Recommended Practices for the Experimental Characterization of Gridded Ion Engines

This paper provides a comprehensive overview of best practices for characterizing gridded ion engines. It is part of a series of papers designed to serve as guidebooks for the consistent operation and characterization of electric propulsion devices. Understanding and optimizing gridded ion engine performance requires effective methods for measuring operational parameters. These measurements not only offer valuable insights into engine performance, but provide the information needed for flight, as well as enabling direct, meaningful comparisons with existing literature. Additionally, this document informs modelers about the measurement methods and conditions under which performance data were obtained, providing a foundation for model validation and cross-comparison with other engine systems. Methods to characterize the engine are drawn from numerous approaches in the experimental methods sections of thruster publications as well as in texts such as that of Katz and Goebel. In this paper, we highlight key characterization procedures found in the literature and consolidate these methods into a single document. Key performance parameters and how to measure them include: 1) perveance limits, 2) neutralizer operating modes, 3) discharge losses, 4) back-streaming limits, and 5) ion transparency. This work is based on the best approaches developed by national laboratories, space agencies and universities worldwide to understand the transportability of these methods. Transportability is essential to enable comparison of measured performance characteristics from laboratories around the world. This document is intended to serve as a compact guide for those new to the field to for the implementation of best practices for experimental characterization of gridded ion engines.