Nonlinear saturation of stimulated Raman scattering in laser hot spots
- Lodestar Research Corporation, 2400 Central Avenue, P-5, Boulder, Colorado 80301 (United States)
- Los Alamos National Laboratory, Theoretical Division, MS-B213, Los Alamos, New Mexico 87545 (United States)
Two-dimensional simulation studies are reported of the nonlinear development of stimulated Raman scattering (SRS) from a compact laser hot spot using a reduced model, which includes saturation by pump depletion, Langmuir wave decay cascades, Langmuir wave collapse, and ponderomotive density profile modification. The needle-like intensity distribution in a speckle arising from a random phase plate processed laser beam promotes backscatter SRS. The dependence of the saturated reflectivity and (the comparable in magnitude) absorptivity, on ion acoustic wave and Langmuir wave damping, laser power, electron density, and temperature is studied. There are regimes in which the ponderomotive potential (as well as the Ohmic dissipation) of the induced Langmuir turbulence exceeds that of the localized laser pump. The results support the conclusion that the Langmuir wave Landau damping must be determined by an electron velocity distribution modified by quasilinear and Ohmic heating to account for SRS observed at low densities and high temperatures. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 335598
- Journal Information:
- Physics of Plasmas, Vol. 6, Issue 4; Other Information: PBD: Apr 1999
- Country of Publication:
- United States
- Language:
- English
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