地球远磁尾中的磁场重联——（Ⅱ）局部驱动力的影响

基于可压缩磁流体动力学模型,数值研究了由太阳风引起的局部驱动力对地球远磁尾中磁场重联的影响.结果表明,在远磁尾等离子体片中将发生强迫磁场重联,并形成磁岛和等离子体团.形成磁岛的特征时间很大于流动撕裂模不稳定性引起磁岛非线性饱和的特征时间.磁岛宽度随着磁Reynolds数S的增大而减小,随着尾瓣中等离子体压力与磁压之比值β_∞的降低而减小.认为太阳风引起的局部驱动力对地球远磁尾等离子体片中磁场重联的影响,可能不如流动撕裂模不稳定性那样显著.

MAGNETIC RECONNECTION IN THE EARTH'S DISTANT MAGNETOTAIL ——（II） THE EFFECTS OF A LOCAL DRIVING FORCE

In this paper, we study numerically, on the oasis of a compressible magnetohydrodynamic model, the effects of a local driving force delivered by the solar wind on magnetic reconnection in the earth's distant magnetotail. The results show that a forced magnetic reconnection is produced and the magnetic islands and plasmo ls are formed in the plasma sheet of distant magnetotail. The characteristic time for the formation of magnetic islands is much longer than that of nonlinear saturation of magnetic islands caused by the streaming tearing instability. The magnetic island width decreases as the magnetic Reynolds numbers S increases and the B decreases. Here B is the ratio between the pla ma and magnetic pressures in the lobes of tail. It is suggested that the effects of a local driving force delivered by the solar wind on the magnetic reconnection in the plasma sheet of the earth's distant magnetotail may be underdeveloped as compared with the streaming tearing instability.