First high gradient test results of a dressed 325 MHz superconducting single spoke resonator at Fermilab

TL;DR

This paper reports the initial high-gradient test results of a dressed 325 MHz superconducting single-spoke cavity at Fermilab, including performance metrics, sensitivities, and comparison to bare cavity results.

Contribution

First high-gradient test results of a dressed 325 MHz superconducting single-spoke cavity, including detailed analysis of performance, sensitivities, and comparison to prior bare cavity data.

Findings

Achieved high gradients in dressed cavity tests.

Analyzed sensitivities to Q disease and magnetic fields.

Compared dressed cavity performance to bare cavity results.

Abstract

A new superconducting RF cavity test facility has been commissioned at Fermilab in conjunction with first tests of a 325 MHz, {\beta} = 0.22 superconducting single-spoke cavity dressed with a helium jacket and prototype tuner. The facility is described and results of full gradient, CW cavity tests with a high Qext drive coupler are reported. Sensitivities to Q disease and externally applied magnetic fields were investigated. Results are compared to bare cavity results obtained prior to hydrogen degassing and welding into the helium jacket.