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

Preval, S P and Badnell, N R and O'Mullane, M G (2017) Partial and total dielectronic recombination rate coefficients for W55+ to W38+. Journal of Physics B: Atomic, Molecular and Optical Physics, 50 (10). 105201. ISSN 0953-4075

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    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.