Simulation study of the influence of drifts on the upstream and target heat flux width under different BT directions

The heat flux width (λq) is a key parameter determining the heat load at divertor targets. In recent years, drifts has been found to play a remarkable role in the edge plasma transport, while its influence on λq has not been well understood. To investigate the influence of drifts on λq, systematic simulations using SOLPS-ITER code are performed in this work. Statistics of the simulation results show that the drift under favorable/unfavorable BT tends to increase the λq in the outer/inner side and decrease the λq in the other side, which is consistent with the experiment observations. At the upstream and the target, the mechanisms of the influences of drifts on λq are different. The upstream λq (λq,u) is directly affected by drift-induced convective heat flux, while λq at the target (λq,t) is indirectly influenced through heat conduction (in the high-recycling regime) and sheath (in the detached regime) due to the change of plasma parameters there. Furthermore, the synergetic effect of geometry and drift under favorable BT leads to an anomalously large λq,t in inner side at high density.