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 W73+ to W56+ 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 W63+ and W56+ yield agreement to within 20% and 10%, respectively, at peak temperature. It is also seen that the Juttner 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.
Highlights
ITER [1] is posited to be the penultimate step in realizing a nuclear fusion power plant
We consider the Dielectronic recombination (DR) rate coefficients first, and we look at the K, L, and M-shells in turn
Large uncertainties exist in the tungsten ionization balance over a wide range of temperatures found in magnetic fusion plasmas
Summary
ITER [1] is posited to be the penultimate step in realizing a nuclear fusion power plant. The authors presented total RR rate coefficients summed up to n = 20 and = 19 To address this situation, we have embarked on a programme of work, as part of The Tungsten Project, which aims to calculate partial final-state resolved DR rate coefficients for use in collisional-radiative modeling with atomic data and analysis structure (ADAS) [31] for the entire isonuclear sequence of tungsten. H-like (1 electron) W73+ will be referred to as 01-like, Ne-like
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