Studies of stimulated Raman scattering in laser plasma interactions

Coupled theoretical and computational work is presented aimed at understanding and modeling stimulated Raman backscattering (SRBS) in large-scale, nearly homogeneous plasmas relevant to laser-plasma interactions (LPIs) in gas-filled hohlraums. In particular, we focus on experimental parameters and results from recent LPI studies of SRBS on the TRIDENT laser facility at the Los Alamos National Laboratory, where a preformed plasma was illuminated with a nearly diffraction-limited single hot spot (SHS) laser to simulate LPIs in a single speckle of a high intensity laser beam. With the aid of a new code for simulating and studying the nonlinear coupling in space-time of a large number of modes, and a Vlasov- Maxwell code for studying the evolution of large amplitude electron plasma waves, we report results and their interpretations to elucidate the following five observed, nonlinear phenomena associated with SRBS: coupling of SRBS to Langmuir decay interactions (LDIs); cascading of LDI; effect of ion-acoustic damping on SRBS; SRS cascades; and stimulated electron acoustic wave scattering. (author)