MHD and kinetic modelling of particle acceleration during forced magnetic reconnection
Mykola Gordovskyy
University of Manchester
P.K. Browning (University of Manchester)
In solar flares, particles are likely to be accelerated by electric fields in large scale reconnecting current sheets. Current sheets are expected to be very thin, with the thickness of about few ion Larmor radii, and, hence, kinetic effects can play an important role.

In this study we consider particle acceleration in 2D current sheets with very different parameters, in order to demonstrate the difference between particle acceleration in MHD and kinetic models. This is done based on the forced magnetic reconnection scenario, where reconnection results from tearing instability caused by external boundary perturbation. Three possible physical regimes are investigated. In models (a) and (b) test-particle trajectories are considered based on single- and two-fluid MHD simulations, respectively. In model (c) particle motion is described self-consistently with field evolution using particle-in-cell code.

Based on these results, we compare different features of particle acceleration in these three regimes, including energy and pitch-angle spectra. In particular, we focus on geometry of particle acceleration and show that there may be two different populations of high-energy particles and, also, that ions and electrons may have preferential acceleration directions.