Influence of Nitrogen Recycling on Toroidally Asymmetric Heat Load on CFETR X-Divertor With EMC3-EIRENE Modeling

Influence of nitrogen recycling on toroidally asymmetric heat load distribution with nitrogen seeding on the Chinese Fusion Engineering Testing Reactor (CFETR) X-divertor configuration has been performed by the three-dimensional (3D) edge fluid transport code package EMC3-EIRENE. The sensitivity studies of the recycling coefficient of nitrogen ions scanned from 0% to 100% show that the larger recycling coefficients of nitrogen ions lead to a significant increment of nitrogen particle content with different charge-states in the simulation volume. The increased contributions to total power loss induced by nitrogen impurities are found both for the in- and out-board seeding positions. While the peak values of electron temperature and heat load rapidly decrease with the larger recycling coefficients of nitrogen ions, especially for the high recycling coefficient cases. A more pronounced toroidal asymmetry of heat load distribution is found for the high nitrogen recycling coefficient compared to the low recycling coefficient scenarios. This is attributed to the relatively enlarged deposition area of toroidal nitrogen ions on divertor targets and the higher power loss by nitrogen impurities as the recycling coefficient of nitrogen ions increases.