Heavy Ion Fusion-a Future PerspectiveHeavy Ion Fusion-a Future Perspective E. Michael Campbell

PPPL, June 7, 2004

Presentation OutlinePresentation Outline

• Present Fusion landscape

• Why HIF

• Challenges

• Opportunities

• Path Forward

Fusion FactsFusion Facts

• No Administration commitment to rapid development of Fusion energy– Budget deficit is increasing problem (approaching % of GDP seen in late

1980’s) and no “cold war windfall”– War, Homeland security are priorities– Energy Priorities are “nearer term” solutions

• Hydrogen (Hydrogen already at ~11 Mtons/year and annual growth is ~10%)• Fission

– Viewed as Science Program with energy S&T deferred to “after Burning plasmas or Scientific feasibility” demonstrated

NGNP at INLNGNP at INL

Fusion Facts (cont’d)Fusion Facts (cont’d)

• ITER and not IFE initiative will be OFES focus for next decade – IFE not supported (“we can’t afford two approaches

today”) by DOE, OFES or OMB– OFES and OS view is ICF/IFE is NNSA

(NNSA$>>OS$) responsibility– OFES priority after ITER is to better exploit existing

facilities (present run time on 3 major OFES facilities is ~14 weeks)

– Some OS interest in High Energy Density Physics

ICF S&T advances, funding and controversy are made possible by its Multiple Missions: HIF lies in the Energy

and S&T plane

StockpileStewardship

National Security

Science/technology

Energy(National Security)

ICF

An IFE initiative should be catalyzed An IFE initiative should be catalyzed by Ignition and High Performance by Ignition and High Performance

Implosion ResultsImplosion Results • Ignition will catalyze IFE interest and may lead to

broad support for an IFE initiative– ICF/IFE community must maintain ignition focus on NIF

(~2010)

• Implosion Experiments will have an impact if successful – Cryogenic, low , DT Direct drive implosions on Omega

(~2006)– Integral Fast Ignition experiments on FIREXI and

Omega-EP (ZR and PW?)– Implosions on Z

And HIF………………………………….And HIF………………………………….

The Motivation for HIF has not The Motivation for HIF has not changedchanged

• HIF accelerators have attractive efficiency, rep-rate and durability for IFE– Large accelerator community experience that is relevant

• Focusing optics are more robust to fusion chamber environment (radiation/debris) than lasers

• < 4 illumination for targets allows for neutronically thick liquid walls

• NNSA indirect target physics program (and FI research (OFES & NNSA))

BUT…………………………BUT…………………………

HIF Development faces significant HIF Development faces significant challengeschallenges

• Development path is costly and has not been viewed as symbiotic with other ICF/IFE programs

• Little/no target experiments

• Advantages are “too far off” to motivate IFE support today

• Competition from HEDP facilities

What Would Marshall say?What Would Marshall say?

Innovation and a broad program approach Innovation and a broad program approach

will position HIF for a future IFE initiativewill position HIF for a future IFE initiative

• Accelerator– Increase modularity (reduce “unit size”)– Beam manipulations in space and time (like lasers!)

• Lasers :– temporal pulse shaping– CPA (extreme temporal compression -103-104)– Phase plates and deformable mirrors

• Pulse Power developing analogous capabilities– Develop “average power” experiments

• Target design and fabrication– Advanced simulations– Targets to compensate for driver limitations– Fast Ignition– Develop “average power experiments”

Innovation and a broad program approach Innovation and a broad program approach will position HIF for a future IFE initiativewill position HIF for a future IFE initiative

• Utilize existing facilities– Implosions to exploit HIF relevant concepts

• Symmetry control (Shims)• Low temperature ablators ( Be:Cu)

– Rad-Hydro with foams– Ions from short pulse lasers

• Ion-plasma interaction• Neutralization physics (?)• Source development required!

• Synergistic Engineering Physics and technology with Pulse Power– Neutronically thick liquid walls– Reactor concepts– Driver technology

There is time to innovate…………….There is time to innovate…………….

IFE requires:

•Drivers Z-R

OMEGA EP & Nike,Trident,..NIF

•Simulations

•Target S&T

3D rad.-hydro Simulation of igniting target

Double shelltarget

AcceleratorsAccelerators

Pulse Shaping for Pulse Shaping for Robust HIF Point Robust HIF Point Design (Indirect Drive) Design (Indirect Drive) 120 beams, 7MJ120 beams, 7MJ

Laser Pulse Shaping Laser Pulse Shaping (Direct Drive) ~60 (Direct Drive) ~60 beams ~2 MJbeams ~2 MJ

Improved HIF Beam Manipulations are required ! Improved HIF Beam Manipulations are required !

Innovations

Beam Production

Accel-decel injector + compression

Transport

Solenoid transport of large-perveance heavy-ion beams

Longitudinal Compression

Transverse Focusing

Neutralized drift compression

Plasma lens, Plasma channel pinch transport

(cm)

•Axial compression 120 X

•Radial compression to 1/e focal spot radius < 1 mm

•Beam intensity on target increases by 50,000 X.

R(c

m)

Ramped 220-390 keV K+ ion beam injected into a 1.4-m long plasma column.

Background plasma at 10 times beam density (not shown).

3.9T solenoid

LSP simulations of neutralized drift and focusing show significant spatial and temporal compression

Z(cm)

Experiments are essential to validate conceptExperiments are essential to validate concept!!

TargetsTargets

Graded Cu dopantIn Be shell

A small fill tube

IFE has benefited from Innovation in Drivers, Physics, and Target Fabrication: Target design and fabrication(graded Be:Cu ablators and fill tubes)

Increased Hydro stabilityIncreased Hydro stability

HIF can benefit from Innovation in Target Design and Fabrication: (Shims to control symmetry)

• Target design and Fabrication can compensate for Driver Limitations (3D Rad-Hydro Codes are required!!!)

Shims

•Experiments are underway at Z to validate conceptsExperiments are underway at Z to validate concepts

•Future Experiments on Omega and NIFFuture Experiments on Omega and NIF

HIFHIF ZZ

Fast Ignition Concepts for HIF and Z are similar

HIF FI Concept (120 ev HIF FI Concept (120 ev radiation Implosion)radiation Implosion)

Ignitor BeamIgnitor Beam

Pulse Power Pulse Power FI ConceptFI Concept

Final Shell Final Shell positionposition

Initial shell Initial shell PositionPosition

Polar Direct Drive on NIF is an example of non-spherical “initial conditions” that may lead to

ignition/gain imploded fuel assemblies)

Baseline Approach:

Move the Beams!

New Approach:

Re-point the Beams!

Multi-Dimensional Calculations and 192 beams make this possible!

Ions From UULIons From UUL

Protons and ions are accelerated in relativistic laser-solid interactions by three principal mechanisms

III. Target Normal Sheath Acceleration

Ei ~ 10 x Te

• Electrons penetrate target & form dense sheath on rear, non-

irradiated surface

• Strong electrostatic sheath field ionizes surface layer

(Eo ~ kT / ed ~ MV/m)

• Rapid (~ps) acceleration in expanding sheath produces very

laminar ion beam

II. Front-surface charge separation

Static limit: Ti ~ Te

- + - + - +- +- + - + - + - +

+ -+ -+ -+ -

II.III.

- - - - - - - - - - - - - - --CD2

I.

Incidentlaser

I. Thermal expansion

Ti ~ 5-10 x Te

Surface Layer (e.g., CaF2)

F7+ ion

Bulk Target(e.g., CD2)

e- D+ ion

Laser-Ion diodes have very interesting characteristics but Laser-Ion diodes have very interesting characteristics but need developmentneed development

0.0 20.0 40.0 60.0 80.0 100.0120.0107

108

109

1010

1011

F7+ heated F7+ unheated

Ions / MeV

Energy [MeV]

50 m W + 1 m CaF2 (900O C)

4% conversion of laser energy to F7+ ion beam observed !!

20 J, 350 fs1.054 m

•Transverse emittance: < 0.006 mm-mrad (

• Longitudinal emittance: < keV-ns (velocity correlated)

• Energy spread: 100%

• Bunch charge: 1011 – 1013 protons/ions

• Source diameter: ~50 m (fwhm)

• Charge state purity: >80% He-like

• Particle current: >100 kA (at source)

• Rep-rate: determined by laser driver

• Laser-ion efficiency: > 1% (4-20% observed

•Neutralization ~100%

Laser-ion diodesLaser-ion diodes

-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)

Time (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)

Time (ns)

480 490 500 510 520

071802#5 flat foil

PW IONs can be focusedPW IONs can be focused

-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)

Time (ns)

470 490 510 530 550COUNT_0719_1727___x

50 m200m >400m

Streak images of visible Planckian emission

Al has been heated to ~23 ev by a focused laser produced proton beam

0.00

0.05

0.10

0.15

0.20

0.25

-0.2 0 0.2 0.4 0.6 0.8

Counts/ps/um2

Time (ns)

Electron heating

Focused proton beam

Planar proton beam

P K Patel et al

Laser to Proton conversion efficiencies ~10% were observed at Nova PWNext generation of PW (2-3 kJ) may lead to ~100ev via ion heating

T ~23 ev (7 x 105 j/g)

(~0.2 joules from 10 joule laser)

Laser-Ion acceleration should be explored in conjunction with Heavy-ion Inertial Fusion program and Fast Ignitor

Proton-driven fast IgnitionRoth, Cowan, Key et al. PRL 86, 436 (2001)

Heavy-Ion Beam Driven Hohlraum

• High particle-current density neutral beam transport physics

• ballistic focusing (FI)• beam self-heating at focus (FI, HIF)

• High energy density beam-target interaction physics (FI & HIF)

• Isochoic heating to ~60 ev has been demonstrated•Beam Focusing has been demonstrated

• Novel Ion Sources for Induction Accelerators

ChambersChambers

HIF and Z pinch employ thick liquid walls HIF and Z pinch employ thick liquid walls enabled by < 4 enabled by < 4 target illumination target illumination

Flibe JetsFlibe Jets

Xray Xray driven driven targetstargets

Z pinch IFEZ pinch IFE HIFHIF

““Reactor Physics” collaboration should be key Reactor Physics” collaboration should be key element of Z and HIF IFE researchelement of Z and HIF IFE research

Multiple reactor chambers are a feature of Pulse Multiple reactor chambers are a feature of Pulse Power IFEPower IFE

Z-Pinch IFE DEMO study used 12 chambers,

Symbiosis with HIF?Symbiosis with HIF?

Innovation and a broad program approach Innovation and a broad program approach will position HIF for a future IFE initiativewill position HIF for a future IFE initiative

• Accelerators

• Target design and fabrication

• Exploit existing Facilities

• Partner with Pulse power for reactor design and Engineering

• Become Champion of “average power” experiments

Always keep sight of the end goal !Always keep sight of the end goal !