电流片的自发重联与无力场──磁岛的形成

SPONTANEOUS RECONNECTION OF CURRENT SHEETS AND FORCE-FREE FIELD──FORMATION OF MAGNETIC ISLANDS

采用二维三分量磁流体力学数值模拟方法，研究了线性无力场对电流片的自发重联的影响．结果表明：电流片的背景场（无力场）对重联的拓扑位形有重要的影响，当无力场因子达到一定值时，在模拟区域内出现大范围的磁岛，磁岛厚度随时间的发展而增加，而无力场因子较小时则没有磁岛形成．当无力场因子为零时，即回到普通的位场情形的单ｘ线重联，位场情形磁场拓扑位形与Ｓｃｈｏｌａｒ的结果一致．

Using the multistep implicit scheme,a numerical study was made to reveal the influence of linear force-free field to the spontaneous reconnection of current sheets.It is found that the background field (force-free field)of current sheets can strongly affect the topology of the reconnection.When the force-free factor a reaches a critical value,a big area of magnetic island forms in the simulation domain,and the thickness of the island is an increasing function of times.But if the force-free factor is smaller,than the critical value, no islands can be formed.When a is zero,it turns to the common single X line reconnection of potential field.The reconnection topology of the potential field agrees to that of Scholar.