Dielectronic recombination of Er-like tungsten

Abstract

Theoretical studies of dielectronic recombination, a very important process for both atomic and plasma physics, are carried out for low-ionized Er-like W. The dielectronic recombination (DR) of the Er-like ion W${}^{6+}$ proceeds via electron capture into the intermediate autoionizing states of the Tm-like ion W${}^{5+}$ followed by the radiative decay to singly-excited bound states. In particular, energy levels, radiative transition probabilities, and autoionization rates for [Cd]$4{f}^{14}5{p}^{5}5{l}^{\ensuremath{'}}nl$, [Cd]$4{f}^{14}5{p}^{5}6{l}^{\ensuremath{'}\ensuremath{'}}nl$, [Cd]$4{f}^{13}5{p}^{6}5{l}^{\ensuremath{'}}nl$, and [Cd]$4{f}^{13}5{p}^{6}6{l}^{\ensuremath{'}\ensuremath{'}}nl$ (${l}^{\ensuremath{'}}=d,f,g$, ${l}^{\ensuremath{'}\ensuremath{'}}=s,p,d,f,g$, $n=5--7$) states in Tm-like tungsten (W${}^{5+}$) are calculated using the relativistic many-body perturbation theory and relativistic all-order single-double method as well as the Hartree-Fock-relativistic method (cowan code). Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines. DR rate coefficients are determined for the singly-excited [Cd]$4{f}^{14}5{p}^{6}nl$ ($n=5--7$) and nonautoionizing doubly-excited [Cd]$4{f}^{14}5{p}^{5}5{d}^{2}$, [Cd]$4{f}^{13}5{p}^{6}5{d}^{2}$, [Cd]$4{f}^{13}5{p}^{6}6{s}^{2}$, [Cd]$4{f}^{13}5{p}^{6}5d6s$, and [Cd]$4{f}^{13}5{p}^{6}5d6p$ states. Also, contributions from the autoionizing doubly-excited [Cd]$4{f}^{14}5{p}^{5}5{l}^{\ensuremath{'}}nl$, [Cd]$4{f}^{14}5{p}^{5}6{l}^{\ensuremath{'}\ensuremath{'}}nl$, [Cd]$4{f}^{13}5{p}^{6}5{l}^{\ensuremath{'}}nl$, and [Cd]$4{f}^{13}5{p}^{6}6{l}^{\ensuremath{'}\ensuremath{'}}nl$ states (with $n$ up to 100), which are very important for calculating total DR rates, are estimated. Synthetic dielectronic satellite spectra from Tm-like W are simulated in a broad spectral range from 140 to 1200 \AA{}. These relativistic calculations provide recommended values critically evaluated for their accuracy for a number of W${}^{5+}$ ion properties useful for a variety of applications, including for fusion applications.