Stochastic Fermi Energization of Coronal Plasma during explosive magnetic energy release

Abstract

The aim of this study is to analyze the interaction of charged particles (ions and electrons) with randomly formed particle scatterers (e.g.\ large scale local "magnetic fluctuations" or "coherent magnetic irregularities"), using the set up proposed initially by \cite{Fermi49}. These scatterers are formed by the explosive magnetic energy release and propagate with the Alfvén speed along the irregular magnetic fields. They are large scale local fluctuations ($\delta B/B\approx 1$), randomly distributed inside the unstable magnetic topology and will here be called {\bf Alfvénic Scatterers (AS)}. We constructed a 3D grid on which a small fraction of randomly chosen grid points are acting as AS. In particular, we study how a large number of test particles evolve inside a collection of AS, analyzing the evolution of their energy distribution and their escape time distribution. We use a well established method to estimate the transport coefficients directly from the trajectories of the particles. Using the estimated transport coefficients and solving the Fokker-Planck (FP) equation numerically, we can recover the energy distribution of the particles. We have shown that the Stochastic Fermi Energization (SFE) of mildly relativistic and relativistic plasma can heat and accelerate the tail of the ambient particle distribution as predicted by \citet{Parker58} and \citet{Ramaty79}. The temperature of the hot plasma and the tail of the energetic particles depend on the mean free path (${\lambda }_{\mathrm{sc}}$) of the particles between the scatterers inside the energization volume.

arXiv comment30 pages, 25 figures. Accepted for publication in the Astrophysical Journal (2016)

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Cited by in corpus (9)

• Sources of Solar Energetic Particles
• Particle Acceleration and Fractional Transport in Turbulent Reconnection
• Particle Acceleration and Heating in a Turbulent Solar Corona
• Superdiffusive Stochastic Fermi Acceleration in Space and Energy
• Two-stage electron acceleration by 3D collisionless guide field magnetic reconnection
• Stochastic Turbulent Acceleration in a fractal environment
• Synergy of stochastic and systematic energization of plasmas during turbulent reconnection
• Particle heating and acceleration by reconnecting and non-reconnecting Current Sheets
• Diffusive Shock Acceleration and Turbulent Reconnection