Study of impurity and radiative losses in divertor plasmas with absolutely calibrated VUV spectrometers in JT-60U

In JT-60U, spectra of deuterium and impurities in divertor plasmas were observed with absolutely calibrated VUV spectrometers. Charge state distributions for C II-IV and O III-VI were obtained from the spectral line intensities. The Li-like ion was dominant for carbon and the B- and Be-like ions were dominant for oxygen. Radiative power losses from divertor plasmas were calculated from the spectroscopic measurements. For a neutral beam heated discharge with a heating power of 12 MW, the fractions of the radiative power losses due to deuterium, carbon and oxygen were 58, 39 and 3.4%, respectively