Summary of Very Low-q Discharges in TORIUT Tokamaks

Abstract

Three different schemes to realize a very low-qdischarge (q_a< 2) have been demonstrated in the TORIUT tokamaks. They are (1) fast current-rise method, (2) application of the ergodization effect of non-resonant helical field, and (3) high filling-pressure operation. Each method has been proved to be independently effective to suppress the major disruption caused by the (m=2, n=1) tearing mode during the current rising-up phase and provides a path into the very low-qregime through the barrier atq_a=2.