Absolute rate coefficients for photorecombination of berylliumlike and boronlike silicon ions

TL;DR

This paper presents experimental measurements of electron-ion recombination rate coefficients for silicon ions Si9+ and Si10+ over a wide energy range, providing data crucial for astrophysical plasma modeling.

Contribution

It extends previous measurements of silicon ion recombination rates to higher energies and offers parameterizations for plasma modeling applications.

Findings

Measured rate coefficients for Si9+ and Si10+ recombination.

Agreement with recent theoretical calculations within uncertainties.

Data applicable to modeling silicon in various astrophysical plasmas.

Abstract

We report measured rate coefficients for electron-ion recombination for Si10+ forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from 0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ [Orban et al. 2010, Astrophys. J. 721, 1603] to much higher energies. Experimentally derived rate coefficients for the recombination of Si9+ and Si10+ ions in a plasma are presented along with simple parameterizations. These rate coefficients are useful for the modeling of the charge balance of silicon in photoionized plasmas (Si9+ and Si10+) and in collisionally ionized plasmas (Si10+ only). In the corresponding temperature ranges, the experimentally derived rate coefficients agree with the latest corresponding theoretical results within the experimental uncertainties.