Report on first plasma processing trial for a FRIB quarter-wave resonator cryomodule

Abstract

Plasma processing has been shown to help mitigate degradation of the performance of superconducting radio-frequency cavities, providing an alternative to removal of cryomodules from the accelerator for refurbishment. Studies of plasma processing for quarter-wave resonators (QWRs) and half-wave resonators (HWRs) are underway at the Facility for Rare Isotope Beams (FRIB), where a total of 324 such resonators are presently in operation. Plasma processing tests were done on several QWRs using the fundamental power coupler (FPC) to drive the plasma, with promising results. Driving the plasma with a higher-order mode allows for less mismatch at the FPC and higher plasma density. The first plasma processing trial for FRIB QWRs in a cryomodule was conducted in January 2024. Cold tests of the cryomodule showed a significant reduction in field emission X-rays after plasma processing.

20 pages, 18 figures

References in corpus (5)

• Field emission mitigation studies in LCLS-II cavities via in situ plasma processing
• Systematic Uncertainties in RF-Based Measurement of Superconducting Cavity Quality Factors
• Improved RF Measurements of SRF Cavity Quality Factors
• Low RF power plasma ignition and detection for in-situ cleaning of 1.3 GHz 9-cell cavities
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