Nonlinear MHD modeling on RMP-induced pump-out under the KSTAR geometry

This work introduces nonlinear 3D MHD simulations and validations with KSTAR geometry that reveal a hybrid particle-MHD transport as a key process for driving the bifurcating dynamics in particle transport under resonant magnetic field perturbation (RMPs). Here, JOREK [1,2] and PENTRC [3] codes are coupled for the modeling. It turns out that the threshold characteristics of pump-out originate from resonant field penetration and island opening [4], showing a good agreement with the previous modeling [5]. However, these toroidal simulations also show that the pump-outs are attributable to both polarization and neoclassical toroidal viscosity (NTV) [6] effects. In particular, the first pump-out observed in KSTAR experiments is reproduced only when both transport mechanisms are integrated into the simulations. [1] G.T.A. Huysmans et al., PPCF 51, 124012 [2] M. Hoelzl et al., NF 61, 065001 [3] N. C. Logan et al., POP 20, 122507 [4] R. Nazikian et al., PRL 114, 105002 [5] Q. Hu et al., POP 26, 120702 [6] Y. Liu NF 60, 036018

*Supported by the US DOE Contract DE-SC0020372.