ANOMALOUS ABSORPTION DURING ARTIFICIAL MODIFICATION AT HARMONICS OF THE ELECTRON GYROFREQUENCY

Observations of the anomalous absorption of low-power HF probe waves c aused by the action of a high-power HF ordinary mode radio wave are pr esented. At pump frequencies in the vicinity of harmonics of the elect ron gyrofrequency the anomalous absorption measured on the low-power p robe waves exhibit local minima. Also at these frequencies, large-scal e changes deduced from phase measurements of the low-power probe waves and heater self-absorption are reduced, whereas the growth time of th e anomalous absorption is increased. The electron gyrofrequency estima ted from the frequency of the absorption minimum compares favorably wi th that derived from the International Geomagnetic Reference Field (IG RF) magnetic field model.