Evolution, Structure, and Topology of Self-generated Turbulent Reconnection Layers
Evolution, Structure, and Topology of Self-generated Turbulent Reconnection Layers
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DOI：
10.3847/1538-4357/ac8eb6
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发表时间：
2022-09
期刊：
影响因子：
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通讯作者：
Raheem Beg;A. Russell;G. Hornig
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作者：
Raheem Beg;A. Russell;G. Hornig
我们提出了一个三维磁流体模拟的两个合并磁通绳展示自生和自持湍流重联（SGTR），是完全三维和快速。SGTR的探索对于理解包括日冕在内的天体物理背景下MHD湍流和磁场重联之间的关系至关重要。我们研究了SGTR的途径，并应用新的工具来分析重连层的结构和拓扑结构。模拟从2.5D Sweet-Parker重联到2.5D非线性撕裂，然后动态过渡到最终的SGTR相位，该相位是全局准稳态的。过渡阶段主要由一个大的“猫眼”磁通绳的扭结不稳定性和广泛的随机层的增殖。重联层有两个一般的特征厚度尺度，这与重联率和相差约6倍：一个内部规模对应的电流和涡度密度，湍流波动，外流射流，和外部规模与场线随机性。重联层的有效厚度是湍流涨落产生的有效重联电场的内尺度，而不是随机厚度。重联层内的动力学与高度拓扑复杂的磁通绳结构密切相关。磁绳结构和独特的中间区域之间的内核和随机分离（“SGTR翼”）的探索是潜在的关键了解SGTR。本研究最后讨论了类质体介导的SGTR和随机观点之间的明显二元论。
We present a 3D MHD simulation of two merging flux ropes exhibiting self-generated and self-sustaining turbulent reconnection (SGTR) that is fully 3D and fast. The exploration of SGTR is crucial for understanding the relationship between MHD turbulence and magnetic reconnection in astrophysical contexts including the solar corona. We investigate the pathway toward SGTR and apply novel tools to analyze the structure and topology of the reconnection layer. The simulation proceeds from 2.5D Sweet–Parker reconnection to 2.5D nonlinear tearing, followed by a dynamic transition to a final SGTR phase that is globally quasi-stationary. The transition phase is dominated by a kink instability of a large “cat-eye” flux rope and the proliferation of a broad stochastic layer. The reconnection layer has two general characteristic thickness scales, which correlate with the reconnection rate and differ by a factor of approximately six: an inner scale corresponding with current and vorticity densities, turbulent fluctuations, and outflow jets, and an outer scale associated with field line stochasticity. The effective thickness of the reconnection layer is the inner scale of the effective reconnection electric field produced by turbulent fluctuations, not the stochastic thickness. The dynamics within the reconnection layer are closely linked with flux rope structures that are highly topologically complicated. Explorations of the flux rope structures and distinctive intermediate regions between the inner core and stochastic separatrices (“SGTR wings”) are potentially key to understanding SGTR. The study concludes with a discussion on the apparent dualism between plasmoid-mediated and stochastic perspectives on SGTR.