Comparison of Pedestal Turbulence Dynamics in ELMing and RMP-Driven ELM Suppression*

With high-speed broadband electron cyclotron emission (ECE) measurements in KSTAR, the electron temperature turbulent fluctuations have been measured in high spatial resolution during the ELMing and ELM suppression phase. To investigate the structure and dynamics of turbulence occurring in the two different phases, spatial scales, parity, and cross-phase between electron temperature and radial velocity fluctuations were evaluated using velocimetry of measured 2-D electron temperature fluctuations. Furthermore, the effect of electron temperature fluctuations on maintaining the final form of the electron transport barrier was studied through comparative analysis with the profile data. Comprehensive comparisons with turbulence properties confirmed that the types and causes of turbulence in the two phases were different and that the role of contributing to heat and particle transport could be different as well.