中文摘要：

利用Cluster卫星的磁场和等离子体探测数据，研究了行星际磁场（IMF）时钟角（clock angle）Ф和锥角（cone angle）θ对磁尾等离子体片边界层（PSBL）区场向电流发生率的影响．当时钟角Ф〉0时，磁尾场向电流的发生率较高，这表明磁尾场向电流的发生与昏向太阳风条件更为密切；当90°〈｜Ф｜〈180°时，场向电流的发生率较高，这表明场向电流的发生与南向IMF更为密切．当锥角θ〈30°时（即IMF与日地连线夹角较小时）场向电流的发生率较低．而当θ〉30°时，场向电流在90°〈｜Ф｜〈180°的情况下发生率明显增大，这说明南向IMF情况下，场向电流发生率明显增大．但是当｜Ф｜〈90°时（北向IMF情况下），尽管θ很大，场向电流的发生率并未明显增大．当θ〉70°时，且在140°〈Ф〈160°的行星际磁场条件下，磁尾等离子体片边界层区场向电流的发生率最大．

英文摘要：

Using the magnetic field and plasma data from Cluster spacecraft, the effect of Interplanetary Magnetic Field （IMF） clock angle Ф and cone angle θ on the Field-Aligned Currents （FAC） occurrence rate at the Plasma Sheet Boundary Layer （PSBL） in the magnetotail is investigated. There were more FAC cases occurred when IMF was within the 0°〈 Ф 〈 180° clock angle range comparing with the range of -180° 〈 Ф 〈 0°. It indicated that FAC occurrences were associated with duskward IMF （IMF By 〉 0）. Also, there were more FAC cases occurred when the IMF was within the 90°〈｜Ф｜〈180° clock angle range. It supported that FAC occurrences were associated with southward IMF （IMF Bz 〈 0）. Most of the FAC cases occurred when IMF was within the 0 〉 30° cone angle. In addition, a few of FAC cases occurred when the IMF clock angle was in the 〈 30° range regardless of the value of Ф. The occurrence rate of FAC was the largest when θ 〉 30°and 140°〈Ф〈160°.