Like every cryo pump the COOLVAC binds the gas molecules which have to be pumped on cold surfaces.
There are surfaces at different temperature levels to capture gases with different freezing points. There are, for instance:
- Argon & Nitrogen
- Water vapour
Water vapor is condensed at a temperature of about 100 K on the baffle of the inlet flange of the pump. The battle is cooled by the first stage of the refrigerator and then connected to the first stage by the radiation shield which has a temperature of 80 – 100 K.
Argon or Nitrogen condense at about 15 K on the cold panels at the second stage of the refrigerator. During pumping the ice layer grows continuously. Hydrogen is absorbed by activated charcoal on the inner side of the cold panels.
The Regeneration Process
The Regeneration processes of the COOLVAC starts after closing the high-vacuum valve.
The cold panels of the second stage are warmed up locally by electrical heaters, whereas the battle at the first stage is not heated at all and maintains its temperature. First, at a temperature between 20-100 K, the Hydrogen is released and removed from the COOLVAC via the roughing pump. The forevacuum valve closes again.
The cold panels of the first and the second stage are warmed up locally by electrical heaters up to room temperature. Between 20-310 K all condensed and adsorbed gases are released and removed from the COOLVAC via the roughing pump at a controlled and safe pressure < 20 mbar. After a self-controlled cleaning step the COOLVAC starts to cool down automatically. The cool down takes about 90 minutes and the COOLVAC is ready to continue production.
Between 100 and 140 K the process gases (Argon, Nitrogen) melt. The liquid starts to boil, so that the pressure within the C00LVAC rises, then the Fast Regeneration valve opens and the process gases are discharged. After pressure relief, the forevacuum valve opens and the COOLVAC is further evacuated by the roughing pump.
A short time later the second stage cold panels are cooled down again and the forevacuum valve closes. After approx. 40 minutes a temperature of less than 20 K is reached and the COOLVAC is again ready to continue production.
The video below introduces the cryogenic technology of Leybold's cryopump COOLVAC — a series of cryogenic high vacuum pumps. Get a closer look at how gases behave and how vacuum is produced, thanks to cryo technique.
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