Characteristics of the impulsive phase of flares

Abstract

The impulsive phase of flares is an observational concept, characterized by spiky emissions from v-rays to radio waves. It is generally agreed that during this time a large fraction of the original flare energy resides in energetic particles which are manifested in these emissions. Here we concentrate on recent decimeter and microwave observations that indicate a high level of fragmentation of this energy release when related to hard X-ray (HXR) flux. Recent attempts to characterize the flare and the distribution of the radio bursts in time and frequency by statistical methods are also reviewed.