Laser imprint and implications for direct drive ignition with the National Ignition Facility
- and others
For direct drive ICF, nonuniformities in laser illumination can seed ripples at the ablation front in a process called imprint. Such nonuniformities will grow during the capsule implosion and can penetrate the capsule shell impede ignition, or degrade burn. We have simulated imprint for a number of experiments on tile Nova laser. Results are in generally good agreement with experimental data. We leave also simulated imprint upon National Ignition Facility (NIF) direct drive ignition capsules. Imprint modulation amplitude comparable to the intrinsic surface finish of {approximately}40 nm is predicted for a laser bandwidth of 0.5 THz. Ablation front modulations experience growth factors up to several thousand, carrying modulation well into the nonlinear regime. Saturation modeling predicts that the shell should remain intact at the time of peak velocity, but penetration at earlier times appears more marginal.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 379069
- Report Number(s):
- UCRL-JC-123315; CONF-9606229-9; ON: DE96013729; TRN: 96:025549
- Resource Relation:
- Conference: 24. European conference on laser interaction with matter, Madrid (Spain), 3-7 Jun 1996; Other Information: PBD: 9 Jul 1996
- Country of Publication:
- United States
- Language:
- English
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Simulations of laser imprint for Nova experiments and for ignition capsules
Simulations of laser imprint for Nova experiments and for ignition capsules