Dielectronic recombination of Zn-likeW44+from Cu-likeW45+

Abstract

Energy levels, radiative transition probabilities, and autoionization rates for $\text{[Ar]}3{d}^{10}4{l}^{\ensuremath{'}}nl (n=4--12, l\ensuremath{\le}n\ensuremath{-}1), \text{[Ar]}3{d}^{10}5{l}^{\ensuremath{'}}nl (n=5--8, l\ensuremath{\le}n\ensuremath{-}1)$, and $\text{[Ar]}3{d}^{9}4{l}^{\ensuremath{'}}4{l}^{\ensuremath{'}\ensuremath{'}}nl (n=4--5, l\ensuremath{\le}n\ensuremath{-}1$) states in Zn-like tungsten (${\mathrm{W}}^{44+}$) are calculated using the relativistic Hartree-Fock method (cowan code), the multiconfiiguration relativistic Hebrew University Lawrence Livermore Atomic Code (hullac code), and the relativistic many-body perturbation theory method (rmbpt code). Autoionizing levels above the thresholds $\text{[Ar]}3{d}^{10}4s$ are considered. It is found that configuration mixing $[4sns+4pnp+4dnd+4fnf], [4snp+4pns+4pnd+4dnp+4fns+4fnd]$ plays an important role for all atomic characteristics. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and dielectronic recombination (DR) rate coefficients are determined for the first excited odd- and even-parity states. It is shown that the contribution of the highly excited states is very important for the calculation of total DR rates. Contributions to DR rate coefficients from the excited $\text{[Ar]}3{d}^{10}4{l}^{\ensuremath{'}}nl$ states with $ng12$ and $\text{[Ar]}3{d}^{10}5{l}^{\ensuremath{'}}nl$ states with $ng8$, and additionally from core-excited $\text{[Ar]}3{d}^{9}4{l}^{\ensuremath{'}}4{l}^{\ensuremath{'}\ensuremath{'}}nl$ states with $ng5$, are estimated by extrapolation of all atomic parameters. The orbital angular momentum quantum number $l$ distribution of the rate coefficients shows two peaks at $l=2$ and $l=5$. The total DR rate coefficient is derived as a function of electron temperature. The dielectronic satellite spectra of ${\mathrm{W}}^{44+}$ are important for $M$-shell diagnostic of very high-temperature laboratory plasmas such as those found in future tokamaks.