Simulation study for divertor design to handle huge exhaust power in the SlimCS DEMO reactor

Kawashima, Hisato; Shimizu, Katsuhiro; Takizuka, Tomonori; Tobita, Kenji; Nishio, Satoshi; Sakurai, Shinji; Takenaga, Hidenobu

By the SOLDOR/NEUT2D simulation for divertor design study on DEMO reactor, SlimCS, we estimated a prospect of handling huge exhausted power. Assuming the exhausted power 500 MW and ion out flux 0.510 s into the scrape-off-layer, the peak heat load is estimated to be 70 MW/m on the outer target on the initial divertor design with introduction of moderate gas puff and Ar fraction. This value exceeds the allowable level 10 MW/m being an initial design target. By installing the "" in bottom of the outer divertor target, and using strong gas puffing or Ar impurity injection, the detached condition with high particle recycling and radiation loss conditions is formed, and the peak heat load is successfully reduced below 10 MW/m. It can also be demonstrated that the peak heat load is reduced exponentially with decrease of the exhaust power and reaches to 7 MW/m at = 300 MW for moderate gas puff flux and Ar fraction.