Energy levels and transition rates for helium-like ions with<i>Z</i> = 10–36

Si, R.; Guo, Xue; Wang, Kai; Li, S.; Yan, Jun; Chen, C. Y.; Brage, Tomas; Zou, Yaming

doi:10.1051/0004-6361/201628656

Cited by 32 publications

(24 citation statements)

References 145 publications

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“…For the sake of completeness, the energy differences ∆E and transition rates A are also listed. However, we replace the CI values with our more elaborate MBPT results (Si et al 2016) and extend the calculation to Z = 42.…”

Section: Large-scale Ipirdw Resultsmentioning

confidence: 99%

“…In our recent work (Si et al 2016), we provided energy levels for the 1snl (n ≤ 6, l ≤ (n − 1)) and 2ln l (n ≤ 6, l ≤ (n − 1)) configurations of He-like ions with Z = 10−36, as well as the radiative rates for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels, by using the second-order many-body perturbation theory (MBPT) implemented in the flexible atomic code (FAC; Gu 2008). The accuracy of the MBPT level energies is expected to be a few tens of a ppm, the line strengths for strong transitions among singly excited levels, and their lifetimes are assessed to be accurate to within 1%.…”

Section: Introductionmentioning

confidence: 96%

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Electron impact excitation for He-like ions withZ= 20–42

Wang

et al. 2017

A&A

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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 IPIRDW calculation 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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Section: Large-scale Ipirdw Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Electron impact excitation for He-like ions withZ= 20–42

Wang

et al. 2017

A&A

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“…As was emphasized earlier [1], almost all working codes are under continuous process of development and improvements, and the errors (as and when detected) are corrected. Similarly, there is always scope for improvement over any calculation, either by improving the accuracy of the wavefunctions and/or enlarging the size by inclusion of additional levels, and this has recently been demonstrated by Si et al [75,76] for He-like ions and by Benda and Houfek [77] for atomic hydrogen.…”

Section: Conclusion and Suggestionsmentioning

confidence: 99%

Discrepancies in Atomic Data and Suggestions for Their Resolutions

Aggarwal

2017

Atoms

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Abstract:The analysis and modelling of a range of plasmas (for example, astrophysical, laserproduced and fusion) require atomic data for a number of parameters, such as energy levels, radiative rates and electron impact excitation rates, or equivalently, the effective collision strengths. Such data are desired for a wide range of elements and their many ions, although all elements are not useful for all types of plasmas. Since measurements of atomic data are mostly confined to only a few energy levels of some ions, calculations for all parameters are highly important. However, often, there are large discrepancies among different calculations for almost all parameters, which makes it difficult to apply the data with confidence. Many such discrepancies (and the possible remedies) were discussed earlier (Fusion Sci. Technol. 2013, 63, 363). Since then, many more anomalies for almost all of these atomic parameters have been noticed. Therefore, this paper is a revisit of various atomic parameters to highlight the large discrepancies, their possible sources and some suggestions to avoid these, so that comparatively more accurate and reliable atomic data may be available in the future.

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“…In the present paper, we continue our effort to produce an accurate and consistent data set of energy levels and transition characteristic for ions of astrophysics interest (Wang et al 2014(Wang et al , 2015(Wang et al , 2016Si et al 2016) by providing energy levels and transition rates for F-like ions with Z=24-30. Using two state-of-the-art approaches, the MCDHF and the second-order many-body perturbation theory (MBPT), we present the 200 lowest bound energy levels arising from s s p…”

Section: Introductionmentioning

confidence: 98%

Extended Calculations With Spectroscopic Accuracy: Energy Levels and Transition Properties for the Fluorine-Like Isoelectronic Sequence With Z = 24–30

Guo

et al. 2016

ApJS

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We have performed extensive multiconfiguration Dirac-Hartree-Fock calculations and second-order many-body perturbation calculations for F-like ions with Z=24-30. Energy levels and transition rates for electric dipole (E1), electric-quadrupole (E2), electric-octupole (E3), magnetic dipole (M1), and magnetic-quadrupole (M2) transitions, as well as radiative lifetimes, are provided for the lowest 200 levels belonging to the s s p configurations of each ion. The results from the two sets of calculations are in excellent agreement. Extensive comparisons are also made with other theoretical results and observed data from the CHIANTI and NIST databases. The present energies and wavelengths are believed to be accurate enough to aid line identifications involving the n=3 and n=4 configurations, for which observations are largely missing. The calculated wavelengths and transition data will be useful in the modeling and diagnostics of astrophysical and fusion plasmas.

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Energy levels and transition rates for helium-like ions withZ = 10–36

Cited by 32 publications

References 145 publications

Electron impact excitation for He-like ions withZ= 20–42

Electron impact excitation for He-like ions withZ= 20–42

Discrepancies in Atomic Data and Suggestions for Their Resolutions

Extended Calculations With Spectroscopic Accuracy: Energy Levels and Transition Properties for the Fluorine-Like Isoelectronic Sequence With Z = 24–30

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