KSTAR ECE Imaging for Temperature and Edge Density Measurements*

ECE imaging (ECEI) system is becoming a powerful diagnostic for studying MHD instabilities in tokamaks. A prominent example is the 2D visualization of sawtooth reconnection physics in the TEXTOR, which revealed the high field side crash and collective heat transport [Park, et al., PRL 96, 195003 (2006)] forbidden in the Ballooning mode model. An improved ECEI system with considerably wider spatial coverage (spanning both high and low field sides) and $\sim\mu$sec time resolution has been installed on the KSTAR. The first KSTAR ECEI images showing the 2D spatial structures of the MHD dynamics of inner/outer regions (e.g. NTMs and ELMs) and Alfv\'en eigenmodes/waves will be presented. The feasibility of using ECEI data from the optically thin edge region to recover 2D electron density changes during L/H mode transitions is also discussed.