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arXiv physics/0603209physics.plasm-phphysics.comp-ph
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等离子体Laser背散射中的电子声波物理问题

Aspects of Electron Acoustic Wave Physics in Laser Backscatter from Plasmas

N. J. Sircombe, T. D. Arber, R. O. Dendy

摘要:

最近的实验结果从三叉戟激光器确认的重要性,在确定高强度的激光反射率的动力学效应。观察到的例子包括从低频电子声波(EAWs)的散射,并通过朗缪尔衰变不稳定性的湍流级联的前几个阶段。在这方面的解释和预测计算能力是由弗拉索夫代码的发展,它提供了高速度的空间分辨率在粒子相空间的高能区域,并不需要分析的基本方程的预处理协助。一个直接的弗拉索夫求解器,能够解决这些动力学过程,在这里使用的电子声波的存在和稳定性,连同其集体散射特性的基本方面。这些模拟扩展到现实的激光和等离子体参数特性的单热点实验。结果与实验显示受激拉曼和受激电子声散射定性一致。模拟的EAWs的振幅大于实验观察到的,并伴随着较高的相速度。这些微小的差异可以归因于一维无碰撞模型的局限性。

英文摘要:

Recent experimental results from the Trident laser confirm the importance of kinetic effects in determining laser reflectivities at high intensities. Examples observed include scattering from low frequency electron acoustic waves (EAWs), and the first few stages of a cascade towards turbulence through the Langmuir decay instability. Interpretive and predictive computational capability in this area is assisted by the development of Vlasov codes, which offer high velocity space resolution in high energy regions of particle phase space, and do not require analytical pre-processing of the fundamental equations. A direct Vlasov solver, capable of resolving these kinetic processes, is used here to address fundamental aspects of the existence and stability of the electron acoustic wave, together with its collective scattering properties. These simulations are extended to realistic laser and plasma parameters characteristic of single hot-spot experiments. Results are in qualitative agreement with experiments displaying both stimulated Raman and stimulated electron acoustic scattering. The amplitude of simulated EAWs is greater than that observed experimentally, and is accompanied by a higher phase velocity. These minor differences can be attributed to the limitations of a one-dimensional collisionless model.

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