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A model for stimulated Raman scattering (SRS) in a homogeneous plasma has been designed to account for the presence of stimulated Brillouin scattering (SBS) and the nonlinear coupling between Langmuir and ion waves described by Zakharov equations. The nonlinear evolution of electron plasma waves also includes an effective damping resulting from electron diffusion in localized Langmuir fields produced during simultaneous SRS and SBS evolutions. Numerical results based on this model show two distinct SRS behaviors. Close to ncr/4 the Langmuir collapse dominates nonlinear evolution of the instability. At lower densities low level SRS is observed for a relatively long time after which SRS is terminated as a result of ion fluctuations produced by SBS. In addition, the anomalous absorption of backscattered SRS radiation by ion fluctuations produced by the collapse is proposed as a mechanism that may explain some recent experimental observations showing a gap in the SRS spectrum.

[1] This paper presents the model equations governing the mutual nonlinear interaction between two small but finite amplitude kinetic Alfven waves using two fluid models when the b of the plasma is less than unity (for high-b cases one has to use the Boltzmann equation). The source of nonlinearity is the nonlinear electron heating and ponderomotive force-driven nonlinear modification in the background density. The solutions of these model equations have been obtained by using analytical and numerical methods to study the effect of their mutual interaction on filament (hot spot) formation. It is concluded that the threshold field required for filament formation and their critical size is significantly affected by the mutual nonlinear interaction. Its effect on solar wind turbulence and coronal heating is also pointed out. Citation: Shukla, A., and R. P. Sharma, Mutual nonlinear interaction between two kinetic Alfven waves and its effect on filamentation: Application to solar wind and coronal heating,