Low q95 (3-5) high bN operation scenario has been developed on EAST tokamak. Sustained high normalized beta (bN ~ 1.9) plasmas with an ITER-like tungsten divertor have been achieved on EAST tokamak recently.
The high power NBI heating system of 4.8 MW and the 4.6 GHz lower hybrid wave of 1 MW were developed and applied to produce edge and internal transport barriers in high bN discharges. The central flat q profile with q(r) ~ 1 at ρ < 0.3 region and edge safety factor q95 = 4.7 is identified by the multi-channel far-infrared laser polarimeter and the EFIT code. The fraction of non-inductive current is about 40%. The relation between fishbone activity and ITB formation is observed and discussed.
A coherent mode (20-100kHz) with characteristics of resistive ballooning mode (RBM) is usually observed in pedestal region and can drive outward particle transport. Enhanced pedestal fluctuation could lead a lower ELM frequency.