On the compatibility of LaB6 and Iodine in Planar and Hollow Cathodes

On the compatibility of LaB6 and Iodine in Planar and Hollow Cathodes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article On the compatibility of LaB6 and Iodine in Planar and Hollow Cathodes Philipp S. Becke, Nils Gerrit Kottke, Max Vaupel, Niccola Kutufa, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8941420/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Iodine is increasingly considered a viable alternative to noble gases for electric propulsion systems, particularly due to its high storage density and non-pressurized form. While various thruster types have been successfully tested with iodine as a propellant, the compatibility of iodine with high-current neutralizers remains insufficiently understood. This work investigates the performance and degradation of LaB6-based hollow and planar cathodes operated with iodine at Airbus Friedrichshafen. A dual-gas feed system enabled heaterless ignition and stable operation with krypton, followed by the transition to iodine. While the planar cathode failed to sustain a stable discharge, the hollow cathode operated for up to 8.5 hours at 2 to 3 A. Post-test SEM/EDX analysis of the emitter revealed significant surface degradation including oxide and iodide formation, and an emitter erosion of up to 15%. The oxygen poisoning of the emitter is attributed to water residues in the iodine tank, which remained despite cleaning procedures. The loss of the emitter material and the high reactivity of lanthanum and boron with iodine suggest an erosion mechanism through volatile reaction products, which is confirmed by thermodynamic considerations. This degradation mechanism resembles the halogen cycle used for tungsten filaments, however without the redeposition of the evaporated material. The short-term effect is a fluctuating discharge voltage due to surface reactions. In the long-term, the cathode performance is expected to degrade due to emitter depletion. Considering the experimental results and the analysis of possible surface reactions, these findings suggest that LaB6 is not suitable as emitter material for long-term operation in hollow cathodes with iodine. A cathode lifetime below 100 hours is projected under the tested configuration. Hollow cathode Planar cathode Iodine Electric Propulsion LaB6 Full Text Additional Declarations No competing interests reported. Supplementary Files BECKETestingData.xlsx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 06 May, 2026 Reviews received at journal 26 Mar, 2026 Reviewers agreed at journal 23 Mar, 2026 Reviewers agreed at journal 04 Mar, 2026 Reviewers invited by journal 26 Feb, 2026 Editor assigned by journal 26 Feb, 2026 Submission checks completed at journal 26 Feb, 2026 First submitted to journal 22 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8941420","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":599322940,"identity":"36c783d5-25c5-477a-84c9-ac8175d9600c","order_by":0,"name":"Philipp S. 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