Ion and electron dynamics in the ion-electron decoupling region of magnetic reconnection with Geotail observations
Ion and electron dynamics in the ion-electron decoupling region of magnetic reconnection with Geotail observations
复制标题
DOI：
10.1002/2013ja019135
复制
发表时间：
2013-12-01
影响因子：
2.8
通讯作者：
Mukai, T.
中科院分区：
文献类型：
--
作者：
Nagai, T.;Zenitani, S.;Mukai, T.
在磁重联部位形成电子流出速度与离子流出速度不同的离子-电子退耦区域。利用近地磁尾磁场重联中Geotail航天器的磁场和等离子体观测，导出了离子-电子退耦区的离子和电子动力学。离子-电子退耦区域沿着GSM x方向具有约11 i（离子惯性长度）的空间范围，并且在该区域上存在具有电子的主要载流子的黎明-黄昏电流片。在X线周围的中心有一个空间范围为0.5-1 i的强电子流层。在中心强电子流层外形成高速电子外流喷流。它们被减速并成为非喷射流出，其速度略高于离子流出速度。电子有平顶分布函数，表明加热和加速的流出射流和非射流流出，然而，加热和加速是弱的中心强电流层。流入的离子进入中央强电子流层，这些离子被加速到10 keV的电子流出射流区域内。离子加速超过10 keV和热化主要在非喷流电子流出区域。电子显示热分布没有任何加热/加速签名立即超出边缘的离子-电子去耦区域，而更高能量的离子渗透，甚至超出边缘和热MHD等离子体流的产生。
The ion-electron decoupling region where electron outflow speed differs from ion outflow speed is formed in the magnetic reconnection site. Ion and electron dynamics in the ion-electron decoupling region is derived with magnetic field and plasma observations by the spacecraft Geotail in near-Earth magnetotail magnetic reconnection. The ion-electron decoupling region has a spatial extent of approximately 11 i (ion inertial length) along the GSM x direction, and the dawn-dusk current sheet with main current carriers of electrons exists over this region. An intense electron current layer with a spatial extent of 0.5-1 i occupies in its center around the X line. High-speed electron outflow jets are formed just outside the central intense electron current layer. They are decelerated and become non-jet outflows with speed slightly higher than ion outflow speed. Electrons have flattop distribution functions indicating heating and acceleration in both the outflow jets and the non-jet outflows; however, heating and acceleration are weak in the central intense current layer. Inflowing ions enter the central intense electron current layer, and these ions are accelerated up to 10 keV inside the electron outflow jet regions. Ion acceleration beyond 10 keV and thermalization operate mostly in the non-jet electron outflow regions. Electrons show thermal distributions without any heating/acceleration signatures immediately beyond the edge of the ion-electron decoupling region, while higher-energy ions pervade even beyond the edge and hot MHD plasma flows are produced.