Plasma current modulation system and AC operation in the CT-6B tokamak

To perform alternating current (ac) operations in the CT-6B tokamak, a newl y developed plasma current modulation system (PCMS) has been designed for t he ohmic heating circuit. The modulation system is reliable, simple in tech nique, easy. to operate, and has ft;ur operation modes to modulate CT-6B pl asma current. Reproducible multicycle ac operation at a current of similar to5 kA and a fast current ramped down and then up with a linear rate of 6 k A/ms ac discharge with trapezoidal waveform have been achieved using PCMS, Feedback control of the plasma current plateau, plasma current weak modulat ion, and the plasma transition from a low to high current for the studies o f the anomalous transport and the plasma edge turbulence have also been dem onstrated.