A variational approach to parametric instabilities in inhomogeneous plasmas II: Stimulated Raman scattering

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872505· OSTI ID:544840

Afeyan, B B ^[1]; Williams, E A ^[2]

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1. University of California, Davis---Livermore, Livermore, California 94550 (United States)
2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The theory of temporally unstable modes or bound states associated with stimulated Raman scattering in inhomogeneous plasmas is recast in the form of a variational principle for the pump strength or intensity of the incident laser. This Minimum Pump Strength{endash}Variational Principle (MPS{endash}VP) formalism allows the unification of disparate results on growth rates, frequency shifts, and threshold conditions, which in the past relied on specific and restrictive assumptions on the density profile, scattering geometry, temperature, and damping rates. The variational approach leads to generalizations of these results in a uniform manner. Various levels of sophistication in the choice of trial and dual functions are explored. Simplifications and short cuts that will be used throughout this series of papers are tested here, and their regions of validity explored. The principle new result of some practical interest is the growth rate of Raman sidescattering occurring anywhere at the peak or on the flanks of a parabolic density profile such as can be found in an exploding foil experiment. This new calculation includes any density at or below quarter-critical, at any temperature, and at low or high damping rate limits.

• OSTI ID: 544840
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 4; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
INHOMOGENEOUS PLASMA
PARAMETRIC INSTABILITIES
PLASMA DENSITY
RAMAN EFFECT
VARIATIONAL METHODS