Sunpower Inc. CryoTel
MT Operating Instructions version 4
17
C. Operation Shutdown
1.
Turn off the controller.
a.
The quick rattle heard when power is cut off from the CryoTel is due to the stored
energy in the vibration absorber being dissipated.
b.
In rare cases where the operating temperature was below 60 K, it has been observed
that the cooler can energize itself during shutdown and become an engine. To
prevent this, allow the cold tip to reach a temperature above 60 K before shutting
down.
2.
Allow the cold tip and the rest of the cryocooler temperature to rise to room temperature
before opening the vacuum in order to prevent the vapor outside the cryostat from
condensing and freezing on the cold tip.
a.
Applying a heat load to the cold tip during the warming process reduces the time
needed to reach room temperature.
b.
Sunpower recommends using a relay in conjunction with the temperature sensor to
ensure that the power supply to the heat load shuts off when the cold tip temperature
reaches 300 K.
