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-Angstrom range recorded from a high-temperature (similar to 1 keV) low-density (similar to 10( 13) cm(-3)) tokamak plasma has been analyzed by comparison with theore tical level structure and line-intensity calculations. In an extension of previous work [Finkenthal et al., Phys. Rev. A 45, 5846 (1992)], t heoretical UXXV, UXXX, UXXXI, and UXXXII n=5 to n=5 spectra have been computed for the relevant plasma parameters. Fully relativistic parame tric 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 an d quasicontinua of UXXX, UXXXI, and UXXXII are identified in the 165-2 00-Angstrom wavelength band. An unambiguous line identification is ham pered by theoretical uncertainties and the blending of emission from a djacent charge states.