磁云边界层中的重联慢激波观测分析  

Observation of a Slow Shock Associated with Reconnection Exhaust inside the Boundary Layer of Magnetic Cloud at 1 AU

作　　者：周梓露 左平兵 宋小健 ZHOU Zilu;ZUO Pingbing;SONG Xiaojian(National Space Science Center,Chinese Academy of Sciences,Beijing 100190;University of Chinese Academy of Sciences,Beijing 100049;Institute of Space Science and Applied Technology,Harbin Institute of Technology,Shenzhen 518000)

机构地区：[1]中国科学院国家空间科学中心,北京100190 [2]中国科学院大学,北京100049 [3]哈尔滨工业大学(深圳)空间科学与应用技术研究院,深圳518000

出　　处：《空间科学学报》2020年第4期471-478,共8页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(41731067和41531073);国家重点实验室专项研究基金项目;中国科学院“十三五”信息化建设专项项目(XXH13505-04)共同资助。

摘　　要：在Petschek模型中,排空区边界处的一对慢激波是能量耗散的重要机制.已有大量行星际空间的Petschek型磁场重联排空区观测事件被报道,但是只有少量的排空区边界处观测到了慢激波.针对一例位于磁云边界层中的Petschek型磁场重联排空区观测事件,在排空区靠近磁云一侧边界处证认了一例慢激波.激波跃变层两侧的磁场和等离子体参数满足Rankine-Hugoniot关系,且激波上下游的中间马赫数均小于1,上游的慢马赫数为2.94(>1),下游的慢马赫数为0.65(<1),符合慢激波的观测特征.磁云内部的等离子体β值很低,局地阿尔芬速度高,同时磁云边界层中可能发生丰富的磁场重联活动,这可能是磁云前边界处慢激波形成的原因.A pair of slow shocks in the Petschek reconnection model facilitate the energy transfer from magnetic field to kinetic and thermal energy of plasmas.In the past decade,a large amount of Petschek-like Reconnection Exhausts(RE)have been reported,but slow shocks bounding the REs are seldom identified.In this paper,a slow shock bounding a reconnection exhaust was identified in the front Boundary Layer(BL)of a Magnetic Cloud(MC)observed by WIND spacecraft on 27 February 2012.The observations of the jump conditions across the shock are in good agreement with the Rankine-Hugoniot relations.The intermediate Mach numbers are less than 1 on both sides of the shock.The slow Mach number is above unit(2.94)in the upstream side but below unit(0.65)in the downstream.The extremely low plasma beta(0.08)in the MC and the occurrence of magnetic reconnection in the MCBL may explain the formation of this slow shock.

关 键 词：磁云 磁场重联 慢激波 

分 类 号：P353[天文地球—空间物理学]