Abstract
The analysis and modelling of a range of plasmas (for example, astrophysical, laser- produced and fusion) require atomic data for a number of parameters, such as energy levels, radiative rates and electron impact excitation rates, or equivalently, the effective collision strengths. Such data are desired for a wide range of elements and their many ions, although all elements are not useful for all types of plasmas. Since measurements of atomic data are mostly confined to only a few energy levels of some ions, calculations for all parameters are highly important. However, often, there are large discrepancies among different calculations for almost all parameters, which makes it difficult to apply the data with confidence. Many such discrepancies (and the possible remedies) were discussed earlier (Fusion Sci. Technol. 2013, 63, 363). Since then, many more anomalies for almost all of these atomic parameters have been noticed. Therefore, this paper is a revisit of various atomic parameters to highlight the large discrepancies, their possible sources and some suggestions to avoid these, so that comparatively more accurate and reliable atomic data may be available in the future.
Highlights
For the analysis and modelling of plasmas, atomic data for various parameters are required
The aim of this paper is to revisit the various atomic parameters to highlight the large discrepancies and their possible sources and to offer some suggestions to avoid these, so that comparatively more accurate and reliable atomic data may be available in the future
It is comparatively more difficult to assess the accuracy of radiative rates (A-values), or the related parameters such as oscillator (f-values) and line (S-values) strengths; see Equations (1)–(5) of [21]
Summary
For the analysis and modelling of plasmas, atomic data for various parameters (including energy levels, radiative rates and electron impact excitation rates, or the effective collision strengths) are required Measurements of these parameters are mostly confined to only a few energy levels of some ions, and the compiled and assessed results are freely available on the NIST (National Institute of Standards and Technology) website: http://www.nist.gov/pml/data/asd.cfm. Often, there are large discrepancies among different calculations for almost all parameters, as has already been discussed in detail earlier [1] Such discrepancies make it difficult for modellers to apply the data with confidence, when neither are measurements available with which to compare nor can the calculations be repeated to verify the accuracy. We note here that most of the methods and codes applied in their determination have been listed in the earlier paper and are not repeated here
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