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Electron impact excitation for He-like ions with Z = 20-42

Si, R.; Li, S.; Wang, K.; Guo, X. L.; Chen, Z. B.; Yan, J.; Chen, C. Y.; Brage, T. LU and Zou, Y. M. (2017) In Astronomy and Astrophysics 600.
Abstract

Aims. Spectral lines of He-like ions are among the most prominent features in X-ray spectra from a large variety of astrophysical and high-temperature fusion plasmas. A reliable plasma modeling and interpretation of the spectra require a large amount of accurate atomic data related to various physical processes. In this paper, we focus on the electron-impact excitation (EIE) process. Methods. We adopted the independent process and isolated resonances approximation using distorted waves (IPIRDW). Resonant stabilizing transitions and decays to lower-lying autoionizing levels from the resonances are included as radiative damping. To verify the applicability of the IPIRDW approximation, an independent Dirac R-matrix calculation was also... (More)

Aims. Spectral lines of He-like ions are among the most prominent features in X-ray spectra from a large variety of astrophysical and high-temperature fusion plasmas. A reliable plasma modeling and interpretation of the spectra require a large amount of accurate atomic data related to various physical processes. In this paper, we focus on the electron-impact excitation (EIE) process. Methods. We adopted the independent process and isolated resonances approximation using distorted waves (IPIRDW). Resonant stabilizing transitions and decays to lower-lying autoionizing levels from the resonances are included as radiative damping. To verify the applicability of the IPIRDW approximation, an independent Dirac R-matrix calculation was also performed. The two sets of results show excellent agreement. Results. We report electron impact excitation collision strengths for transitions among the lowest 49 levels of the 1snl(n ≤ 5; l ≤ (n - 1)) configurations in He-like ions with 20 ≤ Z ≤ 42. The line ratios R and G are calculated for Fe XXV and Kr XXXV. Conclusions. Compared to previous theoretical calculations, our IPIRDWcalculation treats resonance excitation and radiative damping effects more comprehensively, and the resulting line emission cross sections show good agreement with the experimental observations. Our results should facilitate the modeling and diagnostics of various astrophysical and laboratory plasmas.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Atomic data, Atomic processes
in
Astronomy and Astrophysics
volume
600
publisher
EDP Sciences
external identifiers
  • scopus:85017151749
  • wos:000400754000110
ISSN
0004-6361
DOI
10.1051/0004-6361/201630027
language
English
LU publication?
yes
id
12176f6b-0904-4936-b1ff-67b6e0c9cf3d
date added to LUP
2017-05-02 09:51:00
date last changed
2017-09-18 13:33:38
@article{12176f6b-0904-4936-b1ff-67b6e0c9cf3d,
  abstract     = {<p>Aims. Spectral lines of He-like ions are among the most prominent features in X-ray spectra from a large variety of astrophysical and high-temperature fusion plasmas. A reliable plasma modeling and interpretation of the spectra require a large amount of accurate atomic data related to various physical processes. In this paper, we focus on the electron-impact excitation (EIE) process. Methods. We adopted the independent process and isolated resonances approximation using distorted waves (IPIRDW). Resonant stabilizing transitions and decays to lower-lying autoionizing levels from the resonances are included as radiative damping. To verify the applicability of the IPIRDW approximation, an independent Dirac R-matrix calculation was also performed. The two sets of results show excellent agreement. Results. We report electron impact excitation collision strengths for transitions among the lowest 49 levels of the 1snl(n ≤ 5; l ≤ (n - 1)) configurations in He-like ions with 20 ≤ Z ≤ 42. The line ratios R and G are calculated for Fe XXV and Kr XXXV. Conclusions. Compared to previous theoretical calculations, our IPIRDWcalculation treats resonance excitation and radiative damping effects more comprehensively, and the resulting line emission cross sections show good agreement with the experimental observations. Our results should facilitate the modeling and diagnostics of various astrophysical and laboratory plasmas.</p>},
  articleno    = {A85},
  author       = {Si, R. and Li, S. and Wang, K. and Guo, X. L. and Chen, Z. B. and Yan, J. and Chen, C. Y. and Brage, T. and Zou, Y. M.},
  issn         = {0004-6361},
  keyword      = {Atomic data,Atomic processes},
  language     = {eng},
  month        = {04},
  publisher    = {EDP Sciences},
  series       = {Astronomy and Astrophysics},
  title        = {Electron impact excitation for He-like ions with Z = 20-42},
  url          = {http://dx.doi.org/10.1051/0004-6361/201630027},
  volume       = {600},
  year         = {2017},
}