Effects of the Length-width Ratio of Current Sheet on Asymmetry Multiple X-line Reconnection
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摘要: 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。Abstract: 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.-
Key words:
- Magnetic reconnection /
- Magnetohydrodynamics /
- Secondary island /
- Current sheet
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表 1 不同
$ {L_x} $ 条件下多重X重联的发生情况Table 1. Occurrence of multiple-X lines reconnection with different
$ {{\boldsymbol{L}}_{\boldsymbol{x}}} $ Lx 24 25 26 28 30 32 40 是否发生多重X重联 否 否 是 是 是 是 是 -
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