Nonlinear effects in the theory of stimulated Brillouin scattering in a weakly collisional plasma

A relative increase in the thermal conductivity caused by low-intensity rad iation is shown to reduce the spatial amplification coefficient of the stim ulated Brillouin scattering (SBS). Because of the low intensity of the inci dent wave, the nonlinear dependence of the thermal conductivity on the fiel d has an insignificant impact on the threshold for the absolute SBS instabi lity. This nonlinear effect raises the threshold for double-SBS instability in an optically thin plasma slab.