Nonlinear MHD Modeling of the Effect of n$=$2 RMP on Peeling-Ballooning mode in KSTAR

To suppress edge-localized-modes (ELM) via resonant magnetic perturbation (RMP) is critical to reach and sustain high-performance steady state H-mode plasmas. Using the nonlinear 3D MHD code JOREK [1], we have successfully simulated a recent n$=$2 RMP-driven ELM-crash-suppression in KSTAR. In this study, we have found that such ELM-crash-suppression has been not only attributable to degraded pedestal but also to direct coupling between peeling-ballooning mode (PBM) and RMP-driven plasma response. Specifically, the pedestal pressure gradient was reduced, since radial transport was enhanced due to the formation of the stochastic layer and kink-peeling response (KPM) [2] driven by RMP. While the linear stability of PBM improved owing to the degraded pedestal, it was not a sole contributor to ELM-crash-suppression, in that the other nonlinear mode coupling should be simultaneously taken into account. This outcome is consistent with the previous studies [2, 3]. In addition, the locking of PBMs has been numerically simulated during the ELM suppression phase, which may support the relationship between V$_{\mathrm{ExB}}\approx $0 at the pedestal and the onset of ELM-crash-suppression. [1] G. T. A Huysmans et al., PPCF (2009) [2] F. Orain et al., Phys. Plasma (2019) [3] M. Becoulet et al., PRL (2014)