Electron acceleration in models with a vertical current sheet

Model of solar flares with a vertical current sheet and a cusp above the magnetic arcade is considered. In some flares, such magnetic field geometry can be observed directly in the extreme ultraviolet range. According to the model, the relaxation of helmet-like magnetic loops formed due to magnetic field reconnection is supposed. During the relaxation, the magnetic field and the loop length vary with time. Consequently, a betatron acceleration and first-order Fermi electron acceleration appeared. In a kinetic approach the time-dependent kinetic equation for the distribution function of initially accelerated electrons is numerically solved. It is shown that because of such acceleration, the electron energy spectra changes significantly. The proportion of high-energy electrons with energies of more than 200 keV increases by 1–3 orders of magnitude depending on the pitch-angular distribution of accelerated electrons formed in the primary accelerator – the current sheet.