I-Mode Operation In Helium Plasma With Pure Radio Frequency Wave Heating And Iter-Like Tungsten Divertor On East

The characteristics of I-mode operation in helium (He) plasma with radio-frequency (RF) wave heating and ITER-like tungsten divertor have been investigated for the first time on EAST, under the favorable B (T) configuration. Stationary I-mode in He plasma lasting for similar to 5.4 s was achieved at I (p) = 0.5 MA, B (T) = 2.4 T with a total injected RF power of 3.5 MW, along with the appearance of the 30-90 kHz weakly coherent mode and the similar to 13 kHz edge temperature ring oscillation. The pulse length was only limited by the heating power duration. He concentration was found to play a critical role in I-mode operation, as L-I transition threshold power was increased and the energy confinement was degraded with increasing He concentration. The experimental investigation result on energy confinement and divertor heat flux between I- and H-mode plasma was also given at a similar He concentration.