Pellet Fueling of RMP ELM Suppression Discharges on DIII-D

Experiments and modelling of DIII-D discharges with edge-localized mode (ELM) suppression by resonant magnetic perturbations (RMPs) and that were fueled by pellet injection are presented. Low-density ELM-suppressed shots undergo further density pumpout due to the applied n = 3 RMP, and high-field side pellet fueling is used to recover this density loss. The pellet source is varied in these experiments, with both the size of individual pellets as well as the overall injection rate scanned. Depending on injection parameters, a range of ELM behaviors is observed, including continued ELM suppression, individual triggered ELMs, as well as brief ~100 ms bursts of ELMing before returning to suppression. In addition to raising the density pedestal height, individual pellets can result in significant reduction of the edge rotation, with corresponding modification of the ELM activity. The pedestal MHD response is modelled with the TM1 code, incorporating the detailed experimental measurements of the pedestal profile evolution.