Solar wind turbulent spectrum at plasma kinetic scales

Abstract

The description of the turbulent spectrum of magnetic fluctuations in the solar wind in the kinetic range of scales is not yet completely established. Here, we perform a statistical study of 100 spectra measured by the STAFF instrument on the Cluster mission, which allows to resolve turbulent fluctuations from ion scales down to a fraction of electron scales, i.e. from $\sim 10^2$ km to $\sim 300$ m. We show that for $k_{\perp }{\rho }_e\in [0.03,3]$ (that corresponds approximately to the frequency in the spacecraft frame $f\in [3,300]$ Hz), all the observed spectra can be described by a general law $E(k_{\perp })\propto k_{\perp }^{-8/3}\exp (-k_{\perp }{\rho }_e)$, where $k_{\perp }$ is the wave-vector component normal to the background magnetic field and ${\rho }_e$ the electron Larmor radius. This exponential tail found in the solar wind seems compatible with the Landau damping of magnetic fluctuations onto electrons.

published in APJ, 15 of November 2012 (with reduced "Discussion" section)

References in corpus (2)

• Small Scale Energy Cascade of the Solar Wind Turbulence
• Multi-scale Hall-MHD turbulence in the solar wind

Cited by in corpus (5)

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• Forward Modeling of Reduced Power Spectra From Three-Dimensional k-Space