Absolute Stimulated Raman Scattering Instability in a Finite Collisional Plasma

摘要

The nonlinear saturation of the absolute stimulated Raman scattering (SRS) instability is considered in a finite homogeneous plasma. The amplitude of the incident wave exceeds the absolute instability threshold by the fractional amount delta (<<1). A single backscattered wave and a single plasma wave grow until time-asymptotic saturation occurs. The reflected light intensity is determined analytically and is proportional to delta . The spatial variation of the saturated wave amplitudes is also determined. The reflected intensity is compared to the values predicted for the convective instability, for the same incident intensity. In short plasmas, i.e., ones which extend over only a few convective gain lengths, the reflected intensity is much higher when the absolute instability threshold is exceeded. A reflection coefficient for the SRS instability is discussed for the case when both spatial and temporal effects are important. The paper consists of 15 viewgraphs. 2 refs. (ERA citation 11:015306)