A fully relativistic approach for calculating atomic data for highly charged ions

Sampson, Douglas H.; Zhang, Hong Lin; Fontes, Christopher J.

doi:10.1016/j.physrep.2009.04.002

Cited by 84 publications

(95 citation statements)

References 128 publications

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“…The autoionization rate can be calculated as a configuration average [88,89]. We developed such an approach in the Multi-Configuration Dirac-Fock (MCDF) code developed by Bruneau [90,91], and our results are very close to the ones obtained with the Flexible Atomic Code (FAC) [92] (see Table 5).…”

Section: Autoionizationsupporting

confidence: 61%

Detailed Opacity Calculations for Astrophysical Applications

Pain

Gilleron

Comet

2017

Atoms

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Nowadays, several opacity codes are able to provide data for stellar structure models, but the computed opacities may show significant differences. In this work, we present state-of-the-art precise spectral opacity calculations, illustrated by stellar applications. The essential role of laboratory experiments to check the quality of the computed data is underlined. We review some X-ray and XUV laser and Z-pinch photo-absorption measurements as well as X-ray emission spectroscopy experiments involving hot dense plasmas produced by ultra-high-intensity laser irradiation. The measured spectra are systematically compared with the fine-structure opacity code SCO-RCG. The focus is on iron, due to its crucial role in understanding asteroseismic observations of β Cephei-type and Slowly Pulsating B stars, as well as of the Sun. For instance, in β Cephei-type stars, the iron-group opacity peak excites acoustic modes through the "kappa-mechanism". Particular attention is paid to the higher-than-predicted iron opacity measured at the Sandia Z-machine at solar interior conditions. We discuss some theoretical aspects such as density effects, photo-ionization, autoionization or the "filling-the-gap" effect of highly excited states.

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Section: Autoionizationsupporting

confidence: 61%

Detailed Opacity Calculations for Astrophysical Applications

Pain

Gilleron

Comet

2017

Atoms

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“…However, it is worth noting that this approximation ignores relativistic effects, which may become significant at such high energies. In particular, at high energies the Lotz formula cross section falls off like ln(u)/u as predicted by the Bethe approximation, but in the relativistic limit the Betheapproximation cross section becomes a constant (Sampson et al 2009). Since temperatures above 10 8 K are uncommon, we have neglected these relativistic effects in our analysis.…”

Section: Application Of Fitting Formulae To Iron Ionsmentioning

confidence: 77%

Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron

Hahn

Savin

2015

ApJ

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We describe the influence of electron-impact multiple ionization (EIMI) on the ionization balance of collisionally ionized plasmas. Previous ionization balance calculations have largely neglected EIMI. Here, EIMI cross-section data are incorporated into calculations of both equilibrium and non-equilibrium charge-state distributions (CSDs). For equilibrium CSDs, we find that EIMI has only a small effect and can usually be ignored. However, for nonequilibrium plasmas the influence of EIMI can be important. In particular, we find that for plasmas in which the temperature oscillates there are significant differences in the CSD when including versus neglecting EIMI. These results have implications for modeling and spectroscopy of impulsively heated plasmas, such as nanoflare heating of the solar corona.

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“…Moreover, for Non-LTE plasma spectroscopy, the detailed rates of every process that are involved in the excitation and de-excitation of atomic states have to be taken into account properly to describe experimental spectra as shown for example in the last Non-LTE code comparison workshop [1,2]. Atomic-physics codes dedicated to this application, often use an Hartree-Fock-Slater central potential (or its relativistic version like ATOMIC [3] and FAC [4]) or a parametric potential (such as in HULLAC [5]). This treatment is generally satisfactory to study highly ionized species.…”

Section: Introductionmentioning

confidence: 99%

A project based on multi-configuration Dirac–Fock calculations for plasma spectroscopy

Comet

Pain

Gilleron

et al. 2017

High Energy Density Physics

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We present a project dedicated to hot plasma spectroscopy based on a Multi-Configuration DiracFock (MCDF) code, initially developed by J. Bruneau. The code is briefly described and the use of the transition state method for plasma spectroscopy is detailed. Then an opacity code for localthermodynamic-equilibrium plasmas using MCDF data, named OPAMCDF, is presented. Transition arrays for which the number of lines is too large to be handled in a DLA calculation can be modeled within the Partially Resolved Transition Array method or using the Unresolved Transition Arrays formalism in jj-coupling. An improvement of the original Partially Resolved Transition Array method is presented which gives a better agreement with Detailed Line Accounting computations. Comparisons with some absorption and emission experimental spectra are shown. Finally, the capability of the MCDF code to compute atomic data required for collisional-radiative modeling of plasma at non local thermodynamic equilibrium is illustrated. Additionally to photoexcitation, this code can be used to calculate photoionization, electron impact excitation and ionization cross-sections as well as autoionization rates in the Distorted-Wave or Close Coupling approximations. Comparisons with cross-sections and rates available in the literature are discussed.

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A fully relativistic approach for calculating atomic data for highly charged ions

Cited by 84 publications

References 128 publications

Detailed Opacity Calculations for Astrophysical Applications

Detailed Opacity Calculations for Astrophysical Applications

Influence of Electron-Impact Multiple Ionization on Equilibrium and Dynamic Charge State Distributions: A Case Study Using Iron

A project based on multi-configuration Dirac–Fock calculations for plasma spectroscopy

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