Investigations of Plasma Response Associated with Resonant Magnetic Perturbation Fields in KSTAR H-Mode Plasmas

We report the investigations of the plasma response associated with the application of Resonant Magnetic Perturbation (RMP) fields in KSTAR H-mode plasmas using small edge perturbations produced by a modulated Supersonic Molecular Beam Injection (SMBI) during steady state RMP. The modulated SMBI provides a time varying perturbation to both the plasma density source in the region just inside the LCFS (via modulation of the neutral density) and a modulated flow damping rate (via ion-neutral charge exchange and elastic scattering). The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then plasma response propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations (VPRMP) response equal to 32.5 m/s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. The propagation velocity of the resonant magnetic perturbations response on the q=2 surface is larger than the radial propagation velocity of the perturbed toroidal rotation.