非均匀等离子体中受激Raman散射非线性行为

鉴于实际中等离子体不均匀性和非周期性边界条件，建立了受激Ｒａｍａｎ散射（ＳＲＳ）和受激Ｂｒｉｌｌｏｕｒｉｎ散射（ＳＢＳ）非线性耦合模型。ＳＢＳ对ＳＲＳ的影响主要表现在两方面：１）Ｌａｎｇｍｕｉｒ波与离子声波的非线性相互作用，２）ＳＢＳ与ＳＲＳ的竞争。本文研究了离子声衰变不稳定性、离子声波对Ｌａｎｇｍｕｉｒ波的非共振散射两种非线性过程在ＳＲＳ发展过程中的作用，给出一维不均匀等离子体中ＳＲＳ发展图象。Ｌａｎｇｍｕｉｒ波向短波转换，从而被强烈阻尼是抑制ＳＲＳ的重要机制。文中给出了ＳＢＳ／ＳＲＳ耦合过程中决定ＳＲ关键词：

NONLINEAR BEHAVIOR OF STIMULATED RAMAN SCATTERING IN INHOMOGENEOUS PLASMA

Nonlinear behavior of stimulated Raman scattering (SRS) in inhomogeneous plasma is investigated numerically with aperiodic boundary conditions. The effects that modify SRS behavior with stimulated Brillouin scattering (SBS) and Langmuir driven ion fluctuation are 1) nonlinear coupling of Langmuir/ion acoustic wave and 2) energy competition between SRS and SBS. The various processes of the nonlinear coupling which may inhibit SRS are discussed and the SRS evolution features are illustrated in inhomogeneous 1D plasma. Langmuir wave conversion to more strongly damped waves appear to be important to suppress SRS. The γ_eff,R/γ_eff,B, the ratio of growth rates of SRS and SBS, and l_R/l_B, the ratio of growth lengths are presented as two important parameters to define the different paths of simutaneous SRS/SBS evolution. When γ_eff,R<γ_eff,B or l_R/l_B, SBS is potent to saturate even terminate SRS.