Instability Increments of Stimulated Mandelshtam–Brillouin Scattering in a Bounded Region with Allowance for Collisions

The problem of Mandelstam–Brillouin scattering in the region bounded in the direction of pump wave propagation and infinite in the transverse direction is considered. Such situations can arise, for example, in plasma heating or diagnostic problems. Since the time of scattered radiation escape for the examined geometry upon scattering at a certain angle increases substantially, this effect compensates for a decrease in the nonlinear feedback coefficient upon oblique scattering and leads to instability development. Since the convective losses at scattering angles close to π/2 are small, collisional absorption of waves plays an important role in this case. The instability increments are calculated taking into account not only the convective losses, but also the collisional wave attenuation.