Spectral lines from highly charged Tungsten ions in the soft-X-ray region for quantitative diagnostics of fusion plasmas

X-ray spectra in the range from 5.5 to 19 Angstrom from highly charged tung sten (Z = 74) ions were recorded in the tokamak ASDEX Upgrade from plasma d ischarges with electron temperatures up to 5 keV. Lines emitted from W39+ t o W50+ were identified by comparison with ab initio calculations using the fully relativistic parametric potential code RELAC. In the short wavelength region the measured spectra could be simulated to a high degree of coincid ence by using ion density distributions from impurity transport calculation s and line intensities calculated by a collision al-radiative model, wherea s in the long wavelength region not all of the stronger predicted lines are found. The measured absolute intensities from several spectral lines are u sed to calculate the tungsten density present in the tokamak plasma. The ex tracted tungsten concentrations are in the range of 10(-5)-10(-4) indicatin g that a sensitive W impurity diagnostic can be based on the presented spec tral lines.