Sawtooth Control With ECCD On Tore Supra

Sawtooth control is a potentially important method for avoiding MHD instabilities triggered by sawtooth crashes, such as neoclassical tearing modes in a reactor‐size tokamak. The aim of the present study is to investigate the effect of localised current drive on Sawtooth activity. In recent experiments in the Tore Supra tokamak, Electron Cyclotron Current Drive has been observed to strongly affect the Sawtooth period, even at modest ECCD power levels. For instance, with 8 MW of ICRH long, fast ion stabilised, sawteeth were shortened from 0.6 s to 0.3 s by application of 0.6 MW of co‐ECCD. In these experiments it is estimated that only 2–3% of the total current was driven by ECCD, but this was sufficient to significantly affect the sawtooth period provided the driven current was localized accurately with respect to the q = 1 surface