Impact of resistive MHD plasma response on perturbation field sidebands

Here, single fluid linear simulations of a KSTAR RMP ELM suppressed discharge with the M3D-C¹ resistive magnetohydrodynamic code have been performed for the first time. The simulations show that the application of the n = 1 perturbation using the KSTAR in-vessel control coils (IVCC), which apply modest levels of n = 3 sidebands (~20% of the n = 1), leads to levels of n = 3 sideband that are comparable to the n = 1 when plasma response is included. This is due to the reduced level of screening of the rational-surface-resonant n = 3 component relative to the rational-surface-resonant n = 1 component. The n = 3 sidebands could play a similar role in ELM suppression on KSTAR as the toroidal sidebands (n = 1, 2, 4) in DIII-D n = 3 ELM suppression with missing I-coil segments. This result may help to explain the uniqueness of ELM suppression with n = 1 perturbations in KSTAR since the effective perturbation is a mixed n = 1/n = 3 perturbation similar to n = 3 ELM suppression in DIII-D.. Authors: Orlov, D. M. [Univ. of California San Diego, La Jolla, CA (United States); General Atomics]; Evans, T. E. [General Atomics, San Diego, CA (United States)]; Moyer, R. A. [Univ. of California San Diego, La Jolla, CA (United States)]; Lyons, B. C. [General Atomics, San Diego, CA (United States); Oak Ridge Institute for Science Education, Oak Ridge, TN (United States)]; Ferraro, N. M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)]. DOE Contract: AC02-09CH11466; FC02-04ER54698; FC02-06ER54873; FG02-05ER54809. Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELM control; edge stochastic layer; plasma response; resonant magnetic perturbation; tokamak