Real-time reduction of tungsten impurity influx using lithium powder injection in EAST

•The real-time lithium powder injection successfully suppressed the accumulation of tungsten impurity in the plasma core both in L-mode and H-mode discharges.•The reduction of divertor electron temperature, which resulting by strong Li radiation in upper divertor region, was the main reason for the reduction of tungsten impurity.•The continuous real-time lithium powder injection coat a thin lithium film on the tungsten divertor plate, which will protect plate from plasma bombardment. We report the first successful use of solid material injection, in powder form, to reduce core tungsten impurities in EAST discharges with tungsten divertor plasma-facing components. Tungsten is the leading plasma-facing material for use in ITER as well as future fusion devices. However, tungsten sometimes accumulates in the plasma core of fusion devices, which is an impediment to the achievement of high-power, long-pulse H-modes. In this work, tungsten impurity influx from the tungsten divertor was reduced by real-time injection of lithium powder into EAST discharges. An increase in stored energy and confinement accompanied the sharp reduction of core tungsten with real-time lithium powder injection in L-mode discharges. In H-mode discharges, real-time lithium powder injection reduced the tungsten core impurity emission while also mitigating ELMs. During powder injection, the divertor electron temperature was reduced, which reduced the tungsten source. The tungsten impurity emission remained low in discharges even after active lithium injection was terminated, a signature of improved and lasting wall conditioning in the tungsten divertor.