A model for the interaction of superthermal electrons with the magnetohydrodynamic modes during electron cyclotron resonant heating

The interaction of electron cyclotron resonant heating (ECRH) with the m/n=2/1 magnetohydrodynamic (MHD) mode, which was observed in toroidal plasmas, is attributed to the superthermal electrons that are produced on the EC resonance by the ECRH. Superthermal electrons, as they drift across the q=2 surface, exchange power with the m/n=2/1 MHD mode which is either suppressed or enhanced. When the EC resonance is outside the rational surface, the mode is always suppressed. When the EC resonance is inside the rational surface, modes with a large amplitude are enhanced while modes with a small amplitude are suppressed.