N=5 to n=5 soft-x-ray emission of uranium in a high-temperature low-density tokamak plasma

The soft-x-ray uranium emission in the 60200- range recorded from a high-temperature (1 keV) low-density (1013 cm-3) tokamak plasma has been analyzed by comparison with theoretical level structure and line-intensity calculations. In an extension of previous work [Finkenthal et al., Phys. Rev. A 45, 5846 (1992)], theoretical U xxv, U xxx, U xxxi, and U xxxii n=5 to n=5 spectra have been computed for the relevant plasma parameters. Fully relativistic parametric potential computer codes have been used for the ab initio atomic-structure calculations, and electron-impact excitation rates have been computed in the distorted-wave approximation. 5s-5p spectral lines and quasicontinua of U xxx, U xxxi, and U xxxii are identified in the 165200- wavelength band. An unambiguous line identification is hampered by theoretical uncertainties and the blending of emission from adjacent charge states.