无碰撞等离子体电流片中的低频波  

Low-frequency waves in collisionless plasma current sheet

作　　者：周国成[1] 曹晋滨[1] 王德驹[1] 蔡春林[1] 

机构地区：[1]中国科学院空间科学与应用研究中心,北京100080

出　　处：《物理学报》2004年第8期2644-2653,共10页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :40 1740 42 ;40 0 740 43 );国家杰出青年科学基金 (批准号 :40 0 2 5 413 )资助的课题 .~~

摘　　要：采用两种无碰撞二维三分量不可压缩磁流体力学 (MHD)模型 ,计入电子扰动压力张量效应 ,研究了电流片等离子体的色散性质和波 .由于得到的一般色散关系较为复杂 ,只解析讨论了电流片的中心区和电子 β e =0两种特殊情况 .主要结果如下 :(1 )在短波区 (kdi>1 ) ,存在快磁声 动理学Alfven波和斜Alfven 哨声模 ,电子磁流体力学模型是足够精确的MHD模型 ;在长波区 (kdi<1 ) ,存在Alfven波和离子声波 ,理想的MHD模型是适用的 .(2 )电子 β e=0情况下的结果 ,显然遗漏了一些波模 (如离子声波和快磁声 动理学Alfven波等 ) ,因此它并不完全适合电流片的一般情况 .(3)在电流片中心区两种模型的结果中都有快磁声 动理学Alfven波 .Linear dispersion properties and waves of collisionless plasma current sheet at small scales are discussed, using 2 5 dimensional, collisionless and incompressible magnetohydrodynamic (MHD) models with the full electron pressure tensor. General dispersion relations are very complex. Two special cases, i.e., the central region of current sheet and the electron β * e=0 , are analytically studied here. The main results are as follows. (1) In the ion inertial region ( kd i>1), there are fast magnetosonic kinetic Alfven waves and obliquely Alfven whistler waves, and the electron magnetohydrodynamic (EMHD) model is a precise MHD model. In the long wavelength region ( kd i<1), there are Alfven waves and ion acoustic waves, and the ideal MHD model is valid. (2) When electron β * e=0, the results drop off some modes, e.g., the fast magnetosonic kinetic Alfven wave and ion acoustic wave. This case is not exactly valid for the current sheet plasma. (3) At central region of current sheet, results from both of physical models have fast magnetosonic kinetic Alfven waves.

关 键 词：不可压缩磁流体力学 电流片 色散关系 电子压力张量 离子声波 快磁声-动理学Alfven波 

分 类 号：O539[理学—等离子体物理]