ИСТИНА

Using the appropriate kinetic equation, we considered the problem of propagation of accelerated electrons into the solar corona and chromosphere. Its analytical solution was used for modeling the M7.7 class limb flare occurred on 19th July 2012. Coronal above-the-loop-top Hard X-Ray (HXR) source was interpreted in the thin-target approximation, the foot-point source – in the thick-target approximation with account of the reverse-current electric field. For the foot-point source we found a good accordance with the RHESSI observations. For the coronal source we also got very accurate estimate of the power-law spectral index, but significant differences between the modeled and observed HXR intensities were noticed. The last discrepancy was solved by adding the coronal magnetic trap model to the thin target model. The former one implies that the trap collapses in two dimensions, locks and accelerates particles inside itself. It this theoretically well-studied model, two acceleration mechanisms do work very well: the Fermi first-order acceleration and the betatron heating of fast electrons. In our report, we confirm an existence and high efficiency of the electron acceleration in collapsing magnetic traps during solar flares. Our new results represent (e.g. for RHESSI observations) the theoretical prediction of the two-step particle acceleration in solar flares, when the first step is the acceleration in reconnection area and the second one – the acceleration in coronal trap.