arXiv 0912.26682009-12-14physics.space-phphysics.plasm-ph

从MHD到电子尺度的太阳风湍流谱

Solar wind turbulent spectrum from MHD to electron scales

O. Alexandrova, J. Saur, C. Lacombe, A. Mangeney, S. J. Schwartz, J. Mitchell, R. Grappin, P. Robert

备注：: to be published in "Solar Wind 12 Proceedings", AIP Conference Proceedings, 2010
DOI：: 10.1063/1.3395821

摘要：

利用星团观测，从MHD到电子尺度研究了自由太阳风中磁涨落的湍流谱。我们讨论了电子尺度下的仪器噪声及其对测量的影响。我们确认的频谱$\sim \exp{\sqrt{kρ_e}}$在宽频率范围$\sim[10,100]$ Hz的曲率的存在下，表示存在的耗散。在不同的等离子体条件下的七个光谱的分析清楚地表明，在MHD和离子尺度的准普适幂律谱的存在。然而，从惯性范围$\sim k^{-1.7}$到离子标度$\sim k^{-2.7}$的光谱的转变不是普遍的。最后，我们讨论了不同的动力学等离子体尺度上的光谱形状的作用，考虑归一化的无量纲光谱。

英文摘要：

Turbulent spectra of magnetic fluctuations in the free solar wind are studied from MHD to electron scales using Cluster observations. We discuss the problem of the instrumental noise and its influence on the measurements at the electron scales. We confirm the presence of a curvature of the spectrum $\sim \exp{\sqrt{kρ_e}}$ over the broad frequency range $\sim[10,100]$ Hz, indicating the presence of a dissipation. Analysis of seven spectra under different plasma conditions show clearly the presence of a quasi-universal power-law spectrum at MHD and ion scales. However, the transition from the inertial range $\sim k^{-1.7}$ to the spectrum at ion scales $\sim k^{-2.7}$ is not universal. Finally, we discuss the role of different kinetic plasma scales on the spectral shape, considering normalized dimensionless spectra.

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