Code Comparison Workshop Research Articles

New parametrization for differences between plasma kinetic codes

Validation and verification of plasma kinetics codes requires the development of quantitative methods and techniques for code comparisons. We describe two parameters that can be used for characterization of differences between such codes. It is shown that these parameters, which are determined from the most general results of kinetic codes, can provide important information on the differences between the basic rate coefficients employed. Application of this method is illustrated by comparisons of some results from the 3rd NLTE Code Comparison Workshop for carbon, germanium, and gold plasmas.

Comparing plasma population kinetics codes: Review of the NLTE-3 Kinetics Workshop

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.

NLTE emissivities via an ionisation temperature

We present recent work aimed at obtaining opacities and emissivities in NLTE plasmas, at sufficiently low cost to be used in-line by hydrodynamics codes. We try to improve the basic ingredients of the RADIOM model, namely the ionisation temperature T Z and the source function. The accuracy of the estimated T Z is tested by comparing the resulting ionisation curves to some submitted to the 1996 NLTE Kinetics Code Comparison Workshop. We examine the quality of the source function by comparing the emission spectra to some recent results from average-atom, detailed configuration and superconfiguration codes.