UC San Diego

The structure and evolution of the ion temperature (Ti) and toroidal rotation (V-) profile have been investigated in neutral beam injection (NBI)-heated KSTAR H-mode plasmas, both without and with resonant magnetic pertubations (RMPs). A clear disparity between the width of the ∇Vφpedestal and that of the ∇Ti-pedestal was observed. Also, it was found that there exists a close correlation and weak relative hysteresis between the pedestal ∇Vφand ∇Ti during both L →H and H →L transitions. During the L →H transition, the Vφpedestal is observed to form ahead of the Ti-pedestal, and build inward from the separatrix. Linear gyrokinetic stability analysis of these KSTAR profiles was performed. The results indicate that parallel velocity shear is a relevant drive for pedestal turbulence and transport. This was largely ignored in previous studies of the pedestal micro-stability. Pedestal ion temperature and rotation profiles were also measured during edge localized mode (ELM) suppression experiments on KSTAR using an n = 1 RMPs. It was found that the top values of the ion temperature and toroidal rotation pedestal drop with RMPs when ELMs are suppressed.