吕浩宇^1,2,,
李芸¹,
葛亚松³
1. 北京航空航天大学空间与环境学院, 北京 100191
2. 澳门科技大学月球与行星科学实验室-中国科学院月球与深空探测重点实验室伙伴实验室, 澳门
3. 中国科学院地质与地球物理研究所, 北京 100029

基金项目: 国家自然科学基金(41674176, 41474124, 41474144, 40931054, 11372028), 澳门科技大学月球与行星科学实验室-中国科学院月球与深空探测重点实验室伙伴实验室开放课题(FDCT编号：039/2013/A2)资助


详细信息

作者简介: 吕浩宇, 博士, 副教授, 主要研究方向为空间等离子体数值模拟研究.E-mail:Lvhy@buaa.edu.cn

中图分类号: P353

收稿日期:2016-12-08
修回日期:2017-07-21
上线日期:2018-02-05

On the kinetic nature of dipolarization fronts produced by interchange instability in the magnetotail

Lü HaoYu^1,2,,
LI Yun¹,
GE YaSong³
1. School of Space and Environment, Beihang University, Beijing 100191, China
2. Lunar and Planetary Science Laboratory, Macau University of Science and Technology-Partner Laboratory of Key Laboratory of Lunar and Deep Space Exploration, Chinese Academy of Sciences, Macau, China
3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China


MSC: P353

--> Received Date: 08 December 2016
Revised Date: 21 July 2017
Available Online: 05 February 2018


摘要
摘要:本文利用考虑了Hall效应和有限Larmor半径(FLR)效应的磁流体数值模拟研究了在离子惯性长度/离子Larmor半径尺度内偶极化锋面的动力学特性.偶极化锋面由磁尾近地区域中由于热压尾向梯度和磁场曲率力不平衡所引起的交换不稳定性自洽产生.数值研究表明, 偶极化锋面是切向间断, 在相对该锋面结构静止的参考系中等离子体穿过偶极化锋面的法向速度为零.Hall效应主要影响与偶极化锋面的切平面相正交的电场, 使得锋面切向电流增大, 同时产生锋面结构不对称.研究表明离子在Larmor半径尺度产生的FLR效应可导致锋面结构的大尺度漂移运动.由FLR效应产生的离子磁化流速在偶极化锋面的日下点处指向昏向, 锋面后区域的速度晨向分量增长, 从而导致整个锋面结构向晨向漂移.
关键词: 偶极化锋面/
交换不稳定性/
Hall MHD/
有限Larmor半径效应/
数值模拟

Abstract:A two-dimensional extended MHD simulation, including Hall effect and finite Larmor radius (FRL) effect, is performed to study the kinetic nature of dipolarization fronts (DFs) in the scale of the ion inertial length/ion Larmor radius.The DF is self-consistently produced by the interchange instability, arising due to the force imbalance between the tailward gradient of thermal pressure and Earthward magnetic curvature force in the near-Earth region.Numerical investigations indicate that the DF is a tangential discontinuity, which means that the normal plasma velocity across the DF should be zero in the reference system that is static with the DF structure.Hall effect arising in the scale of ion inertial length determines the electric system, including electric field and current.Hall effect mainly contributes on the electric field normal to the tangent plane of the DF, increases the current along the tangent plane of the DF, but also makes the DF structure asymmetric.The drifting motion of the large-scale DF structure is determined by the FLR effect arising in the scale of ion Larmor radius.The ion magnetization velocity induced by the FLR effect is towards to duskward at the subsolar point of the DF, but the dawnward component of velocity in the region after the DF is increased, which dominantly results in the drifting motion of the whole mushroom structure towards the dawn.
Key words:Dipolarization fronts/
Interchange instability/
Hall MHD/
Finite Larmor radius effect/
Numerical simulation



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