MF地磁场模型中磁尾感应电场研究与磁尾离子加速

THEORETICAL STUDY ON THE INDUCED ELECTRICAL FIELD WITH MF GEO-MAGNETIC MODEL AND ION ACCELERATION IN THE MAGNETOTAIL

为研究磁尾感应电场对上行离子的加速，对磁层亚暴期间尾向地磁场在向偶极位形弛豫过程中产生的感应电场进行了理论研究。结果表明：在偶极化过程中磁场的ＢＸ分量下降，ＢＺ分量上升，并产生随时间变化的单峰结构的感应电场，其峰值可超过２０ｍｖ／ｍ；当子午面内地心距离由６Ｒ，变化到１６ＲＥ时，感应电场峰值呈逐渐增大趋势；随着ｚ坐标的增大（远离赤道面）或Ｙ坐标的增大（远离子午面），感应电场峰值呈逐渐减小趋势；感应电场峰值随磁场向偶极形弛豫周期的减小而增大．理论计算得到的感应电场随时间变化曲线及峰值与观测结果符合较好，本文还对上行离子在感应磁场中的加速进行了估算．

In this paper,the induced electrical field during the magnetic depolarization in the subetorm in the magnetotail is investigated.The results show that the magneticcomponent Bx is decreasing and the Bz is increasing during the magnetic dipolarization. In the same time,the single peak-like electrical field is induced and its peak valuecan be higher than 20mV/ m. On the meridian plane, from earth center distance 6REto 16RE, the peak value of the induced electrical field is increasing. With thecoorinate GMS Z or GMS Y increasing,the peak value of the induced electrical field is decreasing,The peak value of the induced electrical field is increasing withthe duration period of the magnetic dipolarazation decreasing. The theoretical curvesand peak value of the induced electrical field are consistence with the observed results.The ion acceleration in the induced magnetic field is estimated, Also.