Development of a Multispecies Model for RMP Simulations in NIMROD

Edge localized modes (ELMs) deliver cyclic particle and heat loads to the wall which limit its lifetime in future burning plasma reactors. ELM mitigation or suppression is essential for the success of the burning plasma tokamaks. ELM suppression via the application of resonant magnetic perturbations (RMPs) is a proven technique that both ITER and SPARC plan to use. Standard RMP response models treat the plasma as having a single bulk ion species; however, in the edge, where RMP calculations are relevant, the plasma includes a significant mix of impurities ions and neutrals. Here we discuss the development and application of the NIMROD’s multispecies model to study the impact of ion mix and neutral species on the RMP response. The model dynamically models the density evolution of multiple ion species. The ions are assumed to flow at the center of mass flow velocity, but plans to incorporate a diffusive or dynamical velocity evolution are discussed. KSTAR experimental discharges are used to test the model treating carbon impurities with ion impurities inferred from experimental measurements. Neutral drag is accounted for using passive neutral carbon profiles adapted from EMC3-EIRENE simulations.