Abstract
The results of an analysis of 25 impulsive solar flares, observed simultaneously with the Nobeyama Radioheliograph
and the Yohkoh satellite, are presented. From the relative locations of microwave, hard X-ray, and soft X-ray
sources, we have found that, for half out of the 25 analyzed events, at least two loops are involved. Typical sizes of
the two loops are different from each other; one is typically <= 20′′ and the other
30′′-80′′. These observations suggest that in the majority of impulsive flare events two
loops interact with each other, releasing magnetic energy and producing energetic electrons. We have analyzed 2 out
of the 25 events in detail and find that a triple source structure corresponding to footpoints of the short and long loops
are related by a single event. An analysis of HXT flux spectra and time profiles of these footpoint sources suggests
that in these events trapping and diffusion of the high energy electrons in the loops play dominant rolls.