Extreme-ultraviolet spectra of Pd, Ag, Cd, and Sn ions observed in a 13-keV tokamak plasma

The elements Pd, Ag, Cd, and Sn were each injected by laser ablation into a tokamak plasma of 1.3-keV electron temperature. Spectra in the range of 50–400 Å were observed photographically with a 2.2-m grazing-incidence spectrograph. We identified lines in the isoelectronic sequences of S, Cl, Ar, and K that were not previously classified. They fall in the range of 51–78 Å and were measured with an uncertainty of ±0.010 Å. Graphs of the differences between the measured and the calculated transition energies vary smoothly and confirm the identifications. Least-squares fits to these differences permit accurate predictions for elements Tc, Ru, Rh, and In that have not been investigated. Similar fits to ground-state doublet splittings in the Cl and K sequences provide accurate values of magnetic dipole transition energies for these ions.