Using Poisson-regularized inversion of Bremsstrahlung emission to extract full EEDFs from x-ray pulse-height detector data

TL;DR

This paper introduces a novel Poisson-regularized inversion method to accurately extract electron energy distribution functions from x-ray pulse-height data in plasma experiments, covering a broad energy range.

Contribution

The study presents a new Poisson-regularized spectrum inversion algorithm applied to x-ray data for detailed EEDF measurement in plasma physics.

Findings

Successfully measured EEDFs from 200 eV to over 8 keV.

Achieved high-resolution EEDF extraction using calibrated SDD detectors.

Demonstrated the method's effectiveness across five orders-of-magnitude in intensity.

Abstract

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV.