Extending the Lifetime of Microwave-Driven Ion Sources*

Microwave-driven plasma sources can be utilized to generate deuterons for use in neutron production. At low power these types of sources have very long lifetimes, on the order of 1000s of hours, but at high power that lifetime can drop by 50% or more. This becomes especially important when tritium is utilized due to radiological concerns when executing a source swap. To better understand source performance and lifetime at high power, including the underlying causes and mechanisms, a SHINE ion source is being retrofitted with an array of diagnostic equipment. A combination of Langmuir probes, spectrometry, calorimetry, and magnetic field measurements will allow characterization of important plasma parameters both internally and emitted from the source as well as the ideal operational conditions and parameters. Using this information, we aim to identify the mechanisms which enable high-power standard operation as well as those that drive towards instability and failure. Correctly identifying these mechanism and mitigating those that lead to failure could enable high-power microwave-driven plasma sources to operate with greater ease-of-operation and extended lifetimes like their low-powered bretheren.