Hydrogen and helium entrapment in flowing liquid metal plasma-facing surfaces

The ability to use liquids as plasma-facing component (PFCs) depends on their interaction with the plasma and the magnetic field. One important issue for the moving liquid is the ability to entrain particles that strike the PFC surface (helium and hydrogen isotopes) while accommodating high heat loads. To study this problem, a numerical model has been developed using the HEIGHTS computer simulation package. The model was used to investigate pumping of He particles by the flowing liquid rather than requiring a standard vacuum system. Hydrogen isotope (DT) particles are likely be trapped in the liquid metal surface (e.g., lithium) due to the high chemical solubility of hydrogen. The incident He particles in the established low-recycling regime at PFCs could be harder to pump using standard vacuum pumping techniques. The analysis results indicate, however, a reasonable chance of adequate helium self-trapping in flowing lithium as PFC without active pumping.