Spectra and measured wavelengths of intrashell n = 3 transitions in highly charged tungsten ions with partially filled 3p and 3d valence shells, Al-like W 61+ through Fe-like W 48+ , are presented. The ions were created and excited at the electron-beam ion trap facility at the Lawrence Livermore National Laboratory and measured with a high-resolution grazing-incidence spectrometer. The spectral lines were studied in the 27-41 Å range and were analyzed by a comparison with synthetic spectra based on a collisional-radiative model. We determined that the emission not only includes electric dipole allowed transitions, but also several electric quadrupole and magnetic dipole transitions. Line-position uncertainties as low as 25 ppm were achieved. Thus, our measurements provide much needed benchmarks for calculations of the atomic structure of highly charged ions with a partially filled subshell, since these ions are difficult to calculate due to electron-correlation effects.

The extreme ultraviolet (EUV) emission from few-times ionized tungsten atoms has been experimentally studied at the Livermore electron beam ion trap facility. The ions were produced and confined during low-energy operations of the EBIT-I electron beam ion trap. By varying the electron-beam energy from around 30-300 eV, tungsten ions in charge states expected to be abundant in tokamak divertor plasmas were excited, and the resulting EUV emission was studied using a survey spectrometer covering 120-320 Å. It is found that the emission strongly depends on the excitation energy; below 150 eV, it is relatively simple, consisting of strong isolated lines from a few charge states, whereas at higher energies, it becomes very complex. For divertor plasmas with tungsten impurity ions, this emission should prove useful for diagnostics of tungsten flux rates and charge balance, as well as for radiative cooling of the divertor volume. Several lines in the 194-223 Å interval belonging to the spectra of five-and seven-times ionized tungsten (Tm-like W VI and Ho-like W VIII) were also measured using a high-resolution spectrometer.

Abstract. Atomic physics has played an important role throughout the history of experimental plasma 5 physics. For example, accurate knowledge of atomic properties has been crucial for understanding the plasma 6 energy balance and for diagnostic development. With the shift in magnetic fusion research toward high-7 temperature burning plasmas like those expected to be found in the ITER tokamak, the atomic physics of 8 tungsten has become of importance. Tungsten will be a constituent of ITER plasmas because of its use as a 9 plasma-facing material able to withstand high heat loads with lower tritium retention than other possible 10 materials. Already, ITER diagnostics are being developed based on using tungsten radiation. In particular, 11 the ITER Core Imaging X-ray Spectrometer (CIXS), which is designed to measure the core ion temperature 12 and bulk plasma motion, is being based on the x-ray emission of neonlike tungsten ions (W 64+ ). In addition, 13 tungsten emission will at ITER be measured by extreme ultraviolet (EUV) and optical spectrometers to 14 determine its concentration in the plasma and to assess power loss and tungsten sputtering rates. On present-

The hyperfine structure of a large number of transitions in Al II cannot be described using A and B hyperfine constants and the hyperfine structure is therefore said to be anomalous. In this paper, we have studied the hyperfine structure of a few transitions in Al II, 3s5s 3 S-3s5p 3 P, 3s4d 3 D-3s5p 3 P and 3s5p 3 P-3s5d 3 D, by combining theory and experiment. It is shown that the anomalous hyperfine structure is due to strong off-diagonal hyperfine interaction resulting not only in a deplacement of the energies of the hyperfine levels, but also resulting in large intensity redistribution among the individual hyperfine lines. It is shown that the hyperfine mixing in 3s4d 3 D and 3s5d 3 D is very large, whereas small but not negligible in 3s5p 3 P. By combining experimental spectra and theory we could obtain accurate wavefunctions for the 3s4d 3 D and 3s5d 3 D hyperfine levels which were used to calculate the gf-values of all individual hyperfine transitions not only for 3s5p 3 P, but also for 3s3p 3 P and 3s4p 3 P, where the off-diagonal hyperfine interaction leads to negligible intensity redistribution.

The intensity-calibrated spectra of W II have been recorded in the spectral interval 23 000-51 300 cm −1 (1950-4350Å), using the FT500 UV Fourier Transform Spectrometer at Lund Observatory. Combining the intensity data in this work with lifetimes previously measured using the time-resolved laser-induced-fluorescence (TR-LIF) technique resulted in transition probabilities and log gf values for 95 transitions in W II, originating from nine different upper levels with energies between 47 179 and 55 392 cm −1 . Of these transitions, 85 have never been measured before. The new data are compared with theoretical calculations and with previously measured values when available.