Simulation of Sawtooth Oscillation in Burning Plasma

Abstract

The sawtooth oscillation is one of the important instabilities driven by the plasma current in tokamak plasma. The sawtooth period is a key parameter that characterizes the effect of the sawtooth oscillation on the plasma behavior. For prediction of sawteeth in burning plasma, the sawtooth model in the 1.5-dimensional transport code TOTAL has been extended to include the effects of fast particles and the magnetic shear. By using the newly implemented model, we simulated sawteeth in the presence of the alpha particles as the fast ion in ITER. It is found that the sawtooth periods in DT plasma are longer than those in DD plasma. In DT plasma, the sawtooth period doesn’t change monotonically but has a peak as a function of the average central ion temperature or the RF heating power. This is because the mechanisms of triggering sawteeth are different in the low RF heating power region and in the high RF heating power region.