD calibration, filter



Research of shaped pulse driven hohlraum asymmetry by 2D

X-ray radiography

Jiang Wei



We have developed an experimental platform for 2D radiography at the SG-III laser

facility. This techniques can be used for measuring the drive symmetry both at picket and

pick under a carefully trigger design. The symmetry can be tuned efficaciously by CF both

at picket and pick of the pulse.

In our experiment, we observe an unexpected negative P2/P0 at picket, which

means fewer X-ray incidents on the waist of capsule than we expect, and finally induce an

unacceptable core asymmetry. According to the simulation, more than 90% of the inner

cone energy has lost at picket. The inner beam couplings are far beyond our design, and

may be contributed to the lower albedo in inner cone or absorption of inner cone by gas

and tent. We cannot increase the inner cone energy to compensate the lack of inner cone,

because that will affect the pick of the pulse and change the design. The lost energy of

inner cone at picket may cause by the absorption of tent which used to support the capsule,

or cause by the absorption of gas which filled the hohlraum. Using thinner tent or delaying

the outer cone pulse may improve the drive symmetry at picket. In the future, we planned

to use reemit-capsule supported by tent or stalk respectively to evaluate the influence of

tent. And we can also use a hohlraum with slit to measure the intensity distribution of inner

cone and outer cone directly.

Keywords: radiography; radiation asymmetry



Development of X-ray framing camera for inertial confinement

fusion experiments on SGⅢ laser facility

Qiangqiang Wang



X-ray framing camera (XFC) is a powerful diagnostic instrument for analyzing

spatial (2d) and temporal evolution of high temperature plasma produced in inertial

confinement fusion (ICF) experiment. We present in this paper the recent advances on

design and preliminary application of the XFC system on SG-III laser facility. The whole

system consists of four parts: the detector part, the multipinhole imaging part, the electronic

part and the air box. To meet the requirements of the equatorial Diagnostic Instrument

Manipulator (DIM) on SGⅢ facility, a square air box with internal structure like a drawer

is developed to integrate the electronic part and create an internal environment that is close

to 1 atm. The detector part of the XFC system is characterized as a spatial resolution better

than 30lp/mm and a temporal resolution better than 70ps. The electronic part enable the

remote control of the system status through the host computer. The XFC system has been

applied on measuring the imploding symmetry. The 2D self-emission image of the

compressed D-D capsule under different energy balance between the outer laser and the

inner laser were obtained. The results show that the XFC system we have developed is of

great significance for improving the implosion symmetry in indirect ICF experiment.

Keywords: X-ray framing camera; Inertial confinement fusion



The preheat and ultrafast carrier dynamics of diamond

window material in VISAR

Xiangming Liu



The velocity interferometer system for any reflectors (VISAR) has become the

primary diagnostic for shock-timing experiments. The VISAR can provide precise shock

velocity, which is caused by a Doppler shift at the reflecting shock front in a window

material and subsequently determined by the fringe shifts observed by the interferometer.

So far, several transparent window materials have been employed to the shock-timing

experiments, including quartz, diamond and polystyrene. However, the preheat of window

materials has become a severe problem, which influences the VISAR measurements. It has

been commonly accepted that the preheat is mainly induced by x-ray radiation and/or hot

electrons, which reach the window material earlier than shock wave. The resulting

ionization leads to the strong absorption of the probe beam.

Among the window materials, diamond is a dielectric of uniquely high strength and

thermal conductivity and has been extensively studied under shock compression. Recently,

we have carried out the VISAR measurements with diamond window in an indirect-drive

hohlraum on the Shenguang III laser facility and observed the blanking of signal. The

preheating regime and the shock-compressed regime are clearly seen. Compared with

quartz window, diamond is less robust when it is exposed to x rays.

Further investigation is necessary to understand the behavior of diamond under x-

ray exposure and the mechanism responsible for the changes in optical

properties.Furthermore, the ultrafast carrier dynamics in a CVD diamond is investigated

by employing a femtosecond two-color pump-probe scheme with a phase objective. The

diamond is excited by UV laser pulses at 351 nm and the nonlinear optical behavior is

probed with weak laser pulses at 515 nm. The changes in normalized transmittances

indicate that the modifications in nonlinear refraction and nonlinear absorption are

significant. In particular, a fast negative change in nonlinear absorption is followed by a

return to unity with a fast time factor of around 80 ps and a slow time factor of several

nanoseconds. It indicates that the free-carrier absorption is significantly strong. And the

fast time factor is consistent with previous measurements.

Keywords: VISAR, ultrafast carrier dynamics, window material



Design of Streaked Crystal Spectrpmeter On Shenguang III

Laser Facility

Deng Keli



Electron temperature and density could be determined from the analysis of argon

K-shell line spectra from argon doped deuterium-filled implosion cores, which is crucial

understanding of the plasma conditions in inertial confinement fusion (ICF) experiments.

We design a streaked crystal spectrometer for Shenguang III laser facility to obtain the

time-resolved X-ray line spectra. Different spectral ranges are easily switched with the

combinations of the different crystal materials, the delicate designed brace racks and blocks.

High quality argon K shell line spectra is acquired via this streaked crystal spectrometer in

the recent experiments with argon and xenon doped deuterium-filled implosion cores.

Keywords: streaked crystal spectrometer, time-resoved X-ray line spectra, argon K-shell

line spectral, electron temperature and desity, ICF



A new method to measure temporal resolution of X-ray

framing camera

Zheng Yuan



In Inertial Confinement Fusion, X-ray framing cameras (XFCs) are used as a

principal diagnostic tool. Methods to precisely calibrate the temporal resolution are an

important topic for XFCs with several picoseconds gate time. A new method to measure

the temporal resolution of XFCs is proposed based on a high-power sub-picosecond

ultraviolet laser facility called LLG-Ultimate. A series of duraluminium alloy stepped

reflective surfaces was used to separate the incident laser beam into sequentially-delayed

beams of equal size, spacing, and time interval. The temporal resolution of an XFC can be

measured if the sequentially-delayed beams irradiate a gold photocathode micro-strip line,

as the high-voltage pulse transfers along the same area simultaneously. A Fabry-Perot

etalon was used in the light path, to improve the probability of synchronization of the

voltage pulse and laser pulse. This measurement can be easily performed, and very high

accuracy can be achieved by reducing the time interval of the sequentially-delayed beams.

Keywords: X-ray framing camera; temporal resolution; beam separate and delay



Coaxial CVD diamond detector for neutron diagnostics at

ShenGuang-Ⅲ laser facility

Bo Yu

Department of Modern Physics, University of Science and Technology of China, China



Based on the advantages of radiation hardness, large linear dynamic range, and

insensitive to X-ray, a coaxial, high performance diamond detector has been developed for

neutron diagnostics of inertial confinement fusion at ShenGuang-III laser facility. A

Φ10mm×1mm “optical grade” chemical-vapor deposition diamond wafer is assembled in

coaxial-designing housing, and the signal is linked to a SubMiniature A connector by the

cathode cone. The coaxial diamond detector performs excellently for neutron measurement

with the rise time of the CVD diamond detector to be 175ps, the fall time of the detector to

be 1.02ns, and the full width at half maximum of response time to be 444ps for a 50Ω

measurement system. The diamond detector is tested at ShenGuang-III laser facility with

DT implosion. A hollow Al rod is inserted into the target chamber to hold the diamond

detector and isolate the chamber vacuum. The average sensitivity is 0.677μV·ns/n for 14

MeV (DT fusion) neutrons at an electric field of 1000V/mm, and the linear dynamic range

is beyond three orders of magnitude. The signal deviates from the linear fits by a standard

deviation of 4.8%. The saturating phenomenon does not appear. The measured signals are

also deconvolved the ion temperature. The ion temperature results fluctuate widely from

the neutron time-of-flight scintillator detector results. The standard deviation for the ratio

is 25%. There are two reasons for fluctuation: 1.86m distance of the diamond detector is

too close for the ion temperature measurement, and the azimuths of two detectors are

completely opposite. These characteristics of small size, large linear dynamic range, and

insensitive to x-ray make the diamond detector suitable to measure the neutron yield, ion

temperature, and neutron emission time.

Keywords: Diamond detector, Neutron yield, Ion temperature




Calibration and performance study of streaked optical

pyrometer system in SG-III prototype facility for temperature

measurement of compressed materials

Chen Zhang



Streaked optical pyrometer is used to determine the temperature of dynamically

compressed materials. Due to the advantage of high time resolution of streaked camera, it

is widely applied in inertial confinement fusion and equation of state research on laser

driven platform. Full understanding of camera performance and reliable calibration method

are important for increasing system accuracy. In this paper, a systematic study on streaked

camera performance based on NIST traceable light source is introduced along with

calibration results based on aluminum are presented, which gives 16% relative uncertainty

of temperature. Furthermore, an absolute calibration method is preliminarily demonstrated

and will be implemented in the near future.

Keywords: temperature measurement, calibration, streaked optical pyrometer,

dynamically compressed materials



Investigating effects of ablative Rayleigh-Taylor instability on

implosion acceleration

Pu Yudong



In the context of inertial confinement fusion, the effects of ablative Rayleigh-Taylor

instability (ARTI) on implosion acceleration were noticed recently. The ARTI would

change the surface geometry from flat to be rippled, and it was the change of geometry that

resulted in the loss of ablation pressure. It was considered by analytical derivations with

simple assumptions. It was shown that the ablation pressure was lower when the interface

was disturbed by the ARTI and the radiation field was of anisotropy. This conclusion

implied that the effects discussed in this paper cannot be captured by most of current two-

dimensional radiative hydrodynamic codes in which diffusion approximation was adopted

and isotropic radiation field was assumed. Further theoretical and experimental works

could be motivated by this paper

Keywords: ablative Rayleigh-Taylor instability, implosion velocity



The effect of filled gas to the kinetic process of ICF hohlraum

plasma interaction

Zongqiang Yuan

Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China

Academy of Engineering Physics, China


In previous works, we developed a novel method to explore the kinetic effects

launched in the interpenetration region between the laser-driven hohlraum plasma Au

bubbles and the corona plasma of the compressed CD pellet on Shenguang-III prototype

laser facility through measurements of the yield and spectrum of the DD fusion neutron. In

this study, we carry out a series of 2D3V particle-in-cell simulations to investigate the

influence of the gas filled hohlraum to the kinetic effects. In details, the varieties of the CD

ions energy spectrum due to the changes of the plasma density of Au, the drift velocity of

Au plasma, and the temperature of CD plasma are simulated. These studies will improve

our understanding on the kinetic effects in the hohlraum wall/ablator interpenetration

region in indirect-drive inertial confinement and may have potential applications in the

design of the hohlraum.

Keywords: kinetic process; gas-filled; ICF hohlraum



A high performance X-ray streak camera for Laser-Plasma

Interaction Studies

Li Jin(李晋)*, Deng Keli(邓克立), Hu Xin (胡昕),Chen Tao(陈韬), Deng Bo(邓博), Li Yukun(黎

宇坤), Wang Chuanke（王传珂）, Cao Zhurong(曹柱荣), Liu Shenye(刘慎业), Jiang Shaoen

(江少恩), Ding Yongkun (丁永坤)



With the development of laser-plasma interaction studies, X-ray streak cameras

with a wide dynamic range, a high temporal and spatial resolution, and a large

photocathode length are required. To satisfy these requirements, a high performance X-ray

streak camera has been designed. The dynamic range exceed 900, the spatial resolution is

20 lp/mm, the temporal resolution is approximately 10 ps, and the photocathode length is

28 mm. The good performance of the streak camera has been verified in experimentsof

laser induced plasma physics studies which were carried out at the SG-III Prototype laser

facility.

PACS Codes:52.70.-m,52.70.La

Key words:laser-plasma interaction studies; X-ray streak camera; wide dynamic range;

high temporal and spatial resolution; large photocathode length



Higher order harmonics suppression in extreme ultraviolet

and soft X-ray

Chen Yong*, Qian Feng, Yang Zuhua, Wang Shaoyi, Zhang Qiangqiang, Fan Quanpin, Wu

Yinzhong, Wei Lai† and Cao Leifeng



The extreme ultraviolet and soft X-ray sources are widely used in various domains.

Suppressing higher order harmonics and improving spectral purity of the sources are

significant. At present, synchrotron radiation often uses filters, suppression mirrors, and

gas absorption cell to suppress higher order harmonics. These methods should be used in

combination to cover the total energy range of extreme ultraviolet and soft X-ray. And it

will be accompanied by higher costs, larger space, and lower photon flux. This paper

describes a novel method of higher order harmonics suppression with single order

diffraction gratings in extreme ultraviolet and soft X-ray. The principle of harmonic

suppression with single order diffraction grating is described, and some extreme ultraviolet

and soft X-ray non-harmonics grating monochromators are designed based on the single

order diffraction grating. The contributions of the higher orders are measured by

transmission grating spectrometer. The results show that the single order diffraction grating

can suppress higher order harmonics effectively, and it is expected to be widely used in

synchrotron radiation, diagnostics of laser induced plasma, and astrophysics.

Keywords: Higher order harmonics suppression; Extreme ultraviolet and soft x-ray;

Monochromator; Single order diffraction grating

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High efficiency terahertz diffraction grating with trapezoidal

elements

Yinzhong Wu



A newly designed grating used in terahertz region is proposed, which is composed

of the trapezoidal elements repeated successively along one dimension of the substrate,

and uniform interval (the grating period) repeated along the other dimension. The

transmission of the grating owns a designable trapezoidal profile dependent on the

geometric dimensions of the element. The far-field diffraction patterns of a designed

grating at incident broadband terahertz frequencies, with element dimensions of upper,

lower side and period of 50, 250, and 300 μm, respectively, are simulated by the scalar

diffraction theory. The simulation results indicate that the terahertz grating exhibits a

property of single-order diffraction, and the diffraction effciency of the first order reaches

6.6%, exceeding that of a traditional sinusoidal amplitude grating with identical period and

duty cycle. Owing to the regular architecture and the high single-orderdiffraction efficiency,

the grating is easy to fabricate and shows great potential applications in single-shot spectral

measurements of weak broadband terahertz pulse.

Keywords: Grating; Terahertz; High efficiency



Characterization of a high energy x-ray source produced by

the SG-II-U laser facility

Minghai Yu1,*, Yuchi Wu1,2, Tiankui Zhang1, Lianqiang Shan1,Chao Tian1,Weiming

Zhou1,2,Leifeng Cao1,2,Yuqiu Gu1,2

1. Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center,




A high-energy (>50keV) X-ray source with a small size and high brightness has been

produced by irradiating an Au wire target with the petawatt beamline in SG-II-U laser

facility. The spectra (10 keV~1 MeV), were recorded by a transmission curved crystal

spectrometer and three filter stack spectrometers。The measured energy conversion

efficiency, into 50~200 keV X-rays, was about 1.4×10-4. High quality 2-dimensions point

projection radiographs were recorded by a new developed high energy X-ray imager,

showing a spatial resolution between 12 μm to 15 μm。

Keywords: picosecond laser, Au wire target, high energy X-ray source, radiograph



Toward Gabor zone plates by modulating zones width

Qiangqiang Zhang*, Lai Wei, Zuhua Yang, Yong Chen, Quanping Fan, Yinzhong Wu, Leifeng

Cao

Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, China

Academy of Engineering Physics


In this paper, a novel concept of modulated width zone plate (MWZP) is proposed

to realize a binary Gabor zone plate (GZP) with single focus. By modulating the zones

width as sinusoidal random distribution, higher-order foci can be effectively suppressed.

The physical design is verified with Numerical simulation results. The performance of the

modulated width zone plate is determined by the number of zones used. It works well only

when enough zones are utilized. The zone plate is easy to be fabricated employing

nanofabrication technology, since it is composed of complete zones, similar to Fresnel zone

plates (FZP). This work offers new opportunities for X-ray spectroscopy and microscopy

in physics research

Keywords: Gabor zone plate; single focus zone plate; X-ray spectroscopy and microscopy



Calibration of Image Plate Scanner

Feng Lu



The calibration of the sensitivity function of the image plate scanner was studied in

this paper.GE Typhoon FLA 7000 scanner was used as the calibration element and the

concerned signals were hot electrons.The hot electrons signals were produced from the

interaction of a short pluse laser plasma with a solid target. Both image plate and absolutely

calibrated LiF TLDs were exposed to the same eletron source. And the sensitivity function

of the scanner was calibrated relativly by image plate and LiF TLDs. Fitting analysis shows

that the sensitivity function of the scanner decreases slowly in two-component exponentail

function.This method provides a reliable approach for calibrating the image plate scanner.

Keywords: image plate scanner; calibration; image plate; LiF TLD



A tool of X-LAB v1.5 for optical design and its application

Zuhua Yang


To design the monochorator beamlines of synchrotron radiation, XFEL and the X-

ray diagnoses of inertia fusion, dynamic process in extreme physical conditions, we

developed a useful tool and a platform, X-LAB v1.5, for optical design, optimization and

simulation with independent intellectual property rights. X-LAB v1.5 is a useful and

friendly tool that comprises sequence ray-tracing, vector diffraction simulation and layout

drawing of complex micro-structure optical element. Also, this tool is easy to operate and

can provide accustomed service, characteristic functions for users to freely design,

optimize an optical system. Currently, X-LAB v1.5 has been applied in designing and

simulating of the 3B1 monochromatic beamline in Beijing synchrotron radiation facility

with spectral resolution 1000, and spectral range 10-100eV, the X-ray diagnosis optical

systems of inertia fusion and dynamic process in extreme physical conditions, the KB

microscope with spatial resolution up to 6μm, and studying the single order diffraction

property of grating photon sieves.

Keywords: X-LAB, simulation, X-ray,optical design



A novel superconducting magnetic levitation method to

support the laser fusion capsule by using permanent magnets

Xiaojia Li



A novel magnetic levitation support method is proposed, which can relieve the

perturbation caused by traditional support methods and provide more accurate position

control of the capsule. This method can keep the perfect symmetry ofthe octahedral

spherical hohlraum and has the characteristics in stability, tunability and simplicity. It is

also favorable that all the results, such as supporting forces acting on the superconducting

capsule, are calculated analytically, and numerical simulations are performed to verify

these results. A typical realistic design is proposed and discussed in detail. The

superconducting coating material is suggested, and the required superconducting properties

are listed. Damped oscillation of the floating capsule in thin helium gas is discussed, and

the restoring time is estimated.

Keywords: ICF capsule support, Magnetic levitation, Symmetry



Research on time-integrated spectrum of backscattered light in

Shenguang-Ⅲ laser facility

Tao Xu



Inertial confinement fusion (ICF) experiments rely on efficient coupling of the laser

energy with the targets. One important energy loss mechanism is backscattered light out of

the hohlraum which will results in loss of X-ray drive on the capsule and potential loss of

symmetry control. It is therefore important to diagnose in real time and control the energy

backscattered light. Besides, backscattered light measurement is a basic tool used to

provide insight into laser-plasma interactions (LPI). Both ion and electron waves in the

plasma are driven to large amplitude by the progress of stimulated Brillouin scattering

(SBS) over the wavelength range of 348-354nm and stimulated Raman scattering (SRS)

over the wavelength range of 400-700nm. Several suites of backscattered light diagnostic

system are now implemented in Shenguang-III laser facility. Due to the non-flat

transmittance in board band of the optical system especially for the SRS in full aperture

backscattered light diagnostic system (FABS), employing the method which multiply the

attenuation factor of single wavelength with the count of calorimeter is not an accurate way

for measuring the energy of backscattered light. Therefore, a time-integrated spectrum

diagnostic part consists of fiber and spectrometer is now added into the FABS of beam

A4N1. The SRS light is coupled into a 600μm fiber by a focus lens and spatially smoothed

by transmissible scattering plates. Several configurations especially the positions of the

fiber and the scattering plates were simulated and tested in the paper. Experiment results

demonstrated that the way placing the plates both before and after the fiber optic is the

most suitable method for acquiring SRS spectrum compared with the counts recorded by

calorimeter.

Keywords: backscatter; time-integrated spectrum; spatial distribution; laser facility



An improved calculation of spectral response of gold and CsI

photocathodes in a 10 - 100 keV X-ray energy region

Yu-Kun Li,Tao Chen, Jin Li,Zhi-Wen Yang, Ke-Li Deng



It has been known for a long time that gold and CsI are very good secondary electron

emitters when irradiated by X-rays. This feature of gold and CsI is mainly due to their low

work function and their large electron escape lengths. Thus gold and CsI materials are

always attractive and widely applied in X-ray imaging detectors in astronomy and high

energy density physics.

Knowledge of the X-ray-induced secondary electron emission from gold and CsI is

very important for designing X-ray imaging detectors that combine such photocathode

converters. The general features of secondary electron emission irradiated by X-rays from

photocathode were obtained from the pioneering works of Henke and Fraser et al. They

demonstrated a semi analytical model of secondary electron emission and predicted the

quantum efficiency of many photo-electric materials, and the predictions agreed well with

the experimental data in soft X-ray region. But there are still some objects to be solved.

This model is not suitable in hard X-ray region. Obvious deviation existed between model’s

prediction and the experimental data. It’s thus necessary to improve the estimation model

of secondary electron emission.

In Henke and Fraser’s model, Compton scattering which usually occurred in hard X-

ray region were not considered. The influences of Compton to spectral response were

analyzed in this article. And the mean escape depth of secondary electrons was assumed to

be a constant independent with reduced X-ray photon energy in their calculation. But it’s

proved that mean escape depth varied a lot during hard X-ray region in this article. The

mean escape depths of gold and CsI increased from tens of nms at several keV to several

ten thousandsnms at 100keV. These increasements were proved to have a remarkable

influence to the spectral responses of gold and CsI. So it is necessary to take the variation

of secondary electron mean escape depth for account.

In the present work, the Compton scattering cross sections of gold and CsI were

compared with photo-ionization cross sections. The results showed that the Compton

scattering processes could be ignored in the spectral response calculation in the 10 – 100

keV X-ray region. The formula of spectral response of gold and CsI was then deduced as

a function of photocathode thickness and secondary electron mean escape depth. Then the

formula of mean escape depth was also deduced as a function of X-ray photon energy. And

the variation of mean escape depth was taken into account during the spectral response

calculation.



The gold and CsI’ spectral responses data calculated from these formulae were

compared with experimental data from different source. The data agreed well and dedicated

that CsI have a better spectral response than gold for hard X-ray detecting. The agreement

of the data also proved the deduced formulae to be reliable for spectral response prediction.

The optimal thicknesses of gold and CsI photocathodes for imaging hard X-rays of

different energies could also be obtained by these formulae. The calculation for different

induced photon energy showed that spectral responses of both gold and CsI rose with

thickness to a maximum and then decreased. The corresponding thicknesses of the

maximums were the optimal thicknesses. This calculation will be very useful to predict a

photocathode thickness for designing hard X-ray imaging detectors.

Finally an improved calculation photocathode spectral response for gold and CsI was

obtained and proved to be reliable in a 10-100 keV X-ray region. The formula of spectral

response will do a good favor to the designing of hard X-ray imaging.

Keywords: spectral response, gold, CsI, photocathode, X-ray



Asymmetry diagnosis of implosion hot spot by using multi-

channel Kirkpatrick-Baez microscope

Jianjun Dong



Multi-channel Kirkpatrick-Baez microscope has a high spatial resolution of about

3μm which can be used to measure the details of the implosion compression hot spot. In

this paper, the X-ray self emission of the hot spot is measured along the two orthogonal

directions of the equator and the polar, and the spatial distribution of the two dimensional

X-ray intensity is obtained. The X-ray image data shows that the equatorial asymmetry

component of the hot spot is larger than that of the polar about 8%. The P0 component in

polar is 2μm larger than that in the equatorial region. This results show that the compressing

of the hot spot is stronger than that in the equatorial region. It reflects that the radiation

driven in polar region is stronger than that in the equatorial region, which causes the shape

of the hot spot to be oblate at the implosion stagnation.

Keywords: Kirkpatrick-Baez microscope; spatial-resolution; implosion hot spot; hot spot

asymmetry



Experimental study of megagauss magnetic field applications

in laser indirect-drive inertial confinement fusion

HangLI1,2,*, Longyu KUANG 1,2, Longfei JING1, Zhiwei LIN1, Feng WANG1,Shaoen JIANG1, Jian

ZHENG2, Ke LAN3, Jie LIU3, Yongkun DING1,2,3 andB.Grant LOGAN4


2. CAS Key Laboratory of Basic Plasma Physics and Department of Modern Physics,

University of Science and Technology of China, China

3. Institute of Applied Physics and Computational Mathematics, China

4. Lawrence Livermore National Laboratory, USA


500-700 T magnetic field was generated in a cylindrical hohlraum by the interaction of

1.8 kJ-1.0 ns-1064 nm laser with capacitor-coil target on SG-II laser facility, which was

proven by B-dot probe. Magnetic field suppressed plasma filling, forming a hollow region

of the plasma corona in the vacuum hohlraum, which was observed by an x-ray framing

camera. Therefore, strong magnetic field is proven to effectively suppress the plasma filling

in vacuum hohlraum instead of gas, providing an important potential way for hohlraum

design in the laser indirect-drive inertial confinement fusion.

Keywords: megagauss magnetic field，laser indirect-drive inertial confinement fusion，

plasma filling

Reference

[1] H. Daido et al. Phys. Rev. Lett., 56, 846 (1986).

[2] S. Fujioka, Z. Zhang, K. Ishihara et al. Scientific Reports, 3, 1170 (2013).

[3] J.J. Santos, M. Bailly-Grandvaux, L. Giuffrida et al.NewJ.Phys. 17, 083051 (2015).

[4] D. H. Froula et al. Phys. Rev. Lett. 98, 135001 (2007).

[5] D.S. Montgomery et al. Phys. Plasmas 22, 010703 (2015).

[6] H.B. Cai, S. P. Zhu, and X. T. He, Phys. Plasmas, 17, 072701 (2013).

[7] P. Y. Chang, G. Fiksel, M. Hohenberger et al. Phys. Rev. Lett., 107, 035006 (2011).

[8] L.J. Perkins et al. Phys. Plasmas 20, 072708 (2013).



First measurement of plasma stagnation radiation in a

hohlraum in the Shenguang-III prototype

Kuan Ren



The measurement of plasma stagnation radiation in a hohlraum is of key importance

when exploring the influence of plasma stagnation on hohlraum drive symmetry in

indirectly driven inertial confinement fusion experiments. In two typical hohlraum

experiments conducted on the Shenguang-III prototype laser facility, the x-ray flux and

radiation temperature from a plasma stagnation area 0.2 mm in diameter inside the

hohlraum were measured for the first time through the hohlraum laser entrance hole (LEH)

using a time and space-resolving flux detector (SRFD). The different flux intensities and

radiation temperatures of the plasma stagnation area in the LEH measured using the SRFD

were compared with the results detected for the entire LEH using flatresponse x-ray

detectors. The stagnation area radiation detected using the SRFD was found to be transient

and 8.57% lower than that of the entire LEH, which is obviously higher than the tolerable

drive asymmetry of an implosion. This important improvement in x-ray

radiationmeasurement of plasma stagnation will further the quantitative understanding of

the drive symmetry inside the hohlraum and conduct a strict adjustment for that.

Keywords: first measurement，plasma stagnation， hohlraum interior，quantitative

measurement



Simulation investigation of magneto-Rayleigh-Taylor

instabilities in implosion of a thin liner drive by magnetic field

XiaoguangWang*,DelongXiao,ShunkaiSun,YangZhang,NingDing,XiaojianShu

Institute of applied physics and computational mathematics, Beijing, China


Magneto-Rayleigh-Taylor instabilities are one of the most important topics in z-

pinch physics, which will disrupt the uniformity of imploding plasma dramatically. An

open source resistive magnetohydrodynamic code was employed to simulate the magneto-

Rayleigh-Taylor instabilities in implosion of a thin liner drive by magnetic field. Fisrt, we

investigated the single and multimode magneto-Rayleigh-Taylor instabilities in implosion

of a thin plasma shell load, of which the results are consistent with Douglas‘s [Phys.

Plasmas, 5, 4183 (1998)]. Then we analysed the evolution characteristics of magneto-

Rayleigh-Taylor instabilities for the thin liner imploding experiments in JULONG-I. The

analyses results are consistent with the observation in experiments qualitatively.

Keywords: Magneto-Rayleigh-Taylor instability, thin liner, Z-pinch



Diagnostic progress of Laser direct-drive implosions on the SG

Ⅲ prototype laser facility

Jiaqin Dong1, Erfu Guo1, Zhiheng Fang1, Jiwei Li2, Dongxiao Liu3, Shengzhen Yi4 Wei Wang1,

Jun Xiong1, Minxi Wei3 , Qi Tang3 , Gang Shen2, Jinghong Li

1. Shanghai Institute of Laser Plasma, China

2. Institute of Applied Physics and Computational Mathematics, Beijing, China;


4. Tongji University, Shanghai, China


Laser direct-drive implosions were performed on the SGⅢ prototype laser facility.

Gas-filled capsules are imploded using by 8 beams at 6.5-kJ laser energy. Nine different

types of diagnostic instruments are used in the experiments, providing an understanding of

the relevant target physics. The 2D blow-off emission images of the in-flight shell and

asymmetric shapes of hot spot are characterized by a novel 16-framed x-ray K-B framing

camera. The measured D-D neutron yield of the gas-filled capsule is 1×10-8 in best shots,

and decreases with the asymmetry of in-flight shell, which is meanly decided by the laser

spot distribution at the capsule surface.

Keywords: implosion, direct-drive, ICF, diagnosis



Primary study on the mixing of ejected fragments and foam

Min Shui*


To study the mixing of micro-jetting tin particles and low density foam, the

correlative experiments have been conducted at the SG-II upgrade facility. High energy

side-on X-ray (50-200 keV) photography have been used to study the mixing process via

the interaction between the golden-wire target and picosecond laser pulse. Some shots have

obtained the side-on radiograph image with high spatial resolution. On the basis of the

experimental results, the mixing process, areal density as well as the bulk density were

primary analyzed.

Keywords: dynamic fragmentation, areal density, soft recovery

References

[1] T. de Resseguier, E. Lescoute, A. Sollier, et al. Microjetting from grooved surfaces in

metallic samples subjected to laser driven shocks, Journal Applied Physics,

2014,115:043525

[2] J R Asay. Thick-plate technique for measuring ejecta from shocked surfaces. J Appl

Phys., 1978, 49 (12)：6173～6175

[3] L Sigor, G Roy, P –Y Chanal , et al. Debris cloud ejection from shock-loaded tin

melted on release or on compression. Shock Compression of Condensed Matter, 2009,

AIP Conf.Proc., 1195： 1065～1068

[4] L Sigonr, A Dragon, T de Rességuier, et al. Dynamic fragmentation of melted metals

upon intense shock-wave loading. Modelling issues applied to micro-spalling of tin.

Arch.Mech.,2008,60(4):323～343

[5] P Andriot, P Chapron, F Olive, Ejecton of material from shocked surfaces of tin,

tantalum and lead-alloys. AIP conf. Proc.,1982, 78:505～509

[6] T de Rességuier, L Sigonr, A Dragon, et al. Experimental investigation of liquid spall

in laser shock-loaded tin. Journal of Applied Physics, 2007, 101(1):013506

[7] L Sigonr, E Lescoute, D Loison, et al, Experimental study of dynamic fragmentation

of shock-loaded metals below and above melting. EPJ Web of Conferences,

2010,6:39012



Study On Dynamic Response Of Shocked Aluminum Under

Laser Loading With Dynamic X-Ray Diffraction

Xi Tao*, He Weihua, Xin Jianting, Chu Genbai, Shui Min, Zhao Yongqiang, Fan Wei, Gu Yuqiu



A direct experimental measurement of material lattice behavior under shock-loaded

is important in the study of material dynamic response. Dynamic x-ray diffraction not only

can provide direct information about crystal lattice, but also owns high temporal resolution

and high spatial resolution, making it the most powerful technique of studying transient

dynamics. Experimental methods to permit dynamic X-ray diffraction measurements, with

picosecond temporal resolution, in laser experiments were developed and used to examine

lattice deformation in shocked aluminum single crystal. The experiments were performed

in XGⅢ laser facility, samples of 300 μm thick single crystal aluminum, 10 mm in

diameter, were coated with 100 μmCHBr and then 100 μm B4C. These samples were shock

loaded by direct laser radiation of CHBr-coated side of the target with 0.351 μm laser

radiation in a laser spot of diameter approximately 1 mm, these pulses had 3-ns-long

duration with rise and fall time of 300 ps. Cu nanowire array targets [1] were irradiated by

ps laser beam to generate Kα rays as source x rays. Image plate recorded the shocked

diffraction signal of the lattice plane(200) as well as the unshocked signal. The

experimental results show that the crystal lattice is compressed, the position of the

diffraction lines associated the (200) lattice plane indicate the compression along [100]

direction by 9.9%, but the signal to noise ratio need to be improved.

Reference

[8] Niu Gao, Tan Xiulan, Han Shangjun, et al. Structure and performance of Cunanowire

array target for intense radiation source. High Power Laser And Particle Beams,

2011, 23(3): 681-684.



Towards high repetition rate ultra-intense lasers, latest

developments at Amplitude Technologies

Franck Falcoz

Amplitude Technologies, France


September 2014, Amplitude Technologies has been selected for the supply and

commissioning of the HF laser system at the ELI Attosecond Light Source Pulse Source

(ELI-ALPS) facility in Szeged, Hungary, one of the three pillars of the ELI program in

Europe dedicated to attosecond science with light sources delivering ultrashort pulses

between THz and X-ray frequency range at high repetition rate [1].

HF laser system will provide 2 PW laser pulses with duration down to 17 fs at a

repetition rate of 10 Hz. In this presentation we will introduce the different R&D programs

launched within the Amplitude Laser Group to develop this innovative industrialized laser

solution. As a matter of fact, HF laser system will follow a typical architecture based on a

OPCPA front-end (R&D program with FASTLITE, Institut d‘Optique, CEA and

Amplitude Systèmes) which will seed the PW-class CPA-Ti:Sa laser with broadband

pulses and ultra-high temporal contrast (10 μJ at 4 kHz, 16.5 fs FTL, ASE at 1012). A

separated front-end output will provide 1 mJ, 10 fs laser pulses at 100 Hz. Besides, to

deliver around 50 J pulses before compression at 10 Hz, we are developing new generation

of pump laser providing 60 J at 10 Hz in one single beam. This new generation of pump

laser is also designed to be compatible with OPCPA amplifier. Furthermore, we have

recently demonstrated high repetition rate sub-20 fs PW-class laser (ORION family) with

pulse duration of 16.4 fs and pulse energy of 14.4 J at 2.5 Hz (880 TW at 2.5 Hz). The

pulse duration was characterized and the measurements show a very high stability (0.76 %

rms) of the performances leading to new generation of ultra-intense lasers for ultrafast high

energy physics.

Keywords: ELI-ALPS



High energy & high average power PUMP LASERS…The

route to High average power petawatt lasers

Franck Falcoz

Amplitude Technologies, France


September 2014, Amplitude Technologies has been selected for the supply and

commissioning of the HF laser system at the ELI Attosecond Light Source Pulse Source

(ELI-ALPS) facility in Szeged, Hungary, one of the three pillars of the ELI program in

Europe dedicated to attosecond science with light sources delivering ultrashort pulses

between THz and X-ray frequency range at high repetition rate [1].

HF laser system will provide 2 PW laser pulses with duration down to 17 fs at a

repetition rate of 10 Hz. In this presentation we will introduce the different R&D programs

launched within the Amplitude Laser Group to develop this innovative industrialized laser

solution. As a matter of fact, HF laser system will follow a typical architecture based on a

OPCPA front-end (R&D program with FASTLITE, Institut d‘Optique, CEA and

Amplitude Systèmes) which will seed the PW-class CPA-Ti:Sa laser with broadband

pulses and ultra-high temporal contrast (10 μJ at 4 kHz, 16.5 fs FTL, ASE at 1012). A

separated front-end output will provide 1 mJ, 10 fs laser pulses at 100 Hz. Besides, to

deliver around 50 J pulses before compression at 10 Hz, we are developing new generation

of pump laser providing 60 J at 10 Hz in one single beam. This new generation of pump

laser is also designed to be compatible with OPCPA amplifier.We will present the last

results of the 60 J pump laser and the PW amplifier.

Keywords: Laser, PW, Pump, High Average Power


IV - Laser Plasma Interaction


Poster Presentation Laser Plasma Interaction

Nonlinear transition of convective to absolute instability of

stimulated Raman backscattering with trapped electrons and

inflationary growth of reflectivity in

a single laser speckle [hot spot]

Yanxia Wang1, C. S. Liu2, Qing Wang1, Chunyang Zheng3, Zhanjun Liu3, Xiantu He3

1. Center of Applied Physics and Technology, Peking University, Beijing, China

2. University of Maryland, USA



The rapid growth of reflectivity of several orders of magnitude, with small

increment of pump laser intensity, has been observed in experiment for stimulated Raman

scattering. [Montgomery. Phys. Plasmas 23, 055601 (2016)] This "inflation" has been

interpreted as a result of competition between collisional velocity diffusion and electron

trapping. [Vu et al. Phys. Plasmas 14, 012702 (2007)] Here, a new and general mechanism

is presented—nonlinear transition from convective to absolute instability of stimulated

Raman backscattering. Trapped electrons tend to flatten electron distribution function,

resulting in reducing Landau damping of the plasma wave substantially, and then reducing

the threshold of absolute instability significantly with a slight increase of pump laser power.

Once absolute instability is triggered, it will grow exponentially everywhere in the hot spot.

The nonlinear consequences of it, including the dramatic increase of reflectivity of three

orders of magnitude with small increment of laser power, will be discussed.

Keywords: stimulated Raman backscattering, inflation



Ballistic Injection and acceleration of positrons in bubble

regime

Zhiyi Xu1, Zhaofan Xiao1, Ronghao Hu1, Jinqing Yu1, Xingtai Xue1, Zheng Gong1, Yinren Shou1,

Xueqing Yan1,2 , and Haiyang Lu1,2,*

1. State Key Laboratory of Nuclear Physics and Technology, and Key Laboratory of HEDP

of the Ministry of Education, CAPT, Peking University, Beijing, China

2. Collaborative Innovation Center of Extreme Optics, Shanxi University, Shanxi, China


Intense relativistic positron beams are crucial to the study of basic plasma physics

and pair-production in the field of fundamental physics[1]. They are also believed to exist

in violent high-energy astrophysical phenomena, and a stable method to generate intense,

mono-energetic and fully tunable positron beams enables experimental study with the

rising interest in the explanation of gamma-ray bursts and black holes[2,3]. Positrons

usually generated from LINACs and synchrotron accelerators through hitting a thick,

high Z target, while the quality is not as good as required which have restrictions for

many applications.

Since the concept of laser-plasma accelerator was proposed[4], plenty of works

has been done on electron acceleration using plasma wakefields [5-19]. Until recently,

experiments demonstrated the generation of sub-hundred MeV positrons by interacting

electrons beams from laser plasma accelerators with high-Z solid targets[20]. However,

the result positron beams are limited both in energy and positron count. Hybrid schemes

have also been proposed and conducted experimentally to generate low energy (E < 20

MeV) and broad divergence (~1rad) positron jets with high positron count (up to

1011)[21-23]. However, a scheme for injecting positrons into laser-plasma accelerators

has yet been absent.

A new scheme for trapping and injecting relatively low energy positron into

electron bubble in plasma is presented. The positrons can enter the second period of the

bubbles, and trapped by the transverse electric field in the front, then be accelerated. The

magnitude of accelerating field for positrons are close to those of electron acceleration in

the bubble. Simulations show that the positrons can be accelerated to 200MeV, while

retaining the quasimono-energetic spectrum.

Keywords: positron injection; positron acceleration; LWFA; laser plasma accelerator;

Reference

[1] C. M. Surko and R. G. Greaves, Phys. Plasmas 11 (5), 2333 (2004).

[2] J. F. C. Wardle et al., Nature 395 (6701), 457 (1998).

[3] G. Weidenspointner et al., Nature 451 (7175), 159 (2008).



[4] T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43 (4), 267 (1979).

[5] W. Lu et al., Phys. Rev. Lett. 96 (16), 165002 (2006).

[6] J. Faure et al., Nature 431 (7008), 541 (2004).

[7] C. G. R. Geddes et al., Nature 431 (7008), 538 (2004).

[8] S. P. D. Mangles et al., Nature 431 (7008), 535 (2004).

[9] W. P. Leemans et al., Nat. Phys. 2 (10), 696 (2006).

[10] J. S. Liu et al., Phys. Rev. Lett. 107 (3), 035001 (2011).

[11] H. Lu et al., Appl. Phys. Lett. 99 (9), 091502 (2011).

[12] X. M. Wang et al., Nat. Commun. 4, 1988 (2013).

[13] W. P. Leemans et al., Phys. Rev. Lett. 113 (24), 245002 (2014).

[14] J. Faure et al., Nature 444 (7120), 737 (2006).

[15] I. Blumenfeld et al., Nature 445 (7129), 741 (2007).

[16] W. Lu et al., Phys. Rev. Spec. Top.- Accel. Beams. 10 (6), 061301 (2007).

[17] W. H. Takashi Kameshima, Kiyohiro Sugiyama, Xianlun Wen, et al., Appl. Phys.

Express. 1, 066001 (2008).

[18] S. Kneip et al., Phys. Rev. Lett. 103 (3), 035002 (2009).

[19] C. E. Clayton et al., Phys. Rev. Lett. 105 (10), 105003 (2010).

[20] G. Sarri et al., Phys. Rev. Lett. 110 (25), 255002 (2013).

[21] H. Chen et al., Phys. Rev. Lett. 102 (10), 105001 (2009).





Background radiation analysis for optical Thomson scattering

from laser-produced hohlraum plasmas on SG-III prototype

laser facility

Hang Zhao

Research Center of Laser Fusion, China Academy of Engineering Physics


Optical Thomson scattering is a widely used technique in measuring underdense

plasma conditions in high-energy-density experiments. With proper configurations,

collective Thomson scattering from ion-acoustic waves (IAW) and electron plasma waves

(EPW) can be observed, and a set of plasma parameters - electron temperature, electron

density, ion temperature, plasma flow velocity - can be obtained by fitting the measured

spectral features with theoretically calculated ones. The Thomson scattering system on SG-

III prototype laser facility (SG-IIIp) uses a 4ω (263.3nm) probe laser and measures the ion

spectral feature and the red-shifted electron spectral feature of the scattered light. An

outstanding problem in measuring Thomson scattering from laser-produced hohlraum

plasmas is the weak signal versus potentially strong background. The two primary sources

of background radiation are bremsstrahlung and Thomson scattering from beams other than

the probe beam. We have calculated the intensity of the background, as well as the signal,

according to the experimental configuration on SG-IIIp, with plasma conditions obtained

from radiation hydrodynamic simulations. The spectral response and resolution of the

diagnostic system, and the inverse bremsstrahlung absorption along the light path have

been taken into account in the calculation. The results show that, in the electron feature

range (300nm~400nm), Thomson scattering from the drive beams is the primary

background, and is likely to overwhelm the signal; in the ion feature range (261nm~265nm),

the background level is relatively low, and measurements with high signal-to-noise ratio is

possible. The calculation is in good accordance with the experimental measurements.

Keywords: Thomson scattering; hohlraum; SG-III prototype; background radiation;



Laser-plasma optics and acceleration under high magnetic

field

Qian Zhao

Shanghai Jiao Tong University


In the first part of the talk, we will report an extreme case of the Faraday effect that

a linearly polarized ultrashort laser pulse splits in time into two circularly polarized pulses

of opposite handedness during its propagation in a highly magnetized plasma[1]. This

offers a new degree of freedom to manipulate ultrashort and ultrahigh power laser pulses.

Together with technologies of ultra-strong magnetic fields, it may pave the way for novel

optical devices, such as magnetized plasma polarizers. The latter could allow the

generation of circularly polarized laser pulses as high power as 10 PW in up-to-date laser

facilities. The resultant high-power circularly polarized pulses are particularly attractive

for laser-driven ion acceleration, and optical control of mesoscopic objects. In addition, it

may offer a powerful means to measure strong magnetic fields broadly existing in objects

in the universe and in laser-matter interactions in laboratories.

In the second part, we will report the Ionization injection in a laser wakefield

accelerator subject to a transverse magnetic field. The ionization injection stands out from

other injection mechanisms of the LWFA because it only requires relatively low laser

intensity. However, to reduce the energy spread in the ionization injection, electron

injection must be limited to a short distance, which is usually accompanied by a reduction

of the beam charge. Fortunately, we find that a nonlinear ionization injection process

occurs when the plasma is subject to an appropriate magnetic field, which postpones the

electron injection while enhancing the peak injection rate. As a consequence, the energy

spread can be reduced simultaneously with an increase in the beam charge, for the

magnetic-controlled ionization injection scheme.

Keywords: Farady effect, Laser wakefield acceleration, High magnetic field



Generation and dynamics of relativistic electron vortex in laser

near critical density plasma interaction

Dongning Yue*, Min Chen, Xiaohui Yuan, Zheng-Ming Sheng, Jie Zhang

Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy,


Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, China


Electron vortex is an important localized nonlinear structure. It usually contains

strong dipole magnetic field which could be used to accelerate charged particles through

magnetic annihilation or reconnection. Here by using Particle-in-Cell simulations, we

study electron vortex generation and its dynamics when an intense short laser pulse

interacts with a near critical density plasma which has a density gradient. The dipole

magnetic fields generated form these electron vortices separate from each other and move

toward opposite directions. We found that the velocity of such moving vortices can be as

high as 0.6c, which is much faster than the one reported by K.V. Lezhnin et al (2017).

Furthermore, we found there is a low-frequency electromagnetic field inside these vortex

structures. We show the dynamics of such vortices and discuss their applications to particle

accelerations.

Keywords: electron vortex; dipole magnetic field; low-frequency electromagnetic field



Laser Plasma Instabilities at Large-Angle Oblique Laser

Incidence

Changwang Lian1,2,*, Yu Ji1, Rui Yan1, Guangyue Hu1, Jian Zheng1,3, Liang Hao4, Shihui Cao5,

Chuang Ren5

1. University of Science and Technology of China, Anhui, China




5. University of Rochester, USA


Laser plasma instabilities (LPI) are identified as one of the major concerns in

inertial confinement fusion (ICF) due to their impact on laser coupling and hot-electron-

induced fuel preheating. Hot electrons may also benefit the shock formation in shock

ignition. When the laser incidence angle is large, the LPI regime is different from that at

normal laser incidence due to field swelling and lower turning-point density. The large

angle regime is also important to the cross beam energy transfer (CBET).

We study LPI in the large-incident-angle (θ) regime with both fluid-like and

particle-in-cell (PIC) simulations. The incident laser has a large angle (>45 deg) with

respect to the plasma density gradient. The fluid code FLAME-MD is used to study the

linearly-growing phase of the two plasmon decay instability (TPD). Nonlinear effects, such

as laser pump depletion, kinetic saturation, and hot electron generation, are not yet taken

into account in the fluid model but studied using a full PIC code OSIRIS. When θ~60 deg,

the turning-point density can be as low as 1/4 critical density thus overlaps with the region

where TPD and stimulated Raman scattering (SRS) modes are developed. The turning-

point effect significantly lowers LPI thresholds. TPD and SRS can develop with a much

lower laser intensity and produce significant amount of hot electrons. The linear growth of

LPI is sensitive to the incident angle. The ion density fluctuations, either driven by large-

amplitude plasma waves or by stimulated Brillouin scattering (SBS), can affect the local

laser turning points and LPI evolutions. Lower LPI thresholds and hot electron generation

in large-incident-angle configurations may introduce more preheating risk to implosion

while rich ion density fluctuation features may put more uncertainties on CBET.

Keywords: Laser Plasma Instabilities, Oblique Laser Incidence



Gamma-ray generation in laser-irradiated solids with different

pre-plasma scale length

Xiangbing Wang1,2,*, Zhimeng Zhang2, Jian Zheng1,3, Guangyue Hu1, Yuqiu Gu2





In the quantum electrodynamics (QED) dominated regime, when intense laser

interacts with target, amounts of γ-ray will be generated by the synchrotron radiation of the

high-energy electrons traveling in the strong background electromagnetic field. The

generation process is sensitive to the parameters of the target in different ways. In all target

properties, pre-plasma scale length plays an important role in the generation of the γ-ray,

such as angular distribution of the γ-ray, spectrum, physical processes and so on.

Meanwhile, solid targets with different pre-plasma scale length will be induced by the

various pre-pulses in experiment. So ultraintense laser (1022 W/cm2) irradiating the solid

target Al with different pre-plasma scale length were investigated by two-dimensional

particle-in-cell simulations, including the QED model, which takes into account the

important QED effects in the synchrotron radiation of γ-rays and Breit-Wheeler production

of electronpositron pairs by a Monte Carlo algorithm. The features of the γ-rays produced

in different scale length are identified and compared mutually. We find that, with the

longest pre-plasma scale length in our simulations, electrons can be accelerated to the

maximum longitudinal momentum under both of the longitudinal laser ponderomotive

force and the restoring electrostatic force. The energy conversion efficiency of laser to γ-

ray, strongly affected by the spectrum of electrons, is the highest in all conditions,

implicating that the electrons get the most energy from laser. The angular distribution of

the γ-ray is the results of the transverse oscillation and the longitudinal join force, which

determinate the motion trajectory of electrons. In order to specify the physical processes in

the interaction, the force and motion of a typical electron was analyzed theoretically. From

our work, the pre-plasma state and the typical motion of electrons can be evaluated by the

angular distribution of γ-ray. And it is beneficial for us to get the bright γ-ray source with

good collimation, high energy conversion efficiency and simple target manufacture.

Keywords: Synchrotron radiation, pre-plasma scale length, gamma-ray source, angular

distribution, spectrum, conversion efficiency



Effective suppression of parametric instabilities with

decoupled broadband lasers in plasma

Y. Zhao1,*, S.M. Weng1, M. Chen1, J. Zheng1, H.B, Zhuo2, C. Ren3, J. Zhang1, and Z.M. Sheng1,4

1. Key Laboratory for Laser Plasmas (MoE), School of Physics and Astronomy, Shanghai

Jiao Tong University, China

2. College of Science, National University of Defense Technology, Changsha, China

3. Department of Mechanical Engineering and Laboratory for Laser Energetics, University

of Rochester, Rochester, USA

4. SUPA, Department of Physics, University of Strathclyde, Glasgow, UK


We present a type of laser beam structures called decoupled broadband lasers (DBLs)

which can be used to suppress the parametric instabilities effectively. A theoretical analysis

for the stimulated Raman scattering (SRS) instability driven by two laser beams with

certain frequency difference is presented. It is found that strong coupling and enhanced

SRS take place only when the unstable regions corresponding respectively to the two

beams are overlapped in the wavenumber space. Hence a threshold of the beam frequency

difference for their decoupling is found as a function of their intensity and plasma density.

Based upon this, a strategy to suppress the SRS instability with DBLs is proposed. A DBL

can be composed of tens or even hundreds of beamlets, where the beamlets are distributed

uniformly in a broad spectrum range such as over 10% of the central frequency. Decoupling

among the beamlets is found due to the limited beamlet energy and suitable frequency

difference between neighboring beamlets. Particle-in-cell simulations demonstrate that

SRS can be almost completely suppressed with DBLs at the laser intensity ∼ 1015 W/cm2.

Moreover, stimulated Brillouin scattering (SBS) will be suppressed simultaneously with

DBLs as long as SRS is suppressed. DBLs can be attractive for driving inertial confined

fusion.

Keywords: Stimulated Raman scattering, instability suppression, incoherent light, inertial

confinement fusion

References

1. Y. Zhao et al., Phys. Plasmas 24, 112102 (2017).

2. Y. Zhao et al., Matter and Radiation at Extremes 2,190-196 (2017).


Satellite workshop on Fluid Interface Instability at Extremes

Laser induced photoneutron source

Wei Qi



Keywords: photoneutron, laser, neutron source

Satellite workshop on Fluid Interface

Instability at Extremes



Fluctuating Hydrodynamics Simulations of

the Richtmyer-Meshkov Instability

Ravi Samtaney, Kiran Narayanan,

Mechanical Engineering, Physical Science and Engineering Division, King Abdullah

University of Science and Technology, Thuwal, Saudi Arabia

We present results from simulations of the two-fluid fluctuating compressible

Navier-Stokes equations (FCNS), which consistently account for thermal fluctuations

from meso to macro scales, in order to study the effect of such fluctuations on the mixing

behavior in the Richtmyer- Meshkov instability (RMI). We present results for three He/Ar

systems having length scales with decreasing order of magnitude that span from

macroscopic to mesoscopic, with different levels of thermal fluctuations characterized by

a non-dimensional Boltzmann number (Bo). For a multi-dimensional FCNS system on a

regular cartesian grid, the space-time stochastic flux Z (x, t), first postulated by Landau, is

the form Z (x, t) → 1/√htN (ih, n∆t) for spatial interval h, time interval t, h and

Gaussian noise N. The discrete mesh size should correspond to a cell volume that contains

a sufficient number of molecules of the fluid such that the fluctuations are physically

meaningful and produce the right equilibrium spectrum. Our simulations show that for

systems with Bo ≪ 1 deterministic mixing behavior emerges as the ensemble-averaged

behavior of several fluctuating instances, whereas when Bo ≈ 1, a deviation from

deterministic behavior is observed. For all cases, the FCNS solution provides bounds on

the growth rate of the amplitude of the mixing layer.



On converging shock and converging

Richtmyer-Meshkov instability

Xisheng Luo*, Juchun Ding, Zhigang Zhai, Ting Si

Department of Modern Mechanics, University of Science and Technology of China,

Hefei 230026, China

Email: [email protected]

Richtmyer-Meshkov (RM) instability occurs when an initially perturbed interface

separating two different fluids is impulsively accelerated, and plays a central role in

understanding the hydrodynamic processes involved in inertial confinement fusion (ICF)

and supernova explosions. During past few decades, the interaction of a planar shock with

a two-dimensional (2D) single-mode interface was studied extensively. However, the

physical background of ICF cares more about the interaction of a spherically converging

shock with a spherically disturbed interface. For this great significance, the converging RM

instability has become an imperative. Here we will review on studies on the converging

shock and its interaction with a density interface, namely the converging RM instability.

Compared with the planar shock counterpart, a perfectly converging shock wave is

difficult to generate because it can be easily disturbed. There are only several methods to

produce a converging shock, including horizontal annular shock tube with a coaxial tear-

drop-shaped inner core, vertical annular coaxial shock tube, shock tube with a conically

shaped test section, gas lens technique and cylindrical shock tube with a curved wall

designed by shock dynamics theory.

Compared with the planar RM instability, the mechanism of the converging RM

instability is much more complicated because both the radial and angular directions need

to be considered, while only the spanwise direction is involved in the planar RM instability.

It is found that the geometry contraction (BP effect), non-uniform acceleration (RT effect)

and multiple shock (compressibility) together with RM instability appear in this

circumstance and complicate the interface evolution. There are few experiments on this

topic, however. It is found that both the RT and compressible effects restrain the amplitude

growth while the RM instability facilitates the amplitude growth. It also indicates that the

RM instability with BP effect dominates the amplitude growth in fast growing stage, and

the RT stabilization effect with the BP effect prevails the stage before reshock, which

causes a quick drop of the interface amplitude. This work was supported the National

Natural Science Foundation of China (Nos. 11772329, U1530103 and 11625211) and the

Science Challenge Project (No. TZ2016001).

Keywords: converging shock wave; Richtmyer-Meshkov instability




Studies of High-Energy-Density Hydrodynamics at Laser

Fusion Research Center

Pu Yudong*, Miao Wenyong, Yuan Yongteng, Tu Shaoyong

Laser Fusion Research center, China Academy of Engineering Physics, China

We summarized the works related to the studies of high-enegy-density (HED)

hydrodynamics that had been carried out by Laser Fusion Research Center (LFRC). The

subject of ablative Rayleigh-Taylor instability (RTI) was concerned most intensively. The

growth rate of single mode ablative RTI were carefully measured for the plastic ablator in

flat geometry. The ablative RTI was also speculated to increase or decrease the ablation

pressure depending on the radiation field anisotropy besides causing bubble penetration,

perturbation feedthrough and interface mixing. To study the evolution of interface

instabilities under reshocked condition or convergent geometry, we developed

experimental platforms employed spherically bent crystal imaging system and precisely

fabricated and characterized targets. As complementary to the technique of backlight

photography, x-ray fluorescence imaging would be useful in the research of HED

hydrodynamics. Preliminary results of x-ray fluorescence imaging experiments was

described showing the potential of this technique on revealing particular informations of

HED hydrodynamics.



A nonlinear theory for spikes and bubbles at Richtmyer-

Meshkov unstable interfaces with arbitrary density ratio

Qiang Zhang

Department of Mathematics, City University of Hong Kong, China

The dominant feature of Richtmyer-Meshkov instability is the growth of unstable

fingers at the interface. The portions of the heavy fluid penetrating into the light fluid are

known as spikes and the portions of the light fluid penetrating into the heavy fluid are

known as bubbles. It is well known that spikes are more unstable than the bubbles and

consequently more difficult to predict the behavior of spikes. For this reason, most of the

theoretical works in the literature are focused on bubbles. In this talk, we present closed

form solutions for both spikes and bubbles for systems with arbitrary density ratios. We

provide analytical predictions for the growth rates and amplitudes of spikes and bubbles.

We show that our theoretical predictions are in remarkably good agreement with the results

from numerical simulation from earlier to late times.



Particle jetting instability

K. Xue* , J. Q. Liu, K. Y. Du

State Key Laboratory of Explosive Science and Technology, Beijing Institute of

Technology, Beijing, China


When particle rings/shells are dispersed by the divergent impulsive loads, the

destabilization of the internal and external interfaces gives rise to a dual hierarchical

particle jetting pattern. Although this dual hierarchical pattern remains consistent in the

late stage regardless of the magnitude of overpressure of loadings, a mechanism crossover

takes place when the magnitude of overpressure deceases from O(101) GPa to O(10-1) MPa.

In the strong blast wave limit, the external jetting instability occurs alongside the reflection

of the rarefaction waves into the bulk, whereas the instability of the inner compacted layer

can be well accounted for by the Rayleigh-Taylor instability of the accelerating shell. By

contrast, in the weak shock wave limit, it is the internal interface of ring that becomes

destabilized first shortly after the initial acceleration. The external jetting instability in this

scenario would not be initiated until the expanding external interface transitions from the

acceleration to deceleration, indicative of a Rayleigh-Taylor instability. The crossover of

the jetting instability with the overpressure magnitude of the impulsive loads is controlled

by the competition of two characteristic time scale, namely the localized particle flow

timescale and the macroscopic expansion timescale. Besides, the material properties of

particles affect both the internal and external jetting. The former is related to the correlation

between the material properties and the force structures in particles. The latter is

determined by the competition between the viscous forces and the inertial forces.

Keywords: Particle Jetting, Interface Instability, DEM, Divergent Shock Waves



Dynamical behavior of the Richtmyer–Meshkov instability-

induced turbulent mixing

Tao Wang1,2, Jingsong Bai1, Ping Li1, Bing Wang1, Jianyu Lin1, Gang Tao2


2. School of Energy and Power Engineering, Nanjing University of Science and

Technology, Nanjing, China

The classical Richtmyer-Meshkov instability is a complex phenomenon happening

at a geometrical perturbed interface between two different fluids and hit by a shock wave.

Its mechanism is the baroclinic vorticity deposition owing to the misalignment of the

pressure gradient of across the shock front and the local density gradient at the interface.

At late times the Richtmyer-Meshkov instability can induce the turbulent mixing. It is very

important in a variety of applications ranging from man-made to natural phenomena, and

has gained much attention all long.

In this paper, the three-dimensional multi-mode Richtmyer-Meshkov instability

and the induced turbulent mixing in air/SF6 configuration are numerical investigated by

using our in-house large-eddy simulation code MVFT (multi-viscous-flow and turbulence).

The initial perturbation modes still exist in a long time after the incident shock. The width

of turbulent mixing zone (TMZ) grows as different ways in different stage, but the statistics

in turbulent mixing zone decay with time in the similar. At early times, the baroclinic

vorticity mainly develops in transverse direction which is in the plane perpendicular to the

shock direction; the normal generalized Reynolds stress in the streamwise direction (shock

direction) dominates the averaged momentum transport. At late times, the baroclinic

vorticity and the normal generalized Reynolds stresses in three directions (transverse and

streamwise directions) tend to be uniform respectively. That is to say the turbulent mixing

behaves a strong anisotropy in early times, and the anisotropy weakens in late times but

the isotropy is not achieved, although the approximate power law of 35 appears in the

energy spectra.



Self-generated magnetic field induced by Richtmyer-Meshkov

Instability in inertial confinement fusion plasmas

Yaqun Yu1, Chang Liu2, Baolin Tian3,*

1. Graduate School of Chinese Academy of Engineering Physics, Beijing, China,

2. Hong Kong University of Science and Technology, Mathematics department, Hong

Kong, China

3. Laboratory of Computational Physics, Institute of Applied Physics and

Computational Mathematics, Beijing, China

Self-generated magnetic fields have been observed in inertial confinement fusion

(ICF) experiments [1,2]. The magnetic fields are not large enough to affect the implosion

hydrodynamics, while the generated magnetic field can inhibited the electron thermal

conduction through the Hall parameter e e when the electron gyro-frequency e

exceeds the collision frequency e . The Richtmyer-Meshkov instabilities (RMI) in inertial

confinement fusion occur at the gas-ice interface (where the temperature gradient is the

largest) can availably amplify the magnetic field via baroclinic mechanism. The magnitude

and characteristics of self-generated magnetic field induced by single-mode RMI are

studied through two-fluid MHD model for 2D. Through the results of scaling study, the

theoretical model of peak magnetic field is determined as a function of density, Atwood

number, Mach number and perturbation wavelength，the results suggest that the Hall

parameters can approach to unity and even get larger in NIF conditions, accordingly reduce

the electron thermal conduction. The result observed via simulation indicate that the peak

magnetic field exists in the largest vorticity field.



Recent Advances in our understanding of the Rayleigh-Taylor

Instability

P. Ramaprabhu

University of North Carolina at Charlotte, Charlotte, NC USA

The Rayleigh–Taylor (RT) instability (after Lord Rayleigh and G. I. Taylor) occurs

when a light fluid is separated from a heavy fluid by a sharp interface and an acceleration

is directed from the light fluid to the heavy. The classic Rayleigh-Taylor problem consists

of a dense fluid on top of a light fluid in the presence of a gravitational acceleration.

Understanding Rayleigh-Taylor instability is particularly important to Inertial

Confinement Fusion (ICF), a process where nuclear fusion reactions release large

quantities of energy by heating and igniting a target fuel. Mixing due to RT and other

hydrodynamic instabilities reduce the energy yield from the ICF process. RT instability

and mixing also plays a key role in nuclear stockpile management, Type 1a supernovae

detonations, atmospheric inversions, extraction of oil, etc. The nonlinear phase of RT

evolution has traditionally been described by potential flow-type models. I will describe

recent numerical simulations that challenge the validity of well-established models of RT.

In contrast to the terminal velocity predicted by the potential flow theory, RT bubbles

instead experience transients in the form of an acceleration before saturating at a higher

Froude number (velocity non-dimensionalized). This transient behavior is explained by the

formation of secondary instabilities such as Kelvin-Helmholtz vortex rings that drive the

bubbles to acceleration through an induced velocity. I will also discuss recent

developments in our understanding of the role of initial conditions, material properties, and

variable drive histories.



Structure and Dynamics of Plasma Interfaces in Laser-Driven

Hohlraums

C. K. Li1,*, S. C. Wilks2, P. E. Masson-Laborde3, S. Laffite3, P. A. Amendt2, R. Betti4, E. M.

Campbell4, J. A. Frenje1, R. D. Petrasso1, T. C. Sangster4, F. H. Séguin1, V. Tassin3

1. Massachusetts Institute of Technology, Cambridge, MA 02139 USA

2. Lawrence Livermore National Laboratory, Livermore, CA 94550 USA

3. CEA, DAM, DIF F-91297 Arpajon FRANCE

4. University of Rochester, Rochester, NY 14627 USA

E-mail: [email protected]

Understanding the structure and dynamics of plasma interfaces in laser-driven

hohlraums is important to inertial confinement fusion. Such interfaces are either kinetically

unstable, leading to, for example, forming a diffusion layer and developing an ambipolar

electric field, or hydrodynamically unstable, leading to generating Rayleigh-Taylor

instabilities. It has been realized that the modelling of such phenomena with the

conventional single-spices-averaged hydrodynamic codes are largely responsible for some

disagreements between the experimental results and numerical simulations. A number of

plasma kinetic effects which play critical roles in these processes have been missed in

hydrodynamic simulations, including ion interpenetration and diffusion. In particular,

coupled with ion-kinetic processes, self-generated fields and plasma instabilities observed

by blowing off from hohlraum laser entrance holes provide compelling experimental

evidence of such non-hydrodynamic processes. To that end, a series of experiments was

performed at Omega laser facility to explore these important phenomena. Experimental

data obtained from several diagnostics, such as proton radiography and x-ray imaging, are

compared with modified three-dimension hydrodynamic simulations, providing new

insight into hohlraum stagnation and a more completed physical picture about hohlraum

dynamics. The work described herein was performed in part at the LLE National Laser

User’s Facility (NLUF), and was supported in part by US DOE (Grant No. DE-FG03-

03SF22691), LLNL (subcontract Grant No. B504974) and LLE (subcontract Grant No.

412160-001G).




Dynamics evolution of chaotic Rayleigh-Taylor bubble fronts

Yousheng Zhang, Zhirui Zhou, Baolin Tian

Institute of applied physics and computational mathematics, Beijing, China

Mechanisms governing the general evolution of chaotic Rayleigh-Taylor bubble

fronts are explored, including merger, competition and their interaction. Evolutions of

characteristic quantities, i.e., the diameter of dominant bubble D and the height of bubble

mixing zone h, are formulated and validated. The D expands self-similarly with universal

aspect ratio D/h ≈ (1+A)/4. In contrast, the h grows quadratically with growth coefficient

α≡ h/(Agt2) depending on mechanism:α=αm ≈1/36 for pure merger, α=αc ≈[2Φ/ln(2η0)]2 for

pure competition, and α=maxαm, αc when two mechanisms co-work, where A,η0 and Φ

denote dimensionless density ratio, initial perturbation amplitude, and linear-growth-rate

ratio of actual fluid to ideal fluid, respectively.



An approximate deconvolution-kinematic simulation (AD-KS)

subgrid scale model for LES of Lagrangian relative dispersion

Guodong Jin*

LNM, Institute of Mechanics, Chinese Academy of Sciences, China


An approximate deconvolution and kinematic simulation (AD-KS) hybrid model is

proposed to predict the Lagrangian relative dispersion of fluid particles in large eddy

simulation (LES) of isotropic turbulent flows. In the model, a physical connection between

the resolved and subgrid scales is established through the energy flux rate at the filter width

scale. Due to the lack of subgrid scale (SGS) turbulent structures and SGS model errors,

LES cannot accurately predict two- and multi-point Lagrangian statistics of fluid particles.

In order to improve the predictive capability of LES, we use the approximate deconvolution

model (ADM) to improve the resolved scales near the filter width and kinematic simulation

method (KSM) to recover the missing velocity fluctuations beneath the subgrid scales. To

validate the proposed hybrid model, we compare the Lagrangian statistics of two- and four-

particle dispersion with the corresponding results from DNS and the conventional LES. A

significant improvement in the prediction of Lagrangian statistics of fluid particles is

achieved through the AD-KS hybrid model. Furthermore, we carry out the parameter study

about the wavenumbers and orientation wavevectors, aiming at reducing the computational

cost. Good results can be obtained using a small number of wavenumber modes and

orientation wavevectors. Thus, we can improve the prediction of Lagrangian dispersion of

fluid particles in LES by applying the AD-KS hybrid model at acceptable computational

cost.

Fig1: One-time two-point Lagrangian velocity correlation functions of particle pairs with

different initial separation distances

r(

r,

0 50 100 1500

0.2

0.4

0.6

0.8

1 DNS 5123: 1/4

8

LES 643

LES 643+KS

LES 643+AD+KS

(a)



High order consistent finite difference algorithm for multi-

material interfacial instabilities problems under extreme

conditions

Zhiwei He*, Yousheng Zhang, Li Li, Baolin Tian



In order to simulate multi-material interfacial instabilities problems under extreme

conditions, we propose a high-order consistent finite difference algorithm. First of all, in

order to treat the non-conservative product consistently, we derive a new general numerical

methodology that successfully avoids any special treatments as those required in previously

reported algorithms. In this new algorithm, we rewrite the non-conservative term as a

conservative term with a source term containing the velocity divergence. By consistently

treating the advection velocity in the conservative term and the velocity divergence in the

source term by imposing a new additional criterion, specifically, that a multicomponent-

fluid algorithm should have the ability of maintaining a pure single-fluid, we finally derive

a new general algorithm that does not need any special treatment, and is very convenient

to implement. Second, a pressure-equilibrium-consistent intermediate state (augmented

with approximations of pressure derivatives) for performing local characterisitic

decomposition is proposed. In this intermediate state, we not only mimic the state of the

mixture, but also mimic the relations between pressure derivatives. The final physical-

compatible Roe linearization can be applied to material with complicated equations of state.

Finally, we propose a dynamical filter to enforce a strict maximum principle of volume of

fraction and the positivity of certain physical quantities, such as density and internal energy

because high-order methods are usually not maximum-principle-satisfying and positivity-

preserving. The results of some benchmark tests, including some interfacial instabilities

problems, show that the final algorithm is suitable for problems regarding the interaction

of interfaces and strong shock and rarefaction waves.




High Order Numerical Simulation of Compressible Multi-

Material Flows and Turbulent Mixing with CFD2 Code

Baolin Tian*, Yousheng Zhang, Zhiwei He, Li Li,Haifeng Li



Compressible multi-material flows and turbulent mixing can be found in many

engineering and nature science fields, such as inertia confined fusion (ICF), astrophysics

and so on. In this work, a high order multi-physics code, CFD2 (Code of Finite Difference

for Compressible Flow Dynamics), was developed for the simulation of compressible

multi-material flows under extreme conditions. The code solves the equations of

multidimensional hydrodynamics with high order accuracy in space and time, including a

series of high order difference schemes, such as WENO, MP, GVC and WCNS schemes

based on flux splitting techniques. The CFD2 code is implemented on non-uniform mesh

and can simulate flow problems with billion mesh cells on thousands CPU cores with MPI

parallelization. The code can simulate multi-physics flow problems, such as detonation,

radiation, and so on. Some recent progress on high order schemes has been integrated into

the code in order to prevent the non-physical oscillations near material interfaces. A series

of typical model problems have been simulated to validate the code. Moreover, turbulent

mixing induced by RM and RT instability was simulated systematically to study the

turbulent mixing mechanism.

Satellite workshop on Laser and Plasma

Instabilities


Satellite workshop on Laser and Plasma Instabilities

Stimulated Raman backscattering : Convective (C)and

Absolute (A）instabilities ：Nonlinear transformation from

（C) to (A)and consequences of Reflection Enhancement

( Inflation) to Laser fusion.

Chuansheng Liu

University of Maryland, USA



Non-local radiation hydrodynamics and laser absorption in the

context of direct-drive ICF

Stefan Weber

Institute of Physics, Czech Academy of Sciences, Czech Republic



Current Improvement in the Computer Code MULTI

Rafael Ramis

Polytechnic University of Madrid, Spain



The role of hot electrons in the dynamics of a laser-driven

strong converging shock

Vladimir Tikhonchuk

University of Bordeaux, France



On the use of gas target for laser plasma interaction

Victor Malka

Centre National de Larecherche Scientifique, France

Satellite workshop on Laser Fusion and

Science


Satellite workshop on Laser Fusion and Science

High Energy Electron Transport and Heating in Magnetized

Fast Ignition

K.Mima1, Y.Sentoku2, T.Taguchi3, T.Johzaki4, H.Nagatomo2, M.Hata2, N.Iwata2,H.Sakagami5,

and A.Sunahara6, S.Fujioka2, and R.Kodama2

1 The Graduate School for the Creation of New Photon Industries, 1955-1 Kurematsu, Nishi-

ku,Hamamatsu, Shizuoka 431-1202, Japan,

2 Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871,

Japan,

3Faculty of Engineering, Setsunan University, Neyagawa, Japan

4 Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-

Hiroshima,Hiroshima 739-8527, Japan,

5 National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi,

Toki,Gifu 509-5292, Japan,

6 Center for material under extreme environment (CMUXE), School of Nuclear

Engineering,Purdue University, 500 Central Dr. West Lafayette, IN 47907 USA.

Electron beam driven fast ignition has been widely investigated by experiments,

simulation, and theory. The critical issue of this concept is the low coupling efficiency due

to the laser driven hot electron beam divergence and the low stopping power because of

hardening of the electron energy spectrum. In order to overcome this issue, two new ideas

have been proposed. The one is the application of external magnetic field for guiding the

electron beam. The other is the elongation of the heating pulse from picosecond to tens of

picosecond.

Hot electron guding with the external magnetic field has been found in the GXII-

LFEX experiments and simulations in the FIREX-I project[1][2]. In the experiments, the

kT magnetic field generated by a laser capacitor coil is applied to the solid ball cone target

which contains cupper dopant. The X-ray spectra of the series of cupper Kα and shifted-

Kα indicate that the high density plasma was heated to higher than 2 keV.

In this talk, the mechanism of the enhanced heating will be discussed. One possible

mechanism is the magnetic guiding of the heat conduction from a few tens of keV over-

dense plasma to the high density plasma[3][4]. The other mechanism is the enhanced

stopping of high energy electron in magnetized over-dense[5], which enhances the

coupling of high energy electron with the background plasmas. The simulation results on

the high energy electron stopping and scattering will be presented.

Reference

1) J. J. Santos, M. Bailly-Grandvaux, L. Giuffrida, P. Forestier-Colleoni, S. Fujioka,Z.

Zhang, P. Ko-rneev, R. Bouillaud, S. Dorard, D. Batani, et al., New J. Phys. 17 ,

083051(2015)

2) T. Johzaki, T. Taguchi, Y. Sentoku, A. Sunahara, H. Nagatomo, H. Sakagami, K.

Mima,S.Fujioka, and H. Shiraga, Nucl. Fusion 55, 053022 (2015)



3) N.Iwata, S.Kojima, Y.Sentoku, M.Hata., and K.Mima, Nature Communications volume

9, 623(2018)

4) Y.Sentoku, et al, IFSA 2017, San Malo, France, plenary talk

5) T.Taguchi, T.Antonsen, and K.Mima, J. Plasma Phys. (2017), vol. 83, 905830204



Numerical Simulation of exploding pusher targets

S. Atzeni,1 M. J. Rosenberg,2 M. Gatu Johnson,3 R. D. Petrasso,3 H. Sio3

1) Dipartimento SBAI, Università di Roma "La Sapienza", Italy

2) Laboratory for Laser Energetics, University of Rochester, NY, USA

3) Plasma Fusion Center, M.I.T., Cambridge, MA, USA

Exploding pusher targets, i.e. gas-filled large aspect-ratio glass or plastic shells,

driven by a strong laser-generated shock, are widely used as pulsed sources of neutrons

and fast charged particles. Recent experiments on exploding pushers provided evidence

for the transition from a purely fluid behavior to a kinetic one [1,2]. Indeed, fluid models

largely overpredict yield and temperature as Knudsen number Kn (ratio of ion mean-free

path to compressed gas radius) is comparable or larger than one. At Kn = 0.3 - 1, fluid

codes reasonably estimate integral quantities as yield and neutron-averaged temperatures,

but still do not reproduce burn profiles and DD/DHe3 yield ratio. This motivated a

detailed simulation study of intermediate-Kn exploding pushers. We will show how

simulation results depend on models for laser-interaction, electron conductivity (flux-

limited local vs nonlocal), viscosity (physical vs artificial), preheating and ion mixing.

Work partially supported by Sapienza projects RM11615502006B04 (2016) and

C26A15YTMA (2015)

Reference

[1] M. J. Rosenberg et al., Phys. Rev. Lett. 112, 014022 (2014)

[2] M. J. Rosenberg et al., Phys. Plasmas 22, 062702 (2015).



Internal Capsule Defects Quenching Thermonuclear Ignition

in ICF

Masakatsu Murakami

Institute of Laser Engineering, Osaka University

Hydrodynamic instabilities such as the Rayleigh-Taylor (RT) instability may amplify

perturbations on the capsule, and finally mix the cold main fuel and the capsule material

into the hot spark, thereby quenching thermonuclear ignition in inertial confinement fusion

targets. Surface roughness is generally considered as a primary source of the hydrodynamic

instabilities, but internal capsule defects can also seed perturbations on the surface, being

amplified by the instabilities. It is found by analyzing mode spectra of these defects that

the perturbation amplitudes are well above the canonical surface roughness specification.

Our mixing calculation for high gain targets suggests that the internal capsule defects in

the present level are large enough to quench the thermonuclear ignition. It appears that in

order to achieve ignition and burn one should adopt a technique such as density matched

emulsion method that is free from the internal defects.



Electron and ion fast ignition: Present status and perspectives

Javier Honrubia

Polytenchnic University of Madrid



Kinetic effect of plasma interaction in ICF hohlraum

Shan Lianqiang,Cai Hongbo, Gu Yuqiu

Laser Fusion Research Center;Institute of Applied Physics and Computational Mathematics;Laser

Fusion Research Center


In indirect-driven ICF, the interaction between Au plasma and ablator target

plasma/gas filled plasma cannot be well described by the traditional single-hydrodynamic

code. The collisionless electrostatic shock-wave (CES) is expected to be driven in the

plasma interface. In experiment, we use DD neutron to represents the kinetic effect for

the first time. The information of DD neutron yield and spectrum broadening indicates

that the main mechanism for neutron production is beam-target reaction, which is

consistent with the CES physics. The ratio of reflected D-ion energy by the CES to total

laser energy is about 1%, which is important for the hohlraum energetics and the

symmetry of implosion compression.

Keywords: Kinetic effect, hohlraum



Liquid Scintillator Neutron Detection System and Transient

Dosimeter

Hongjie Liu



Scintillator detectors in inertial confinement fusion experiments are predominantly

used to measure neutron yield and ion temperature of the primary fusion reactions. The

detection of neutrons in fast-ignition experiments is very challenging since it requires the

neutron detection system to recover within 100 ns from a high background orders of

magnitude stronger than the signal of interest. Liquid scintillator with different

compositions was investigated. We present several designs of liquid scintillator using the

Geant4 Code and the X-Lab Code. Our liquid scintillator is based on PPO, dissolved in

xylene and enriched with molecular O2. The detector consists of a 2-3 liters volume of

liquid scintillator coupled to a gated MCP. A small air bubble allows for thermal expansion

of the liquid without a significant pressure increase. The gating performance under high-

intensityγrays was experimentally checked. The typical flight time spectrum of the

neutrons from (p,n) reaction driven a PW laser was obtained. The neutron yield in the fast

ignition experiments on Shenguang-II laser facility was successfully measured using this

detector. In fast ignition experiments, a PW laser beam was employed to produce high

intense electron beams to ignite the compressed fuel. Our neutron detection system could

suppress the background signal and eliminate the afterglow present in conventional plastic

scintillators.

Keywords: liquid scintillator, Neutron, Transient Dosimeter

Satellite workshop on Advanced

Diagnostics Technique for HEDP


Satellite workshop on Advanced Diagnostics Technique for HEDP

Physics of shock ignition and approach to ICF

Dimitri Batani

Univeristy of Bordeaux, CELIA, France



Hollow atom spectroscopy to study radiation dominated

matter

Sergey A. Pikuz

Joint Institute for High Temperature, Russia



Atomic processes and spectroscopy modeling of plasmas

Hyun-Kyung Chung

Gwangju Institute of Science and Technology, Korea



Measurement of the Radiation Flux from the Capsule within a

Cylindrical Hohlraum at the SGIII-prototype Facility

Xufei Xie



Direct measurement of the radiation flux from the capsule is of great interest in

indirect dirve inertial confinement fusion, as it is closely related to the radiation intensity

irradiated on the capsule, which is found to be lower than the expected value from

numerical calculations. Therefore, a novel technique, namely space-resolving flux

detection, is developed for the absolute measurement of the time-dependent radiation flux

from the capsule. In the experiment established at the SG-III prototype laser facility, the

space-resolving flux detector (SRFD) is placed at the upper pole of the target chamber,

aiming at the capsule in a downward direction. The capsule is located at the center of a

cylindrical hohlraum, and it is a hollow glass ball doped with aluminum on the surface,

while the thickness of the aluminum is about 30 um. The spatial coverage of the SRFD at

the capsule area is about 400 um, which is similar with the diameter of the capsule, and

the accuracy of the aiming is about 20 um. As the view field of the SRFD is quite limited

and smaller than the diameter of the laser entrance hole (LEH), only the radiation flux

from the capsule and the filling plasma along the sight of view could be collected by the

detector, while the radiation flux from the capsule includes the re-emitted flux and the

one generated during the compression of the capsule. Two-dimensional LARED

simulation indicates that the radiation flux from the filling plasma along the sight of view

is less than 5%, and the simulated intensity of the radiation flux is generally consitent

with the measured data.

Keywords: radiation flux, space-resolving flux detection, cylindrical hohlraum



Ion temperature measurements in polar and equator directions

at the SG-III laser facility

Zhongjing Chen



Two neutron time-of-flight (nToF) detectors have been employed to measure the

neutron time-of-flight spectrum in two different directions, i.e., equator and polar, at

Shengguang-III (SG-III) laser facility. The contribution of scattered neutrons has been

calculated with the Monte Carlo code JMCT for each nToF detector. The results show

that the scattered neutron spectrum is dominated by neutrons scattered on materials in the

experiment hall, including the vacuum chamber. The shape of scattered neutron spectrum

depends on the view line, which has been observed with nToF detectors located in the

experiment hall of the SG-III laser facility. A new method based on the convolution of a

Gaussian and the calculated neutron time-of-flight spectrum has been developed for the

ion temperature determination. The calculated scattered neutron spectrum can fit the

measured result very well. The ion temperatures determined with three methods have

been compared and good agreement has been achieved. No obvious ion temperature

anisotropy has been observed at the SG-III laser facility.

Keywords: ICF, ion temperature, scattered neutron, anisotropy

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