TWO-STAGE PARTICLE ACCELERATION IN SOLAR FLARES

摘要

The acceleration of protons and electrons by the electric field of a non-neutral current sheet with the following scattering on MHD turbulence is considered. The DC electric field in the top of the corona generates rather coherent electron or protons beams which are being separated at the ejection into the opposite semi-spaces of the X-component of a transverse magnetic field. Further scattering on the phase mixed Alfven waves occurring while the protons precipitate into deeper atmosphere towards the footpoints produces a complicated proton beam energy spectra with a power-law part from the energies of 100 KeV up to 100 MeV and the exponential part for higher energies (up to 20 GeV). The assessment of the electron and proton beams precipitation times into footpoints was compared with the asymmetry in hard X-ray emission from the footpoints of the 20 July '02 flare observed with RHESSI.