Hybrid collisional-radiative modeling for high-fidelity atomic kinetics

TL;DR

This paper introduces hybrid collisional-radiative models that combine detailed fine-structure states with superconfiguration averaging to improve accuracy and efficiency in modeling atomic kinetics in fusion plasmas.

Contribution

The paper develops and evaluates hybrid CR schemes for helium, lithium, and beryllium that balance accuracy and computational efficiency by combining detailed states with statistical averaging.

Findings

Hybrid models accurately predict radiative power loss and charge states.

Hybrid schemes offer a practical compromise between detail and computational cost.

Benchmarking shows good agreement with fully resolved models.

Abstract

The fidelity of collisional-radiative (CR) models is critical for advancing our understanding of radiative properties and ionization balance in fusion plasmas. In this work, we present and evaluate hybrid CR schemes that combine fine-structure resolution with superconfiguration averaging, offering a practical compromise between accuracy and computational efficiency. Two hybrid CR models are developed for helium, lithium, and beryllium, retaining detailed fine-structure states up to selected principal quantum numbers, while higher-lying states are statistically averaged to form superconfigurations. These models are applied to compute radiative power loss, as well as average and effective charge states, across a wide range of electron temperatures and densities. The results are benchmarked against a fully fine-structure-resolved CR model to assess the accuracy of the hybrid approach. The findings demonstrate the versatility of hybrid CR schemes and their suitability for detailed plasma simulations where predictive fidelity must be balanced with computational cost.