This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 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

350MJ-Class HAPL Baseline Target DT gas DT fuel 2.295mm DT + 100mg/cc CH foam KrF (0.248  m), DPSSL (3  ) I=I 0 cos 2  60beams 800A Au/Pd 5  m CH 2.114mm 1.780mm Time 0.25P max prepulse zoom ns 57:1 foot 425TW 350TW zoom-2 Power KrF DPSSL (3  ) at Same Peak Power DPSSL (3  ) at Same Peak I. 2 Peak Power (TW) Peak I. 2 (Wcm -2  m 2 ) ~1e141.9e14~1e14 E_laser (MJ)2.46 (3.05 un-zoomed) Yield (MJ) Gain148 (121 un-zoomed) /3r 0 ~31, CRs~33, V max ~2.9e7cm/s,  abl 2/3r 0,  fuel max KE /

Target Gain Curves * KrF: a=90.6, b=0.138 DPSSL at 3  : a=67.8, b=0.210 Nominal Gain Curves * G~a(E-b)  (0.25  m) 3  (0.35  m) Driver energy (MJ) ~350MJ yield Target gain Gain Curve for Fixed Baseline Target Design Target gain Baseline design point Over-driven (ignites before fully assembled) Gain increasing (ignition delayed) Velocity insufficent to create hotspot Driver energy (MJ)

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

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

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

HAPL - High Average Power Laser Program: Point-of-Departure Reactor Design Conventional Direct Drive - 4Pi illumination - Gain - Drywall chamber from The Economic Future of Nuclear Power, University of Chicago report to US DOE, August A.Erlandson, W.Meier (LLNL) Cost of Electricity ( ｢ / kWh) Coal Gas Fission low est. high est. +$100/ton C tax goal COE (¢/kWh)* 3.0MJ 6Hz 2.4MJ 10Hz 1.5MJ 20Hz

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

2-Sided Direct Drive* - 2-sided illumination - Gain - Liquid wall chamber Can Advanced Targets Lead to Smaller, Less Complex Reactor Configurations? * Preliminary configuration Conventional Direct Drive - 4Pi illumination - Gain - Drywall chamber

Shock Ignition: Decouple the Compression from 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 Power Time Conventional hotspot drive must do double duty: Fuel assembly and high velocity(~3.5e7cm/s) for ignition Spike lauches late-time shock to reach fuel at stagnation  ignition Drive pulse assembles fuel at low velocity (~2e7cm/s)  no ignition Decouple Compression and Ignition 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

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

Shock e7 180 High Gain NIF / Reactor Target 1.64mm Shock e7 100 High Stability NIF Target 1.35mm ( to scale ) DT gas DT fuel DT/CH abl. Shock e7 8 Low Energy NIF Target 0.7mm Time Laser power CANDIDATE NIF SHOCK IGNITION TARGETS (≥2012) Energy Hotspot Ignition Type 34 IFAR 3.4e7 Velocity (cm/s) 10 Yield (MJ) NIF Indirect- Drive Target Time Laser power NIF HOTSPOT IGNITION TARGET (~2010) Be/Cu abl. DT fuel DT gas 1.0mm Hohlrau m

Shock Ignition for HAPL: High Gain at Low Drive Energy Conventional HAPL Target Low Energy NIF Target High Stability NIF Target High Gain Reactor Targets Ignition Type Conv. hotspotShock Yield (MJ) Velocity (cm/s) 3.5e72.5e71.8e7~2e7 IFAR ~ mm 1.5+mm ( to scale ) 0.7mm Time Laser power 2.3mm Time Laser power DT fuel DT/CH abl. DT gas

Advanced Targets: Critical R&D Issues Direct DriveFast Ignition2-SidedOthers… Scoping Studies Basic concepts Variants √√√√ √x√x √x√x √x√x 1-D Calcs Basic 1D Design optimization Hot e, channeling… Gain curves √ NA IP √ x IP x xxxxxxxx √xxx√xxx 2-D Calcs Single mode Symmetry, beam bal. Multi-mode 2D gain curves √ IP x √ IP x xxxxxxxx xxxxxxxx 3-D Calcsxxxx Advanced targets

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

HAPL Direct Drive Target : Draft Laser/Target Specs – Nov ‘05 Energy on target (MJ) ~ MJ dependent on wavelength (2-4  ) Pulse lengths (ns) Total~25; time at peak power ~5; picket~0.35; rise/fall times between pedistals ns Power (W)~4.25e14(peak), 7.5e12(foot), 1.0e14(picket)Contrast ratio~57 Intensity (W/cm 2 )1.5e15(peak, ~1e15 (av. over peak power) Beam parameters 60 ports; Cosine-squared dist; focus at 2r0 at t=0 ; two zooms Pulse shock precision: time/power ± 0.05ns (± 0.3ns  -7% in gain); ± 3% (± 10%  -7% in gain) Beam-beam power bal8% in 0.5ns Quad-quad power bal4% in 0.5ns (indep quads) Individual beam non-uniformity3% in 0.5ns (all modes) Bandwidth/smoothing/RMS imprint 1THz(3  ) / 2D SSD / 50nm Polarization smoothing 2x50  rad (needed?) Overall uniformity; low modes (beam-beam variation; pointing, power-bal.....) dI/I=1.5% (for CR=29,  r h /r H ≤1/3) Overall uniformity; high modes l= (from individual beam structures) <0.5% RMS for t smooth =0.5ns (indiv beam uniform. ~3%) Laser alignment /target tracking ± 20  m rel to target center Capsule outer CH surface finish<50nm * Inner ice layer uniformity/ roughness ± 5  m (± 20  m  -7% in gain); <0.5  m for l ≥ 10 * Sources: J.Perkins HAPL w/shop presentations UCLA (June 2004), PPPL (Oct 2004); D.Eimeral “Configuring the NIF for Direct Drive” UCRL-ID LLNL (1995); R.McCrory “NIF Direct-Drive Ignition Plan” plus briefing VGs (April 1999); LLE Reviews 98 p67, 79 p121, S.Skupsky(LLE) pvte comm. (May 2005) * NIF indirect drive specs: 12nm (CH), 33nm (Be/Cu), 0.5  m (inner ice l>10) /