Formation of phase space holes and clumps.
Formation of phase space holes and clumps.
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DOI：
10.1103/physrevlett.112.155002
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发表时间：
2014-04
影响因子：
8.6
通讯作者：
M. Lilley;R. Nyqvist
中科院分区：
文献类型：
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作者：
M. Lilley;R. Nyqvist
研究表明，动力学驱动、耗散系统中相空间空穴和团簇的形成并不局限于之前报道和广泛认为的近阈值状态。具体而言，我们观察到从未调制的相空间平台的边缘产生的空穴团，通过激发，相混合和随后的耗散衰减的线性不稳定的体等离子体模式中的静电碰撞尾部模型。这使我们能够首次阐明空穴团形成过程的基本物理学。空穴和团块从负能量波发展而来，负能量波是由于平台和几乎未受扰动的环境分布之间的界面处的急剧梯度而产生的，并且在体等离子体中存在耗散时不稳定。我们证实了这一点，通过证明这种非线性结构的形成一般不依赖于“种子”波，只有在系统的能力，以产生一个平台。此外，我们观察到重复周期的高原生成和侵蚀，后者由于孔丛的形成和脱离，这似乎是不敏感的初始条件，可以持续很长一段时间。我们提出了一个直观的讨论，为什么这种持续的再生发生。
It is shown that the formation of phase space holes and clumps in kinetically driven, dissipative systems is not restricted to the near threshold regime, as previously reported and widely believed. Specifically, we observe hole-clump generation from the edges of an unmodulated phase space plateau, created via excitation, phase mixing and subsequent dissipative decay of a linearly unstable bulk plasma mode in the electrostatic bump-on-tail model. This has now allowed us to elucidate the underlying physics of the hole-clump formation process for the first time. Holes and clumps develop from negative energy waves that arise due to the sharp gradients at the interface between the plateau and the nearly unperturbed, ambient distribution and destabilize in the presence of dissipation in the bulk plasma. We confirm this picture by demonstrating that the formation of such nonlinear structures in general does not rely on a "seed" wave, only on the ability of the system to generate a plateau. In addition, we observe repetitive cycles of plateau generation and erosion, the latter due to hole-clump formation and detachment, which appear to be insensitive to initial conditions and can persist for a long time. We present an intuitive discussion of why this continual regeneration occurs.