A Measurement Technique For Checking The Net Refrigeration Capacity Of Cryopumps Under Operating-Conditions

Monitoring the pump surface temperature is not always sufficient for assessing the function of a cryopump in vacuum systems. Furthermore, the temperature may deviate from its operating point due to various process-related interferences without the pump having changed its performance. Because of these problems, a measuring device has been developed which allows the temperature and the net refrigeration capacity at both stages of the cryopump to be monitored during operation and to obtain information about its operating status. The potential applications will be described together with some examples from the industrial use of refrigerator-cryopumps.