EXPERIMENTAL OBSERVATION AND MODELING OF HIGH-Z IMPURITY TRANSPORT BY TUNGSTEN POWDER INJECTION IN KSTAR PLASMAS

Because tungsten may cause detrimental effects on plasma operation by radiative cooling owing to its high mass and charge, relevant studies regarding the tungsten impurity with respect to its behavior in the plasma have become an indispensable research topic. To address this issue, an integrated system including a powder injector, a state-of-art spectrometer, and a high-Z impurity transport code with plasma rotation has been developed in KSTAR. The status and preliminary results of the on-going study on tungsten transport are discussed herein based on experimental observations of 12-μm-size tungsten powder injection and the corresponding diagnostic results of quasi-continuum radiation measured by a compact advanced extreme ultraviolet spectrometer working in 1–7 nm wavelength range, followed by modeling of high-Z impurity transport that accounts for the centrifugal force effect on the tungsten distribution. Preliminary results of the model showed a poloidal asymmetry of the tungsten density in the rotating plasma and quasi-continuum emission of the tungsten which is similar to that of the measured data.