The conventional theory of convective stimulated Brillouin scattering (SBS) in inhomogeneous plasmas is generalized for arbitrary coupling and angle of incidence of the pump wave. Taking into account the SBS growth rate in a homogeneous plasma through the numerical solution of the dispersion relation, a general expression for the convective SBS gain coefficient G in the directly backward direction of the obliquely incident laser light with arbitrary coupling in an expanding and inhomogeneous laser plasma is derived. The expressions for G in the weak- and strong-coupling limits, which incorporate the corresponding analytical expressions for , are also obtained. It is observed from the numerical results that the values of and G under the condition of arbitrary coupling are significantly smaller than those in the weak- and strong-coupling limits for the pump wave intensities where is comparable to the ion-acoustic frequency . The results show the importance of the use of the generalized theory for adequate interpretation of SBS data of laser-plasma interaction experiments where .
Theory of the ordinary and extraordinary mode coupling in fluctuating plasmas