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Review of the Department of Energy's Inertial Confinement Fusion Program The National Ignition Facility (1997) / Chapter Skim
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3 Scientific Readiness
Pages 15-20

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From page 15...
... An experimental campaign toward meeting the HEP 5 milestone, involving reconfigured NOVA and OMEGA lasers, is in progress and would increase confidence in reaching ignition with the NIF. In the committee's judgment the additional technical 1 Steps taken by the DOE toward construction and operation of the NIP are called Critical Decisions (formerly Key Decisions)
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From page 16...
... bending, CR=20 bending, CR=7-15 CR=10 HLP-5 Stimulated scattering L= 3-4 mm,f/8, L=2-3 mm, L= 1 mm, L= 1 mm, in long-scale-length scattering <10% scattering <10-20% scattering = 2-10% scattering = 10-15% plasmas at 1 -2 x 10'5 W/cm3 Te=3~4 keV, n/nC= 0.07 to 0.25 HLP-6 Filamentation Small Small No evidence Evidence of forward spraying HLP-7 X-ray conversion 70% 70% 70% 70% HEP-1 Capsule hydra: 700-1200 g/cm3 170-270 g/cm3 170-270 g/cm3 pusher, 140-170 g/cm3 pusher, increased pusher pusher, 45-75 g/cm3 pusher, 20-30 g/cm3 20-30 g/cm3 fuel, 11 20-30 g/cm3 fuel, 8 density, fuel density, fuel, 40-60 contrast fuel, 11 contrast contrast ratio; CR=24 contrast ratio; CR=24 with pulse-shaping ratio, CR=25-35 ratio; CR=24 contrast ratio; convergence ratio HEP-2 Reduced growth of G=6-7 acceleration to G=4-5 to breakup G=4-5 to breakup and Extended results to planar Rayleigh- breakup and 6-7 and 4-5 to mix 4-5 to mix multimode Taylor instabilities deceleration to mix HEP-3 Mix of fuel and pusher G=6-7 defines surface G=4-5 to breakup G=4-5 to breakup and G=4-5 to breakup and due to surface finish requirement and 4-5 to mix 4-5 to mix 4-5 to mix perturbations HEP-4 Low convergence with growth factors and surface mode spectrum of NIF CR=20 and G=6-7 CR=7-15 and G=4-5 CR=7-15 and G=4-5 CR=7-15 and G=4-5 HEP-5 High convergence CR=25-35 CR up to 20, limited CR=10 CR=10 with growth factors by number of NOVA and surface mode beams spectrum of NIF NOTE: CR = convergence ratio; G = e-foldings of growth; L = plasma scale length, nc = electron density at which laser light will no longer propagate. confidence that might be gained by completion of this milestone is not sufficient to justify delaying the NIF program.
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From page 17...
... , the effect is qualitatively understood and is consistent with the high transverse flow velocity of the hohiraum plasma near the laser entrance hole. The shift can be compensated by optics on the NIF and/or by laser beam smoothing using random phase plates (RPPs)
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From page 18...
... Other computer codes are routinely used now to model propagation of laser beams through the system and to compute critical properties such as opacities and other aspects of complex TCF-related physics. Despite the significant simulation capabilities now available, the ICE program would benefit from improved, more comprehensive simulations of ignition and burn.
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From page 19...
... In addition, in ~990 there were far fewer experimental data and a more rudimentary modeling capability for the NIF targets than now exist. Developing an integrated modeling capability with full radiation transport, developing the experimental and diagnostic techniques required to quantitatively evaluate target performance, and developing a variety of capsule materials along with demonstrating smooth cryogenic layers, have all represented significant challenges to the NOVA team, the national ICE program, and the NIF project.
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From page 20...
... The likelihood of ignition and burn propagation through direct drive has increased significantly since 1990 owing to better understanding of both laser-beam imprinting and the growth of hydrodynamic instabilities. By an optimal choice of port locations for indirect drive, the direct-drive geometric requirements can be met by moving one-half of the NIF beams to 24 new beam ports that have been added to the chamber.
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Key Terms

  • contrast ratio
  • time average
  • computer codes
  • hydrodynamic instabilities
  • target design

  • beam smoothing
  • target physics
  • lined hohlraums
  • time variation
  • nif design

  • critical decisions
  • imploding capsule
  • surface finish
  • increases confidence
  • laser entrance

  • underlying physics
  • burn propagation
  • capsule materials
  • significant challenges
  • laser beams

  • lined hohlraum
  • modeling capability
  • ignition facility
  • entrance hole
  • growth factors

  • laser energy
  • surface mode
  • ntc requirement
  • laser light
  • inertial confinement


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