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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Nature of axial tail instability and bubble-blob formation in near-Earth plasma sheet
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Nature of axial tail instability and bubble-blob formation in near-Earth plasma sheet

机译：轴向的尾巴不稳定和bubble-blob的性质形成近地等离子板

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Previous global magnetohydrodynamic (MHD) simulations of substorm events have identified the dynamic presence of an axial tail instability that is uniform in the dawn-dusk direction in the near-Earth plasma sheet. The axial tail instability is found to be a major cause of the initial growing MHD force imbalance on closed field lines prior to the subsequent magnetic reconnection and substorm expansion onset processes. In this work, energy principle analysis indicates that a two-dimensional thin current sheet configuration in the magnetotail is typically stable to the axial mode within the framework of ideal MHD model. However, linear resistive MHD calculations find axial tail instabilities on closed field lines in the generalized Harris sheet configurations. The properties of these instabilities are similar to the axial tail modes observed in the global MHD simulations. The axial tail mode is unstable in regimes of low Lundquist number and regions with small normal component of magnetic field. Such resistive axial tail instability would by many researchers be considered as tearing instability in a two-dimensional tail configuration. Unlike the conventional tearing mode of Harris sheet, the linear axial tail instability does not involve any reconnection process. Instead, the nature of the mode is dominantly a slippage process among neighboring flux tubes as facilitated by resistive dissipation. A natural consequence of the axial tail instability is shown to be the formation of bubble-blob pairs in the pressure and entropy profiles in the near-Earth plasma sheet. Key Points Axial tail instability leads to formation of entropy bubble-blob structuresLinear axial tail instability does not involve magnetic reconnection processLinear axial tail instability is a resistive slippage process
机译：前全球磁流体动力(磁流体动力)已经确定了模拟亚暴事件尾巴的动态存在轴向不稳定这是统一在dawn-dusk方向近地等离子板。发现不稳定的主要原因初始发展磁流体动力力不平衡在关闭电场线前后续磁重新连接和亚暴开始扩张流程。分析表明,二维薄在磁尾电流片配置一般稳定的内轴向模式理想磁流体动力模型的框架。找到轴向电阻磁流体动力计算的尾巴不稳定的封闭电场线哈里斯广义表的配置。这些不稳定的性质是相似的尾轴向模式中观察到全球磁流体动力模拟。低伦德奎斯特数和地区的政权小磁场的正常组成部分。电阻轴尾部不稳定会很多研究人员被视为撕裂不稳定性在一个二维的尾巴配置。传统的哈里斯,撕裂模线性轴向尾巴不稳定不涉及任何重联过程。模式的本质主要是滑移过程中相邻磁流管中通过电阻耗散。轴向的尾巴不稳定的结果证明是bubble-blob对的形成下压力和熵的特性近地等离子板。不稳定导致熵的形成bubble-blob structuresLinear轴向的尾巴不涉及磁不稳定性重新连接processLinear尾轴向不稳定是一个电阻滑动的过程吗

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