初始电流片长宽比对非对称多重X线重联的影响

Effects of the Length-width Ratio of Current Sheet on Asymmetry Multiple X-line Reconnection

采用可压缩电阻性磁流体力学模型,研究了初始电流片的长宽比L_(x)对非对称多重X线磁场重联的影响。研究结果发现,当L_(x)超过一定的阈值时,非对称磁场重联的演化过程中将伴有多重X线重联发生。进一步地研究结果表明,当L_(x)越大,多重X线重联就越容易出现,相同时间间隔内所诱发的次级磁岛的尺寸也随之相应变大,不仅如此,次级磁岛的尺寸占整个模拟尺寸的比例也有所增大。对于L_(x)比较大的情形,当非对称多重X线磁场重联发展到一定程度后,非对称多重X线磁场重联的重联点基本不随时间变化,并且所诱发的大尺度次级磁岛的大小也基本稳定,该结论与Magnetospheric Multiscale(MMS)观测现象一致。因此这些结果可以用来解释一些卫星观测现象,尤其对空间物理中有关次级磁重联产生的多重X重联的观测有一定指导作用。

Effects of the length-width ratio of current sheet(L_(x)) on asymmetry multiple X-line reconnection are investigated using a two-dimensional compressible resistive Magnetohydrodynamics(MHD) model. It is found that multiple-X lines induced by secondary tearing instability occur during the asymmetry reconnection processes when L_(x) exceeds a critical value. Multiple X-line reconnection occurs faster as L_(x) becomes larger, and percent of secondary island is also increases. For large L_(x) cases,locations of the reconnection points of asymmetry multiple X-line reconnection and sizes of the secondary island are tend to stationary with the evolution of the multiple X-line reconnection, which is consistent to the Magnetospheric Multiscale(MMS) observations. The results here can be useful for understanding some observed data, even for the secondary tearing instability and multipleX-line reconnection observations.