A cryopump is a capture pump, this means that the gases pumped from the chamber stay inside the cryopump, mostly as ice.  When the pump is ‘full' to capacity, it has to be regenerated. Regeneration in the simplest terms means warming the pump to ambient room temperature so that the captured frozen gases return to the gas state and leave the pump. In the simplest university R&D system, the regeneration can easily be done manually - switch off the compressor, turn on the nitrogen purge valve and nitrogen heater and wait until the pump reaches room temperature.  Then, manually turn on the roughing pump to pump down the cryopump, close the roughing valve and turn on the compressor. In most production vacuum systems for optical coating, space simulation etc., it is more efficient and convenient for the regeneration to be done automatically.  Either press one button on the Automatic Regeneration Controller or send a computer signal via RS232 to initiate regeneration.

The Austin Scientific Automatic Regeneration Controller, model M2200 goes through a complete regeneration cycle of the pump.  At the end of the cycle, the pump has cooled down and is ready to pump.