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HAPL Target Physics: (a) Stability of the Baseline (b) Future Target Options

HAPL Target Physics: (a) Stability of the Baseline (b) Future Target Options. L. J. Perkins, M. Tabak, C. Bibeau (LLNL) R. Betti, C. Zhou ( University of Rochester) High Average Power Laser Program Meeting Oak Ridge National Laboratory, November 8, 2006. KrF (0.248  m), DPSSL (3  )

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HAPL Target Physics: (a) Stability of the Baseline (b) Future Target Options

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  1. HAPL Target Physics: (a) Stability of the Baseline (b) Future Target Options L. J. Perkins, M. Tabak, C. Bibeau (LLNL) R. Betti, C. Zhou (University of Rochester) High Average Power Laser Program Meeting Oak Ridge National Laboratory, November 8, 2006

  2. KrF (0.248m), DPSSL (3) I=I0cos260beams 800A Au/Pd 5m CH zoom-2 Power zoom-1 DT + 100mg/cc CH foam 0.25Pmax prepulse 2.295mm 425TW 1.0 0.1 0.01 350TW 2.114mm DT fuel 1.780mm 57:1 foot DT gas Time 22.4ns 350MJ-Class HAPL Baseline Target IFARs @ 2/3r0~31, CRs~33, Vmax~2.9e7cm/s, abl~3.6 @ 2/3r0, fuel~1.21 @ max KE http://aries.ucsd.edu/HAPL/DOCS/

  3. Nominal Gain Curves * G~a(E-b)0.585 Gain Curve for Fixed Baseline Target Design Gain increasing (ignition delayed) Baseline design point 4w (0.25mm) 3w (0.35mm) Target gain Velocity insufficent to create hotspot Target gain ~350MJ yield Over-driven (ignites before fully assembled) Driver energy (MJ) Driver energy (MJ) Target Gain Curves * KrF: a=90.6, b=0.138 DPSSL at 3: a=67.8, b=0.210 http://aries.ucsd.edu/HAPL/DOCS/

  4. t=0 single  mode Laser Power Laser ablation front picket prepulse ablator Fuel/ablator interface fuel Fuel/gas interface gas Time @t = 0 @ late time Baseline target - picket Baseline target - no picket @ fuel/abl. interface mesh problems @ ablation front Mode No. l= 2r/ Mode No. l= 2r/ Stability: Single Mode 2D Growth Factors

  5. Perturbation amplitude at ablation front Laser power 10-9cm Time Time The Mode Shape Should be Preserved Fundamental Relative amplitude 2nd harmonic 3rd harmonic 4th harmonic 5th harmonic 6th harmonic Degrees Stability Progress: We Think We Know Why High Mode Numbers (short ) are Hard to Model

  6. Amplitude at ablation front (l=150) Fundamental (1st harmonic) Amplitude (cm) Amplitude (cm) Time (ns) Time (ns) 2nd harmonic 4th harmonic 3rd harmonic 5th harmonic 6th harmonic Amplitude (cm) Amplitude (cm) Time (ns) Time (ns) Stability Progress: Problem Seems to be Chevron Modes (4-5th harmonics) Driven by Zone-Popping Fourier Decomposition of Ablation Front Amplitude l=150, No Picket

  7. Conventional Direct Drive - 4Pi illumination - Gain ~125-150@2.5-3MJ - Drywall chamber 9 3.0MJ 6Hz 2.4MJ10Hz 1.5MJ20Hz 8 7 6 goal 5 Cost of Electricity (｢/ kWh) COE (¢/kWh)* 4 3 +$100/ton C tax 2 high est. low est. 1 • from The Economic Future of Nuclear Power, University of Chicago report to US DOE, August 2004 • + A.Erlandson, W.Meier (LLNL) 0 Coal Gas Fission HAPL - High Average Power Laser Program:Point-of-Departure Reactor Design

  8. Direct Drive Indirect Drive Polar Direct Drive Shock Ignition Fast Ignition Two-Sided Direct Drive FI ? Candidate Advanced Targets for Laser IFE

  9. Conventional Direct Drive - 4Pi illumination - Gain ~125-150@2.5-3MJ - Drywall chamber 2-Sided Direct Drive* - 2-sided illumination - Gain ~250@≤1MJ - Liquid wall chamber Can Advanced Targets Lead to Smaller, Less Complex Reactor Configurations? * Preliminary configuration

  10. Spike lauches late-time shock to reach fuel at stagnation  ignition Conventional hotspot drive must do double duty: Fuel assembly and high velocity(~3.5e7cm/s) for ignition Power Drive pulse assembles fuel at low velocity (~2e7cm/s)  no ignition Time • NIF indirect-drive port configuration • 3-4-times the energy in shell at max KE rel. to indirect-drive • Early-time picket for stability • Won’t work in indirect-drive anyway Polar Direct Drive on NIF Decouple Compression and Ignition • Same idea as fast-ignition, but time/spatial requirements less stringent and uses same laser • Target ignites and burns like a regular hot-spot target • Major issue is late-time LPI but may be more benign Shock Ignition:Decouple the Compression from Ignition

  11. The Value of HAPL Target Physics to DOE NIF/NNSA Programs Following Indirect-Drive Ignition, “Shock Ignited” Targets on NIF Offer the Potential for….  A high yield, reactor-relevant target ≤200MJ @ 1+MJ drive (1200MWth/500MWe if rep-rated at 6Hz*)  High yield targets for SSP applications See associated VGs for specifics  High gain targets at low drive energy Gain ~50 @ ~150kJ drive (10MJ-yield class)  Non-cryo, simple (single shell) high pressure gas targets Gain unity @ ~1MJ with central ignition * On a separate, rep-rated, high-average-fusion-power facility

  12. NIF HOTSPOT IGNITION TARGET (~2010) CANDIDATE NIF SHOCK IGNITION TARGETS (≥2012) Laser power Laser power Time 1.64mm Time 1.35mm DT/CH abl. 1.0mm Be/Cu abl. DT fuel DT fuel 0.7mm Hohlraum DT gas DT gas ( to scale ) NIF Indirect-Drive Target Low Energy NIF Target High Stability NIF Target High Gain NIF / Reactor Target Ignition Type Hotspot Shock Shock Shock Gain @ Energy 10 @1MJ 50 @0.16M 100 @1MJ 150 @1.2MJ Yield (MJ) 10 8 100 180 Velocity (cm/s) 3.4e7 2.5e7 1.8e7 2.3e7 IFAR 34 35 10 33

  13. 2.3mm DT/CH abl. Laser power DT fuel Time 1.5+mm DT gas Laser power 1.35mm 0.7mm Time Shock Ignition for HAPL: High Gain at Low Drive Energy ( to scale )

  14. Advanced targets Advanced Targets: Critical R&D Issues

  15. How do we Accommodate “Shock Ignited” Targets in the NIF Experimental Plan?  What limits NIF maximum power? B-integral in main amplifier, freq convertor…? ~600TW needed, 11/9 limits may be >700TW. But only need ≤ 1MJ  What front-end changes are required? Present risetimes >200ps; ~100-150ps needed; cost ≤$10M?  3 phase plates for polar direct drive? Spot sizes are ~3mm (level-3 milestone for definition in Sept ‘06)  SSD smoothing and bandwidth requirements? nb: smoothing not required for high intensity shock spike

  16. HAPL Direct Drive Target :Draft Laser/Target Specs – Nov ‘05 Sources: J.Perkins HAPL w/shop presentations UCLA (June 2004), PPPL (Oct 2004); D.Eimeral “Configuring the NIF for Direct Drive” UCRL-ID-120758 LLNL (1995); R.McCrory “NIF Direct-Drive Ignition Plan” plus briefing VGs (April 1999); LLE Reviews 98 p67, 79 p121, 84 181. S.Skupsky(LLE) pvte comm. (May 2005) * NIF indirect drive specs: 12nm (CH), 33nm (Be/Cu), 0.5mm (inner ice l>10) http://aries.ucsd.edu/HAPL/DOCS/

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