Anisotropy of solar wind turbulence between ion and electron scales.
Anisotropy of solar wind turbulence between ion and electron scales.
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DOI：
10.1103/physrevlett.104.255002
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发表时间：
2010-02
影响因子：
8.6
通讯作者：
C. Chen;T. Horbury;A. Schekochihin;R. Wicks;O. Alexandrova;J. Mitchell
中科院分区：
文献类型：
--
作者：
C. Chen;T. Horbury;A. Schekochihin;R. Wicks;O. Alexandrova;J. Mitchell
利用多航天器分析技术直接观测到了快速太阳风中离子和电子回旋尺度之间湍流的各向异性。针对垂直和平行于平均磁场的磁涨落，计算了与局地磁场呈不同角度的二阶结构函数。在这两个分量中，与磁场呈大角度的结构函数值\(S_{\perp}\)大于小角度的\(S_{\parallel}\)：在垂直分量中\(S_{\perp} / S_{\parallel}=5\pm1\)，在平行分量中\(S_{\perp} / S_{\parallel}>3\)，这意味着空间上存在各向异性涨落，\(k_{\perp}>k_{\parallel}\)。垂直分量在大角度时的谱指数为\(-2.6\)，在小角度时为\(-3\)，这与临界平衡的哨声波和动力学阿尔文波的预测大致相符。然而，对于平行分量，其谱指数比\(-1.9\)更平缓，比动力学阿尔文波级联所预测的要平缓得多。
The anisotropy of turbulence in the fast solar wind, between the ion and electron gyroscales, is directly observed using a multispacecraft analysis technique. Second order structure functions are calculated at different angles to the local magnetic field, for magnetic fluctuations both perpendicular and parallel to the mean field. In both components, the structure function value at large angles to the field S{⊥} is greater than at small angles S{∥}: in the perpendicular component S{⊥}/S{∥}=5±1 and in the parallel component S{⊥}/S{∥}>3, implying spatially anisotropic fluctuations, k{⊥}>k{∥}. The spectral index of the perpendicular component is -2.6 at large angles and -3 at small angles, in broad agreement with critically balanced whistler and kinetic Alfvén wave predictions. For the parallel component, however, it is shallower than -1.9, which is considerably less steep than predicted for a kinetic Alfvén wave cascade.