Sawtooth control experiments on HT-7 and EAST tokamak

Sawtooth control experiments were performed on HT-7 with a limiter configuration and on the Experimental Advanced Superconducting Tokamak (EAST) with a double null configuration. The sawtooth period can be modified by lower hybrid wave (LHW) and ion cyclotron resonance frequency (ICRF). Different sawtooth behavior was observed with the same plasma density, LHW power but different plasma currents on HT-7. There was a dwell time between LHW added and the sawtooth stabilization on HT-7 while the sawtooth stabilization immediately happened when LHW power was injected on EAST. The possible mechanism of the sawtooth control is discussed in this paper. All the experimental results have proved that power deposition of the radio frequency (RF) should be the key factor for sawtooth control.