EVIDENCE FOR A COMMON SOURCE OF FRAGMENTED DECIMETER EMISSION AND METER WAVE TYPE-II BURSTS IN SOME SOLAR-TYPE IV BURSTS

The paper presents facts of relevance for flare particle acceleration and shock wave excitation in the solar corona from a detailed analysis of meter wave (40 - 800 MHz OSRA Tremsdorf spectrograms) and microwav e data (3.1 - 50 GHz polarimeter records Bern University) of several t ype IV bursts. We argue for a slowly uprising (about 0.1 of the local Alfven speed) quasi-periodically acting (1... 3 min period) accelerato r in the 10(11)...10(9) cm-3 density region. It produces particles emi tting patches of fragmented decimetric/metric radio emission. One of t he quasi-periodically appearing patches is associated with the microwa ve burst emission, the same (or a later, lower frequency one) immediat ely preceeds the meter wave type II burst lanes. Therefore the onset o f the patch source seems to induce also the MHD-like disturbance which can steepen to the type II burst emitting shock. In some events the f ragmented patches in the frequency - time plane show a linear spreadin g toward lower and higher frequencies. This can be a signature of an a ccelerated movement. Our interpretation of the data allows to understa nd some of the timing and location problems between the type II shockf ront and other CME or flare components.