TC-1和Geotail对亚暴过程中近地等离子体片磁扰动的联合观测

摘要

On the basis of joint observations of TC-1 at about -12.5Re and Geotail at about -8 - -9 Re in the near-Earth plasma sheet in the magnetotail, the plasma instabilities in the vicinity of substorm onset occurred at about 02：53：20UT on 28 September 2004 were investigated. The observation results indicate that （1） the location of substorm onset triggering region is small within the inner plasma sheet in the near-Earth magnetotail, （2） the lower-hybrid instability is incited in the substorm triggering region and the lower-hybrid waves with the quasi-perpendicular propagation occur during substorm onset, （3） the magnetic dipolarization and the magnetic disturbance in the outside of near-Earth plasma sheet are very weak during substorm onset. The multiple magnetic dipolarization with different feature took place during substorm onset and substorm expansion phase.%以2004年9月28日02：53：20UT的亚暴为例，通过TC-1在磁尾约12．5Re和Geotail卫星在近地磁尾等离子体片约8—9R。的联合观测，研究亚暴触发过程中近地磁尾等离子体片中等离子体波动特征．结果表明，亚暴触发区是近地磁尾中心等离子体片中较小的一个区域，在亚暴触发区中低混杂不稳定性在近地磁尾等离子体片中存在，准垂直传播的低混杂波发生在亚暴触发过程中，而亚暴触发过程中近地磁尾等离子体片外边界区内的磁场偶极化信号和扰动都非常微弱．在亚暴触发和亚暴膨胀相过程中出现了多次具有不同特征的磁场偶极化现象．