Simultaneous Brillouin and Raman scattering in CO2 laser-plasma interaction

The authors report on experimental and theoretical studies of stimulated Brillouin and Raman scattering occurring simultaneously in moderate density, long scale length plasma irradiated by a moderate intensity CO2 laser beam. Saturated Brillouin (20%) and Raman (0.7%) backscatter are observed, the former as a convective and the latter as an absolute instability. Importantly, it is found both experimentally and theoretically that the presence of ion fluctuations associated with the Brillouin process can profoundly affect the Raman instability. (Auth.)