Determination of tungsten and molybdenum concentrations from an X-ray range spectrum in JET

Nakano, Tomohide; Shumack, A.*; Maggi, C. F.*; Reinke, M.*; Lawson, K.*; Ptterich, T.*; Brezinsek, S.*; Lipschultz, B.*; Matthews, G. F.*; Chernyshova, M.*; Jakubowska, K.*; Scholz, M.*; Rzadkiewicz, J.*; Czarski, T.*; Dominik, W.*; Kasprowicz, G.*; Pozniak, K.*; Zabolotny, W.*; Zastrow, K.-D.*

In an European tokamak device, JET, an existing high-resolution X-ray crystal spectrometer was upgraded together with installation of the W divertor for the purpose of monitoring the W density in the core plasma. We have identified W, W and Mo lines by comparing the spectrum observed by this spectrometer and that calculated by an atomic structure code. Further, from the intensities of these spectral lines, the W density and the Mo density over an electron density were determined to be and , respectively. The determined W density was in good agreement with that from another spectrometer. In addition, the plasma effective charge evaluated from the continuum intensity observed by the X-ray spectrometer was in agreement with that from a visible spectrometer within a factor of three. From these agreements, it is probable that the determined W and Mo density are valid. In contrast, the determined W density is only 15% compared with that from an soft X-ray array measurement. This inconsistency will be investigated in the near future.