Radiative decay rates for electric dipole transitions in doubly-, trebly- and quadruply-charged rhenium ions (Re III – V) of interest to nuclear fusion research and astrophysical spectra analyses

A new set of radiative parameters (oscillator strengths and transition probabilities) was obtained for the most intense spectral lines in Re III, Re IV and Re V ions. These parameters were calculated using two independent methods, namely the pseudo-relativistic Hartree–Fock approach including core-polarization effects (HFR+CPOL) and the fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) approach. Detailed comparisons between the results obtained from these two methods as well as with the few data available in the literature allowed us to estimate the precision of the calculations carried out. The radiative parameters reported in the present paper concern a total of 368 electric dipole (E1) transitions in Re III, Re IV and Re V covering the ultraviolet spectral region from 655 to 2135 Å. These are of great interest for the analysis of spectra emitted by plasmas in nuclear fusion reactors, such as ITER where rhenium can be produced by neutron bombardment of the tungsten divertor wall, as well as for the investigation of astrophysical spectra observed from chemically peculiar stars or from kilonovae where rhenium can be produced by the nucleosynthesis r-process.