### Abstract

^{2}

^{1}S

_{0 }-> 2s2p

^{3}P

_{0,1,2, }

^{1}P

_{1 }core excitations and the trielectronicrecombination (TR) resonances associated with the 2s

^{2}

^{1}S

_{0 }-> 2p

^{2 3}P

_{0,1,2,}

^{1}D

_{2, }

^{1}S

_{0 }core excitations. In addition,the AUTOSTRUCTURE code was used to calculate the recombination rate coefficients for comparison with theexperimental results. Resonant recombination originating from parent ions in the long-lived metastable state 2s2p

^{3}P

_{0 }ions has been identified in the recombination spectrum below 1.25 eV. A good agreement is achievedbetween the experimental recombination spectrum and the result of the AUTOSTRUCTURE calculations whenfractions of 95% ground-state ions and 5% metastable ions are assumed in the calculation. It is found thatthe calculated TR resonance positions agree with the experimental peaks, while the resonance strengths areunderestimated by the theoretical calculation. Temperature dependent plasma rate coefficients for DR and TR inthe temperature range of 103–108 K were derived from the measured electron–ion recombination rate coefficientsand compared with the available theoretical results from the literature. In the temperature range of photoionizedplasmas, the presently calculated rate coefficients and the recent results of Gu & Colgan et al. are up to 30% lowerthan the experimentally derived ones, and the older atomic data are even up to 50% lower than the presentexperimental result. This is because strong resonances situated below electron–ion collision energies of 50 meVwere underestimated by the theoretical calculation, which also has a severe influence on the rate coefficients inlow-temperature plasmas. In the temperature range of collisionally ionized plasmas, agreement within 25% wasfound between the experimental result and the present calculation as well as the calculation by Colgan et al. Thepresent result constitutes a set of benchmark data for use in astrophysical modeling.

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

Number of pages | 7 |

Journal | Astrophysical Journal |

Volume | 862 |

Issue number | 2 |

Early online date | 31 Jul 2018 |

DOIs | |

Publication status | E-pub ahead of print - 31 Jul 2018 |

### Fingerprint

### Keywords

- atomic data
- atomic processes
- plasmas

### Cite this

^{40}Ca

^{16+ }.

*Astrophysical Journal*,

*862*(2). https://doi.org/10.3847/1538-4357/aacc69

}

^{40}Ca

^{16+ }'

*Astrophysical Journal*, vol. 862, no. 2. https://doi.org/10.3847/1538-4357/aacc69

**Electron-ion recombination rate coefficients of Be-like ^{40}Ca^{16+ }.** / Wang, S. X.; Xu, X.; Huang, Z. K.; Wen, W. Q.; Wang, H. B.; Khan, N.; Preval, S. P.; Badnell, N. R.; Schippers, S. ; Mahmood, S.; Dou, L. J.; Chuai, X. Y.; Zhao, D. M.; Zhu, X. L.; Mao, L. J.; Ma, X. M.; Li, J.; Mao, R. S.; Yuan, Y. J.; Tang, M. T.; Yin, D. Y.; Yang, J. C. ; Ma, X.; Zhu, L. F.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Electron-ion recombination rate coefficients of Be-like 40Ca16+

AU - Wang, S. X.

AU - Xu, X.

AU - Huang, Z. K.

AU - Wen, W. Q.

AU - Wang, H. B.

AU - Khan, N.

AU - Preval, S. P.

AU - Badnell, N. R.

AU - Schippers, S.

AU - Mahmood, S.

AU - Dou, L. J.

AU - Chuai, X. Y.

AU - Zhao, D. M.

AU - Zhu, X. L.

AU - Mao, L. J.

AU - Ma, X. M.

AU - Li, J.

AU - Mao, R. S.

AU - Yuan, Y. J.

AU - Tang, M. T.

AU - Yin, D. Y.

AU - Yang, J. C.

AU - Ma, X.

AU - Zhu, L. F.

PY - 2018/7/31

Y1 - 2018/7/31

N2 - Electron–ion recombination rate coefficients for beryllium-like calcium ions in the center of mass energy from 0 to51.88 eV have been measured by means of the electron–ion merged-beam technique at the main cooler storage ringat the Institute of Modern Physics in Lanzhou, China. The measurement energy range covers the dielectronicrecombination (DR) resonances associated with the 2s2 1S0 -> 2s2p 3P0,1,2, 1P1 core excitations and the trielectronicrecombination (TR) resonances associated with the 2s2 1S0 -> 2p2 3P0,1,2, 1D2, 1S0 core excitations. In addition,the AUTOSTRUCTURE code was used to calculate the recombination rate coefficients for comparison with theexperimental results. Resonant recombination originating from parent ions in the long-lived metastable state 2s2p 3P0 ions has been identified in the recombination spectrum below 1.25 eV. A good agreement is achievedbetween the experimental recombination spectrum and the result of the AUTOSTRUCTURE calculations whenfractions of 95% ground-state ions and 5% metastable ions are assumed in the calculation. It is found thatthe calculated TR resonance positions agree with the experimental peaks, while the resonance strengths areunderestimated by the theoretical calculation. Temperature dependent plasma rate coefficients for DR and TR inthe temperature range of 103–108 K were derived from the measured electron–ion recombination rate coefficientsand compared with the available theoretical results from the literature. In the temperature range of photoionizedplasmas, the presently calculated rate coefficients and the recent results of Gu & Colgan et al. are up to 30% lowerthan the experimentally derived ones, and the older atomic data are even up to 50% lower than the presentexperimental result. This is because strong resonances situated below electron–ion collision energies of 50 meVwere underestimated by the theoretical calculation, which also has a severe influence on the rate coefficients inlow-temperature plasmas. In the temperature range of collisionally ionized plasmas, agreement within 25% wasfound between the experimental result and the present calculation as well as the calculation by Colgan et al. Thepresent result constitutes a set of benchmark data for use in astrophysical modeling.

AB - Electron–ion recombination rate coefficients for beryllium-like calcium ions in the center of mass energy from 0 to51.88 eV have been measured by means of the electron–ion merged-beam technique at the main cooler storage ringat the Institute of Modern Physics in Lanzhou, China. The measurement energy range covers the dielectronicrecombination (DR) resonances associated with the 2s2 1S0 -> 2s2p 3P0,1,2, 1P1 core excitations and the trielectronicrecombination (TR) resonances associated with the 2s2 1S0 -> 2p2 3P0,1,2, 1D2, 1S0 core excitations. In addition,the AUTOSTRUCTURE code was used to calculate the recombination rate coefficients for comparison with theexperimental results. Resonant recombination originating from parent ions in the long-lived metastable state 2s2p 3P0 ions has been identified in the recombination spectrum below 1.25 eV. A good agreement is achievedbetween the experimental recombination spectrum and the result of the AUTOSTRUCTURE calculations whenfractions of 95% ground-state ions and 5% metastable ions are assumed in the calculation. It is found thatthe calculated TR resonance positions agree with the experimental peaks, while the resonance strengths areunderestimated by the theoretical calculation. Temperature dependent plasma rate coefficients for DR and TR inthe temperature range of 103–108 K were derived from the measured electron–ion recombination rate coefficientsand compared with the available theoretical results from the literature. In the temperature range of photoionizedplasmas, the presently calculated rate coefficients and the recent results of Gu & Colgan et al. are up to 30% lowerthan the experimentally derived ones, and the older atomic data are even up to 50% lower than the presentexperimental result. This is because strong resonances situated below electron–ion collision energies of 50 meVwere underestimated by the theoretical calculation, which also has a severe influence on the rate coefficients inlow-temperature plasmas. In the temperature range of collisionally ionized plasmas, agreement within 25% wasfound between the experimental result and the present calculation as well as the calculation by Colgan et al. Thepresent result constitutes a set of benchmark data for use in astrophysical modeling.

KW - atomic data

KW - atomic processes

KW - plasmas

UR - http://iopscience.iop.org/journal/0004-637X

U2 - 10.3847/1538-4357/aacc69

DO - 10.3847/1538-4357/aacc69

M3 - Article

VL - 862

JO - Astrophysical Journal

T2 - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

ER -

^{40}Ca

^{16+ }. Astrophysical Journal. 2018 Jul 31;862(2). https://doi.org/10.3847/1538-4357/aacc69