Ion hole formation and nonlinear generation of electromagnetic ion cyclotron waves: THEMIS observations
Ion hole formation and nonlinear generation of electromagnetic ion cyclotron waves: THEMIS observations
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DOI：
10.1002/2017gl074254
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发表时间：
2017-09-16
影响因子：
5.2
通讯作者：
Omura, Yoshiharu
中科院分区：
文献类型：
--
作者：
Shoji, Masafumi;Miyoshi, Yoshizumi;Omura, Yoshiharu
电磁等离子体波被认为是空间等离子体中带电粒子之间能量交换的原因。离子分布函数中发现的相空间空穴和等离子体波电场与离子速度的点积测量证明了这种能量交换过程。我们开发了一种识别离子空穴形成的方法，考虑了离子回旋运动和电磁离子回旋波之间的相位差。利用该方法，我们从亚暴（THEMIS）观测的事件时程和宏观尺度相互作用中识别出分布函数中的离子空穴和由此产生的非线性EMIC波演化。这些离子空穴是离子电流通过非线性波粒相互作用进行波生长和频率漂移的关键，本研究通过计算机模拟识别了这一点。
Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyromotion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion holes in the distribution function and the resulting nonlinear EMIC wave evolution from Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave-particle interactions, which are identified by a computer simulation in this study.