Kinetic Alfvén wave explanation of the Hall fields in magnetic reconnection

	Kinetic Alfvén wave explanation of the Hall fields in magnetic reconnection
	Lei Dai; Chi Wang; Yongcun Zhang; Benoit Lavraud; James Burch; Craig Pollock; Roy B. Torbert
刊名	Geophysical Research Letters
	2017
卷号	44 期号:2 页码:634–640
关键词	kinetic Alfven wave Hall fields magnetic reconnection Hall current
英文摘要	Magnetic reconnection is initiated in a small diffusion region but can drive global-scale dynamics in Earth's magnetosphere, solar flares, and astrophysical systems. Understanding the processes at work in the diffusion region remains a main challenge in space plasma physics. Recent in situ observations from Magnetospheric Multiscale and Time History of Events and Macroscale Interactions during Substorms reveal that the electric field normal to the reconnection current layer, often called the Hall electric field (E_n), is mainly balanced by the ion pressure gradient. Here we present theoretical explanations indicating that this observation fact is a manifestation of kinetic Alfvén waves (KAWs) physics. The ion pressure gradient represents the finite gyroradius effect of KAW, leading to ion intrusion across the magnetic field lines. Electrons stream along the magnetic field lines to track ions, resulting in field-aligned currents and the associated pattern of the out-of-plane Hall magnetic field (B_m). The ratio ΔE_n/ΔB_m is on the order of the Alfvén speed, as predicted by the KAW theory. The KAW physics further provides new perspectives on how ion intrusion may trigger electric fields suitable for reconnection to occur.
语种	英语
内容类型	期刊论文
源URL	[http://ir.nssc.ac.cn/handle/122/5734]
专题	国家空间科学中心_空间科学部
推荐引用方式 GB/T 7714	Lei Dai,Chi Wang,Yongcun Zhang,et al. Kinetic Alfvén wave explanation of the Hall fields in magnetic reconnection[J]. Geophysical Research Letters,2017,44(2):634–640.
APA	Lei Dai.,Chi Wang.,Yongcun Zhang.,Benoit Lavraud.,James Burch.,...&Roy B. Torbert.(2017).Kinetic Alfvén wave explanation of the Hall fields in magnetic reconnection.Geophysical Research Letters,44(2),634–640.
MLA	Lei Dai,et al."Kinetic Alfvén wave explanation of the Hall fields in magnetic reconnection".Geophysical Research Letters 44.2(2017):634–640.