The high-precision magnetoelectric velocity sensor can measure the vibration of the superconducting cavity in a low-temperature environment.

This study aims to quantitatively investigate the effects of temperature on the vibration characteristics of a superconducting cavity and provide recommendations for designing mechanical and cryogenic systems cryomodule.

The superconducting cavity in a 1.3 GHz cryomodule of the Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) was taken as research object. The mechanical vibration in frequency range of 1~100 Hz, with a direction perpendicular to the beam direction was concerned, and six vibration sensors were arranged at two measuring points to monitor the velocity signals of different components. Subsequently, the displacement power spectral density, displacement root mean square, and frequency response function of superconducting cavity at the temperature of 300.0 K, 125.0 K, and 2.0 K were quantitatively analyzed using the spectrum analysis method.

Vibrations of the superconducting cavity caused by the flow at 2.0 K is 9.4% and 4.5% in the vertical and transverse directions, respectively, of that caused by ground source at the Shanghai Synchrotron Radiation Facility. In a cryogenic environment, the new vibration source is the cold flow, and the different fluid states have different effects on the vibration of the superconducting cavity in the vertical and lateral directions.

The study is valuable for guiding the tests and optimal design of cryomodules. The vibration of superconducting cavities at low temperatures can be measured using high-precision magnetoelectric velocity sensors. It is necessary to measure and analyze the potential source and its impact to satisfy the sub-micron beam stability requirements of superconducting linac and suppress the cavity frequency shift caused by mechanical vibration.