TECXY simulations of multi-species impurity seeding in DEMO reactor

Numerical studies have been performed to investigate the influence of the few impurity species on the heat load reduction and the SOL plasma parameters in the European DEMO reactor. Two-dimensional multi-fluid TECXY code has been used to model edge plasma transport described by the classical set of transport equations of multi-species plasma derived by Braginskii. The TECXY code solves transport equations for few impurity species and all associated ionization stages simultaneously in a two-dimensional poloidal geometry. This paper describes the results of numerical simulations of the edge plasma performed for the DEMO reactor with neon and krypton seeding, as well as with a mixture of neon and krypton impurities. We aimed to obtain the energy flux reduction to the target plate at the smallest possible increase of the effective charge value considering gas puffing with various mixtures of impurities. It has been found that the heat load reduction can be improved for a specific mixture of impurity species seeded simultaneously to the edge plasma.