A novel numerical tool to study electron energy distribution functions of spatially-anisotropic and non-homogeneous ECR plasmas

TL;DR

This paper introduces a new numerical method for analyzing electron energy distribution functions in anisotropic, non-homogeneous ECR plasmas, validated through experimental X-ray spectrum reproduction and applicable to improving plasma simulations.

Contribution

The paper presents a novel trial-and-error fitting method for EEDFs in anisotropic plasmas, validated with experimental data, enhancing the realism of plasma modeling and analysis.

Findings

Successfully reproduced experimental X-ray spectra

Provided detailed density and temperature profiles of electrons

Revealed distributions of warm and hot electron populations

Abstract

A numerical tool for analysing spatially anisotropic electron populations in electron cyclotron resonance (ECR) plasmas has been developed, using a trial-and-error electron energy distribution function (EEDF) fitting method. The method has been tested on space-resolved warm electrons in the energy range $2-20\,\mathrm{keV}$, obtained from self-consistent simulations modelling only electron dynamics in ECR devices, but lacked real-world validation. For experimentally benchmarking the method, we attempted to numerically reproduce the experimental X-ray emission spectrum measured from an argon plasma. Results of this analysis have provided crucial information about density and temperature of warm electrons, and competing distributions of warm and hot electron components. This information can be fed back to simulation models to generate more realistic data. Subsequent application of the numerical tool as described to the improved simulation data can result in continuous EEDFs that reflect the nature of charge distributions in anisotropic ECR plasmas. These functions can be also applied to electron dependent reactions, in order to reproduce experimental results, like those concerning space-dependent K$\alpha$ emissions.