The Cryopump Valve Control Unit CVCU is a safety system which protects UHV-chambers from contaminations caused by unexpected warming up of the cryopump. This event can result from compressor or cryopump faults as well as from sudden cooling water or electrical power shutdowns.
The CVCU requires a cryopump cold head temperature sensor and an electro-pneumatic valve with integrated valve state sensor to separate the cryopump from the UHV-system. During regular operation the temperature of the cryopump cold head is shown on the display of the CVCU as well as the current true state of the valve is shown by the LED. The valve is operated by the "OPEN" and "CLOSE" buttons on the front side of the CVCU. In case of sudden power shutdown or a warming up of the cryopump above a temperature setpoint, the valve is closed immediately and remains closed until it is opened manually. The CVCU housing is compatible to the 19" rack system.