Effects of RMP and Rotation on Particle Transport in the DIII-D Tokamak

Results of an experiment to investigate the effects of Resonant Magnetic Perturbations (RMPs) and rotation on electron transport are presented. To prevent intolerable heat fluxes, fusion devices with high power density such as ITER need to operate without edge localized modes (ELMs), which is accomplished on present devices by applying Resonant Magnetic Perturbations (RMPs) to enhance particle transport in the pedestal region to prevent the pedestal from reaching the critical density gradients which trigger an ELM. Pedestals in FPPs and ITER will have limited edge fueling, meaning understanding of particle transport and RMP transport enhancement in this region and will be critical for predicting future pedestal density profiles. To this end, we scan in applied RMP coil current as well as injected torque with a series of discharges in the DIII-D tokamak, to investigate the predicted interrelated particle transport dependences on RMP magnitude, rotation, and ExB shear. Transport information is extracted by gas puff modulation, combined with a time-dependent forward modeling framework with Bayesian inference to optimize a diffusion and convection profile by minimizing the modeled density against experimental measurements. The LLAMA diagnostic is used to measure the penetration of the ionization source and combined with a pressure gauge measuring the time dependence of the neutral population to constrain the contribution of edge fueling. This work contributes to the validation of physics-based predictions for density pedestals under the application of RMPs, a critical predictive capacity for FPPs.