A model of the bifurcated current sheet
A model of the bifurcated current sheet
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DOI：
10.1029/2003gl017218
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发表时间：
2003-07
影响因子：
5.2
通讯作者：
M. Sitnov;P. Guzdar;M. Swisdak
中科院分区：
文献类型：
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作者：
M. Sitnov;P. Guzdar;M. Swisdak
最近的Geotail和Cluster观测显示，近地尾巴中的薄电流片可能具有分叉结构。在某些情况下，发现电子在电流中占支配地位。我们提出了一个概括的哈里斯电流片平衡，再现这些功能。模型离子分布包含一个额外的元素，即离子在片上运动的准绝热不变量，并假设片外的离子温度各向异性。分叉电流片出现在小离子各向异性的情况下，T i > T i（煎饼分布）。在相反的情况下（雪茄分布），该模型描述了嵌入较厚哈里斯片中的单峰值离子主导电流片，这与deHoffman-Teller框架中无碰撞重联模式的流出区域更相关。
Recent Geotail and Cluster observations revealed that thin current sheets in the near‐Earth tail may have a bifurcated structure. In some cases the electrons are found to dominate the current. We present a generalization of the Harris current sheet equilibrium, which reproduces these features. The model ion distribution contains an additional element, viz. the quasi‐adiabatic invariant of the ion motion across the sheet, and assumes ion temperature anisotropy outside the sheet. Bifurcated current sheets appear in the case of small ion anisotropy with T⟂i > T∥i (pancake distributions). In the opposite case (cigar distributions) the model describes a single‐peaked ion‐dominated current sheet embedded in a thicker Harris sheet, which is more relevant to the outflow region of the collisionless reconnection pattern in the deHoffman‐Teller frame.