Transition radiation mechanism for broad-band component of stimulated electromagnetic emission

As is well known in the F-region of the ionosphere modified by high power HF radio waves broad-band electromagnetic stimulated emission (SEE) is observed. It was discovered both the beams of superthermal electrons and intensive small-scale irregularities in modified region. These magnetic field aligned irregularities have caviton shape — deep electron density holes. The presence of such irregularities and superthermal electrons create conditions for generation of transition emission. We consider this radiation mechanism for interpretation the SEE broad-band component.