Three Dimensional Anisotropic k Spectra of Turbulence at Subproton Scales in the Solar Wind
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Sahraoui, F., M. L. Goldstein, G. Belmont, P. Canu, and L. Rezeau. “Three Dimensional Anisotropic $k$ Spectra of Turbulence at Subproton Scales in the Solar Wind.” Physical Review Letters 105, no. 13 (September 23, 2010): 131101. https://doi.org/10.1103/PhysRevLett.105.131101.
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
We show the first three dimensional (3D) dispersion relations and k spectra of magnetic turbulence in the solar wind at subproton scales. We used the Cluster data with short separations and applied the k-filtering technique to the frequency range where the transition to subproton scales occurs. We show that the cascade is carried by highly oblique kinetic Alfvén waves with ωₚₗₐₛ≤ 0.1 ωcᵢ down to k⊥ρᵢ∼ 2. Each k spectrum in the direction perpendicular to B₀ shows two scaling ranges separated by a breakpoint (in the interval [0.4,1]k⊥ρᵢ): a Kolmogorov scaling k⊥⁻¹.⁷ followed by a steeper scaling ∼k⊥⁻⁴.⁵. We conjecture that the turbulence undergoes a transition range, where part of the energy is dissipated into proton heating via Landau damping and the remaining energy cascades down to electron scales where electron Landau damping may predominate.