Effect of the Electric Field on the Agyrotropic Electron Distributions
Effect of the Electric Field on the Agyrotropic Electron Distributions
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DOI：
10.1029/2020gl091437
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发表时间：
2021-03
影响因子：
5.2
通讯作者：
Chujie Gao;B. Tang;Wangping Li;Cunguo Wang;Y. Khotyaintsev;D. Graham;D. Gershman;A. Rager;B. Giles;P. Lindqvist;R. Ergun;C. Russell;J. Burch
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作者：
Chujie Gao;B. Tang;Wangping Li;Cunguo Wang;Y. Khotyaintsev;D. Graham;D. Gershman;A. Rager;B. Giles;P. Lindqvist;R. Ergun;C. Russell;J. Burch
我们研究了由磁层多尺度(MMS)航天器观测到的两个磁层顶事件的偏心性电子分布。各向异性电子分布可以通过电子尺度边界上的有限电子旋转来产生，而垂直于该边界的电场通常有助于电子的加速，从而使各向异性分布更加明显。只有当电场足够强和局域时，电场的作用才变得重要，这意味着它的静电势与电子温度相当或大于电子温度，而它的宽度小于电子热回转半径，因此这个电场可以直接加速部分电子离开原始核心，形成偏心性电子分布。此外，我们还从测试粒子模拟中重现了被测电子的指状结构，这种结构可以通过增加电子测量的采样率来有效地抑制。
We investigate agyrotropic electron distributions from two magnetopause events observed by magnetospheric multiscale (MMS) spacecraft. Agyrotropic electron distributions can be generated by the finite electron gyration at an electron‐scale boundary, and the electric field normal to this boundary usually contributes to the electron acceleration to make the agyrotropic distributions more apparent. The effect of the electric field becomes important only when it is sufficiently strong and local, meaning its electrostatic potential is comparable to or larger than the electron temperature, and its width is smaller than the electron thermal gyroradius, so that this electric field can directly accelerate part of the electrons out of the original core to form agyrotropic electron distributions. Also, we reproduce the measured electron “finger” structures from test particle simulations, which can be effectively suppressed by increasing the sampling rate of the electron measurement.