Relative intensities of 2$s^2$2$p^k$-2s2$p^{k+1\mathrm{}}$ transitions in F i– to B i–like Ti, Cr, Fe, Ni, and Ge in a tokamak plasma: A comparison of experiment and theory

Measured relative intensities of a number of allowed 2$s^2$2$p^k$-2s2$p^{k+1\mathrm{}}$ transitions (60–200 Å) in the F i– to B i–like ions of titanium, chromium, iron, nickel, and germanium are compared with values from level-population calculations. The measurements are from Princeton Large Torus (PLT) tokamak plasmas with electron densities of ∼2.5×${10}^{13}$ ${\mathrm{cm}}^{\mathrm{-}3}$. For titanium and chromium, data from plasmas with densities of ∼5×${10}^{12}$ ${\mathrm{cm}}^{\mathrm{-}3}$ are also presented; a number of density-dependent line-intensity ratios are found. The spectra were obtained with use of a grazing-incidence time-resolving spectrograph which was radiometrically calibrated with use of synchrotron radiation from the National Bureau of Standards Synchrotron Ultraviolet Radiation Facility (SURF II). The measured relative intensities are therefore reliable. For the majority of the observed lines, agreement between the measured and calculated relative intensities is within 30%, the estimated accuracy of the measurements; significant discrepancies are found in the titanium ions at the low density. The discrepancies, some of which are due to blends, are discussed. Thus, the level-population calculations may be used with some confidence for spectroscopic plasma diagnostics. In the C i–like ions, there is some evidence that calculations which include proton-collisional excitation and deexcitation between the levels of the ground configuration are in better agreement with the measurements than those that do not, indicating that proton collisions should be included in the calculations for these ions.