Electric field structure inside the secondary island in the reconnection diffusion region

	Electric field structure inside the secondary island in the reconnection diffusion region
	Zhou, M.; Deng, X. H.; Huang, S. Y.
刊名	PHYSICS OF PLASMAS
	2012
卷号	19 期号:4 页码:42902
ISSN号	1070-664X
通讯作者	Zhou, M (reprint author), Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Peoples R China.
中文摘要	Secondary islands have recently been intensively studied because of their essential role in dissipating energy during reconnection. Secondary islands generally form by tearing instability in a stretched current sheet, with or without guide field. In this article, we study the electric field structure inside a secondary island in the diffusion region using large-scale two-and-half dimensional particle-in-cell (PIC) simulation. Intense in-plane electric fields, which point toward the center of the island, form inside the secondary island. The magnitudes of the in-plane electric fields E-x and E-z inside the island are much larger than those outside the island in the surrounding diffusion region. The maximum magnitudes of the fields are about three times the B0VA, where B-0 is the asymptotic magnetic field strength and V-A is the Alfven speed based on B-0 and the initial current sheet density. Our results could explain the intense electric field (similar to 100 mV/m) inside the secondary island observed in the Earth's magnetosphere. The electric field E-x inside the secondary island is primarily balanced by the Hall term (j x B)/ne, while E-z is balanced by a combination of (j x B)/ne, -(v(i) x B), and the divergence of electron pressure tensor, with (j x B)/ne term being dominant. This large Hall electric field is due to the large out-of-plane current density j(y) inside the island, which consists mainly of accelerated electrons forming a strong bulk flow in the -y direction. The electric field E-y shows a bipolar structure across the island, with negative E-y corresponding to negative B-z and positive E-y corresponding to positive B-z. It is balanced by (j x B)/ne and the convective electric field. There are significant parallel electric fields, forming a quadrupolar structure inside the island, with maximum amplitude of about 0.3B(0)V(A). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3700194]
英文摘要	Secondary islands have recently been intensively studied because of their essential role in dissipating energy during reconnection. Secondary islands generally form by tearing instability in a stretched current sheet, with or without guide field. In this article, we study the electric field structure inside a secondary island in the diffusion region using large-scale two-and-half dimensional particle-in-cell (PIC) simulation. Intense in-plane electric fields, which point toward the center of the island, form inside the secondary island. The magnitudes of the in-plane electric fields E-x and E-z inside the island are much larger than those outside the island in the surrounding diffusion region. The maximum magnitudes of the fields are about three times the B0VA, where B-0 is the asymptotic magnetic field strength and V-A is the Alfven speed based on B-0 and the initial current sheet density. Our results could explain the intense electric field (similar to 100 mV/m) inside the secondary island observed in the Earth's magnetosphere. The electric field E-x inside the secondary island is primarily balanced by the Hall term (j x B)/ne, while E-z is balanced by a combination of (j x B)/ne, -(v(i) x B), and the divergence of electron pressure tensor, with (j x B)/ne term being dominant. This large Hall electric field is due to the large out-of-plane current density j(y) inside the island, which consists mainly of accelerated electrons forming a strong bulk flow in the -y direction. The electric field E-y shows a bipolar structure across the island, with negative E-y corresponding to negative B-z and positive E-y corresponding to positive B-z. It is balanced by (j x B)/ne and the convective electric field. There are significant parallel electric fields, forming a quadrupolar structure inside the island, with maximum amplitude of about 0.3B(0)V(A). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3700194]
学科主题	空间物理
收录类别	SCI ; EI
资助信息	National Science Foundation of China (NSFC) [41004060, 40890163, 41174147]; Specialized Research Fund for State Key Laboratories; Scientific Research Program of the Education Department of Jiangxi Province [GJJ11049]
语种	英语
公开日期	2014-12-15
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/3077]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	Zhou, M.,Deng, X. H.,Huang, S. Y.. Electric field structure inside the secondary island in the reconnection diffusion region[J]. PHYSICS OF PLASMAS,2012,19(4):42902.
APA	Zhou, M.,Deng, X. H.,&Huang, S. Y..(2012).Electric field structure inside the secondary island in the reconnection diffusion region.PHYSICS OF PLASMAS,19(4),42902.
MLA	Zhou, M.,et al."Electric field structure inside the secondary island in the reconnection diffusion region".PHYSICS OF PLASMAS 19.4(2012):42902.