Fluid versus kinetic response to low-n magnetic perturbations in high-β HL-3 plasmas and effect of edge safety factor variation

Abstract

Abstract This work systematically studies the plasma response to externally applied resonant magnetic perturbation (RMP) fields designed to control edge localized modes (ELMs) in the HL-3 reference plasmas, utilizing the MARS-F/K code (Liu et al 2000 Phys. Plasmas 7 3681; Liu et al 2008 Phys. Plasmas 15 112503). The single-fluid resistive model predicts a significant increase in the plasma response amplitude as the plasma pressure approaches the Troyon no-wall limit ( β N no-wall-limit ), in contrast to strong suppression of the response amplitude with the MHD-kinetic hybrid model, for both the n = 1 and n = 2 perturbations (where n is the toroidal mode number). Based on the linear response analysis, it is proposed that the kinetic resonance between the RMP perturbation and particle drift motions changes the growth rate of the relevant modes (mainly kink modes), thereby altering the strength of the plasma response. Finally, results with the MHD-kinetic hybrid model indicate the presence of a window in edge safety factor for achieving ELM control at high-β N (near β N no-wall-limit ), whose size and magnitude is essentially independent of pressure. This also supports the analytic results of the linear response model regarding the relationship between mode stability and response strength.