ESA Science & Technology - Three dimensional anisotropic k spectra of turbulence at subproton scales in the solar wind

Publication date: 28 September 2010

Authors: Sahraoui, F. et al.

Journal: Physical Review Letters
Volume: 105
Issue: 13
Page: 131101-[4 pages]
Year: 2010

Copyright: The American Physical Society

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 w_plas below 0.1w_ci down to k_perpRho_i ~ 2. Each k spectrum in the direction perpendicular to B_o shows two scaling ranges separated by a breakpoint (in the interval [0.4, 1]k_perpRho_i): a Kolmogorov scaling k_perp^-1.7 followed by a steeper scaling k_perp^-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.