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arXiv 0711.4355astro-ph
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磁化Turbulence在天体物理等离子体中的动力学模拟

Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas

G. G. Howes, W. Dorland, S. C. Cowley, G. W. Hammett, E. Quataert, A. A. Schekochihin, T. Tatsuno

摘要:

这封信提出了第一个从头算,完全电磁,在一个均匀的,弱碰撞等离子体中的磁化湍流的动力学模拟在离子拉莫尔半径(离子陀螺仪)的规模。磁场和电场能谱显示在离子陀螺标处有一个断裂;谱斜率与离子陀螺标上方阿尔芬波(谱指数为-5/3)和离子陀螺标下方动力阿尔芬波(谱指数为-7/3的磁波动和-1/3的电波动)的临界平衡湍流的标度预测一致。这种行为也与太阳风中湍流的现场测量定性一致。我们的研究结果支持这样的假设,即太阳风中的湍流波动的频率保持远低于离子回旋频率以上和以下的离子陀螺仪。

英文摘要:

This letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion gyroscale). Magnetic and electric-field energy spectra show a break at the ion gyroscale; the spectral slopes are consistent with scaling predictions for critically balanced turbulence of Alfven waves above the ion gyroscale (spectral index -5/3) and of kinetic Alfven waves below the ion gyroscale (spectral indices of -7/3 for magnetic and -1/3 for electric fluctuations). This behavior is also qualitatively consistent with in situ measurements of turbulence in the solar wind. Our findings support the hypothesis that the frequencies of turbulent fluctuations in the solar wind remain well below the ion cyclotron frequency both above and below the ion gyroscale.

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