Correlation between hard and soft X-ray bursts and small-scale acceleration processes during the rise phase of solar flares

Abstract

Soft and hard X-ray flare bursts were compared during the rise phase of solar flares of moderate importance. The analysis shows that plasma heating in the flare region has two components: permanent heating (like Joule dissipation) and impulsive heating coinciding with relatively short hard X-ray bursts. It is shown that during the primary energy release phase the most probable mechanism of energy release is acceleration of charged particles in direct electric fields. Particles are accelerated within small regions where these fields are excited. Characteristics of such regions are obtained in the paper.