Anomalous phenomena in ECRH experiments at toroidal devices and low-threshold parametric decay instabilities

Abstract

In the paper the possibility of total 3D trapping of electron Bernstein (EB) waves in the tokamak equatorial plane in the vicinity of the local density maximum produced by electron pump-out-effect is demonstrated. Thresholds and growth rates of the associated absolute (temporally growing) parametric decay instability (PDI) leading to anomalous absorption is predicted in the range of less than 100 kW. Its possible role in explanation of ion acceleration observed in ECRH experiments as well as in redistribution of the deposited power is discussed.