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Article Dans Une Revue Planetary and Space Science Année : 2007

Solar wind Cluster observations: Turbulent spectrum and role of Hall effect

Résumé

Turbulent spectrum of magnetic fluctuations in the solar wind nearly follows Kolmogorov's law ˜f below the ion cyclotron frequency fci. Above this frequency, the observed steeper power law is believed to be a 'dissipative range' of the solar wind turbulence. In this paper we analyze magnetic field fluctuations measured onboard Cluster, lasting two decades above fci. Well-defined power law and a strong increase of intermittency with frequency in this range indicates that turbulence cannot be characterized by a 'dissipative range'. Rather we conjecture that above fci the turbulence is generated by a different nonlinear cascade. We suggest that the presence of dispersive effects is responsible for a steepening of the spectral energy density, simply because a cascade can be realized in a time that is shorter than the usual eddy-turnover time. In the Hall MHD formulation, the magnetic power follows a law ˜f, which depends on the degree of plasma compressibility alpha.
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Dates et versions

hal-03733407 , version 1 (21-07-2022)

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Olga Alexandrova, Vincenzo Carbone, Pierluigi Veltri, L. Sorriso-Valvo. Solar wind Cluster observations: Turbulent spectrum and role of Hall effect. Planetary and Space Science, 2007, 55, pp.2224-2227. ⟨10.1016/j.pss.2007.05.022⟩. ⟨hal-03733407⟩
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