Effect of localized gas puffing on divertor plasma behavior in EAST

Abstract Localized D 2 puffing from various divertor locations has been carried out under double null (DN) and lower single null (LSN) divertor configurations to investigate the effect of gas puff locations on the divertor behavior in ohmic L-mode discharges in EAST. Localized gas puffing from the dome has a higher fueling efficiency than that from the inner and outer targets for both DN and LSN configurations. Under the DN configuration, gas puffing from the inner target exhibits a much better fueling efficiency than that from the outer target. In contrast, the gas fueling efficiency shows little difference between the inner and outer divertor gas puff locations in the LSN configuration. In LSN, localized gas puffing from the outer divertor target tends to promote detachment at the outer target. This will be employed as a means to control heat fluxes to the outer divertor target plates for high power long pulse operations.