Application of Coherent Microwave Scattering and Multiphoton Ionization for Diagnostics of Electric Propulsion Systems

TL;DR

This paper explores the use of multiphoton ionization and coherent microwave scattering as non-intrusive diagnostic tools for assessing plasma properties in electric propulsion systems, demonstrated through experiments on a gridded-ion accelerator.

Contribution

It introduces the implementation of MPI-CMS techniques for plasma diagnostics in electric propulsion, expanding non-intrusive measurement capabilities.

Findings

MPI-CMS shows potential for non-intrusive species density measurements

Photoionization spectroscopy provides detailed plasma state information

Optical emission spectroscopy and Langmuir probes complement diagnostics

Abstract

Nonintrusive measurements of plasma properties are essential to evaluate, and numerically simulate, the in-flight performance of electric propulsion systems. As a logical first step in the development of new diagnostic techniques, this work depicts the implementation of multiphoton ionization and coherent microwave scattering (MPI-CMS) in a gridded-ion accelerator operating on rare gases. Presented studies primarily comprise photoionization spectroscopy of ground and excited state-populations of both neutrals and ions supplemented by optical emission spectroscopy and Langmuir probe derived plume properties. Results suggest the potential of MPI-CMS for non-intrusive measurements of specie number densities.