A UNIVERSAL LAW FOR SOLAR-WIND TURBULENCE AT ELECTRON SCALES
A UNIVERSAL LAW FOR SOLAR-WIND TURBULENCE AT ELECTRON SCALES
复制标题
电子尺度太阳风湍流的普遍定律
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
S. Galtier
中科院分区：
文献类型：
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作者：
R. Meyrand;S. Galtier
行星际磁涨落谱在质子惯性长度和陀螺半径以上的尺度上服从柯尔莫哥洛夫幂律，这被认为是惯性范围。在这些尺度以下，经常测量到 -2.5 左右的幂律指数，并且与非线性色散过程相关。最近的观察揭示了电子惯性长度以下尺度的第三个区域。该区域的特点是频谱较陡，有些人将其称为耗散范围。我们研究了电子磁流体动力学近似中的这个尺度范围，并导出了三阶结构函数的精确且普遍的定律。该定律可以预测指数为-11/3的磁涨落谱，与最小尺度下观测到的谱一致。我们得出的结论是，太阳风中可能存在第三种湍流状态，而不是最近假设的耗散范围。
The interplanetary magnetic fluctuation spectrum obeys a Kolmogorovian power law at scales above the proton inertial length and gyroradius which is well regarded as an inertial range. Below these scales, a power-law index around −2.5 is often measured and associated with nonlinear dispersive processes. Recent observations reveal a third region at scales below the electron inertial length. This region is characterized by a steeper spectrum that some refer to as the dissipation range. We investigate this range of scales in the electron magnetohydrodynamic approximation and derive an exact and universal law for a third-order structure function. This law can predict a magnetic fluctuation spectrum with an index of −11/3 which is in agreement with the observed spectrum at the smallest scales. We conclude on the possible existence of a third turbulence regime in the solar wind instead of a dissipation range as recently postulated.