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Journal ArticleDOI

WorkOp-IV summary: lessons from iron opacities

TL;DR: The fourth international LTE opacity workshop and code comparison study, WorkOp-IV, was held in Madrid in 1997 as mentioned in this paper, with a focus on iron opacities, and the astrophysically important photon absorption region between 50 and 80 eV was emphasized for a sequence of iron plasmas at densities and temperatures that produce nearly the same average ionization stage (Z ∗ ∼8.6).
Abstract: The fourth international LTE opacity workshop and code comparison study, WorkOp-IV, was held in Madrid in 1997. Results of this workshop are summarized with a focus on iron opacities. In particular, the astrophysically important photon absorption region between 50 and 80 eV is emphasized for a sequence of iron plasmas at densities and temperatures that produce nearly the same average ionization stage (Z ∗ ∼8.6) . Experimental data that addressed this spectral region is also reviewed.

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Citations
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Journal ArticleDOI
TL;DR: It was found that good agreement between codes and with experiments is observed near closed shells, but significant differences exist otherwise, or when density effects are important, as well as plans for the next workshop and for a kinetics database.
Abstract: Comparison of plasma population kinetics codes, which has become an important tool for their testing and verification, was the subject of the third Non-LTE Code Comparison Workshop held at the National Institute of Standards and Technology in December 2003. The motivations for the workshop are presented here, together with its technical organization. The cases studied range from carbon to gold, and include both steady-state and time-dependent calculations. The set of results represents the current capabilities in kinetics modeling, and illustrates the effectiveness of this workshop approach to code comparisons. It was found that good agreement between codes and with experiments is observed near closed shells, but significant differences exist otherwise, or when density effects are important. On a more general level, we discuss how to meaningfully compare kinetics data. We conclude with plans for the next workshop and for a kinetics database.

86 citations

Journal ArticleDOI
TL;DR: In this article, the first "virtual workshop" designed to compare NLTE emissivities produced by widely differing types of atomic physics codes is presented, and a small set of significant results illustrate the progress that is still to be achieved.
Abstract: We review the first “virtual workshop” designed to compare NLTE emissivities produced by widely differing types of atomic physics codes. A small set of significant results, illustrating the progress that is still to be achieved, is presented. We conclude with some lessons learned and possible avenues for future progress.

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Journal ArticleDOI
TL;DR: A detailed review of the state-of-the-art EOS models for inertial confinement fusion (ICF) implosions can be found in this paper, where the authors present a detailed comparison with experiments.

65 citations

Journal ArticleDOI
TL;DR: In this paper, a flexible computation package for calculating radiative properties for low and high Z optically thin and thick plasmas, both under local thermodynamic and non-local thermodynamic equilibrium conditions, named RAPCAL is presented.
Abstract: Radiative properties are fundamental for plasma diagnostics and hydro-simulations. For this reason, there is a high interest in their determination and they are a current topic of investigation both in astrophysics and inertial fusion confinement research. In this work a flexible computation package for calculating radiative properties for low and high Z optically thin and thick plasmas, both under local thermodynamic equilibrium and non-local thermodynamic equilibrium conditions, named RAPCAL is presented. This code has been developed with the aim of providing accurate radiative properties for low and medium Z plasmas within the context of detailed level accounting approach and for heavy elements under the detailed configuration accounting approach. In order to show the capabilities of the code, there are presented calculations of some radiative properties for carbon, aluminum, krypton and xenon plasmas under local thermodynamic and non-local thermodynamic equilibrium conditions.

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ReportDOI
01 Aug 2003
TL;DR: The use of code comparisons for validation is improper and dangerous, and while code comparisons may be argued to provide a beneficial component in code verification activities, there are higher quality code verification tasks that should take precedence.
Abstract: This report presents a perspective on the role of code comparison activities in verification and validation. We formally define the act of code comparison as the Code Comparison Principle (CCP) and investigate its application in both verification and validation. One of our primary conclusions is that the use of code comparisons for validation is improper and dangerous. We also conclude that while code comparisons may be argued to provide a beneficial component in code verification activities, there are higher quality code verification tasks that should take precedence. Finally, we provide a process for application of the CCP that we believe is minimal for achieving benefit in verification processes.

43 citations

References
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Journal ArticleDOI
TL;DR: In this article, measurements of the absorption of X-rays by 1 to 2 transitions in Al XII through Al VIII have been made in a laser-heated slab plasma at the measured temperature and density of 58 ^ 4e V and 0.020 g cm~3.
Abstract: Measurements of the opacity of aluminum in a well characterized, hot, dense, laser produced plasma are reported. Measurements of the absorption of X-rays by 1 to 2 transitions in Al XII through Al VIII have been made in a laser-heated slab plasma at the measured temperature and density of 58 ^ 4e V and 0.020 ^ 0.007 g cm~3. Separate measurements of the temperature and density were made. The con- ditions in the plasma were determined to be reproducible, spatially uniform, and in nearly complete local thermodynamic equilibrium. The absorption spectra and the temperature-density data obtained provide an improved means for comparison with detailed atomic physics and opacity calculations. Subject headings: atomic datamethods: laboratoryplasmasX-rays: general

150 citations

Journal ArticleDOI
TL;DR: Results of a niobium absorption experiment are presented that represent a major step in the development of techniques necessary for the quantitative characterization of hot, dense matter.
Abstract: Results of a niobium absorption experiment are presented that represent a major step in the development of techniques necessary for the quantitative characterization of hot, dense matter. The general requirements for performing quantitative analyses of absorption spectra are discussed. Hydrodynamic simulations are used to illustrate the behavior of tamped x-ray-heated matter and to indicate potential two-dimensional problems inherent in the technique. The absorption spectrum of a low-Z material, in this case aluminum, mixed with niobium provides a temperature diagnostic, which together with radiography as a density diagnostic fully characterizes the sample. A discussion is presented of opacity calculations and a comparison to the measurements is given that illustrates the need for experiments to provide a critical test of theory. The experimental technique is placed in context with a review of previous measurements using absorption spectroscopy to probe hot, dense matter. It is shown that the overall experimental concepts, although understood, were not always achieved in previous experiments. \textcopyright{} 1996 The American Physical Society.

106 citations

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