MODEL FOR SOLAR RADIO PULSATIONS AT SHORT CENTIMETRIC BAND

In this paper, the observed solar radio pulsations during the bursts a t 9.375 GHz are considered to be excited by some plasma instability. U nder the condition of the conservation of energy in the wave-particle interaction, the saturation time of plasma instabilities is inversely proportional to the initial radiation intensity, which may explain why the repetition rate of the pulsations is directly proportional to the radio burst flux at 9.375 GHz as well as 15 GHz and 22 GHz. It is als o predicted that the energy released in an individual pulse increases with increasing the flux of radio bursts, the modularity of the pulsat ions decreases with increasing the flux of radio bursts, these predict ions are consistent with the statistical results at 9.375 GHz in diffe rent events. The energy density of the non-thermal particles in these events is estimated from the properties of pulsation. For the typical values of the ambient plasma density (10(9) cm(-3)) and the ratio betw een the nonthermal and ambient electrons (10(-4)), the order of magnit ude of the energy density and the average energy of the nonthermal ele ctrons is 10(-4) erg/cm(3) and 10 kev, respectively. It is interesting that there are two branches in a statistical relation between the rep etition rate and the radio burst flux in a special event on March 11-1 7, 1989, which just corresponds to two different orders of magnitude f or the 'quasi-quantized' energy released in these five bursts. This re sult may be explained by the different ratios between the thermal and the nonthermal radiations.