Increased heat exhaust by a sas-like divertor in a large-scale tokamak

 Development of a reactor-compatible divertor is a challenging and important task for the realization of nuclear fusion, as the divertor is a part that directly interacts with hot plasma particles and neutrals. It is believed that the heat flux imposed on the divertor region in DEMO-class reactors will be more than 20 which is a technological limit of PFC for maintaining steady state. One promising solution to the reduction of heat flux on the divertor target is using and controlling the detachment phenomenon. From lots of previous studies, it has been confirmed that the change of the divertor structure (especially the shape) directly affects the detachment. In this study, we investigate the effect of SAS-like divertor shape on detachment in a large-scale Tokamak. We carried out comparison studies of original and SAS-like shapes on the ITER environment using the SOLPS-ITER package. From our simulations, we observed that the heat flux decreases by less than 1/3 in the SAS-like cases for similar upstream densities. Interestingly, although the SAS-like shape was employed only in the outer target, a considerable decrease of the heat was observed in the inner target also. We discuss the origins that leads to those results by analysis of neutral trajectories in the different shapes of divertors.