Theory of type IV DM bursts

It is noted that the study of fine structures in continuum radio emission from the sun is of importance in order to probe the physics of radio sources and of flares in particular. The existing fine structure theories are reviewed and an application to a radio flare is given. Attention is given to stationary magnetic traps including discussion of high frequency electrostatic instability, and high frequency electromagnetic instability. It is shown that the most important high frequency instability in such traps in the solar corona is the loss-cone instability of upper hybrid waves at the resonant surfaces. In addition, the characteristics of the most important fine structures in type IV dm bursts in the 160-320 MHz band as described mainly by Slottje (1980) are presented and the type IV dm burst of June 25, 1978 is examined.