Transition from Thermally-Driven to Ponderomotively-Driven Stimulated Brillouin Scattering and Filamentation of Light in Plasma.

Berger, R. L. ; Valeo, E. J. ; Brunner, S.

Technical Information Center Oak Ridge Tennessee

关键词: Wave interaction;    Stimulated scattering;    Filamentation;    Generalized dispersion equation;    Laser-plasma interactions;   

RP-ID  :  DE2005838510

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The dispersion properties of ion acoustic waves and their nonlinear coupling to light waves through ponderomotive and thermal forces are sensitive to the strength of electron-ion collisions. Here, we consider the growth rate of stimulated Brillouin scattering (SBS) when the driven acoustic wave frequency and wavelength span the range of small to large compared to electron-ion collision frequency and mean free path respectively. We find in all cases the thermal contributions to the SBS growth rate are insignificant if the ion acoustic wave frequency is greater than the electron-ion collision frequency and the wavelength is much shorter than the electron-ion mean free path. On the other hand, the purely growing filamentation instability remains thermally driven for shorter wavelengths than SBS even when the growth rate is larger than the acoustic frequency.