Plasma opacity calculations using the Starrett and Saumon average-atom model with ion correlations

Ovechkin, A. A.; Loboda, P. A.; Falkov, A. L.

doi:10.1016/j.hedp.2019.01.003

Cited by 11 publications

(6 citation statements)

References 62 publications

(127 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Regarding plasma embedding effects in the solar interior, Krief et al (2018) have used the ion-ion correlation model of Rozsnyai (1991Rozsnyai ( , 1992 to re-evaluate the Fe Rosseland mean opacity in conditions similar to the base of the convection zone and have found a 15% increase. However, a more recent calculation (Ovechkin et al 2019) based on the Starrett-Saumon average-atom model has questioned this result as an overestimate due to a limited treatment of the ion-ion repulsion, which is one of the points we have emphasized in the present work.…”

Section: Astrophysical Implicationsmentioning

confidence: 77%

Plasma environment effects on K lines of astrophysical interest

Deprince

Bautista

Fritzsche

et al. 2019

A&A

View full text Add to dashboard Cite

Aims. In the context of accretion disks around black holes, we estimate plasma-environment effects on the atomic parameters associated with the decay of K-vacancy states in highly charged iron ions, namely Fe xvii -Fe xxv. Methods. Within the relativistic multiconfiguration Dirac-Fock (MCDF) framework, the electron-nucleus and electron-electron plasma screenings were approximated with a time-averaged Debye-Hückel potential. Results. Modified ionization potentials, K thresholds, wavelengths, radiative emission rates, and Auger widths are reported for astrophysical plasmas characterized by electron temperatures and densities in the ranges 10 5 −10 7 K and 10 18 −10 22 cm −3 , respectively. Conclusions. We conclude that the high-resolution microcalorimeters on board future X-ray missions such as XRISM and ATHENA are expected to be sensitive to the lowering of the iron K edge due to the extreme plasma conditions occurring in accretion disks around compact objects. Key words. black hole physics -plasmas -atomic data -X-rays: generalArticle published by EDP Sciences A83, page 1 of 8 A&A 626, A83 (2019)

show abstract

Section: Astrophysical Implicationsmentioning

confidence: 77%

Plasma environment effects on K lines of astrophysical interest

Deprince

Bautista

Fritzsche

et al. 2019

A&A

View full text Add to dashboard Cite

show abstract

“…Detailed finite temperature density functional theory (DFT) calculations in the spherical average atom approximation [33,[37][38][39][40][41][42][43][44][45] followed by STA calculations using the atomic code STAR [28,29], were performed over a wide range of plasma temperatures: 100eV-10keV and densities: 10 −3 − 10 3 g/cm 3 , for the following low, mid and high Z elements -Silicone (Z=14), Iron (Z=26), Xenon (Z=54) and Gold (Z=79). The results are shown in Figs 5-8, and include the average ionization, the chem-ical potential, the number of bound shells, the combinatoric number of configurations over all ionization levels (eq.…”

Section: Resultsmentioning

confidence: 99%

“…where A is the set of all shells from which configurations are constructed. We note that, in general, the number of bound shells is a function of the atomic number, temperature and density, which determines the self consistent central potential -for example, a higher Z element has a larger number of bound shells, due to the higher nucleus charge and a higher density plasma may have a smaller number of shells due to an increased pressure ionization effect (bound states dissolving into the continuum [33,[37][38][39][40][41][42][43][44][45]).…”

Section: Combinatoric Number Of Configurationsmentioning

confidence: 99%

“…[28,29]. In this method, only the bound shells and chemical potential are needed -so that the estimate for the number of populated configurations can be obtained, for example, by solving the Dirac equation in a Thomas-Fermi potential [55] or in a more advanced average atom model potential [33,[37][38][39][40][41][42][43][44][45].…”

Section: Estimation Of the Number Of Populated Configurationmentioning

confidence: 99%

See 1 more Smart Citation

Number of populated electronic configurations in a hot dense plasma

Krief

2021

Phys. Rev. E

View full text Add to dashboard Cite

In hot dense plasmas of intermediate or high-Z elements in the state of local thermodynamic equilibrium, the number of electronic configurations contributing to key macroscopic quantities such as the spectral opacity and equation of state, can be enormous. In this work we present systematic methods for the analysis of the number of relativistic electronic configurations in a plasma. While the combinatoric number of configurations can be huge even for mid-Z elements, the number of configurations which have non negligible population is much lower and depends strongly and nontrivially on temperature and density. We discuss two useful methods for the estimation of the number of populated configurations: (i) using an exact calculation of the total combinatoric number of configurations within superconfigurations in a converged super-transition-array (STA) calculation, and (ii) by using an estimate for the multidimensional width of the probability distribution for electronic population over bound shells, which is binomial if electron exchange and correlation effects are neglected. These methods are analyzed, and the mechanism which leads to the huge number of populated configurations is discussed in detail. Comprehensive average atom finite temperature density functional theory (DFT) calculations are performed in a wide range of temperature and density for several low, mid and high Z plasmas. The effects of temperature and density on the number of populated configurations are discussed and explained.

show abstract

“…To investigate the effect of ion correlations on plasma opacities, Ovechkin et al performed opacity calculations using an ion-correlation average-atom model, following the recent Starrett and Saumon formulation [58,59]. The model was implemented in the RE-SEOS code [60][61][62] that implements a generalized version of the STA approach providing a substantial acceleration of the photo-absorption and photo-ionization calculations with almost the same accuracy as that one obtained with the original superconfiguration approach. As a result, RESEOS predicts a much smaller increase of the Rosseland mean opacity due to ionic correlations (5.5%) than the above mentioned STAR code does (20%).…”

Section: The Reseos Code By Ovechkin Et Almentioning

confidence: 99%

Super Transition Arrays: A Tool for Studying Spectral Properties of Hot Plasmas

Pain

2021

Plasma

View full text Add to dashboard Cite

For the theoretical study of X and extreme-UV spectra of ions in plasmas, quantum mechanics brings more detailed results than statistical physics. However, it is impossible to handle individually the billions of levels that must be taken into account in order to properly describe hot plasmas. Such levels can be gathered into electronic configurations or superconfigurations (groups of configurations) and the corresponding calculations rely on appropriate statistical methods, for local or non-local thermodynamic equilibrium plasmas. In this article we present the basic principles of the Super-Transition-Array approach as well as its practical implementation. During the last decades, calculations performed with the SCO code (Superconfiguration Code for Opacity) have been compared to opacity measurements. The code includes static screening of ions by plasma and is well suited for studying plasma density effects (for example pressure ionization) on opacity and equation of state. The recently developed SCO-RCG code (Superconfiguration Code for Opacity combined with Robert Cowan’s “G” subroutine) combines statistical methods from SCO and fine-structure (detailed-level-accounting) calculations using subroutine RCG from Cowan’s code. SCO-RCG enables us to obtain very detailed spectra and to significantly improve the interpretation of experimental spectra. The Super-Transition-Array formalism is still the cornerstone of several opacity codes, and new ideas are emerging, such as the Configurationally Resolved-Super-Transition-Array approach or the extension of the Partially Resolved-Transition-Array concept to the superconfiguration method.

show abstract

Plasma opacity calculations using the Starrett and Saumon average-atom model with ion correlations

Cited by 11 publications

References 62 publications

Plasma environment effects on K lines of astrophysical interest

Plasma environment effects on K lines of astrophysical interest

Number of populated electronic configurations in a hot dense plasma

Super Transition Arrays: A Tool for Studying Spectral Properties of Hot Plasmas

Contact Info

Product

Resources

About