LONG-TIME SCALE EVOLUTION OF HIGH-POWER RADIO-WAVE IONOSPHERIC HEATING .1. BEAM-PROPAGATION

The long time scale evolution, that is, for times long compared to an electron collision period of high-power radio wave ionospheric heating , is studied. Preliminary studies are made to model high-power radio w ave propagation in an ionosphere containing a dynamically produced ele ctron density cavity. We show that high-power radio wave-induced plasm a density depletions in the F region ionosphere will convect and steep en in the direction perpendicular to the geomagnetic field due to iono sphere-thermosphere coupling effects. We treat high-power radio wave p ropagation including nonlinear self-induced thermal effects in the pre sence of a steepened density depletion. We find that the beam is disto rted, shifts in direction, and changes its peak intensity due to nonli near self-induced thermal effects. For weak beams, we find a decrease in beam intensity while for strong beams we observe an increase in bea m intensity.