Several vertical test stands for the characterization of superconducting accelerator cavities
The characterization of superconducting cavities usually happens in so-called vertical test stands. The cavities are attached to the insert of a large dewar. The cavity vacuum system is pumped, the cavity cooled down to typ. 2 Kelvin. At DESY the inserts are adaptive for different cavity types, and usually have an adjustable RF antenna. Typical measurements start with the accelerating gradient as a function of the loaded quality factor (eq. to cryogenic losses). More sophisticated are RF measurements in the different pass-band modes, the temperature map or a second-sound measurement to locate quenches. Sensors checking radiation caused by field emission and magnetic flux complete the picture.