IPAC'24 - 15th International Particle Accelerator Conference

Development of plasma processing for coaxial cavity cryomodules

WEPS22

22 May 2024, 16:00

2h

Blues (MCC Exhibit Hall A)

Poster Presentation MC7.T07 Superconducting RF Wednesday Poster Session

Speaker

Walter Hartung (Facility for Rare Isotope Beams, Michigan State University)

Description

Several groups have demonstrated that plasma processing can help to mitigate degradation of the performance of superconducting radio-frequency cavities. Plasma processing provides 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 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. Driving the plasma with a higher-order mode (HOM) shows promise, as it allows for less mismatch at the FPC. Before-and-after cold tests showed a significant reduction in field emission X-rays with judicious application of plasma processing. The first attempt at plasma processing of FRIB QWRs in a cryomodule is planned for December 2023/January 2024. A repeat bunker test of the cryomodule is planned to assess the results.

Funding Agency

Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0023633, the State of Michigan, and Michigan State University.