Identification of visible lines from multiply charged W8+ and W9+ ions

Abstract

We present an investigation of previously unidentified visible lines for ${\mathrm{W}}^{8+}$ and ${\mathrm{W}}^{9+}$ from the spectra observed using an electron-beam ion trap. The analysis is based on collisional-radiative (CR) modeling with fine-structure sublevel population kinetics. To ensure the identification of lines done by the CR model, we have also performed an accurate calculation of transition energies and transition probabilities within the multiconfigurational Dirac-Fock approach using grasp2018. In the spectrum, most of the observed lines are assigned as magnetic dipole transitions belonging to the first two lower-lying configurations of these ions.