Absolute Instability of Stimulated Raman Scattering in Finite Length Plasma

Mao Syun Wong^1*, Shih Hung Chen¹

¹Physics, National Central University, Chungli, Tauyuan, Taiwan

* Presenter:Mao Syun Wong, email:minioperate@gmail.com

The finite-length effect of Stimulated Raman Scattering(SRS) was investigated via both analytical theory and numerical simulation. An analytical dispersion relation to the absolute instability in a finite-length plasma system has been derived using two-scale-length expansion. The scaling of the linear growth rate of the scattered wave with the interaction length and the pump wave intensity has been examined and demonstrated. The three-wave simulation has been developed for studying the nonlinear behaviors of SRS, and the stability map obtained by the three-wave simulation reveals the non-oscillation zone, stationary oscillation zone, and non-stationary-oscillation zone of SRS. The depletion of pump power plays a crucial role in SRS, which results in the contraction of the field profile of the scattered wave. The start oscillation and the stationary oscillation can be achieved while the finite system reaches the energy balance condition. The theoretical results show good agreement with the simulation which is based on three-wave interactions. The Vlasov simulation code has also been developed for studying the kinetic effects in SRS, such as Landau damping and wave breaking in the finite-length system.
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Keywords: stimulated Raman scattering, finite length system, simulation, two-scale-length expansion