Power and spectral index anisotropy of the entire inertial range of turbulence in the fast solar wind
By Robert T. Wicks, T. Horbury, C. Chen, A. Schekochihin. 2010
145 citations recorded by the source corpus.
We measure the power and spectral index anisotropy of magnetic field fluctuations in fast solar wind turbulence from scales larger than the outer scale down to the ion gyroscale, thus covering the entire inertial range. We show that the power and spectral indices above the outer scale of turbulence are approximately isotropic. The turbulent cascade causes the power anisotropy at smaller scales manifested by anisotropic scalings of the spectrum: close to k−5/3 across and k−2 along the local magnetic field, consistent with a critically balanced Alfvenic turbulence. By using data at different radial distances from the Sun and calculating the radial dependence of the ratio of the outer scale to the ion gyroscale, we show that the width of the inertial range does not change with heliocentric distance. At the smallest scales of the inertial range, close to the ion gyroscale, we find an enhancement of power parallel to the magnetic field direction coincident with a decrease in the perpendicular power. This is most likely related to energy injection by ion kinetic modes such as the firehose instability and also marks the beginning of the kinetic range, sometimes called the dissipation range, of solar wind turbulence.
Subfields: Artificial Intelligence, Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics
View Paper: https://www.semanticscholar.org/paper/5be2f9aa21a23058358072bd0fbdbffe3daadf73
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Citations in the corpus
- Solar Wind Turbulence and the Role of Ion Instabilities (2013, methodology): “The same figure as a function of kρi can be found in Wicks et al. (2010) AU from the Sun).”
- Recent progress in astrophysical plasma turbulence from solar wind observations (2016, background): “10 −3, where ρi is the ion gyroradius) the turbulence is isotropic (Wicks et al. 2010) with δB/B0 ∼ 1, and in the inertial range (10−3 . kρi .”