The three-dimensional (3D) edge Monte Carlo transport code EMC3-EIRENE has been employed to study edge plasma and impurity transport with toroidally localized argon seeding using the Chinese fusion engineering testing reactor (CFETR) X-divertor configuration. The argon impurity seeded at different poloidal locations was investigated to evaluate the varied profile of the main plasma in the scrape-off layer (SOL) and on the divertor targets, which showed a strong dependence on the poloidal position of argon gas puffing. The argon impurity seeded in the upstream SOL regions can result in a toroidally asymmetric distribution of electron density and temperature, while a toroidally symmetric distribution was obtained for argon seeded in the strike point regions. The deposition pattern of electron density and temperature showed several lobe-like and island-like structures on the 3D divertor targets of CFETR with upstream argon injection, whereas a perturbed profile was achieved for argon seeding in the strike point regions. In order to verify the toroidal asymmetry of heat load distribution, the argon impurity seeded at different poloidal locations was investigated to estimate its influence on the toroidal heat load on divertor plates. The argon injected in the strike point regions gave rise to a toroidal asymmetry of heat load distribution on divertor targets, while a toroidal symmetry of heat load distribution was observed for argon injected in upstream SOL locations.
This paper investigates how injecting the argon impurity at different locations in the tokamak edge can affect the plasma properties and heat load distribution on the divertor targets. The simulations show that argon injection in the upstream regions leads to toroidal asymmetry in the plasma, while injection near the strike points results in more toroidal symmetry. This information is crucial for optimizing impurity seeding to control the heat load on the divertor in future fusion devices like CFETR.