High contrast 2D visualization of edge plasma instabilities by ECE imaging

Abstract

High contrast high resolution 2D images of edge MHD instabilities have been obtained for the KSTAR H-mode plasmas in 2010 using an electron cyclotron emission (ECE) imaging system. A fast structural evolution of the edge instabilities has been identified where the validity of the observed structures, i.e., the local measurement is ensured by the high contrast. On the other hand, the exact interpretation of the ECE intensity (T-rad) is not straightforward due to the marginal optical depth (similar to 1) in the plasma edge region. The effect of the electron temperature (T-e) and density (n(e)) profiles in the edge region on the ECE localization and intensity have been evaluated for typical KSTAR H-mode discharges.