Analysis of geometric variations in high-power tokamak divertors

Quantitative assessment of the performance of high-power tokamak divertors for a range of geometric variations is conducted using the MHD code Corsica (Crotinger et al 1997 Technical Report LLNL) and edge transport code UEDGE (Rognlien et al 1992 J. Nucl. Mater. 196-198 347). In a multi-parametric study the divertor performance is compared for a high-power tokamak with standard and snowflake (Ryutov 2007 Phys. Plasmas 14 064502) configurations for the same core plasma parameters. Divertor and edge quantities that are varied include x-point flux expansion, shape of target plates, and radiating impurity species and concentrations. For a range of studied cases, in the snowflake the peak heat load on the target plates is significantly reduced compared with the standard divertor due to larger plasma-wetted area and a larger fraction of power radiated in the edge.