Fast Magnetic Field Annihilation in Magnetotail Electron-scale Current Sheet
Fast Magnetic Field Annihilation in Magnetotail Electron-scale Current Sheet
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DOI：
10.1002/essoar.10507891.1
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
H. Hasegawa;R. Denton;Takuma K. M. Nakamura;K. Genestreti;T. Phan;R. Nakamura;K. Hwang;N. Ahmadi;Q. Shi;M. Hesse;J. Burch;J. Webster;R. Torbert;B. Giles;D. Gershman;C. Russell;R. Strangeway;H. Wei;P. Lindqvist;Y. Khotyaintsev;R. Ergun;Yoshifumi Saito;Los Angeles;K. Hwang;P. Lindqvist
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文献类型：
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作者：
H. Hasegawa;R. Denton;Takuma K. M. Nakamura;K. Genestreti;T. Phan;R. Nakamura;K. Hwang;N. Ahmadi;Q. Shi;M. Hesse;J. Burch;J. Webster;R. Torbert;B. Giles;D. Gershman;C. Russell;R. Strangeway;H. Wei;P. Lindqvist;Y. Khotyaintsev;R. Ergun;Yoshifumi Saito;Los Angeles;K. Hwang;P. Lindqvist
我们目前的观测地球的磁尾的磁层多尺度航天器是一致的磁场湮灭，而不是磁拓扑结构的变化，导致快速的磁场到电子的能量转换在一个细长的电子尺度的电流片。这种能量转换过程与重连电流片的标准电子扩散区（EDR）中的能量转换过程相反，在标准电子扩散区中，反平行磁场的能量主要转换为电子体流能量。完全动力学模拟还表明，一个细长的EDR是受电子尺度的磁岛的形成，其中快速的能量转换是由湮灭为主。理论分析表明，在非共沸电子效应存在的情况下，细长EDR中可以发生快磁偏转，这与观测和模拟结果一致。湮灭主导的EDR的发现揭示了无碰撞重联过程中能量转换的一种新形式。
We present observations in Earth’s magnetotail by the Magnetospheric Multiscale spacecraft that are consistent with magnetic field annihilation, rather than magnetic topology change, causing fast magnetic-to-electron energy conversion in an elongated electron-scale current sheet. This energy conversion process is in contrast to that in the standard electron diffusion region (EDR) of a reconnecting current sheet where the energy of antiparallel magnetic fields is mostly converted to electron bulk-flow energy. Fully kinetic simulation also demonstrates that an elongated EDR is subject to the formation of electron-scale magnetic islands in which fast energy conversion is dominated by the annihilation. Consistent with the observations and simulation, theoretical analysis shows that fast magnetic diffusion can occur in an elongated EDR in the presence of nongyrotropic electron effects. The discovery of the annihilation-dominated EDR reveals a new form of energy conversion in the collisionless reconnection process.