Numerical study of the cascading energy conversion of the reconnection current sheet in solar eruptions
Numerical study of the cascading energy conversion of the reconnection current sheet in solar eruptions
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DOI：
10.1093/mnras/sty2716
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发表时间：
2017-12
影响因子：
4.8
通讯作者：
Jing Ye;Jing Ye;Chengcai Shen;J. Raymond;Jun Lin;U. Ziegler
中科院分区：
文献类型：
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作者：
Jing Ye;Jing Ye;Chengcai Shen;J. Raymond;Jun Lin;U. Ziegler
磁场重联在太阳爆发的能量转换过程中起着重要的作用。在这项工作中，我们提出了一个电阻磁流体动力学研究（2.5D）的磁通绳喷发的基础上林和福布斯模型级联重联。我们使用的二阶Goddom计划代码，以更好地了解负责高重联率和内部结构的物理机制，特别是在混乱或动荡的地区，日冕物质抛射（CME）/耀斑电流片（CS）。在CS附近的两组Lundquist数分别为1.18 × 105和2.35 × 105的模拟结果表明，在CS附近产生了一个缓慢的CME和一个中等的CME，其全球动力学特征与耀斑模型基本一致。在CS的精细结构中，磁场重联在早期同时采用Sweet-Parker模式和时间相关的小尺度Petschek模式。当磁绳上升时，流出区域变得湍流，这进一步提高了重联率。我们的研究结果表明，等离子体团的合并和融合过程提供了大量的小，瞬态局部扩散区域耗散磁能，并确认耗散开始在宏观MHD尺度，而不是离子惯性长度。这两次运行具有与日冕物质抛射相关的相同的局部重连率范围（10−4-0.3）。快速率与多个小尺度CS的纵横比的平方成正比。磁场的拓扑结构和能量级联的湍流谱的统计处理以及。
Magnetic reconnection plays an important role in the energy conversion during solar eruptions. In this work, we present a resistive magnetohydrodynamical study (2.5D) of a flux rope eruption based on the Lin and Forbes model regarding cascading reconnection. We use a second-order Godunov scheme code, to better understand the physical mechanisms responsible for high reconnection rates and the internal structure, particularly in chaotic or turbulent regions, of the coronal mass ejection (CME)/flare current sheet (CS). Two sets of simulations with Lundquist numbers of 1.18 × 105and 2.35 × 105in the vicinity of the CS, generating a slow CME and a moderate one, show global dynamic features largely consistent with the flare model. Looking into the fine structure of the CS, magnetic reconnection employs simultaneously the Sweet–Parker mode and time-dependent small-scale Petschek patterns in the early stage. As the flux rope rises, the outflow region becomes turbulent, which further enhances the reconnection rates. Our results show that coalescence and fusion processes of plasmoids provide a large number of small, transient local diffusion regions to dissipate magnetic energy, and confirm that the dissipation starts at macro-MHD scales rather than ion inertial lengths. The two runs have the same range of the local reconnection rates (10−4–0.3) relevant to CMEs. The fast rates are closely proportional to the square of the aspect ratio of multiple small-scale CSs. The topology of the magnetic field and the turbulence spectrum of the energy cascade are statistically addressed as well.