Measurements of laser-plasma instability relevant to ignition hohlraums
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- Physics International, San Leandro, California 94577 (United States)
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
The potential for laser-plasma instability is a serious concern for indirect-drive inertial confinement fusion (ICF), where laser beams illuminate the interior of a cavity (called a hohlraum) to produce x-rays for imploding a fusion capsule symmetrically. The speckled nature of laser beams used in ICF is an important factor in laser-plasma instability processes. For example, models which calculate the spatial growth of convective instability by properly accounting for the laser speckles successfully predict the observed onsets of backscattering due to stimulated Brillouin and Raman scattering instabilities (SBS and SRS). Assuming pump depletion as the only saturation mechanism in these models results in very large predicted levels of SBS and SRS backscattering from the long-scale plasmas expected in ignition hohlraums. However, in the long-scale plasmas studied in the Nova and Trident lasers [E. M. Campbell, Rev. Sci. Instrum. {bold 57}, 2101 (1986) and N. K. Moncur {ital et al.}, Appl. Opt. {bold 34}, 4274 (1995)], SRS and SBS are observed to saturate much below the levels expected from pump depletion. While the mechanism of SBS saturation is not understood at present, the observations of SRS saturation are qualitatively understood. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 560635
- Report Number(s):
- CONF-961102-; ISSN 1070-664X; TRN: 98:000733
- Journal Information:
- Physics of Plasmas, Vol. 4, Issue 5; Conference: Meeting of the Division of Plasma Physics of the American Physical Society, Denver, CO (United States), 11-15 Nov 1996; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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