Time-resolved measurements of secondary Langmuir waves produced by the Langmuir decay instability in a laser-produced plasma
Time-resolved measurements of secondary Langmuir waves produced by the Langmuir decay instability in a laser-produced plasma
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DOI：
10.1063/1.872692
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发表时间：
1998-06
影响因子：
2.2
通讯作者：
C. Labaune;H. Baldis;B. Bauer;V. Tikhonchuk;G. Laval
中科院分区：
文献类型：
--
作者：
C. Labaune;H. Baldis;B. Bauer;V. Tikhonchuk;G. Laval
本文介绍了由主朗缪尔波的参量衰变不稳定性产生的次级朗缪尔波的直接观测结果。测量已获得使用汤姆逊散射的短波长探测激光束，并解决了时间，空间，频率和波数。在预成型等离子体中，平滑激光束的受激拉曼散射（SRS）驱动了一次朗缪尔波。测量了与一次和二次朗缪尔波相关的密度涨落的振幅，结果表明朗缪尔衰变不稳定性（LDI）的阈值与拉曼不稳定性的阈值接近。这与理论预测一致。然而，与二次和主朗缪尔波相关的密度波动的振幅比不同意现有的理论SRS饱和由于LDI级联和/或强朗缪尔湍流在均匀等离子体。最后根据相互作用光束的光强分布特性给出了解释。
Direct observations of secondary Langmuir waves produced by the parametric decay instability of primary Langmuir waves are presented. The measurements have been obtained using Thomson scattering of a short-wavelength probe laser beam and are resolved in time, space, frequency, and wave number. The primary Langmuir waves were driven by stimulated Raman scattering (SRS) of a smoothed laser beam in a preformed plasma. Measurements of the amplitude of the density fluctuations associated with primary and secondary Langmuir waves show that the threshold of the Langmuir decay instability (LDI) is close to the threshold of the Raman instability. This is in agreement with theoretical predictions. However, the ratio of amplitudes of the density fluctuations associated with both secondary and primary Langmuir waves does not agree with existing theories of SRS saturation due to LDI cascading and/or strong Langmuir turbulence in homogeneous plasmas. An explanation based on the interaction beam intensity distribution p...