Partial and total dielectronic recombination rate coefficients for W⁵⁵⁺ to W³⁸⁺

Dielectronic recombination (DR) is the dominant mode of recombination in magnetically confined fusion plasmas for intermediate to low-charged ions of W. Complete, final-state resolved partial isonuclear W DR rate coefficient data is required for detailed collisional-radiative modelling for such plasmas in preparation for the upcoming fusion experiment ITER. To realize this requirement, we continueThe Tungsten Project by presenting our calculations for tungsten ions W⁵⁵⁺ to W³⁸⁺. As per our prior calculations for W⁷³⁺ to W⁵⁶⁺, we use the collision package AUTOSTRUCTURE to calculate partial and total DR rate coefficients for all relevant core-excitations in intermediate coupling (IC) and configuration average (CA) using κ-averaged relativistic wavefunctions. Radiative recombination (RR) rate coefficients are also calculated for the purpose of evaluating ionization fractions. Comparison of our DR rate coefficients for W⁴⁶⁺ with other authors yields agreement to within 7-19% at peak abundance verifying the reliability of our method. Comparison of partial DR rate coefficients calculated in IC and CA yield differences of a factor ∼ 2 at peak abundance temperature, highlighting the importance of relativistic configuration mixing. Large differences are observed between ionization fractions calculated using our recombination rate coefficient data and that of Pütterich et al [Plasma Phys. and Control. Fusion 50 085016, (2008)]. These differences are attributed to
deficiencies in the average-atom method used by the former to calculate their data.