Sawtooth control via n=1 applied magnetic perturbation in tokamak

This paper reports about a novel and simple technique to control sawteeth in tokamak, which has been experimentally found in RFX-mod used as tokamak. Experiments in RFXmod demonstrate that an externally applied and feedback-controlled n=1 magnetic perturbation - of the order of 0.05% of the average toroidal field - causes a strong reduction of the sawtooth amplitude. Experimental findings are described and explained by simulations performed with the visco-resistive non-linear MHD code PIXIE3D.