Increase of the backward Raman reflectivity caused by the langmuir decay instability in an inhomogeneous plasma: the loss of gradient stabilization.
Increase of the backward Raman reflectivity caused by the langmuir decay instability in an inhomogeneous plasma: the loss of gradient stabilization.
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DOI：
10.1103/physrevlett.100.055006
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发表时间：
2008-02
影响因子：
8.6
通讯作者：
T. Fouquet;D. Pesme
中科院分区：
文献类型：
--
作者：
T. Fouquet;D. Pesme
本文研究了后向受激拉曼散射（BSRS）在非线性饱和机制为Langmuir衰减不稳定性的情况下的非线性演化过程。在非均匀等离子体的情况下，我们给出了在一维和二维空间维度上用流体型代码获得的数值结果。等离子体密度在四分之一临界下，线性依赖于纵向空间坐标，在该区域，振幅的Rosenbluth增益因子，表示为G(Ros)，在pi/2<或=G_(Ros)<或=6的范围内。我们观察到Langmuir衰减不稳定性能够抑制梯度稳定并恢复BSRS的绝对性质，从而导致BSRS反射率显著增加。
We investigate the nonlinear evolution of the backward stimulated Raman scattering (BSRS) in the regime where the nonlinear saturation mechanism is the Langmuir decay instability resulting from the coupling of the BSRS-generated Langmuir wave with the ion acoustic waves. We present numerical results obtained with a fluid-type code in one- and two-dimensional spatial dimensions, in the case of an inhomogeneous plasma. The plasma density is under quarter-critical and depends linearly on the longitudinal spatial coordinate, in the regime where the Rosenbluth gain factor for the amplitude, denoted as G(Ros), is in the range pi/2< or =G_(Ros)< or =6. We observe that the Langmuir decay instability is able to suppress the gradient stabilization and restore the absolute nature of BSRS, thus leading to a significantly increased BSRS reflectivity.