Electron-Impact Multiple Ionization Cross Sections for Atoms and Ions of Helium through Zinc

TL;DR

This paper compiles and analyzes electron-impact multiple ionization cross sections for ions of helium through zinc, providing fitted parameters for plasma modeling and highlighting unresolved issues in the data.

Contribution

It offers a comprehensive set of fitted cross section parameters for 3466 ions, improving plasma modeling accuracy for astrophysical applications.

Findings

Comparison of semiempirical formulas with experimental data

Interpolated and extrapolated cross section parameters

Identification of unresolved issues in EIMI data

Abstract

We have compiled a set of electron-impact multiple ionization (EIMI) cross sections for astrophysically relevant ions. EIMI can have a significant effect on the ionization balance of non-equilibrium plasmas. For example, it can be important if there is a rapid change in the electron temperature or if there is a non-thermal electron energy distribution, such as a kappa distribution. Cross sections for EIMI are needed in order to account for these processes in plasma modeling and for spectroscopic interpretation. Here, we describe our comparison of proposed semiempirical formulae to the available experimental EIMI cross section data. Based on this comparison, we have interpolated and extrapolated fitting parameters to systems that have not yet been measured. A tabulation of the fit parameters is provided for 3466 EIMI cross sections. We also highlight some outstanding issues that remain to be resolved.