Alfvén wave heating and runaway discharges in the TCABR tokamak

Abstract

Recent results of experiments on Alfvén wave heating and runaway discharges carried out in the TCABR tokamak are presented. A new antenna type has been installed to allow wave excitation with higher RF currents and lower dynamic polarization of the antenna straps than for the one previously used. In spite of edge plasma heating, which causes influx of impurities, we have obtained a clear confirmation of wave deposition inside the plasma from a localized increase of the electron temperature measured with the ECE radiometer. Detailed profiles of the plasma density and Ha emission were obtained in runaway disharges with currents around 100 kA. These profiles confirm our model of a low-temperature plasma maintained in equilibrium by the relativistic electron beam. Analysis of the Ha and density spikes indicate that recombination plays a substantial role in the particle and energy balance.