ABSTRACT

Various plasma waves and instabilities are abundantly present in the solar wind plasma, as evidenced by spacecraft observations. Among these, propagating modes and instabilities driven by temperature anisotropies are known to play a significant role in the solar wind dynamics. In situ measurements reveal that the threshold conditions for these instabilities adequately explain the solar wind conditions at large heliocentric distances. This paper pays attention to the combined effects of electron firehose instability driven by excessive parallel electron temperature anisotropy (T_⊥e < T_∥e) at high beta conditions, and electromagnetic ion cyclotron instability driven by excessive perpendicular proton temperature anisotropy (T_⊥i > T_∥i). By employing quasilinear kinetic theory based upon the assumption of bi-Maxwellian velocity distribution functions for protons and electrons, the dynamical evolution of the combined instabilities and their mutual interactions mediated by the particles is explored in depth. It is found that while in some cases, the two unstable modes are excited and saturated at distinct spatial and temporal scales, in other cases, the two unstable modes are intermingled such that a straightforward interpretation is not so easy. This shows that when the dynamics of protons and electrons are mutually coupled and when multiple unstable modes are excited in the system, the dynamical consequences can be quite complex.

中文翻译：

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电子流束和电磁离子回旋加速器的不稳定性：准线性方法

摘要

航天器的观测结果证明，太阳风等离子体中大量存在各种等离子体波和不稳定性。其中，由温度各向异性驱动的传播模式和不稳定性在太阳风动力学中起着重要作用。原位测量表明，这些不稳定性的阈值条件足以解释大日心距下的太阳风条件。本文注重过度并行电子温度各向异性驱动的电子流水不稳定的组合效果（Ť _{⊥ Ë} < Ť _{∥ ë}）在高贝塔的条件下，并且通过过度垂直质子温度各向异性（驱动电磁离子回旋不稳定Ť _⊥我> Ť _∥我）。通过基于质子和电子的双麦克斯韦速度分布函数假设的准线性动力学理论，深入研究了复合不稳定性及其由粒子介导的相互作用的动力学演化。发现在某些情况下，这两种不稳定模式在不同的时空尺度上被激发和饱和，而在其他情况下，这两种不稳定模式混合在一起，以致于简单的解释并不那么容易。这表明，当质子和电子的动力学相互耦合并且系统中激发了多个不稳定模式时，动力学后果可能非常复杂。