Special Issue "Atomic Data for Tungsten"

A special issue of Atoms (ISSN 2218-2004).

Deadline for manuscript submissions: closed (30 July 2015).

Special Issue Editors

Dr. Peter Beiersdorfer
E-Mail Website
Guest Editor
Physics Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
Interests: Spectroscopy and line formation processes involving highly charged ions; diagnostic measurements of laboratory and astrophysical plasmas
Dr. Bastiaan J. Braams
E-Mail Website
Guest Editor
Nuclear Data Section, Division of Physical and Chemical Sciences, International Atomic Energy Agency, Vienna International Centre, P. O. Box 100, 1400 Vienna, Austria
Interests: plasma physics; fusion energy research; atomic and molecular physics; plasma-material interaction; computational science
Special Issues and Collections in MDPI journals
Dr. Alfred Müller
E-Mail Website
Guest Editor
Institut für Atom- und Molekülphysik, Justus-Liebig-Universität Giessen, Leihgesterner Weg 217, 35392 Giessen, Germany
Interests: Electronic, photonic and atomic collisions involving atomic, molecular and cluster ions; spectroscopy of highly charged ions
Dr. Yuri Ralchenko
E-Mail Website
Guest Editor
Atomic Spectroscopy Group, Quantum Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
Interests: Development of Internet atomic databases, high-precision atomic structure calculations, modeling of plasma population kinetics and other aspects of plasma spectroscopy
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Tungsten is planned to be used as a plasma-facing material in regions having the highest heat load in ITER because of its excellent thermal conductivity, high melting temperature and low affinity for tritium. However, as an impurity in the plasma tungsten poses severe problems due to its high radiation efficiency. Therefore, it is important to know the atomic properties of tungsten in plasma under conditions ranging from the cold temperature (≃1 eV) of near-wall plasma to the ≃20 keV electron temperature expected in the plasma core. These properties are studied experimentally using plasma devices, beams and trapped ions and theoretically by atomic structure and scattering calculations.

The IAEA Coordinated Research Project (CRP) on “Spectroscopic and Collisional Data for Tungsten in Plasma from 1 eV to 20 keV” was organized with the objective of generating experimental and calculated data for radiative and collisional processes involving tungsten ions in a fusion plasma environment. Processes of interest are excitation and ionization by electron, photon, and proton impact, auto-ionization, radiative de-excitation and recombination, dielectronic recombination, and charge exchange. Data include cross sections, spectroscopic signatures (line radiation), and integrated power loss. The present Special Issue of Atoms invites articles reporting on results obtained in the course of this CRP.

Dr. Peter Beiersdorfer
Dr. Bastiaan J. Braams
Dr. Alfred Müller
Dr. Yuri Ralchenko
Guest Editors

Manuscript Submission Information

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Keywords

  • Atomic data for tungsten
  • spectroscopy of tungsten ions in plasma
  • transition probabilities
  • excitation, ionization
  • recombination
  • radiative energy loss

Published Papers (10 papers)

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Research

Open AccessArticle
Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions
Atoms 2015, 3(4), 474-494; https://doi.org/10.3390/atoms3040474 - 20 Nov 2015
Cited by 16
Abstract
Electron impact excitation (EIE) and dielectronic recombination (DR) of tungsten ions are basic atomic processes in nuclear fusion plasmas of the International Thermonuclear Experimental Reactor (ITER) tokamak. Detailed investigation of such processes is essential for modeling and diagnosing future fusion experiments performed on [...] Read more.
Electron impact excitation (EIE) and dielectronic recombination (DR) of tungsten ions are basic atomic processes in nuclear fusion plasmas of the International Thermonuclear Experimental Reactor (ITER) tokamak. Detailed investigation of such processes is essential for modeling and diagnosing future fusion experiments performed on the ITER. In the present work, we studied total and partial electron-impact excitation (EIE) and DR cross-sections of highly charged tungsten ions by using the multiconfiguration Dirac–Fock method. The degrees of linear polarization of the subsequent X-ray emissions from unequally-populated magnetic sub-levels of these ions were estimated. It is found that the degrees of linear polarization of the same transition lines, but populated respectively by the EIE and DR processes, are very different, which makes diagnosis of the formation mechanism of X-ray emissions possible. In addition, with the help of the flexible atomic code on the basis of the relativistic configuration interaction method, DR rate coefficients of highly charged W37+ to W46+ ions are also studied, because of the importance in the ionization equilibrium of tungsten plasmas under running conditions of the ITER. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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Open AccessArticle
Detailed Analysis of Configuration Interaction and Calculation of Radiative Transition Rates in Seven Times Ionized Tungsten (W VIII)
Atoms 2015, 3(3), 299-319; https://doi.org/10.3390/atoms3030299 - 30 Jun 2015
Cited by 4
Abstract
A new set of oscillator strengths and transition probabilities for EUV spectral lines of seven times ionized tungsten (W VIII) is reported in the present paper. These results have been obtained using the pseudo-relativistic Hartree-Fock (HFR) method combined with a semi-empirical optimization of [...] Read more.
A new set of oscillator strengths and transition probabilities for EUV spectral lines of seven times ionized tungsten (W VIII) is reported in the present paper. These results have been obtained using the pseudo-relativistic Hartree-Fock (HFR) method combined with a semi-empirical optimization of the radial parameters minimizing the discrepancies between computed energy levels and available experimental data. The final physical model considered in the calculations has been chosen further to a detailed investigation of the configuration interaction in this atomic system characterized by complex configurations of the type 4f145s25p5, 4f145s25p4nl, 4f145s5p6, 4f135s25p6, 4f135s25p5nl and 4f125s25p6nl (nl = 5d, 6s). Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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Open AccessArticle
Spectra of W VIII and W IX in the EUV Region
Atoms 2015, 3(3), 273-298; https://doi.org/10.3390/atoms3030273 - 30 Jun 2015
Cited by 3
Abstract
The results obtained on the W VIII spectrum as well as on the isoelectronic spectra Lu V, Hf VI, Ta VII, and Re IX in the VUV wavelength region are summarized with emphasis on the main trends along the isoelectronic sequence. A total [...] Read more.
The results obtained on the W VIII spectrum as well as on the isoelectronic spectra Lu V, Hf VI, Ta VII, and Re IX in the VUV wavelength region are summarized with emphasis on the main trends along the isoelectronic sequence. A total of 187 lines of W VIII in the region of 160–271 Å were accurately measured and identified, 98 levels were found, and transition probabilities calculated. The isoelectronic regularities support the data on W VIII. A list of spectral lines in the region of 170–199 Å, considered as belonging to W IX, is presented. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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Open AccessArticle
Tungsten Data for Current and Future Uses in Fusion and Plasma Science
Atoms 2015, 3(2), 260-272; https://doi.org/10.3390/atoms3020260 - 15 Jun 2015
Cited by 16
Abstract
We give a brief overview of our recent experimental and theoretical work involving highly charged tungsten ions in high-temperature magnetically confined plasmas. Our work includes X-ray and extreme ultraviolet spectroscopy, state-of-the-art structure calculations, the generation of dielectronic recombination rate coefficients, collisional-radiative spectral modeling [...] Read more.
We give a brief overview of our recent experimental and theoretical work involving highly charged tungsten ions in high-temperature magnetically confined plasmas. Our work includes X-ray and extreme ultraviolet spectroscopy, state-of-the-art structure calculations, the generation of dielectronic recombination rate coefficients, collisional-radiative spectral modeling and assessments of the atomic data need for X-ray diagnostics monitoring of the parameters of the core plasma of future tokamaks, such as ITER. We give examples of our recent results in these areas. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
Open AccessArticle
Tungsten Ions in Plasmas: Statistical Theory of Radiative-Collisional Processes
Atoms 2015, 3(2), 162-181; https://doi.org/10.3390/atoms3020162 - 25 May 2015
Cited by 10
Abstract
The statistical model for calculations of the collisional-radiative processes in plasmas with tungsten impurity was developed. The electron structure of tungsten multielectron ions is considered in terms of both the Thomas-Fermi model and the Brandt-Lundquist model of collective oscillations of atomic electron density. [...] Read more.
The statistical model for calculations of the collisional-radiative processes in plasmas with tungsten impurity was developed. The electron structure of tungsten multielectron ions is considered in terms of both the Thomas-Fermi model and the Brandt-Lundquist model of collective oscillations of atomic electron density. The excitation or ionization of atomic electrons by plasma electron impacts are represented as photo-processes under the action of flux of equivalent photons introduced by E. Fermi. The total electron impact single ionization cross-sections of ions Wk+ with respective rates have been calculated and compared with the available experimental and modeling data (e.g., CADW). Plasma radiative losses on tungsten impurity were also calculated in a wide range of electron temperatures 1 eV–20 keV. The numerical code TFATOM was developed for calculations of radiative-collisional processes involving tungsten ions. The needed computational resources for TFATOM code are orders of magnitudes less than for the other conventional numerical codes. The transition from corona to Boltzmann limit was investigated in detail. The results of statistical approach have been tested by comparison with the vast experimental and conventional code data for a set of ions Wk+. It is shown that the universal statistical model accuracy for the ionization cross-sections and radiation losses is within the data scattering of significantly more complex quantum numerical codes, using different approximations for the calculation of atomic structure and the electronic cross-sections. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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Open AccessArticle
Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States
Atoms 2015, 3(2), 120-161; https://doi.org/10.3390/atoms3020120 - 20 May 2015
Cited by 25
Abstract
Collisional processes and details of atomic structure of heavy many-electron atoms and ions are not yet understood in a fully satisfying manner. Experimental studies are required for guiding new theoretical approaches. In response to fusion-related needs for collisional and spectroscopic data on tungsten [...] Read more.
Collisional processes and details of atomic structure of heavy many-electron atoms and ions are not yet understood in a fully satisfying manner. Experimental studies are required for guiding new theoretical approaches. In response to fusion-related needs for collisional and spectroscopic data on tungsten atoms in all charge states, a project has been initiated in which electron-impact and photon-induced ionization as well as photorecombination of Wq+ ions are studied. Cross sections and rate coefficients were determined for charge states q ranging from q = 1 to q = 5 for photoionization, for q = 1 up to q = 19 for electron-impact ionization and for q = 18 to q = 21 for electron-ion recombination. An overview, together with a critical assessment of the methods and results is provided. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
Open AccessArticle
Radiative Recombination and Photoionization Data for Tungsten Ions. Electron Structure of Ions in Plasmas
Atoms 2015, 3(2), 86-119; https://doi.org/10.3390/atoms3020086 - 18 May 2015
Cited by 6
Abstract
Theoretical studies of tungsten ions in plasmas are presented. New calculations of the radiative recombination and photoionization cross-sections, as well as radiative recombination and radiated power loss rate coefficients have been performed for 54 tungsten ions for the range W6+–W71+. The data are [...] Read more.
Theoretical studies of tungsten ions in plasmas are presented. New calculations of the radiative recombination and photoionization cross-sections, as well as radiative recombination and radiated power loss rate coefficients have been performed for 54 tungsten ions for the range W6+–W71+. The data are of importance for fusion investigations at the reactor ITER, as well as devices ASDEX Upgrade and EBIT. Calculations are fully relativistic. Electron wave functions are found by the Dirac–Fock method with proper consideration of the electron exchange. All significant multipoles of the radiative field are taken into account. The radiative recombination rates and the radiated power loss rates are determined provided the continuum electron velocity is described by the relativistic Maxwell–Jüttner distribution. The impact of the core electron polarization on the radiative recombination cross-section is estimated for the Ne-like iron ion and for highly-charged tungsten ions within an analytical approximation using the Dirac–Fock electron wave functions. The effect is shown to enhance the radiative recombination cross-sections by ≲20%. The enhancement depends on the photon energy, the principal quantum number of polarized shells and the ion charge. The influence of plasma temperature and density on the electron structure of ions in local thermodynamic equilibrium plasmas is investigated. Results for the iron and uranium ions in dense plasmas are in good agreement with previous calculations. New calculations were performed for the tungsten ion in dense plasmas on the basis of the average-atom model, as well as for the impurity tungsten ion in fusion plasmas using the non-linear self-consistent field screening model. The temperature and density dependence of the ion charge, level energies and populations are considered. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
Open AccessArticle
Collisional-Radiative Modeling of Tungsten at Temperatures of 1200–2400 eV
Atoms 2015, 3(2), 76-85; https://doi.org/10.3390/atoms3020076 - 30 Apr 2015
Cited by 3
Abstract
We discuss new collisional-radiative modeling calculations of tungsten at moderate temperatures of 1200 to 2400 eV. Such plasma conditions are relevant to ongoing experimental work at ASDEX Upgrade and are expected to be relevant for ITER. Our calculations are made using the Los [...] Read more.
We discuss new collisional-radiative modeling calculations of tungsten at moderate temperatures of 1200 to 2400 eV. Such plasma conditions are relevant to ongoing experimental work at ASDEX Upgrade and are expected to be relevant for ITER. Our calculations are made using the Los Alamos National Laboratory (LANL) collisional-radiative modeling ATOMIC code. These calculations formed part of a submission to the recent NLTE-8 workshop that was held in November 2013. This series of workshops provides a forum for detailed comparison of plasma and spectral quantities from NLTE collisional-radiative modeling codes. We focus on the LANL ATOMIC calculations for tungsten that were submitted to the NLTE-8 workshop and discuss different models that were constructed to predict the tungsten emission. In particular, we discuss comparisons between semi-relativistic configuration-average and fully relativistic configuration-average calculations. We also present semi-relativistic calculations that include fine-structure detail, and discuss the difficult problem of ensuring completeness with respect to the number of configurations included in a CR calculation. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
Open AccessArticle
Fully Relativistic Electron Impact Excitation Cross-Section and Polarization for Tungsten Ions
Atoms 2015, 3(2), 53-75; https://doi.org/10.3390/atoms3020053 - 28 Apr 2015
Cited by 4
Abstract
Electron impact excitation of highly charged tungsten ions in the framework of a fully relativistic distorted wave approach is considered in this paper. Calculations of electron impact excitation cross-sections for the M- and L-shell transitions in the tungsten ions Wn+ (n [...] Read more.
Electron impact excitation of highly charged tungsten ions in the framework of a fully relativistic distorted wave approach is considered in this paper. Calculations of electron impact excitation cross-sections for the M- and L-shell transitions in the tungsten ions Wn+ (n = 44–66) and polarization of the decay of photons from the excited tungsten ions are briefly reviewed and discussed. New calculations in the wide range of incident electron energies are presented for M-shell transitions in the K-like through Ne-like tungsten ions. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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Open AccessArticle
Ab-Initio Calculations of Level Energies, Oscillator Strengths and Radiative Rates for E1 Transitions in Beryllium-Like Iron
Atoms 2015, 3(1), 2-52; https://doi.org/10.3390/atoms3010002 - 20 Jan 2015
Cited by 4
Abstract
In the present work, energy levels, oscillator strengths, radiative rates and wavelengths of Be-like iron (Fe\(^{22+}\)) from ab-initio calculations using the multiconfiguration Dirac-Hartree-Fock method are presented. These quantities have been calculated for a set of configurations in the general form \(1s^2\,nl\,n'l'\) where [...] Read more.
In the present work, energy levels, oscillator strengths, radiative rates and wavelengths of Be-like iron (Fe\(^{22+}\)) from ab-initio calculations using the multiconfiguration Dirac-Hartree-Fock method are presented. These quantities have been calculated for a set of configurations in the general form \(1s^2\,nl\,n'l'\) where \(n=2,3\) and \(\,n'=2,3,4,5\) and \(l=s,p,d\) and \(\,l'=s, p, d, f, g\). In addition, excitations of up to four electrons, including core-electron excitations, have been considered to improve the quality of the wave functions. This study comprises an extensive set of E1 transition rates between states with different \(J\). The present results are compared with the available experimental and theoretical data. Full article
(This article belongs to the Special Issue Atomic Data for Tungsten)
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