极隙区电子束流模电磁不稳定性  

ELECTROMAGNETIC INSTABILITIES FOR THE ELECTRON BEAM-MODE IN THE CLEFT REGIONS

作　　者：周国成[1] 金长文[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：《地球物理学报》1997年第1期10-17,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金

摘　　要：解析地研究了中高度（离他心3－4个地球半径）极隙区极低密度上行电子束流引起的沿磁力线传播的电磁个稳定性，上行电子束流和背景等离子体都考虑成冷等离子体．结果表明，上行电子引起的左旋和右旋圆偏振电磁来流模是不稳定的，当它与离子回旋模耦合时增长率达到最大值，频率色散关系仍为电子束流模特征这此结果对解释权隙区纬度地面站低频电磁波观测资料和理解极隙区动力学过程是很有益的．Electromagnetic instabilities for the electron beam-mode propagating along themagnetic force lines by the upwelling electron beams with the ultra-low density inthe cleft regions, at altitudes between 2 and 3 Earth radii, are analytically studied inthis paper. It has been used some simple assumptions in the physical model: theupwelling electrons prossess a monoenergetical beam distribution. The results showthat the circularly polarized electromagnetic beam-modes with left-hand andright-hand are unstable. When the electron beam-mode frenquencys with the ioncyclotron-mode frenquencys coincide, the growth rates have maximum, and thedispersion relation for the electron beam-mode keeps up. These results are very helpful to explain the data of low-frequency electromagnetic wares observed at theground stations in the cusp /cleft latitude range and to understand the dynamic processes in the cleft plasma.

关 键 词：极隙区 电磁 不稳定性 电子束流模 

分 类 号：P352.3[天文地球—空间物理学]