Zapdos-CRANE implementation of a lithium vapor shielding model

Liquid metals have recently been gaining in popularity as alternatives to solid plasma facing components (PFCs), with lithium a promising candidate which was shown in past experiments to improve plasma performance. When a lithium PFC is exposed to the high plasma fluxes in a fusion environment, it reaches high enough temperatures for the lithium to evaporate and create a vapor cloud in between the plasma and PFC. This cloud can radiate a large portion of the plasma heat flux away from the PFC, improving its power handling capabilities. A mathematical model was developed to describe a lithium vapor cloud, and investigate its behavior under different conditions. The model includes the various plasma chemical reactions the different lithium and plasma species undergo inside the cloud, and uses the drift-diffusion approximation to simplify the energy equation for each species. An initial implementation of this model was done coupling two codes falling under the MOOSE framework: Zapdos (a finite element plasma transport solver) and CRANE (a plasma chemical network solver). The computational model was tuned against experimental data obtained from runs on Magnum-PSI and allows to obtain the various species densities, the electron temperature, the vapor cloud width and the radiated power. Further improvements of the model are underway which will allow it to track the ions and neutrals individual temperatures and incorporate more advanced evaporation and sputtering boundary conditions.