Sub-MeV Electron Precipitation Driven by EMIC Waves in Plasmaspheric Plumes at High L Shells

IF 2.6 2区 地球科学 Q2 ASTRONOMY & ASTROPHYSICS
Murong Qin, Wen Li, Yukitoshi Nishimura, Sheng Huang, Qianli Ma, Miroslav Hanzelka, Luisa Capannolo, Xiao-Chen Shen, Vassilis Angelopoulos, Xin An, Anton V. Artemyev, Longzhi Gan
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引用次数: 0

Abstract

Electromagnetic ion cyclotron (EMIC) waves are known to be efficient for precipitating >1 MeV electrons from the magnetosphere into the upper atmosphere. Despite considerable evidence showing that EMIC-driven electron precipitation can extend down to sub-MeV energies, the precise physical mechanism driving sub-MeV electron precipitation remains an active area of investigation. In this study, we present an electron precipitation event observed by ELFIN CubeSats on 11 January 2022, exclusively at sub-MeV energy at L ∼ 8–10.5, where trapped MeV electrons were nearly absent. The THEMIS satellites observed conjugate H-band and He-band EMIC waves and hiss waves in plasmaspheric plumes near the magnetic equator. Quasi-linear diffusion results demonstrate that the observed He-band EMIC waves, with a high ratio of plasma to electron cyclotron frequency, can drive electron precipitation down to ∼400 keV. Our findings suggest that exclusive sub-MeV precipitation (without concurrent MeV precipitation) can be associated with EMIC waves, especially in the plume region at high L shells.

高L壳层等离子体羽流中主波驱动的亚mev电子沉淀
众所周知,电磁离子回旋波可以有效地将1兆电子伏的电子从磁层析出到上层大气中。尽管大量证据表明emic驱动的电子沉淀可以延伸到亚mev能量,但驱动亚mev电子沉淀的精确物理机制仍然是一个活跃的研究领域。在这项研究中,我们展示了ELFIN立方体卫星在2022年1月11日观测到的一个电子沉淀事件,仅在亚MeV能量为L ~ 8-10.5的情况下,捕获的MeV电子几乎不存在。THEMIS卫星在磁赤道附近的等离子体羽流中观测到共轭h波段和he波段的EMIC波和hiss波。准线性扩散结果表明,观测到的等离子体与电子回旋加速器频率之比高的he波段EMIC波可以驱动电子沉淀降低到~ 400 keV。我们的研究结果表明,亚MeV降水(没有同时发生的MeV降水)可能与地源波有关,特别是在高L壳的羽流区域。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Geophysical Research: Space Physics
Journal of Geophysical Research: Space Physics Earth and Planetary Sciences-Geophysics
CiteScore
5.30
自引率
35.70%
发文量
570
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