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 60--200-A range recorded from a high-temperature ([similar to]1 keV) low-density ([similar to]10[sup 13] cm[sup [minus]3]) tokamak plasma has been analyzed by comparison with theoretical level structure and line-intensity calculations. In an extension of previous work [Finkenthal [ital et] [ital al]., Phys. Rev. A 45, 5846 (1992)], theoretical U XXV, U XXX, U XXXI, and U XXXII [ital n]=5 to [ital n]=5 spectra have been computed for the relevant plasma parameters. Fully relativistic parametric potential computer codes have been used for the [ital ab] [ital initio] atomic-structure calculations, and electron-impact excitation rates have been computed in the distorted-wave approximation. 5[ital s]-5[ital p] spectral lines and quasicontinua of U XXX, U XXXI, and U XXXII are identified in the 165--200-A wavelength band. An unambiguous line identification is hampered by theoretical uncertainties and the blending of emission from adjacent charge states.