Observations of kinetic Alfvén waves by THEMIS near a substorm onset  

作　　者：DUAN SuPing LIU ZhenXing ANGELOPOULOS Vassilis 

机构地区：[1]State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China [2]Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095, USA

出　　处：《Chinese Science Bulletin》2012年第12期1429-1435,共7页

基　　金：supported by the National Natural Science Foundation of China(40974099,40731054,40704027 and 40921063);the Specialized Research Fund for State Key Laboratories and the National Basic Research Program of China(2011CB811404)

摘　　要：Low frequency electromagnetic fluctuations in the vicinity of a magnetospheric substorm onset were investigated using simultaneous observations by THEMIS multiple probes in the near-Earth plasma sheet in the magnetotail.The observations indicate that in the vicinity of a substorm onset,kinetic Alfvén waves can be excited in the high-βplasma sheet(β=2μ0nT/B 2 ,the ratio of plasma thermal pressure to magnetic pressure)within the near-Earth magnetotail.The kinetic Alfvén wave has a small spatial scale in the high-βplasma.The parallel electric field accompanying kinetic Alfvén waves accelerates the charged particles along the magnetic field.The kinetic Alfvén waves play an important role in the substorm trigger process,and possibly in the formation of a substorm current wedge.Low frequency electromagnetic fluctuations in the vicinity of a magnetospheric substorrn onset were investigated using simulta- neous observations by THEMIS multiple probes in the near-Earth plasma sheet in the magnetotail. The observations indicate that in the vicinity of a substorm onset, kinetic Alfven waves can be excited in the high-β plasma sheet （β=2μonTIB2, the ratio of plas- ma thermal pressure to magnetic pressure） within the near-Earth magnetotail. The kinetic Alfven wave has a small spatial scale in the high-β plasma. The parallel electric field accompanying kinetic Alfven waves accelerates the charged particles along the magnetic field. The kinetic Alfven waves play an important role in the substorm trigger process, and possibly in the formation of a substorm current wedge.

关 键 词：阿尔文波 动力学 暴发病 观测 等离子体片 亚暴电流楔 地球磁尾 空间尺度 

分 类 号：P352.4[天文地球—空间物理学] TL612.3[天文地球—地球物理学]