Energy Release Mechanism of Solar Flares:
Nonsteady Fast Reconnection Induced by Plasmoid Ejections and 
Associated Particle Acceleration

K. Shibata (Kwasan Obs., Kyoto Univ.)

We first review recent development of observations of the impulsive phase of 
solar flares, with particular attention on plasmoid ejections and associated 
particle acceleration. These observations suggest that the reconnection in the 
impulsive phase of solar flares, often called impulsive bursty reconnection, 
is induced by plasmoid ejections in a highly time dependent manner, indicating 
fractal-like time variation, and such fractal-like nonsteadiness of dynamics 
may have a key to understand the mechanism of fast reconnection and associated 
particle acceleration. Recent development of related theories/simulations is 
also briefly discussed. Finally, we discuss a future plan of observations of 
solar flares at Hida Observatory of Kyoto University, which aims at observation
s with a high time and high spatial resolutions using adaptive optics 
instruments. Collaboration of such newly developed ground-based observations 
and Solar B mission would reveal particle acceleration site, basic physics of 
chromospheric evaporation, and the role of plasmoid ejections in fast 
reconnection.