KAPPA: A Package for Synthesis of Optically Thin Spectra for the Non-Maxwellian Kappa-Distributions. III. Improvements to Ionization Equilibrium and Extension to Kappa < 2

TL;DR

The paper enhances the KAPPA spectral synthesis package by extending its database to include extreme ppa<2 values, incorporating electron impact multi-ionization effects, and accounting for dielectronic recombination suppression at high densities, improving diagnostics of the solar atmosphere.

Contribution

It introduces significant improvements to the KAPPA package, enabling accurate spectral calculations for extreme ppa values and more comprehensive ionization equilibrium modeling.

Findings

Extended the database for ppa<2 spectra.

Included electron impact multi-ionization effects.

Accounted for dielectronic recombination suppression.

Abstract

The KAPPA package is designed for calculations of optically thin spectra for the non-Maxwellian \k{appa}-distributions. This paper presents extension of the database to allow calculations of the spectra for extreme values of \k{appa} < 2, which are important for accurate diagnostics of the \k{appa}-distributions in the outer solar atmosphere. In addition, two improvements were made to the ionization equilibrium calculations within the database. First, the ionization equilibrium calculations now include the effect of electron impact multi-ionization (EIMI). Although relatively unimportant for Maxwellian distribution, the EIMI becomes important for some elements such as Fe and low values of \k{appa}, where it modifies the ionization equilibrium significantly. Second, the KAPPA database now includes the suppression of dielectronic recombination at high electron densities, evaluated via the suppression factors. We find that at the same temperature, the suppression of dielectronic recombination is almost independent of \k{appa}. The ionization equilibrium calculations for the \k{appa}-distributions are now provided for a range of electron densities.