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arXiv 2112.03316physics.plasm-ph
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无碰撞等离子体中快速磁重联和等离子体团不稳定性的新动力学机制

A novel kinetic mechanism for the onset of fast magnetic reconnection and plasmoid instabilities in collisionless plasmas

W. Fox, G. Fiksel, D. B. Schaeffer, D. Haberberger, J. Matteucci, K. Lezhnin, A. Bhattacharjee, M. J. Rosenberg, S. X. Hu, A. Howard, D. Uzdensky, K. Germaschewski

摘要:

当相反的磁场通过电流片合并和湮灭时,磁重联可以爆炸性地释放磁能,驱动等离子体射流并将非热粒子群加速到高能量,在从空间和天体物理到实验室尺度的等离子体中。通过实验室实验和航天器观测,在证明在狭窄的动力学尺度电流片中如何快速耗散和重联方面取得了重大的实验进展。然而,一个挑战是要证明是什么触发了重新连接,以及它如何作为一个比这些动力学尺度大得多的全球系统的一部分快速有效地进行。在这里,我们显示实验的全面发展的过程中,电流片的形式,然后在离子动力学尺度分解成多个载流结构。结果是一致的撕裂的电流片,但修改碰撞动力学离子效应,这导致更大的增长率和数量的等离子体团比以前的实验中观察到的或相比,从标准的撕裂不稳定性理论和以前的非线性动力学重联模拟的预测。这一效应将增加等离子体团不稳定性在许多自然重联系统中的作用,在触发大范围自然等离子体的快速重联时应加以考虑,这些自然等离子体具有无碰撞、可压缩的流动,包括在地球磁鞘和磁尾以及在日球顶、在吸积盘以及在湍流高马赫数无碰撞激波中。

英文摘要:

Magnetic reconnection can explosively release magnetic energy when opposing magnetic fields merge and annihilate through a current sheet, driving plasma jets and accelerating non-thermal particle populations to high energy, in plasmas ranging from space and astrophysical to laboratory scales. Through laboratory experiments and spacecraft observations, significant experimental progress has been made in demonstrating how fast dissipation and reconnection occurs in narrow, kinetic-scale current sheets. However, a challenge has been to demonstrate what triggers reconnection and how it proceeds rapidly and efficiently as part of a global system much larger than these kinetic scales. Here we show experimentally the full development of a process where the current sheet forms and then breaks up into multiple current-carrying structures at the ion kinetic scale. The results are consistent with tearing of the current sheet, however modified by collisionless kinetic ion effects, which leads to a larger growth rate and number of plasmoids than observed in previous experiments or compared to predictions from standard tearing instability theory and previous non-linear kinetic reconnection simulations. This effect will increase the role of plasmoid instabilities in many natural reconnection systems and should be considered in triggering rapid reconnection in a broad range of natural plasmas with collisionless, compressible flows, including at the Earth's magnetosheath and magnetotail and at the heliopause, in accretion disks, and in turbulent high-Mach-number collisionless shocks.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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