Current singularities at finitely compressible three-dimensional magnetic null points
Current singularities at finitely compressible three-dimensional magnetic null points
复制标题
有限可压缩三维磁零点处的电流奇点
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
I. Craig
中科院分区：
文献类型：
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作者：
D. Pontin;I. Craig
研究了非电阻磁流体环境中二维和三维(分别为二维和三维)磁零点电流奇异性的形成。结果表明，尽管2D和3D零点的分界线结构不同，但电流奇点可以以形式上等价的方式启动。无论崩塌是由封闭的线系零点内的通量不平衡触发的，还是由开放的、不可压缩的几何图形中的外部施加的速度场驱动的，这都是正确的。用拉格朗日数值模拟程序研究了在二维和三维零点坍塌过程中产生奇异电流片的有限振幅扰动。分析了奇异电流分布形式作为零点空间各向异性的函数，并量化了有限气体压力的影响。文中指出，压力虽然不会阻止奇点的形成，但却显著地改变了奇点的形态。
The formation of current singularities at line-tied two- and three-dimensional (2D and 3D, respectively) magnetic null points in a nonresistive magnetohydrodynamic environment is explored. It is shown that, despite the different separatrix structures of 2D and 3D null points, current singularities may be initiated in a formally equivalent manner. This is true no matter whether the collapse is triggered by flux imbalance within closed, line-tied null points or driven by externally imposed velocity fields in open, incompressible geometries. A Lagrangian numerical code is used to investigate the finite amplitude perturbations that lead to singular current sheets in collapsing 2D and 3D null points. The form of the singular current distribution is analyzed as a function of the spatial anisotropy of the null point, and the effects of finite gas pressure are quantified. It is pointed out that the pressure force, while never stopping the formation of the singularity, significantly alters the morphology of the cu...