Abstract: The characteristics of the field-aligned currents (FACs) measured by ISEE 1 and 2 satellites during substorms are studied. These characteristics include the variations of FACs with the Interplanetary Magnetic Field(IMF), local time, L-value, and the current density and intensity versus the substorm phases. Moreover, the characteristics of substorm current wedge are given special attention. It is found that the density and intensity of FACs reach their peak during the expansion phase, the onset of the expansion phase is triggered when IMF is changed to southward from northward or the southward IMF decreases, and the positions of onset are most likely to be at the edge of plasma sheet near the earth.

Key words: field-aligned current, substorm, substorm current wedge

摘要： 分析了由ISEE-1和ISEE-2飞船在亚暴期间观测到的场向电流的特性，包括场向电流所伴随的行星际磁场、地方时与L值分布以及场向电流强度和密度随亚暴位相的变化，并着重分析了亚暴电流楔的特征。结果表明，亚暴膨胀相的场向电流强度和密度都达到极大值；亚暴的膨胀相是由行星际磁场转向或南向分量变小触发的，其起始位置很可能位于近地等离子体片内边缘。

关键词: 场向电流, 亚暴, 亚暴电流楔