Radiative Recombination Plasma Rate Coefficients for Multiply Charged Ions

Fritzsche, S.; Maiorova, A. V.; Wu, Z. W.

doi:10.3390/atoms11030050

Cited by 4 publications

(2 citation statements)

References 49 publications

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“…During the past years, JAC has been sizeably enlarged along different lines both to assist "additional" physics computations and to make the code more readily accessible to users. Apart from calculating the electronic structure and properties of free atoms and ions, the focus in JAC's development was placed on the treatment of open f -shell elements [46], the computations of radiative and dielectronic recombination plasma rate coefficients [47,48], the setup of approximate Green functions [49], the algebraic evaluation of expressions from Racah's algebra [50] and even estimating atomic (line) energies and decay rates under different plasma environments [51]. We here follow similar objectives, as summarized above, by adding features to JAC for providing useful empirical estimates of the partial and total EII cross sections.…”

Section: The Jac Toolboxmentioning

confidence: 99%

Rapid Access to Empirical Impact Ionization Cross Sections for Atoms and Ions across the Periodic Table

Fritzsche,

Jiao,

Visentin

2024

Plasma

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Electron-impact ionization (EII) processes are essential for modelling high-temperature plasma in quite different research areas, from astrophysics to material science to plasma and fusion research and in several places elsewhere. In most, if not all, of these fields, partial and total EII cross sections are required, and often for a good range of electron energies, in order to determine, for instance, the level population of ions and spectral line intensities in plasma under both local and non-local thermodynamic equilibrium conditions. To obey these needs, various kinds of semi-empirical EII cross sections have been applied in practice, often simply because of the large computational demands in dealing explicitly with two free electrons within the continuum. Here, we expand Jac, the Jena Atomic Calculator, to provide such empirical EII cross sections for (most) atoms and ions across the periodic table. Five empirical models from the recent literature have been implemented to support a simple and rapid access to the partial EII cross sections for electrons from a (partly filled) shell (nℓ)q as well as the total ionization cross sections. We here restrict ourselves to the direct part of the EII cross section, whereas the impact excitation of electrons with subsequent autoionization and the resonant electron capture with double autoionization have been left aside in this first implementation. Rapid access to the (direct) EII cross sections will help already to better understand the role of electron-impact processes in the diagnostics of fusion plasma or the interpretation of astrophysical spectra.

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Section: The Jac Toolboxmentioning

confidence: 99%

Rapid Access to Empirical Impact Ionization Cross Sections for Atoms and Ions across the Periodic Table

Fritzsche,

Jiao,

Visentin

2024

Plasma

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“…During the past few years, JAC has been (enlarged and) applied to the computation of level structures and decay rates of open shell atoms, the prediction of DR resonance spectra and plasma rate coefficients [19], the photorecombination for multiply charged ions [46], as well as for simulating atomic cascades and photon emission spectra [47]. It has been applied especially to model a number of decay cascades as relevant for astrophysical observations [48][49][50].…”

Section: Computation Of Collision Strengths With the Jena Atomic Calc...mentioning

confidence: 99%

Collision Strengths of Astrophysical Interest for Multiply Charged Ions

Fritzsche

Jiao

Wang

et al. 2023

Atoms

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The electron impact excitation and ionization processes are crucial for modeling the spectra of different astrophysical objects, from atmospheres of late-type stars to remnants of supernovae and up to the light emission from neutron star mergers, to name just a few. Despite their significance, however, little is known quantitatively about these processes for low- and medium-impact energies of, say, Ekin≲5000 eV of the free incident electron. To further explore the role of impact excitation, we here expanded Jac, the Jena Atomic Calculator, to the computation of distorted wave collision strengths for fine-structure-resolved, as well as configuration-averaged transitions. While we excluded the formation of dielectronic resonances, these tools can be readily applied for ions with a complex shell structure and by including the major relativistic contributions to these strengths. Detailed computations of the collision strengths are shown and explained for the impact excitation of lithium- and chlorine-like ions. When compared with other, well-correlated methods, good agreement was found, and hence, these tools will support studies of effective collision strengths for a wide range of electron impact energies, levels, and ionic charge states.

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Merits of atomic cascade computations

Fritzsche,

Sahoo,

Sharma

et al. 2024

Eur. Phys. J. D

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Atomic cascades refer—first and foremost—to the stepwise de-excitation of excited atoms owing to the emission of electrons or photons. Apart from dedicated experiments at storage rings and synchrotrons, such cascades frequently occur in astro and plasma physics, material research, surface science and at various places elsewhere. In addition, moreover, “atomic cascades” have been found a useful concept for modeling atomic behavior under different conditions, for instance, when dealing with the photoabsorption of matter, the generation of synthesized spectra, or for determining a rather wide class of (plasma) rate coefficients. We here compile and discuss several atomic cascades (schemes) that help predict cross sections, rate coefficients, electron and photon spectra, or ion distributions. We also demonstrate how readily these schemes have been implemented within JAC, the Jena Atomic Calculator. Emphasis is placed on the classification of atomic cascades and their (quite) natural breakdown into cascade computations, to deal with the electronic structure and transition amplitudes of atoms and ions, as well as the cascade simulation of those properties and spectra, that are experimentally accessible. As an example, we show and discuss the computation of dielectronic recombination plasma rate coefficients for beryllium-like gold ions. The concept of atomic cascades and its implementation into JAC can be applied for most ions across the periodic table and will facilitate the modeling and interpretation of many forthcoming observations. Graphical abstract

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Radiative Recombination Plasma Rate Coefficients for Multiply Charged Ions

Cited by 4 publications

References 49 publications

Rapid Access to Empirical Impact Ionization Cross Sections for Atoms and Ions across the Periodic Table

Rapid Access to Empirical Impact Ionization Cross Sections for Atoms and Ions across the Periodic Table

Collision Strengths of Astrophysical Interest for Multiply Charged Ions

Merits of atomic cascade computations

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