Real time control of the sawtooth period using EC launchers

Tokamak plasmas operating at high performance are limited by several MHD instabilities. The sawtooth instability limits the core plasma pressure and can drive the neoclassical tearing mode unstable, but also prevents accumulation of impurities in the core. Electron cyclotron heating and current drive systems can be used to modify the local current profile and therefore tailor the sawtooth period. This paper reports on demonstrations of continuous real time feedback control of the sawtooth period by varying the EC injection angle.