LESIA - Observatoire de Paris

Reduced Power Spectra of Critically Balanced Solar Wind Turbulence with Damping by Kinetic Alfvén Waves

mardi 25 octobre 2016, par Anne Schreiner (University of Cologne)

Jeudi 27 octobre 2016 à 11h00 , Lieu : Salle de conférence du bâtiment 17

Analytical dissipation models for solar wind turbulence are usually derived as a function of the perpendicular wavenumber, however, magnetic field fluctuations in the solar wind are mostly measured for angles between the mean magnetic field and the solar wind velocity less than 90°. Particularly for small field-to-flow angles, dissipation processes at electron scales influence the spectral scaling of the sub-ion range due to sampling effects, which occur in one-dimensional measurements where several different wavevectors contribute to the spectral energy density at a certain spacecraft frequency. To help better understand the physical mechanism of the dissipation process and its influence on the sub-ion range, we develop a three-dimensional dissipation model under the assumption of critically balanced turbulence and damping via wave-particle interactions of kinetic Alfvén waves obtained from linear Vlasov theory. From the three-dimensional energy distribution in k-space we calculate based on a forward modeling approach by von Papen & Saur (2015) reduced one-dimensional power spectra, which we compare to a set of spectral energy densities obtained from one- dimensional Cluster measurements by Alexandrova et al. (2012).

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