无碰撞电流片哨声波不稳定性  

Whistler Wave Instabilities in the Collisionless Current Sheet

作　　者：周国成[1] 魏新华[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：《空间科学学报》2005年第3期161-166,共6页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(40174042)国家杰出青年科学基金项目(40025413)共同资助

摘　　要：通过数值求解文献[4]中物理模型A得到的一般形式的色散关系,讨论了无碰撞电流片低频波不稳定性问题.结果表明,哨声波能被无碰撞电流片直接激发.在中性片上(z/di=0),在较宽的波数范围内,斜哨声波是可以传播的,但它基本上是稳定的.在离子惯性区内(z/di<1,电子惯性区外),斜传播的哨声波是不稳定的.在离子惯性区边缘(z/di=1),斜传播的哨声波仍然是不稳定的,增长率更大,不稳定的波频率范围更高.此外,朝向中性片方向传播(kzdi<0)的哨声波比离开中性片方向传播(kzdi>0)的哨声波有更大的增长率.Whistler wave instabilities in the collisionless current sheet have been studies in the present paper by solving general dispersion relation obtained from the 2.5-dimenssional and incompressible MHD model (Physical model A) of the paper [4]. In this MHD model, the electron pressure tensor is used in the generalized Ohm's law. The results show that whistler waves can be directly excited by the collisionless current sheet. At the neutral sheet (z/d\ = 0), whistler waves are basically stable in a broad range of wave number. Inside the ion inertial region (z/d\ < 1), obliquely propagating whistler waves are unstable. At the edge of ion inertial region (z/di = 1), obliquely propagating whistler waves have larger growth rate and higher frequency range. Besides, waves propagating towards the neutral sheet (kzdi < 0) have larger growth rate than that propagating away from the neutral sheet (kzdi > 0). There are two kinds of whistler waves: one with the parallel wave number larger and the other with the parallel wave number smaller than the perpendicular wave number.

关 键 词：哨声波 电流片 无碰撞 不稳定性 稳定性问题 惯性区 色散关系 一般形式 物理模型 数值求解 频率范围 斜传播 增长率 低频波 中性 离子 波数 电子 

分 类 号：P353.1[天文地球—空间物理学]