Stabilization of tearing modes in lower hybrid current drive discharges on Petula-B

The effects of the RF current drive on a hybrid RF-OH discharge, in which more than 70% of the plasma current is driven by the RF, have been extensively studied in the Petula-B tokamak. Observations of MHD activity indicate that the presence of RF-driven current cuppresses the growth of the MHD modes and allows stable low-q(a) (as low as 2) discharges with electron density and temperature profiles similar to those of the OH case.