Observational Evidence for Solar Radio Microflares with Unusual Characteristics

A very rare type of solar radio microf lares occurred during 0645～0720 UT on Jan.5, 1994 is introduced in this paper.The radio and optical characteristics of the solar microf lares of a short decimetric wave (1.42 GHz)are discussed.This event co ntains 53 radio fast fine structures (FFS), that is, 53 intermittently periodic impulset rains with similar morphologies superimposed on the continuum radiation backg round.The intensities of the pulses lie within 150～200s.f.u. and the durations (half power width)are of the order of 10～50 milliseconds (ms).18 out of 53 FFSs are doublepeak-separating structures. In this paper we try to discuss the generation mechanism qualitatively and find it is in consistence with the model of current loop explosive coalescence (Sakai and De Jager, 1989a, 1989b): the explosive coalescence of the multiple of cross magnetic flux loops causes the plasma disturbance and so rapidly transform the magnetic energy into the kinetic energy of electrons.