Kinetic ballooning instability of the near-earth magnetotail in voigt equilibrium

作     者：Khan, Abdullah Zhu, Ping Han, Rui Ali, Ahmad 

作者机构：CAS Key Laboratory of Geospace Environment Department of Engineering and Applied Physics University of Science and Technology of China HefeiAnhui230026 China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology WuhanHubei430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States National Tokamak Fusion Program Islamabad3329 Pakistan 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2020年

核心收录：

主　　题：Kinetics 

摘      要：For a long time, ballooning instabilities have been believed to be a possible triggering mechanism for the onset of substorm and current disruption initiation in the near-Earth magnetotail. Yet the stability of the kinetic ballooning mode (KBM) in a global and realistic magnetotail configuration has not been well examined. In this paper, stability of the KBM is evaluated for the two-dimensional Voigt equilibrium of the near-Earth magnetotail based on an analytical kinetic theory of ballooning instability in the framework of kinetic magnetohydrodynamic (MHD) model, where the kinetic effects such as the finite gyroradius effect, wave-particle resonances, particle drifts motions are included usually through kinetic closures. The growth rate of the KBM strongly depends on the magnetic field line stiffening factor S, which is in turn determined by the effects of the trapped electrons, the finite ion gyroradius, and the magnetic drift motion of charged particles. The KBM is unstable in a finite intermediate range of equatorial βeq and only marginally unstable at higher βeq regime for higher Te/Ti values. The finite ion gyroradius and the trapped electron fraction enhance the stiffening factor that tends to stabilize the KBM in the magnetotail far away from Earth. On the other hand, the current sheet thinning destabilizes KBM in the lower βeq regime and stabilizes KBM in the higher βeq regime. Copyright © 2020, The Authors. All rights reserved.