Characterization of Spacecraft Material Erosion from Krypton Ion Sputtering in Electric Propulsion Systems

In electric propulsion (EP), xenon is the most widely used propellant due to its favorable atomic properties and ionization capability. However, krypton has emerged as a potential alternative because of its relatively low cost and high specific impulse during EP ionization. Despite these advantages, krypton's long-term interactions with spacecraft materials are not fully understood, particularly concerning ion-induced sputtering. This research investigates the effects of krypton ion sputtering on materials such as anodized aluminum, boron nitride ceramic, polyimide, and glass. These materials are commonly found in spacecraft construction and are vulnerable to erosion from ion thruster plumes during extended missions. In this project, test samples are exposed to krypton ions under a variety of sputtering conditions, including different ion incidence angles, exposure durations, and applied voltages. These variables influence sputter yield and erosion rates. Total sputter yield is quantified through precise mass measurements and optical profilometry. Sputtered particulates are also collected by silicon slides for analysis to characterize the differential sputter yield and plume distribution, providing insight into contamination risks to nearby components. Analyzing the slides through laser induced breakdown will provide elemental characterization. Samples are prepared for testing by being subjected to low vacuum conditions and weighed prior to testing. Post-test examinations allow for assessment of surface erosion and material loss. The goal of this study is to evaluate the potential impact of krypton-fueled EP systems on spacecraft material longevity, ultimately contributing to improved understanding of alternative EP propellants.