Initial measurements of fast ion loss in KSTAR

A fast ion loss detector (FILD) has been installed and tested in Korea Superconducting Tokamak Advanced Research (KSTAR). KSTAR FILD measures the energy and the pitch-angle of the escaping ions with the striking positions on the scintillator plane. Measurements of the fast ion loss have been performed for the neutral beam heated plasmas. Initial experimental results indicate the prompt losses from neutral beam are dominant and the effects of the resonant magnetic perturbation on the fast ion loss are investigated. In addition, further design change of the detector-head in order to avoid excessive heat load and to detect the fusion products or the fast ions having order of MeV of energy is also discussed.