Effect of E×B on pedestal stability and divertor dissipation via Boron powder injection on EAST*

We present our findings on simultaneously achieving ELM suppression and divertor dissipation via Boron (B) powder injection in EAST. B injection was conducted in upper-single null plasmas, where the B powder was directed into the private flux region just above the upper X-point with a nominated size of ~70μm and a flowrate range of 5-80E20 atoms/s at a velocity of ~10 m/s. We observed different effects of E×B on plasma performance, edge fluctuation, and divertor dissipation when injecting B powder in opposing Bt directions. When the ion grad-B drift to the X-point was favorable, inner divertor Te was reduced from approximately 20-30eV to below 5 eV, while ELMs were suppressed with constant or higher stored energy and an edge multi-harmonic mode. Conversely, in unfavorable Bt cases, B powder injection resulted in ELM suppression and divertor power exhaust, with a decrease in stored energy by 10% and a presentation of a single-frequency (~3-4 kHz) mode, not the harmonic mode. Additionally, both outer and inner divertor targets showed power exhaust, and Te,_UO was reduced from approximately 25eV to below 10eV. Our SOLPS-ITER simulation results indicate that E×B drift drives different D and B particle distributions between the inboard and outboard sides, which may explain the different experimental outcomes.