Dielectronic recombination of the open 4d-shell of tungsten: W$^{37+}$ to W$^{28+}$

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Abstract

Tungsten is an important element for magnetically confined fusion plasmas but has the potential to cool, or even quench the plasma due to it being an efficient radiator. Total and level-resolved dielectronic recombination (DR) rate coefficients, for all ionization stages, are essential to model tungsten. We describe a set calculations performed using the distorted wave code autostructure for the tungsten ions W 37+ to W 28+. We demonstrate the importance of relativistic configuration mixing in such calculations. In particular, we show that the partial DR rate coefficients calculated in level and configuration resolution can differ by as little as 5%, and up to as much as 75%. Using the new data, we calculate a revised steady-state ionization fraction for tungsten. We find that, relative to the ionization fraction calculated using the recombinat ion rate coefficients of Putterich et al (Plasma Phys. Control. Fusion, 50, 085016), the peak temperatures of W 37+ to W 28+ ionization states are shifted to lower temperatures spanning 0.9-1.6keV. This temperature range is important for understanding the performance of large tokamaks, such as ITER, because the tem peratures in the pedestal, edge, scrape-off-layer and divertor region fall in this range.
LanguageEnglish
Article number045004
Number of pages12
JournalJournal of Physics B: Atomic, Molecular and Optical Physics
Volume51
Issue number4
DOIs
Publication statusPublished - 24 Jan 2018

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tungsten
ionization
coefficients
fusion
radiators
configurations
ions
temperature

Keywords

  • dielectronic recombination
  • electrion ion collisions
  • finite density plasmas
  • tungsten

Cite this

@article{c46fe800cedf4ee08f504d14f168fa61,
title = "Dielectronic recombination of the open 4d-shell of tungsten: W$^{37+}$ to W$^{28+}$",
abstract = "Tungsten is an important element for magnetically confined fusion plasmas but has the potential to cool, or even quench the plasma due to it being an efficient radiator. Total and level-resolved dielectronic recombination (DR) rate coefficients, for all ionization stages, are essential to model tungsten. We describe a set calculations performed using the distorted wave code autostructure for the tungsten ions W 37+ to W 28+. We demonstrate the importance of relativistic configuration mixing in such calculations. In particular, we show that the partial DR rate coefficients calculated in level and configuration resolution can differ by as little as 5{\%}, and up to as much as 75{\%}. Using the new data, we calculate a revised steady-state ionization fraction for tungsten. We find that, relative to the ionization fraction calculated using the recombinat ion rate coefficients of Putterich et al (Plasma Phys. Control. Fusion, 50, 085016), the peak temperatures of W 37+ to W 28+ ionization states are shifted to lower temperatures spanning 0.9-1.6keV. This temperature range is important for understanding the performance of large tokamaks, such as ITER, because the tem peratures in the pedestal, edge, scrape-off-layer and divertor region fall in this range.",
keywords = "dielectronic recombination, electrion ion collisions, finite density plasmas, tungsten",
author = "Preval, {S. P.} and Badnell, {N. R.} and O'Mullane, {M. G.}",
year = "2018",
month = "1",
day = "24",
doi = "10.1088/1361-6455/aaa182",
language = "English",
volume = "51",
journal = "Journal of Physics B: Atomic, Molecular and Optical Physics",
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TY - JOUR

T1 - Dielectronic recombination of the open 4d-shell of tungsten: W$^{37+}$ to W$^{28+}$

AU - Preval, S. P.

AU - Badnell, N. R.

AU - O'Mullane, M. G.

PY - 2018/1/24

Y1 - 2018/1/24

N2 - Tungsten is an important element for magnetically confined fusion plasmas but has the potential to cool, or even quench the plasma due to it being an efficient radiator. Total and level-resolved dielectronic recombination (DR) rate coefficients, for all ionization stages, are essential to model tungsten. We describe a set calculations performed using the distorted wave code autostructure for the tungsten ions W 37+ to W 28+. We demonstrate the importance of relativistic configuration mixing in such calculations. In particular, we show that the partial DR rate coefficients calculated in level and configuration resolution can differ by as little as 5%, and up to as much as 75%. Using the new data, we calculate a revised steady-state ionization fraction for tungsten. We find that, relative to the ionization fraction calculated using the recombinat ion rate coefficients of Putterich et al (Plasma Phys. Control. Fusion, 50, 085016), the peak temperatures of W 37+ to W 28+ ionization states are shifted to lower temperatures spanning 0.9-1.6keV. This temperature range is important for understanding the performance of large tokamaks, such as ITER, because the tem peratures in the pedestal, edge, scrape-off-layer and divertor region fall in this range.

AB - Tungsten is an important element for magnetically confined fusion plasmas but has the potential to cool, or even quench the plasma due to it being an efficient radiator. Total and level-resolved dielectronic recombination (DR) rate coefficients, for all ionization stages, are essential to model tungsten. We describe a set calculations performed using the distorted wave code autostructure for the tungsten ions W 37+ to W 28+. We demonstrate the importance of relativistic configuration mixing in such calculations. In particular, we show that the partial DR rate coefficients calculated in level and configuration resolution can differ by as little as 5%, and up to as much as 75%. Using the new data, we calculate a revised steady-state ionization fraction for tungsten. We find that, relative to the ionization fraction calculated using the recombinat ion rate coefficients of Putterich et al (Plasma Phys. Control. Fusion, 50, 085016), the peak temperatures of W 37+ to W 28+ ionization states are shifted to lower temperatures spanning 0.9-1.6keV. This temperature range is important for understanding the performance of large tokamaks, such as ITER, because the tem peratures in the pedestal, edge, scrape-off-layer and divertor region fall in this range.

KW - dielectronic recombination

KW - electrion ion collisions

KW - finite density plasmas

KW - tungsten

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DO - 10.1088/1361-6455/aaa182

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