nif and indirect drive inertial fusion target physics and...
TRANSCRIPT
JDL FESAC IFE 10/28-29/03
NIF and Indirect Drive Inertial Fusion Target Physics and
Applications to High Energy Density Physics
*Work performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48
John Lindl LLNL Fusion Energy Program LeaderSenior Scientist NIF Programs
Lawrence LivermoreNational Laboratory
University of California
Presented to:
FESAC Panel on the Status of IFE and HED
October 28-29,2003
JDL FESAC IFE 10/28-29/03
Summary/Outline
NIF Early Light (NEL) is meeting its performance goals and experiments have begun with the first 4 beams
The ICF Program is making excellent progress on the baselineindirect drive ignition approach
Alternate indirect drive ignition target designs could allow muchhigher yields and target gains
The NIF indirect drive ignition program will provide the ignitiondata required for a range of drivers including HIF and Z-pinches
NIF is designed to test Direct Drive as well as Indirect Drive
The science of ICF targets is applicable to a wide range ofastrophysical phenomena
JDL FESAC IFE 10/28-29/03
NIF will test much of the physics for a widerange of targets being examined for IFE
Heavy Ion Hybrid Target NIF Indirect DriveTarget
Double-ended Z-pinch
Heavy Ion DistributedRadiator Target
Heavy Ion Driver Laser Driver Z-Pinch Driver
Ignitor laserbeam
Fast IgnitionDirect Drive Target
JDL FESAC IFE 10/28-29/03
• Demonstrate ignition and gain for both direct and indirect-drive and
possibly for fast ignition
• Provide key data on target chamber and target fabrication technologies
• Confirm predictive target modeling capabilities
The National Ignition Facility gives the U.S. a uniqueopportunity for demonstrating critical elements ofICF target physics required for IFE
JDL FESAC IFE 10/28-29/03
Both indirect drive and direct drive illuminationgeometries can be accommodated by the NIF design
Irradiation configurations
Indirect drive
Direct drive
(Advanced technology for compact chirped pulse amplification (CPA) beingpursued to allow fast ignition on NIF)
JDL FESAC IFE 10/28-29/03
NIF Target Chamber upper hemisphere
JDL FESAC IFE 10/28-29/03
First four NIF beams installed on the target chamber
View from inside the targetchamber
Quad 31b beamtubes and optics areinstalled and operational
JDL FESAC IFE 10/28-29/03
Target positioner and alignment system insidetarget chamber
JDL FESAC IFE 10/28-29/03
NIF has begun to commission its experimentalsystems
The NIF Early Light (NEL) commissioning of four laser beams hasdemonstrated all of NIF’s primary performance criteria on a per beambasis
— 21 kJ of 1ωωωω light (Full NIF Equivalent = 4.0 Mjoule )
— 11 kJ of 2ωωωω light (Full NIF Equivalent - 2.2 Mjoule) - used baseline3ωωωω crystals not optimized for 2ωωωω
— 10.4 kJ of 2ωωωω light (Full NIF Equivalent = 2.0 MJoule
— 25 ns shaped pulse
— < 5 hour shot cycle (UK funded)
— Better the 6% beam contrast
— Better than 2% energy balance
— Beam relative timing to 6 ps
Initial Experiments on Laser Plasma Interaction are being carried out
JDL FESAC IFE 10/28-29/03
NIF will map out ignition and gain curves formultiple target concepts
— Fast ignition potentially gives more gain and lower thresholdenergy but the science and technology is less well developed
FI at NIF
T ρ
Conventional ICF
Intensity ~1014 - 1015 w/cm2
Fast�injection�of heat
T
r
ρ
Fast Ignitor
Intensity ~1020 w/cm2
Indirect Drive
AdvancedIndirect
Drive on NIF
JDL FESAC IFE 10/28-29/03
The US Indirect Drive ICF Program is based on anextensive data base developed on the Nova andOmega Lasers
• Laser-Target Coupling: U.V. lasers with smoothing gives excellenttarget coupling on Nova and Omega experiments - comprehensivepredictive modeling has not been achieved
• Symmetry: X-ray Drive experiments (Nova and Omega) show adequatesymmetry Pn(t) and ∫Pn(t)dt
• Hydrodynamic Instabilities: Quantitative Rayleigh-Taylor experimentsshow adequate reduction in γ because of flow and ∇ρ effects
• Integral Implosions: Implosions on the Omega laser, using a NIF-likeIllumination geometry, perform at near calculated levels forconvergences greater than 20
• Numerical Modeling: Hohlraum (symmetry and energetics) andhydrodynamic instability experiments, as well as integral implosionexperiments are well-modeled by 2D and 3D radiation-hydro codes
JDL FESAC IFE 10/28-29/03
The NIF baseline indirect-drive target absorbs1.35 MJ and produces a yield of 15 MJ, indetailed calculations
JDL FESAC IFE 10/28-29/03
Development of cryogenic targets are acentral challenge for ignition on NIF
08-00-1299-2932.ppt12JDK
Cooling ring
Heater ring
5.5 mm
Heat-flow �coupler
HOHLRAUM
Cryostat
Cooling ring
2-mm capsule�beryllium or �polymer
Solid D-T �fuel layer��
1-µm polyimide�window
• Sufficiently smooth Deuterium-Tritium fuel layers have been formed
• We have fabricated three types ofcapsules
• Surface finishes meetingrequirements have been achieved(for CH and PI and for gradeddopant Be)
• Development of cryogenichohlraums is underway
• Scientific prototyping of thecryogenic systems has started
JDL FESAC IFE 10/28-29/03
HYDRA now hasall the physicsnecessary to do3D non-LTEintegratedhohlraumsimulations, aswell as 3Dcapsuleimplosions
3D hohlraum simulation withall of the beams, in NIFindirect drive configuration
We are doing 3D simulations of bothhohlraums and capsules
JDL FESAC IFE 10/28-29/03
Several design modifications resulted from 3Dcalculations:
•Increased LEH thickness
•Decreased gas fill density
•Adjusted power balance between cones
•Repointed inner cone beams to reduce m=4
•Moved outer cone to reduce P4
Resulting implosion hasrms deformation of hot spotat bang time 3 µm, factor oftwo safety margin
We now have a hohlraum design optimized in3D with very nice 3D symmetry
JDL FESAC IFE 10/28-29/03
Capsule-onlysimulations w/asymmetry andfabrication perturbations
A few of these havebeen done, including arecent simulation with:
•3D asymmetry inferredfrom integratedsimulation
•Nominal “at spec”perturbations on ice andablator in low,intermediate, and highmodes
•Gave 21 MJ (90% of 1Dcalculation)
Ignition time140 ps beforeignition time
400 g/cc density isosurface (different scale)
60 g/cc density isosurface
Poly/DTinterface
Hohlraumaxis
Stagnationshock
Polyimide Capsule 3D calculations have bothasymmetry and surface roughness
JDL FESAC IFE 10/28-29/03
Be next to fuelis undoped,dopant rises tomax in twosteps andback downagain
0.35%0.7%
0.35%
848928
1105 µm
934940 995
1011
0.0%
Cu(%)
300 eV design:
200
Initial ablator roughness(rms, nm)
0
5
10
15
20
25
Yield(MJ)
Polyimidecapsule
Surfaceachieved with PI
400 600 8000
300 eV graded-dopedBe(Cu) design, at same
scale
New capsule designs using Be with graded Cudopant are spectacularly robust
Be
DT
0.0%
JDL FESAC IFE 10/28-29/03
Typical energy flow in an igniting ICFhohlraum/capsule
JDL FESAC IFE 10/28-29/03
0
10
20
30 NIF PointDesign
11%
22-26%seems possible
Improvements possible for a 250 eV capsule design
A combination of many small effects may allow adoubling of the hohlraum coupling efficiency
JDL FESAC IFE 10/28-29/03
More energy allows largercapsules which require lowerradiation temperatures
Lower temperatures implylower laser intensitiesconsistent with LPIconstraints based on currentunderstanding and initialOmega experiments
NIF’s green light capability may allow muchlarger capsules and yields
JDL FESAC IFE 10/28-29/03
Target Fabrication•Capsules•Cryo layering in hohlraums
Target Design
Diag. techniq.,initial tuning
96 beam tests,2-cone tuning Final
symmetrytuning
Integrated 96beam tests
Optimize Tr
Diag.techniques
Implosion Diagnostics
Shock timing
Ablator tests Final shocktiming
Ignition campaign
Sub-scale& full scalenon-cryo implosions
Firstcluster
& 8-fold2-cones Full NIF
40-00-0997-1989S23BVW/cld
40-00-0997-1989H23RHS/cld 40-00-0997-1989P
23BVW/cld
Beams: 4 48 120 192
Ignition
Large Plasma Experimentswith beam smoothing
Symmetry measurement & controlHigh Convergence Implosions
Shock Timing diag. developmentAblator characterization
Omega
Optimize beam smoothing
Symmetry
IgnitionImplosions
Shock Physics
10 11 120907FY02 03 04 05 06 08
Cooling ring
Cryogenic fuel layer
Capsule ablatorHeater ring
Heat-flow coupler
He + H2 fill
Heat-flow coupler
HOHLRAUM
Cryostat
Cooling ring
13
Trad diagnostic techniquesHohlraumEnergetics
Firstquad
MP-1a
The indirect drive Ignition Plan makes use of existingfacilities, and early NIF, to optimize the ignition design
JDL FESAC IFE 10/28-29/03
The physics issues for ion beam target design forIFE and NIF targets have much in common
• Capsule physics (hydrodynamics, ignition, and burn propagation)
• Symmetry control
• Hohlraum energetics
Yield = 400 MJDriver (using NIF-like hohlraum to capsule radius ratio)
6 MJ of 4 GeV Pb ions ���� gain 677.5 MJ of 8 GeV Pb ions ���� gain 53
Capsuleablator
Cryogenicfuel layer
Heat-flowcoupler
Heaterring
Coolingring
Heat-flowcoupler
Cooling ring
Laser beams
Fe-foam radiator
Gaussian ion beamsFoot pulse beams (3 GeV)Main pulse beams (4 GeV)Au foam
Radiation case
Au foam radiatorCapsule(Be ablator)
He-gas fill
2.7-mm “effectivebeam radius
NIF target HIF Target
JDL FESAC IFE 10/28-29/03
New symmetry control techniques allow targetdesigns with larger spots for distributed radiatortargets for heavy ion fusion
Shine shields tocontrol Legendre
mode P2
Shim tocontrol early
time P4
Pressure balanceholds position of
radiators
Beam spot: 3.8 mm x 5.4 mmEffective radius: 4.5 mm6.7 MJ beam energyGain = 58
(NIF-like baseline symmetry control)Beam spot: 1.8 mm x 4.1 mmEffective radius: 2.7 mm5.9 MJ beam energyGain = 68
These symmetry control techniques can be testedon Z or Omega and ultimately on NIF
Distributed radiator targetHybrid target
JDL FESAC IFE 10/28-29/03
Z double-pinchhohlraum
3.3 mm
4.5 mm
4.7 mm
Capsulediameter: 2.15 mm
Secondary hohlraumRadius ≡≡≡≡ RsecLength ≡≡≡≡ Lsec
P4 vs. length and capsule size6.7 keV backlit images
Time-integrated P4 depends more strongly on capsule size than on hohlraum length
Predicted P2 = 0, P4 = - 5% at Lsec / Rsec = 1.75 to be tested in September shot series
Thin-shell capsules in double z-pinch hohlraumsprovide null cases for P4 shimming tests
JDL FESAC IFE 10/28-29/03
Density contours
Calculations of the proposed Z experiment showthat a shim can take out the P4 asymmetry
JDL FESAC IFE 10/28-29/03
Shape of the imploded shell near ignition time
Calculations of the HIF Hybrid Target with ashim layer show the improvement in symmetry
JDL FESAC IFE 10/28-29/03
A wide range of capsules for Fusion Energyapplications have stability and symmetryrequirements comparable to NIF targets
• The target size appropriate for the first average fusionpower facility in the IFE development plan
Scale
Peak TR
IFAR
Convergence Ratio
Energy Absorbed (kJ)
Yield (MJ)
ETF
246
46
37
631
171
Reactor (6Hz)
223
42
36
1128
381
Reactor (3Hz)
203
35
40
1841
830
• Enhanced NIF capsulesmay reach this scale
NIF
300
45
36
150
15
JDL FESAC IFE 10/28-29/03
The NRL target for KrF driven IFE uses wetted foamdirect drive targets with zooming and a picket pulse
JDL FESAC IFE 10/28-29/03
Wetted foam and “All DT” Direct Drive target designsare being explored for NIF
JDL FESAC IFE 10/28-29/03
With appropriate beam pointing it may be possibleto achieve Direct Drive Ignition on NIF with the
Indirect Drive beam configuration
JDL FESAC IFE 10/28-29/03
ICF scientific issues are relevant to high energydensity phenomena in Astrophysics
JDL FESAC IFE 10/28-29/03
A wide variety of astrophysics phenomena can beinvestigated with experiments on intense lasers
JDL FESAC IFE 10/28-29/03
Summary/Outline
NIF Early Light (NEL) is meeting its performance goals and experiments have begun with the first 4 beams
The ICF Program is making excellent progress on the baselineindirect drive ignition approach
Alternate indirect drive ignition target designs could allow muchhigher yields and target gains
The NIF indirect drive ignition program will provide the ignitiondata required for a range of drivers including HIF and Z-pinches
NIF is designed to test Direct Drive as well as Indirect Drive
The science of ICF targets is applicable to a wide range ofastrophysical phenomena
JDL FESAC IFE 10/28-29/03
Backup Viewgraphs
JDL FESAC IFE 10/28-29/03
Why do we believe that ignition will work on NIF?
• Numerical simulations provide a first principles description of x-ray targetperformance (except for laser-plasma interactions which are expected to besmall for scaled NIF plasma conditions and beam smoothing
• Predictions for NIF target gain have not changed qualitatively since 1990,despite 13 years/15,000 experiments on Nova, Omega and Nike to comparewith codes
• The Halite/Centurion experiments using nuclear explosives havedemonstrated excellent performance, putting to rest fundamental questionsabout basic feasibility to achieve high gain
Halite/Centurion
NIF igniton
Nova, Omega
Energy
Power
JDL FESAC IFE 10/28-29/03
The goal of the target design work is toidentify the optimal targets for a broadspectrum of possible approaches to IFE
Target Requirement HED Scientific Issue Power Plant Impact
Power/Energy
Pulse shaping/pulse length
Beam geometry
Target Material(hohlraum/capsule)
Target Precision
Spot size/Intensity
Drive TemperatureSymmetryStability
Fuel adiabat/EOS
Symmetry/RadiationTransport
Wall albedo …Coupling Efficiency
Capsule Stability
Hydrodynamic InstabilitySymmetry
Drive TemperatureStability
Transport/Focusing
Driver Beam QualityDriver Cost
Driver Beam Conditioning
Chamber DesignWall Protection Approach
ES&HManufacturing
Manufacturing
Optics and ChamberDesign
JDL FESAC IFE 10/28-29/03
Ion target
Ionbeams
Radiationconverter
Direct drive
Ablator (low-Z foam or solid)
Gaseous fuel (atvapor pressureof solid or liquid fuel)
Solid or liquid fuel
Indirect drive
Advantage:• High coupling efficiency• Reduced Laser Plasma
Interaction effects
Advantages:• Relaxed beam uniformity• Reduced hydrodynamic instability• Significant commonality for lasers and ion beams
The principal approaches to ICF utilize direct driveor indirect drive implosions to compress the fuel
Laser target
Laser beams
Low-Z gasHohlraum
JDL FESAC IFE 10/28-29/03
January 1977 January 2002
2D LASNEX and 2D/3D HYDRAInclude Arbitrary Lagrange Eulerian grid motion, material interface reconstruction,multigroup diffusion and realistic radiation transport, charged particle diffusion, laser raytrace, Lee and More conductivities,XSNQ and online opacity servers, QEOS,EOS tables - SESAME, LEOS…•Basis interface, Yorick postprocessing•MPI parallel with threads - both have run onover 1600 processors
HYDRA 104 MFLOPS / processor on IBMWhite x 640 processors (8% of machine)67 GFLOPS (x 16750)
2D LASNEXLaser raytrace, multigroup diffusion, suprathermal electrons, MHD, charged particle diffusion, ionspecies diffusion, XSNQ, EOS tables
LASNEX 4 MFLOPS on CDC 7600
•Direct simulations of multimode surfaceperturbation growth 2D/3D, to 16.8 million zones•First full 3D simulations of NIF ignition hohlraumran 1 week, 1 million zones, 4.8 million photons•Full 3D capsule simulation of drive asymmetry4.4 million zones
•Capsule instability analysis: 1D sim. postprocessed with Artic, or 2D single mode •First 2D hohlraum simulations with capsule ~1500 zones, ran for weeks
Aggressive use of advanced computation hasbeen a hallmark of the ICF Program
JDL FESAC IFE 10/28-29/03
Lasnex is a highly versatile computer code with awide range of physical models for processesimportant to ICF
Laser light:~3D ray tracing~1D EM wave
Electrons:~Thermal conduction (FD&FE)~Non-local conduction~Multigroup diffusion
Radiation (multigroup):~Frequency dependent sources~Diffusion (FD&FE)~Transport eqn.
Atomic physics (LTE&NLTE):~Average atom (XSN)~SCA~DCA~Tabulated opacity (LTE)~Tabulated EOS (LTE)~Inline LTE EOS
Hydrodynmics (2D):~Langrangian (quads)~Semi-Eulerian (SALE)~Slide lines
Ions:~Thermal condution
Burn products (n, γγγγ, CP):~TN reaction source~Multigroup diffusion
JDL FESAC IFE 10/28-29/03
With Nova, the ICF program brought together advancesin laser performance, precision diagnostics, andadvanced modeling tools required for ICF to become amature quantitative scientific effort
— Nova was a 10 beam laser capable of producing 40 kJ of laserenergy at 0.351 µµµµm
JDL FESAC IFE 10/28-29/03
Key results from the Nova program establishedthe specifications for NIF
• Hohlraums can achieveadequate symmetry and 10-25%coupling with multiple cones ofbeams
• Precise pulse shaping can beachieved as required for Fermidegenerate compression
• Hohlraums with pulse shapingare limited to ~300 eV with0.35 µµµµm lasers (I ~2x1015 w/cm2)
• Hydrodynamic instabilities limitshell to R/∆∆∆∆R ~35
200
100
10
1
0.2
Capsule energy gain plotted versus compression
Compression (X liquid density)102 103 104 105
Th
erm
on
ucl
ear
ener
gy
Cap
sule
ab
sorb
ed e
ner
gy
500
50
5
0.5
Capsule energy (KJ)for 15% implosion
efficiencyNIFIncreasing Pressure and
stability requirements
JDL FESAC IFE 10/28-29/03
Advanced diagnostics have been central to measuringthe phenomena critical to understanding NIF
1.6 ns
1.9 ns
2.2 ns
2.5 ns
time
time
Sequence of x-ray backlitimages of imploding capsuleGated MCP x-ray imager
Pinholes MCP +film pack
Gatingelectronics
1 m
MCP gated imagers were operated between 100 eVand 10 keV with 5-50 µm, 30 -300 ps resolution
300µm
JDL FESAC IFE 10/28-29/03
— Unequal absorption between conescan spoil beam balance
— Beam bending, beam spray and crossbeam effects can spoil symmetry
— Backscatter reduces laserabsorption and energycoupled into the capsule
The choice of laser wavelength is central tothe ICF Indirect Drive Ignition Program
JDL FESAC IFE 10/28-29/03
• There is a wavelengthdependent maximumhohlraum temperaturedetermined by laser-plasma interaction -shown by lines labeled2ωωωω and 3ωωωω
• There is a minimum TRthat is dictated bykeeping hydrodynamicinstabilities undercontrol. The reddashed linecorresponds to thosetemperatures neededfor a surfaceroughness of ~200Å
The ICF ignition region in power and energy isbased on constraints for LPI and hydrodynamicinstabilities
JDL FESAC IFE 10/28-29/03
NIF’s 2w capability may provide an operatingwindow for larger capsules with yields muchgreater than the baseline
JDL FESAC IFE 10/28-29/03
• 2ωωωω looks very appealing in Lasnex designs• Preliminary experiments are encouraging
There is a well established physics basis forignition at 3w and experiments are beginningto address critical ignition requirements for 2w
JDL FESAC IFE 10/28-29/03
The Nova ignition physics program utilizedhohlraums and capsules which were scaled totest key issues
Capsules— hydrodynamic instability— implosion symmetry— pulse shaping— implosion dynamics
— hohlraum plasma condition— laser-plasma interaction— hohlraum drive— x-ray wall loss— x-ray flux symmetry
4
6
9
4
6
8 7
2740 µm
1400 µm
700 µm700 µm
700 µm
72 1
1
10 105
39
3-µm-thick-tungsten hohlraumTen-beam irradiationLaser energy ~18 kJ (total)Wavelength = 0.35 µmPulse length = 1 ns (FWHM)
JDL FESAC IFE 10/28-29/03
We have validated our ability to model laserheated hohlraum drive against a broad rangeof experiments
Lasnex can predict hohlraum drive to +/- 10% in x-ray flux
Vacuum and gas-filled hohlraums with 2.2ns shaped pulses
(3:1 and 5:1 contrast ratio)
Scaling of peak drive temperatureDetailed TR
4 comparisonfrom a scale 0.75 hohlraum
1000
800
600
400
200
0-0.5 0.5 1 1.5 2 2.5 3 3.50
300
250
200
150150 200 250 300
Experimental peak Tr (eV)
Las
nex
pea
k T
r (e
V)
time(ns)F
lus[
GW
/sr]
Laser off
JDL FESAC IFE 10/28-29/03
Implosion symmetry can be controlled by varying thehohlraum geometry
JDL FESAC IFE 10/28-29/03
Face-on: StreakedModelData
Side-on: Streaked
Side-on: Gated
08-00-0593-1818B
The measured growth of planar hydrodynamic instabilitiesin ICF is in quantitative agreement with numerical models
JDL FESAC IFE 10/28-29/03
Using a NIF-like Illuminaition Geometry on Omega,Implosion performance is in excellent agreement with
calculations
JDL FESAC IFE 10/28-29/03
The target/driver combination for IFE must meet aminimum product of driver efficiency times gain (ηηηηG)
P P P P faGME
net gross driver gross= − = − −( )1 1ηη
ME ~ 40% where M is the blanket multiplication and E is the thermal toelectric conversion efficiency
ηη
ηη
ηη
G
G
> −
⇒
⇒
7 10 (recirculating power fraction of 25 - 35%)
< 10% > 70 - 100
< 35% G > 20 - 30
Laser
HI
A safety margin of a factor of 2 in target gain is important for making a casethat we can strongly defend
•
•
•
⇒ G > 140
G > 40
Laser
HI
JDL FESAC IFE 10/28-29/03
Distributed radiator:"Baseline" target Close-coupled target:
High gain at low driver energy
CH capsule design:Easier target fab
Fast ignitor target:High gain with low
accelerator peak power
Ignitorbeam
Hybrid target:Large beam spot
Large-angle distributed radiator:Large beam entrance angle
We look at a broad range of target options tomaximize flexibility
JDL FESAC IFE 10/28-29/03
Small spot sizes have high leverage to increasetarget gain and reduce driver energy
Ion beam characteristics:4 GeV Pb+ions
5.9 MJ input energy2.7 mm effective radius spotGain 70
Ion beam characteristics:3.5 GeV Pb+ions
3.3 MJ input energy1.7 mm effective radius spotGain 130
JDL FESAC IFE 10/28-29/03
Callahan 6/2002
Need to balance low order Legendre modes:
- Source behind a shine shield and radiation flows around shield near zero of P2- Case-to-capsule ratio with or without a shim to correct P4
HI distributed radiator
NIF laser (2x scale)
Double-ended Z-pinch
HI hybrid target
- Sources at zeros of P4 and with strengths set to balance P2
Symmetry in indirect drive is controlled by theposition and strength of the sources
JDL FESAC IFE 10/28-29/03
Concept for Z-pinch driven ICF target
Z-Beamlet radiograph
Z-Beamlet target
Z-Beamlet Laser
The LLNL Beamlet laser - NIF’s scientific prototype - is now operationalas a diagnostic backlighter source on Z at Sandia Albuquerque
• The intense x-ray backlighting available from Beamlet has imaged z-pinch implosionswith a resolution not previously available on Z
Substantial progress has been made on thesymmetry of z-pinch driven indirect drive targets
JDL FESAC IFE 10/28-29/03
Substantial progress has been made on the symmetryof double z-pinch driven indirect drive targets
Z830
Z831
Z839
Z833
Time
Radius
Peak density ~40 g/ccCR >14
G. Bennett, M. Cuneo, R. Vesey
68-75 eV peak drive~10 kJ absorbed
Radius vs. time
Z-Beamlet target
Z-pinchWirearrays
JDL FESAC IFE 10/28-29/03
Backlit Implosions on Z measure capsule convergenceand implosion symmetry
JDL FESAC IFE 10/28-29/03
Ignition will be pursued either by heating some ofthe fuel during compression or by rapid injectionof energy into a precompressed cold fuel volume
• Central hot spot ignition relies on precise control of implosion symmetryand hydrodynamic instability
• Fast ignition would utilize new concepts in short pulse laser technologyand will require significant advances in the understanding of chargedparticle production and transport at ultra-high intensity
T ρ
Shock heated central spot ignitesa high-density cold shell
PHS ≈ Pc = ααααρρρρc5/3
Conventional ICF
Fastinjection
T
r
ρ
Fast-e- heated side spot ignitesa lower density, larger uniform
fuel ball PHS >> Pc
Fast Ignitor
Fastinjectionof heat(I~1020
w/cm2)(~10pspulse)
(I~1015 w/cm2)(1-10 ns pulse)
JDL FESAC IFE 10/28-29/03
Fast ignition can utilize a re-entrant tube andcone to provide access for the ignitor beamto the imploded, compressed core:
Main laserbeams
Ignitor beam(s)(short pulse)
capsule(cryogenic)
hohlraum
A NIF-like scheme
Flexibility for compressiondriver: Lasers, ion beamsz-pinch (Tabak 1991)
Potential compatibility withliquid wall chamber
JDL FESAC IFE 10/28-29/03
Experiments on Gekko XII have seen enhancedneutron output from fast heating of a directdrive target with a reentrant cone
Fast heating scalable to laser fusion ignition R. Kodama, et al., Nature 418, 923 (August 2002)
2.5 KJ compression pulse + (60-500), 0.5 ps fast heating pulse
Neu
tro
n e
nh
ance
men
t (a
.u.)
Neu
tro
n s
ign
al (
a.u
.)
10
0
5
200
100
0-200 -100 0 100 200
Ave
rag
e d
enity
(m
l-1)
0.5
02.25 2.35 2.45 2.55 2.65
1.0
Neu
tro
n y
ield
Heating laser power (PW)
Energy (MeV)Injection timing (ps)
10.1104
106
108
JDL FESAC IFE 10/28-29/03
• Same driver and fuel assembly options
•Larger laser focal spot-easier to produce
• Simpler proton energy transport by ballistic focussing
Imploded Fuel
Laser Protons
• Novel physics of Debye sheath proton acceleration
M. Roth et.al. Phys Rev. Lett 86,436 (2000). Ruhl et al. Plas. Phys. Rep.27,363,(2001)
Temporal, et al.Phys Plasmas 9, 3102, 2002
Proton ignition is a newer concept avoiding thecomplexity of electron energy transport
JDL FESAC IFE 10/28-29/03
-400 -200 0 200 400 600
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Distance (microns)
Tim
e (
ns
)
480 500 520 540 560 580 600
071802#4 Hemisphere
-400 -200 0 200 400 600
-0.40
-0.30
-0.20
-0.10
-0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Distance (microns)
Tim
e (
ns
)
480 490 500 510 520
071802#5 flat foil
Recent 100TW,100fs expt. shows first evidence of ballisticproton focusing (to 50 µµµµm) and enhanced isochoric heating
-400 -200 0 200 400 600
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Distance (microns)
Tim
e (
ns
)
470 490 510 530 550COUNT_0719_1727___x
50 µµµµm200µµµµm >400µµµµm
Streak images of Planckian emission
JDL FESAC IFE 10/28-29/03
JDL FESAC IFE 10/28-29/03
We have compared ignition and burn propagation for NIFcapsules and possible future high yield capsules
High yield capsule
NIF capsule
Radiation temperature = 300 eV 210 eVImplosion velocity = 4 x 107 cm/sec 3 x 107 cm/secCapsule absorbed energy = 0.15 MJ 2.0 MJCapsule yield ~ 15 MJ ~ 1000 MJ
CH + 0.25% Br + 5%O
DT solid (0.2 mg)
DT gas 0.3 mg/cc
1.11 mm
0.95
0.87
3.25mm
3.0
2.75
Be
DT solid(7.2 mg)
DT gas0.3 mg/cm3
JDL FESAC IFE 10/28-29/03
Although NIF will not directly test full scale targets forIFE, NIF and high-yield capsules have almost identicalignition conditions and burn propagation physics
Burn propagationProfiles at ignition
0.2-MJ NIF capsule(yield ~15-20 MJ)
0.2-MJ capsule(yield ~1000 MJ)
0.2-MJ NIF capsule(yield =15-20 MJ)
0.2-MJ capsule(yield ~1000 MJ)
Ignition is defined as thethreshold of burn propagation
Burn s sustained by αααα-particledeposition above ignition threshold
ρρρρr (g/cm2) ρρρρr (g/cm2)
Ti (
keV
)
Ion
tem
per
atu
re (
keV
)12
8
4
0.2 0.4 0.6 0.8 1.0
103
102
101
100
10-1
0 1 2 3
ρρρρ
JDL FESAC IFE 10/28-29/03
15. Fireball of Gamma-ray Bursts16. Cosmological Jets (Rel.)17. Weibel Instability in GRB18. Non-LTE QED at AGN Core
Laser-produced Relativistic Plasmas
13. Vishiniac Instability of SNRs14. X-ray Lasers in the Universe
9. Atomic Process in SNRs10. Stellar Jets11. Radiation Hydro. in Early Galaxy12. Photo-ionized Plasmas
8. Opacity Evolution of Stars etc. many
Atomic Physics and X-ray Transport
6. Hydro-instability in Neutrino- driven SN Explosion7. RT Instability of Eagle Nebula
5. RT Instability of SN Explosion
Hydrodynamic Instabilities
4. Collision-less Shocks and Particle Acceleration (Origin of Cosmic Rays)
3. Interaction of Molecular Cloud with Strong Shock by SNR (Morphology)
2.EOSGiant Planets
Hydrodynamics and Shocks
1. Non-local Transport of Neutrinos ina Baby Neutron Star
Electron Energy
Transport
C. ResemblanceB. SimilarityA. Sameness
A wide range of Laboratory and Astrophysical phenomenacan be characterized by their degree of correspondence
JDL FESAC IFE 10/28-29/03
The Rayleigh-Taylor instability occurs when aheavy fluid (ρρρρH) “sits on top of” a light fluid (ρρρρL)
ρρρρH
ρρρρH
ρρρρH
ρρρρL
ρρρρL
ρρρρL
y
y
y
V
g
g
g
x
x
x
r ηηηηb
ηηηηb
“On elephant-trunk structures in the region ofO associations”
…and in astrophysical situationssuch as expanding nebula
A similar situation occursin ICF implosions
v
Frieman, Ap. J. 120, 18 (1954)
Initial conditionηηηη = ηηηηo cos(kx)
Initial conditionηηηη = ηηηηoe(kg)1/2 t
Nonlinear regimeηηηη = 0000....3333((((gλλλλ))))1/2t
JDL FESAC IFE 10/28-29/03
Observations from SN1987A suggest strongmixing of the radioactive core into the envelope
JDL FESAC IFE 10/28-29/03
Initial experiments relevant to the hydrodynamicsof core collapse supernovas were done on Nova
JDL FESAC IFE 10/28-29/03
More “Star-like” instability experiments have beendeveloped on the Omega laser
Three-layer experiment
Cylindrical experiment
Spherical Experiment
More “star-like”
3-layers
Divergent geometry
— Cylindrical
— Spherical
JDL FESAC IFE 10/28-29/03
Image of Tyco SNR by ChandraX-ray Satellite(2001)
Laser Produced Blast Wave in Xe Gas(Courtesy B. Ripin, NRL, 1991)
Astrophysical and Laboratory turbulent blast wavesshow many similar features
JDL FESAC IFE 10/28-29/03
An example Cepheid variable is seen in M100
JDL FESAC IFE 10/28-29/03
Cepheid variables are the most accurate distanceindicators, and establish Ho in the nearby universe
• Opacities are an essential ingredient to understanding Cepheid variables
JDL FESAC IFE 10/28-29/03
Cepheid variables are stars whose intrinsicbrightness varies periodically with time
JDL FESAC IFE 10/28-29/03
Cepheid variables are stars whose intrinsicbrightness varies periodically with time
Each Bump causes a dκ/dTwhich can lead to pulsation
The “beat Cepheids” are verysensitive to the opacity of FE
P1/P0
P0 (days)1 3 5 7
0.70
0.74
The “opacity problem” wassolved through expeirments onthe Nova and Luli lasers