Structure and Dynamics of Magnetic Fields in the Sun, Solar System and Beyond
2D MHD studies of forced reconnection & particle acceleration in solar flares
Max Potter
University of Manchester
There are many proposed mechanisms for particle acceleration in flares, but no single model is able to fully reproduce the range of observed spectra and fluxes from solar flares. It is therefore likely that there are multiple acceleration mechanisms operating as part of a multi-stage process.

Forced magnetic reconnection requires an external process as a trigger and thus operates as part of a chain of perturbative processes in the plasma. Furthermore, many studies of particle acceleration deal with steady reconnection, yet this is unlike the conditions in flares, which are transient event. Forced reconnection has three stages: perturbation to the equilibrium, initial reconnection to form a chain of magnetic islands, and finally the islands begin to coalesce and form ’monster’ islands. Previous studies of magnetic energy release and particle acceleration in flares have considered only the first two stages, but we now incorporate also coalescence.

To this end, we utilise 2D MHD simulations of forced magnetic reconnection using Lare2d with anomalous resistivity, and a long, periodic simulation domain which allows islands to move and coalesce. While forced reconnection models generally use a single sinusoidal disturbance, we consider the effect of multi-wavelength and localised disturbances, building towards more realistic models. The energy release and dynamics are investigated for different forms of external perturbations, focusing on the effects of merging magnetic islands. Test particles are introduced, allowing us to predict the energy spectra of non-thermal ions and electrons, as well as the spatial distributions and temporal evolution on non-thermal particle populations.


09:00 - 10:30
EX - LT1 (100)