Density depletion and Hall effect in magnetic reconnection

	Density depletion and Hall effect in magnetic reconnection
	Yang, H. A. ; Jin, S. P. ; Zhou, G. C.
刊名	Journal of Geophysical Research-Space Physics
	2006
卷号	111 期号:A11 页码:A11223
关键词	collisionless reconnection driven reconnection challenge pressure simulations dissipation field layer mhd
ISSN号	0148-0227
通讯作者	北京8701信箱
英文摘要	Density depletions were detected by Wind, Cluster, and Polar spacecrafts in the observations of diffusion region encounters at the Earth's magnetotail and magnetopause. In this report we investigate the layers of density depletion in magnetic reconnection using a 2.5-dimensional Hall MHD code developed from a multistep implicit scheme. The numerical results at the quasi-steady state of the Hall MHD reconnection with d(i)/L-c >= 1.0, where d(i) is the ion inertial length and L-c is the half thickness of the initial current sheet, show not only the density depletions along the magnetic separatrices but also a density dip in the x direction near the X neutral line. The comparative tests with various Hall terms demonstrate that the density depletion in the magnetic reconnection is a peculiar feature of the case with a strong Hall effect (d(i)/L-c >= 1.0). The layers of low density following the shape of separatrices are in coincidence with the regions of high magnetic pressure. In the spatial profile of density rho along z, which is in quantitative agreement with Cluster observation, the obvious dips located at the separatrices coincide with the peak and valley in the profile of K-H/rho (J x B)(z) for the case with d(i)/L-c = 2.0. It indicates the major role of the Hall term in the formation of the density depletion layers near the separatrices. On the basis of the comparison between Wind observation and simulation results, we argue that the density dip observed by Wind would be distributed around the reconnection X-line, rather than along the magnetic separatrix. In the case with a strong Hall effect, the in-plane ion flows go around the diffusion region, and enterable ions in this region are significantly reduced due to the action of the in-plane Lorentz force. A density dip in the vicinity of the X-line is attributed to the hard entry of in-plane ion flow and might be related to an increase of the ion drift velocity in the y direction.
学科主题	空间物理
收录类别	SCI
原文出处	http://www.agu.org/pubs/crossref/2006/2005JA011536.shtml
语种	英语
内容类型	期刊论文
源URL	[http://ir.cssar.ac.cn/handle/122/1049]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	Yang, H. A.,Jin, S. P.,Zhou, G. C.. Density depletion and Hall effect in magnetic reconnection[J]. Journal of Geophysical Research-Space Physics,2006,111(A11):A11223.
APA	Yang, H. A.,Jin, S. P.,&Zhou, G. C..(2006).Density depletion and Hall effect in magnetic reconnection.Journal of Geophysical Research-Space Physics,111(A11),A11223.
MLA	Yang, H. A.,et al."Density depletion and Hall effect in magnetic reconnection".Journal of Geophysical Research-Space Physics 111.A11(2006):A11223.