Two-fluid plasma response to resonant magnetic perturbations with varying plasma elongation and triangularity

Two-fluid effects on the plasma response to applied resonant magnetic perturbations of toroidal mode numbers n = 1–4 are numerically investigated, with systematic variation of plasma boundary shaping (elongation and triangularity) for both the single-null and double-null (DN) divertor-like tokamak configurations. Two-fluid response models yield similar optimum coil phasings for best edge-localized modes (ELMs) control, to those predicted by the single-fluid counterpart. This explains the previous success of the modeled spectrum optimization for ELMs control experiments using the single-fluid approach. Both single- and two-fluid models predict reduced optimal coil phasing at enhanced plasma elongation, while triangularity variations have minimal influence. However, two-fluid models predict a stronger screening of edge resonant field perturbations than single-fluid counterpartment, due to faster E × B and/or electron flows enclosed in the former in the edge pedestal region. Finally, both predict a weaker edge-peeling response in DN plasmas, consistent with the experimental findings of difficulties in suppressing ELMs in DN plasmas.