On the dominant and subdominant behavior of stimulated Raman and Brillouin scattering driven by nonuniform laser beams
On the dominant and subdominant behavior of stimulated Raman and Brillouin scattering driven by nonuniform laser beams
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DOI：
10.1063/1.873171
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发表时间：
1998-11
影响因子：
2.2
通讯作者：
R. Berger;C. Still;E. Williams;A. Langdon
中科院分区：
文献类型：
--
作者：
R. Berger;C. Still;E. Williams;A. Langdon
在许多实验中，已经观察到受激布里渊（SBS）或拉曼反向散射（SRS）比另一种更有力，尽管基于线性增益指数的预期是它们都应该反射大量的入射光。对非均匀入射激光驱动下这两种不稳定性的增长和饱和进行了多维流体模拟。在快时间尺度上，非线性饱和是通过朗缪尔湍流的基础研究所激发的反常阻尼而发生的[D。F. DuBois等人，公牛。41，1531（1996）]和声波湍流[B。I. Cohen等人，Phys.Plasmas 4，956（1997）]。在较长的时间尺度上，SRS和SBS受到准线性过程的限制，例如从光到等离子体的动量转移引起的流动和SBS中光能损失引起的离子温度增加。模拟结果表明，在强SRS反射条件下，SBS反射率降低。
In a number of experiments, stimulated Brillouin (SBS) or Raman backscattering (SRS) has been observed to be much more vigorous than the other although the expectations based on linear gain exponents are that they should both be reflecting large amounts of incident light. Multidimensional fluid simulations of the growth and saturation of these two instabilities driven by a nonuniform incident laser beam are presented. On the fast time scale, the nonlinear saturation occurs via an anomalous damping inspired by fundamental studies of Langmuir turbulence [D. F. DuBois et al., Bull. Am. Phys. Soc. 41, 1531 (1996)] and acoustic wave turbulence [B. I. Cohen et al., Phys. Plasmas 4, 956 (1997)]. Over a longer time scale, SRS and SBS are limited by quasilinear processes such as flows induced by the transfer of momentum from the light to the plasma and ion temperature increases caused by a loss of light energy in SBS. The simulations show a reduction of the SBS reflectivity under conditions of strong SRS reflectiv...