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

By the SOLDOR/NEUT2D simulation for divertor design study on a compact DEMO reactor, SlimCS, we estimated the prospect of handling the huge exhaust power in the divertor. Assuming exhaust power of 500 MW and ion outflux of 0.5 × 10²³ s^-1 into the scrape-off-layer, the peak heat load is estimated to be 70 MW m^-2 on the outer target on the initial divertor design (vertical target) with the introduction of moderate gas puff flux and Ar fraction. This value significantly exceeds the allowable level of 10 MW m^-2 which is an initial design target. By installing the 'V-shaped corner' in the 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^-2. It can also be demonstrated properly for the dependence of the exhaust power on the divertor heat load. Peak heat load is reduced exponentially with a decrease in the exhaust power and reaches 7 MW m^-2 at Q_total = 300 MW for moderate gas puff flux and Ar fraction.