Experimental validation of rotation effects on resonant magnetic perturbation penetration in Ohmic plasma

The influence of plasma rotation on the penetration of resonant magnetic perturbations (RMPs) is investigated experimentally on the J-TEXT tokamak using externally driven momentum from an electrode biasing system. The results show that penetration threshold of the m/n = 2/1 RMP almost exhibits a linear dependence on the local toroidal rotation velocity near the resonant surface, where m and n are the poloidal and toroidal mode number. The local toroidal rotation velocity is measured by Carbon V (C V) spectroscopy in the experiments. Higher toroidal rotation in the co-current direction is found to decrease the RMP penetration threshold. These observations provide experimental evidence relevant to the understanding of the density dependence of the mode penetration threshold.