Würzburg 2018 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 8: Poster Session
EP 8.11: Poster
Mittwoch, 21. März 2018, 17:00–18:30, BSZ - Pabel HS
Electron acceleration by turbulent plasmoid reconnection — •Xiaowei Zhou1,2, Jörg Büchner1, Fabian Widmar3, and Patricio Munoz1 — 1MPI for Solar System Research, Göttingen, Germany — 2Purple Mountain Observatory, Nanjing, China — 3CEA, IRFM, France
In space and astrophysical plasmas, e.g., in planetary magnetospheres, energetic electrons are often found near current sheets (CSs). The observation of CSs hints at electron acceleration by magnetic reconnection. In this study, we aim to investigate electron acceleration by turbulent plasmoid reconnection via test particle guiding center calculations together with MHD simulations. In order to avoid to resolve scales beyond the grid resolution of MHD simulations, a mean-field turbulence model is used to describe the turbulence in the sub-grid scales and their effects on the grid-scale dynamics via turbulent electromotive force(EMF). In particular, the mean-fields model we consider in this study describes the turbulent EMF as a function of the mean values of current density, vorticity, magnetic field as well as of the energy, cross-helicity and residual helicity of the turbulence. We found that, around X-points of turbulent reconnection, localized strong EMFs cause enhanced electron acceleration and energetic electrons following power-law spectra. Magnetic-field-aligned EMFs, caused by the turbulence, dominate the electron acceleration process. Scaling the acceleration processes to parameters of, e.g., the Hermean magnetotail, electron energies up to 60 keV can be reached out of the thermal plasma.