Observation and Identification of W19+-W23+ Spectra in the EUV Wavelength Region in the Vicinity of 200Å

Tungsten (W) is one of the major impurities in ITER and future DEMO reactors. However, diagnosing ion density, temperature, and spatial distribution for tungsten ions in low charge states such as W17+-W27+ is difficult due to a lack of spectral line data. In this study, we observed tungsten Unresolved Transition Array (UTA) spectra around W20+ in Large Helical Device. Furthermore, the emission spectra of tungsten ions ranging from W19+-W23+ were also measured using Compact electron Beam Ion Trap (CoBIT). Two spectral peaks were detected in the CoBIT experimental setup. Subsequently, these peaks were theoretically identified as 5s-5p and 5p3/2-5d transitions using Flexible Atomic Code (FAC). The identified peaks are useful for impurity diagnostics of ITER edge plasma.