Three-dimensional Material Erosion of Plasma Facing Components During Application of Resonant Magnetic Perturbations*

Modeling of the plasma material interaction in the three-dimensional boundary induced by resonant magnetic perturbation (RMP) fields shows enhanced particle redeposition in the regions between 3D flux lobes at the divertor targets. The kinetic Monte Carlo ERO2.0 code was used to model PWI and impurity transport in RMP scenarios for three devices, reconstructed with EMC3-EIRENE: lower single null L-mode discharges in the DIII-D tokamak, the KSTAR ELM suppression window for the n = 1 mode, and the ITER pre-fusion power operation (PFPO) detachment scenarios. The results for the DIII-D carbon divertor show higher toroidally averaged net erosion for the no-RMP reference case compared to two RMP setups and the effect increases with anomalous diffusion. It is seen that particle re-erosion contributes to impurity deposition between the lobe structures because of impurity transport perpendicular to the lobes. KSTAR modeling of the H-Mode ELM suppression window shows strong carbon erosion of the divertor target plate, with the toroidally averaged profiles showing decreasing net erosion with increasing RMP coil current. Subsequently, this leads to decreased carbon accumulation in the plasma with measurements of Zeff in the ELM suppressed window reaching values between 1.5-2. ITER modeling shows the strong effects of mixing of eroded beryllium from the first wall onto the tungsten divertor in semi-detached scenarios. The inclusion of the particle mixing shows that in the PFPO phase, eroded particles from the first wall quickly accumulate in the divertor, driving the tungsten erosion rates beyond the acceptable limits for low gas puffing scenarios. For large puffing rates, the erosion rates decrease, but beryllium quickly builds up along the divertor target in the private flux region, potentially becoming a safety concern for tritium operation.