### Abstract

Language | English |
---|---|

Article number | 045004 |

Number of pages | 12 |

Journal | Journal of Physics B: Atomic, Molecular and Optical Physics |

Volume | 51 |

Issue number | 4 |

DOIs | |

Publication status | Published - 24 Jan 2018 |

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### Keywords

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

### Cite this

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**Dielectronic recombination of the open 4d-shell of tungsten: W$^{37+}$ to W$^{28+}$.** / Preval, S. P.; Badnell, N. R.; O'Mullane, M. G.

Research output: Contribution to journal › Article

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

UR - http://iopscience.iop.org/article/10.1088/1361-6455/aaa182

U2 - 10.1088/1361-6455/aaa182

DO - 10.1088/1361-6455/aaa182

M3 - Article

VL - 51

JO - Journal of Physics B: Atomic, Molecular and Optical Physics

T2 - Journal of Physics B: Atomic, Molecular and Optical Physics

JF - Journal of Physics B: Atomic, Molecular and Optical Physics

SN - 0953-4075

IS - 4

M1 - 045004

ER -