DESY, Hamburg, Germany
The understanding of local thermal breakdown (“quench“) in superconducting RF cavities is still a challenge. An easy way to find these heat spots is to measure the Second Sound in superfluid helium. This detection technique has been examined in several institutes. At DESY there are currently two vertical bath cryostats where cold RF tests with a cavity mounted in a cryostat insert can be done. At all of the four inserts the Second Sound setup consisting of eight Oscillating Superleak Transducers (OSTs) is mounted. These are connected to amplifier electronics and the measured signals are fed into an ADC to be read out with MATLAB. Within MATLAB the location is derived from the measured propagation times. The present system is already in use on a regular basis. An automated setup which will be implemented into the usual RF measurements is under development and the current status will be described.
