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arXiv 1806.08669physics.space-phastro-ph.EP
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准平行激波下游粘性结构和动力学慢波的二维混合模拟

Two-dimensional hybrid simulations of filamentary structures and kinetic slow waves downstream of a quasi-parallel shock

Yufei Hao, Quanming Lu, Xinliang Gao, Huanyu Wang, De-Jin Wu, Shui Wang

摘要:

本文采用二维混合模拟方法,研究了准平行激波下游粘性结构的产生机制。结果表明,下游磁场幅值和粒子数密度均呈现出明显的分形结构,磁场与粒子数密度呈负相关关系。详细分析发现,这些下游压缩波几乎垂直于磁场传播,且主要波数约为离子动力学标度的倒数。它们的平行和垂直分量大致满足(其中和分别表示磁场的平行分量和面内垂直分量,是垂直方向上的波数,是离子回旋半径上的波数),它们的阿尔芬比也大致符合解析关系式(其中和表示阿尔芬比率和血浆β),而相应的交叉螺旋度和压缩性与以前的理论计算结果吻合得很好。所有这些性质与动力学慢波(KSW)的性质是一致的。因此,我们认为准平行激波下游的边界结构是由于KSW的激发而产生的。

英文摘要:

In this paper, with two-dimensional (2-D) hybrid simulations, we study the generation mechanism of filamentary structures downstream of a quasi-parallel shock. The results show that in the downstream both the amplitude of magnetic field and number density exhibit obvious filamentary structures, and the magnetic field and number density are anticorrelated. Detailed analysis find that these downstream compressive waves propagate almost perpendicular to the magnetic field, and the dominant wave number is around the inverse of ion kinetic scale. Their parallel and perpendicular components roughly satisfies(where and represent the parallel and in-plane perpendicular components of magnetic field, is the wave number in the perpendicular direction, and in the ion gyroradius), and their Alfven ratio also roughly agree with the analytical relation (where and indicate the Alfven ratio and plasma beta), while the corresponding cross helicity and compressibility show good agreement with previous theoretical calculations. All these properties are consistent with those of kinetic slow waves (KSWs). Therefore, we conclude that the filamentary structures in the downstream of a quasi-parallel shock are produced due to the excitation of KSWs.

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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