EUV Spectroscopy of Highly Charged Zr, Nb, Mo, and Pr Ions produced in an Electron Beam Ion Trap

Atomic spectroscopy of highly charged ions is important for investigating atomic processes, identifying new atomic transitions relevant to laboratory, fusion, and astrophysical plasmas, and benchmarking atomic theory. We investigated the extreme ultraviolet (EUV) spectra of highly charged Zr, Mo, Nb, and Pr ions using the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology. Emissions in the 2–20 nm wavelength range were captured with a flat-field grazing-incidence EUV spectrometer. The electron beam energy was varied between 2.5 keV and 11.8 keV to produce the ionization stages of interest. Identification of spectral lines was supported by the NOMAD collisional-radiative model, which accounts for the non-Maxwellian nature of the EBIT plasma. A range of new spectral lines was identified for Li-like through Ne-like ions for Zr, Nb, and Mo ions, and Na-like through Ar-like Pr ions.