Spectroscopic investigations of tungsten EUV spectra for fusion plasma diagnostics

The Livermore WOLFRAM spectroscopy project consists of experimental and theoretical investigations of tungsten ions of relevance to the diagnostics of magnetically confined fusion plasmas. A recent effort has focused on the complex extreme ultraviolet spectra of few-times ionized tungsten atoms that are expected to be abundant in ITER divertor plasmas. The tungsten ions were produced and excited in the Livermore EBIT-I electron beam ion trap by scanning the electron-beam energy between 30 and 300 eV. The emission was studied using a broad-band grazing-incidence spectrometer covering 150 -- 300 {\AA} and a high-resolution spectrometer covering the 180 -- 220 {\AA} region. Experimental spectra are presented together with analysis based on calculations using the FAC, GRASP, Cowan, HULLAC, and RMBPT codes. Part of this work was performed under the auspices of the US DOE by LLNL under Contract No. DE-AC52-07NA-27344.