Progress of KSTAR pellet injection system

Abstract A pellet injection system operating at 20 Hz has been operated in KSTAR (Korea Superconducting Tokamak Advanced Research) since 2016. This system can inject pellets with various size, velocity, and frequency to the KSTAR vacuum vessel during plasma experiments. Various experiments such as peak density control, enhancement of confinement by increasing core beta, and NTM stabilization were carried out with the pellet injection system in 2018. Most of all, the characteristics of the pellet should be studied to better understand the interaction with plasma. The pellet trajectory is one of the interesting topics in KSTAR and therefore a related investigation was carried out outside of the tokamak first. We introduce the preliminary results of the trajectory test, the pellet velocity tendency, and a plasma experiment in this paper.