Atomic structure and excitation cross section by electron impact of tungsten ions, W³⁸⁺

Abstract

Excitation energies, radiative rates, and cross sections of tungsten ions (W38+) by electron impact have been calculated using the multiconfiguration Dirac–Fock and R-matrix methods for a configuration state list, which consists of , and and f. A set of configuration state functions with double excitations up to 5l orbitals have been included within the calculations of energy levels and transition probabilities. R-matrix calculations of collision strength and cross section have been executed for the intercombination transitions between 4d, and 4p54f. Resonance collision strengths have been observed at low energies of incident electrons in the range of ∼5−40 Ryd; however, the strong lines limited between 12−25 Ryd. To estimate the accuracy of the calculated energy levels and transition probabilities, comparisons with experimental observations and theoretical calculations are presented, and between different methods for collision strengths and cross sections, as well.

Comment on "Atomic structure and excitation cross section by electron impact of tungsten ions, W$^{38+}$" by El-Maaref et al [J. Phys. B 52(2019) 065202]

“…For 1-2 and 1-5 transitions both FAC1 and FAC2 Ω are comparable over the entire energy range and hence, do not support the findings of El-Maaref et al (2019), who show different Ω B for the two models, and neither are there any jumps, as demonstrated by them. For the 1-3 transition, the two results are indeed different, but this is an allowed one, for which Ω directly depends on the f-value and the energy difference, ∆E i,j .…”

“…As is well known and has also been emphasised by El-Maaref et al (2019), tungsten is one of the most useful material for fusion reactors, and atomic data for its ions are required for a variety of studies. Since the temperatures in fusion plasmas are very high (in the range of ∼ 10 6 to 10 8 K or equivalently 6.3 to 633 Ryd), calculations for Ω need to be performed up to very high energies, and the one done by them for up to 64 Ryd is of no use.…”

“…In a recent paper, El-Maaref et al (2019) have reported results for energy levels, radiative rates and collision strengths (Ω) for a few transitions of Kr-like W XXXIX, which is an important ion particularly for the studies of fusion plasmas. For the calculations of atomic structure, i.e.…”