Numerical evaluation of plasma boundary response to RMP application in KSTAR

Resonant magnetic perturbations (RMPs) are beneficial for control of edge localized modes (ELMs) in tokamaks which is considered to be one of the major challenges for burning plasma operation. However, a side effect of RMPs is the appearance of a helical striation pattern in the particle and heat loads onto divertor targets which can affect the efficiency of power dissipation in ITER. As the plasma responds to the external perturbations, it is important to accurately predict the resulting magnetic field and the corresponding footprints on the divertor targets. In the present study we evaluate the latter for a KSTAR H-mode plasma with ELM suppression by RMPs. Magnetic footprints are computed by FLARE based on plasma response from GPEC, MARS-F, (linear) M3D-C1 and JOREK, and it is found that the footprint size varies significantly between models (from 2 cm to 14 cm). This is reflected in EMC3-EIRENE simulations of the resulting heat loads: it is found that either the peak magnitude or the extent of the striations appear to be overestimated compared to IR measurements. This suggests that the initial power into the scrape-off layer has been overestimated, and better agreement is found for lower input power and lower cross-field transport.