Bochum 2015 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 12: Helmholtz Graduate School for Plasma Physics I

P 12.3: Fachvortrag

Dienstag, 3. März 2015, 14:50–15:15, HZO 50

Dissipation processes in turbulent plasmas: Hybrid Vlasov-Maxwell simulations — •Silvio Sergio Cerri¹, Francesco Califano², Frank Jenko³, and Francesco Pegoraro² — ¹Max Planck Institute for Plasma Physics, Garching, Germany — ²Physics Dept., Univ. of Pisa, Italy — ³Dept. of Physics and Astronomy, Univ. of California Los Angeles, USA

Turbulence is an ubiquitous phenomenon observed in laboratory, space and astrophysical collisionless plasmas where kinetic effects do play a fundamental role by affecting the turbulent spectrum. In particular, these effects come into play as soon as the ion Larmor scale is approached by the turbulent cascade, entering the so-called dissipation range, on which recent and on-going satellite measurements in the solar wind have focused their attention. This first transition from fluid to ion kinetic turbulence is our main focus. We use a hybrid Vlasov-Maxwell approach (Vespa code) where ions are treated as kinetic and electrons are assumed as a neutralising background massless fluid.

We present a high-resolution numerical study of 2D3V magnetised driven turbulence and a survey of similarities and differences between various regimes is given. One of the main result is the formation of strong current sheets where magnetic reconnection occurs within a turbulent environment. The reconnection events represent a fundamental transition for what concerns the nature of the turbulence as represented by the slope of power-law energy spectra, here covering more than two decades in wave numbers. We also show the formation of plasmoid chains and shocks structures.