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

Abstract

Dielectronic recombination (DR) is a key atomic process which affects the spectroscopic diagnostic modelling of tungsten, most of whose ionization stages will be found somewhere in the ITER fusion reactor: in the edge, divertor, or core plasma. Accurate DR data is sparse while complete DR coverage is unsophisticated (e.g. average-atom or Burgess General Formula) as illustrated by the large uncertainties which currently exist in the tungsten ionization balance. To this end, we present a series of partial final-state-resolved and total DR rate coefficients for W 73+ to W 56+ Tungsten ions. This is part of a wider effort within The Tungsten Project to calculate accurate dielectronic recombination rate coefficients for the tungsten isonuclear sequence for use in collisional-radiative modelling of finite-density tokamak plasmas. The recombination rate coefficients have been calculated with autostructure using kappa-averaged relativistic wavefunctions in level resolution (intermediate coupling) and configuration resolution (configuration average). The results are available from OPEN-ADAS according to the adf09 and adf48 standard formats. Comparison with previous calculations of total DR rate coefficients for W 63+ and W 56+ yield agreement to within 20% and 10%, respectively, at peak temperature. It is also seen that the Jüttner correction to the Maxwell distribution has a significant effect on the ionization balance of tungsten at the highest charge states, changing both the peak abundance temperatures and the ionization fractions of several ions. * simon.preval@strath.ac.uk

Atomic structure and collision dynamics with highly charged ions

“…[124] In addition, a systematic theoretical calculations of recombination rate coefficients for tungsten ions have been performed by employing the AU-TOSTRUCTURE code and can be found in the references in Refs. [125][126][127].…”

Dielectronic recombination of the open 4d-shell of tungsten: W37+–W28+

“…More recently, a calculation by Li et al [27] for 10like showed differences of 30-40% with Safronova et al [21] over a wide temperature range while showing good agreement with Preval et al at peak abundance temperature. In addition, Preval et al [42] recently compared their calculated 28-and 29-like DR rate coefficients to those presented by Safronova et al [15,18].…”

“…The most recent attempt to cover the entire isonuclear sequence is known informally as The Tungsten Project. Using autostructure, Preval et al has calculated DR and RR rate coefficients for ‡ https://www-amdis.iaea.org/FLYCHK/ W 73+ -W 38+ [41,42]. Because of the increased activity in calculating data for tungsten, multiple comparisons have been performed with data from The Tungsten Project, confirming the reliability of the calculation methods used.…”

“…It is for this reason that this paper is dedicated to the 4d q (q 1 10 = -) isonuclear sequence of tungsten, covering charge states W 37+ -W 28+ . As in Prevalet al [41,42] we use some technical notation when discussing the various ionisation stages. Beyond Zn-like, referring to ions by their isoelectronic chemical symbol requires a good memory of the periodic table.…”

Dielectronic recombination of lanthanide and low ionization state tungsten ions: W13+–W1+

“…We now compare two sets of ionization fractions, calculated using recombination rate coefficient data from this work (61-to 73-like) and The Tungsten Project (00-to 46-like, [11,12,13]), and using the scaled data from Pütterich et al [3]. For the ionization fraction calculated using the present data, we use the data from Pütterich et al for 47-to 60-like, as we have not calculated data for these charge states yet.…”