Comprehensive Laboratory Benchmark of K-shell Dielectronic Satellites of Fe XXV-XXI Ions

TL;DR

This study provides a detailed laboratory measurement of K-shell dielectronic satellites of Fe ions, confirming the accuracy of theoretical models used in astrophysics and fusion plasma research.

Contribution

It offers the first comprehensive experimental benchmark of Fe XXV-XXI K-shell dielectronic satellites, validating atomic data crucial for plasma diagnostics.

Findings

High-resolution measurements of satellite resonances up to n'=11.

Experimental cross sections agree within 15% with theoretical calculations.

Validation of FAC distorted-wave calculations for plasma modeling.

Abstract

We report on comprehensive laboratory studies of the K-shell dielectronic recombination (DR) resonances of Fe XXV - XXI ions that prominently contribute to the hard X-ray spectrum of hot astrophysical plasmas. By scanning a monoenergetic electron beam to resonantly excite trapped Fe ions in an electron beam ion trap, and achieving a high electron-ion collision energy resolution of ~7 eV, we resolve their respective KL$n$ satellites up to n'=11. By normalization to known radiative recombination cross sections we also determine their excitation cross sections and that of the continuum with uncertainties below 15%, and verify our results with an independent normalization based on previous measurements. Our experimental data excellently confirm the accuracy and suitability of distorted-wave calculations obtained with the Flexible Atomic Code (FAC) for modeling astrophysical and fusion plasmas.