Simulation of plasma-neutral dynamics for radiation cooling

An advanced heat removal scenario is required to handle the high input power of magnetic fusion reactors. The concepts of gas target and radiative divertors have been explored. A set of self-consistently coupled fluid equations for plasma and neutrals is suitable for this system because of the sophisticated equations for neutrals. The transfer of plasma momentum to neutrals, which is crucial in understanding the plasma-neutral interface, is described through the charge exchange process. Our code results show good agreement with gas target experiments on the PISCES experiment and demonstrate its superiority to the previous simulation. This benchmarked code and a set of equations have been applied to a slot divertor for DEMO reactor. The slot length for the divertor can be determined by producing enough frictional force to overcome the thermal force which creates a backflow of impurities. A small amount of radiating argon is enough to exhaust 40 MW of power from the core plasma in a 40 cm long slot for the inner divertor of DEMO.