Multiscale Hall-Magnetohydrodynamic Turbulence in the Solar Wind
Multiscale Hall-Magnetohydrodynamic Turbulence in the Solar Wind
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DOI：
10.1086/510423
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发表时间：
2006-10
期刊：
影响因子：
--
通讯作者：
S. Galtier;É. Buchlin
中科院分区：
文献类型：
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作者：
S. Galtier;É. Buchlin
太阳风磁涨落的频谱在频率f>；1赫兹处呈现出显著的幂函数陡化。用色散霍尔磁流体动力学方法研究了这种多重标度的成因。我们在一个高湍流壳模型的框架下进行了三维数值模拟，结果表明，大尺度磁涨落的特征是k-5/3型谱，该谱在小于离子惯性长度di的尺度上变陡，如果磁能超过动能则变陡到k-7/3，反之则变陡到k-11/3。这些结果既与科尔莫戈罗夫式的启发式描述一致，也与太阳风中发现的幂定律指数范围一致。
The spectra of solar wind magnetic fluctuations exhibit a significant power-law steepening at frequencies f > 1 Hz. The origin of this multiple scaling is investigated through dispersive Hall magnetohydrodynamics. We perform three-dimensional numerical simulations in the framework of a highly turbulent shell model and show that the large-scale magnetic fluctuations are characterized by a k-5/3-type spectrum that steepens at scales smaller than the ion inertial length di, to k-7/3 if the magnetic energy overtakes the kinetic energy, or to k-11/3 in the opposite case. These results are in agreement both with a heuristic description à la Kolmogorov and with the range of power-law indices found in the solar wind.