Complete Suppression of the m=2/n=1 NTM Using ECCD on DIII-D

Complete suppression of the m=2/n=1 neoclassical tearing mode (NTM) is reported for the first time using electron cyclotron current drive (ECCD) to noninductively generate current at the radius of the island O‐point. Experiments on the DIII‐D tokamak show that the maximum shrinkage of the m=2/n=1 island amplitude occurs when the ECCD location coincides with the q=2 surface. Estimates of the ECCD radial profile width from the island shrinkage are consistent with ray tracing calculations but may allow for a factor‐of‐1.5 broadening from electron radial transport.