Surfatron acceleration of ions by fast magnetosonic shocks generated during two current loops' coalescence

We investigate the coalescence process of two parallel current loops with cohelicity by using the two-dimensional, electromagnetic, relativistic particle-in-cell code. We found that in a later stage of the two current loops' coalescence, fast magnetosonic waves are generated as a result of rebound of the coalescence, and they develop to shock waves propagating away from the coalesced loops. We also found that near the fast magnetosonic shock front the ions can be promptly accelerated by the surfatron acceleration mechanism. We apply the obtained simulation results to the proton acceleration during solar flares.