Periodic acceleration of electrons in the 1998 November 10 solar flare

We present an examination of the multiwavelength observation of a C7.9 flar e that occurred on 1998 November 10. This is the first imaging observation of the quasi-periodic pulsations (QPPs). Four bursts were observed with the hard X-ray telescope aboard Yohkoh and the Nobeyama Radioheliograph during the impulsive phase of the flare. In the second burst, the hard X-ray and microwave time profiles clearly showed a QPP. We estimated the Alfven trans it time along the flare loop using the images of the soft X-ray telescope a board Yohkoh and the photospheric magnetograms and found that the transit t ime was almost equal to the period of the QPP. We therefore suggest, based on a shock acceleration model, that variations of macroscopic magnetic stru ctures, such as oscillations of coronal loops, affect the efficiency of par ticle injection/acceleration.