Follow the below steps to set up your new cryogenic vacuum system.
Compressor:
Check that the static charge in the compressor meets the specified charge - 195 +/- psig.
Check that the frequency switch on the front is set to the correct value for the country - 50 or 60 Hz.
Make sure there is sufficient space for air-flow around the compressor location.
Do not remove the dust covers from the compressor male aeroquips yet.
Before connecting the helium lines and the cryopump, run the compressor for two hours to stabilize helium flow.
Cryopump
Remove the cover from the cryopump, invert the pump to eliminate any loose charcoal that may have fallen off in transit. Do not remove the dust covers from the pump aeroquips yet.
Connect the cryopump to the gate valve on the system in the standard method - ASA, ISO or Conflat.
Connect the roughing valve with thermocouple gauge sensor to the roughing port.
Connect the purge gas valve to the purge fitting on the end of the purge tube assembly on the pump.
Connect the purge gas heater to the purge gas valve and connect a dry nitrogen supply via ¼" tabulation - supply nitrogen at approx 30 psi.
Helium lines and drive cable.
Run the supply and return helium lines from the compressor to the pump in the position that they will be permanently connected. Do not connect the helium lines yet.
Connecting the system.
After running the compressor without lines connected for two hours, connect the lines to the compressor - remove the dust covers from the aeroquips - connect the RETURN helium flexline first, connect the SUPPLY line last.
Then remove the dust covers from the cryopump aerquips - connect the lines to the cryopump - connect the RETURN line first, connect the SUPPLY line last.
Connect the cryopump motor drive cable to the compressor and the other end to the pump motor connector.
Check the static pressure on the compressor - if it is within specification - 195 +/- psig, go to the next step.
If the pressure is too low (add helium) - if too high (vent helium) - see later instructions.
Start-up.
Switch on the compressor, it will start the cryopump motor and the helium flow. Run for a few minutes to make sure the cryopump motor is turning and the standard ‘gas flow' sounds can be heard.
Switch off the compressor.
Automatic System Start-up.
If using the ASC automatic regeneration controller, simply press start and the controller will go through all the stages outlined below, to get the cryopump cold and the system ready for process.
Manual system start-up.
(The cryopump has to be roughed out to a pressure of 100 mtorr or less before starting the compressor and cryopump. A rate of rise test, to ensure the pump is leak free and not exhibiting extreme outgassing should be carried out)
Turn on the the roughing pump.
Open the roughing valve and observe the fall in pressure (measured by the thermocouple gauge sensor on the RV). Choose a vacuum level for roughing out the pump - if using an oil-sealed mechanical pump, do not go below 50 mtorr. If using a dry roughing pump, go to a value as low as practical based on time allowed.
(A good time to reach 10-2 torr from atmosphere is about 20 minutes - too fast a rough down can cause evaporative cooling and may cause water ice in the pump and charcoal).
When this pressure is reached, close the roughing valve and observe the rise in pressure on the t/c gauge.
(There will always be some rise in pressure from outgassing - and perhaps a vacuum leak).
A good rate of rise is 10 mtorr per minute or less.
If the rate of rise exceeds the desired value, open the nitrogen purge valve until the pressure reaches 600 torr - then close the purge valve and open the roughing valve. Observe the fall in pressure.
Repeat several times if outgassing and a high rate of rise continues.
Attain the desired roughing pressure, close the RV and observe the rate of rise again.
Note: outgassing will show a rate of rise that slows over time. A vacuum leak can show a steady rate of rise that keeps a straight slope.
If the desired rate of rise is achieved, close the roughing valve and turn on the compressor - this will start the compressor and pump.
A CP-8 or CP-8LP cryopump should reach 20 kelvin within 90 minutes of start-up.
When the pump reaches 12 kelvin, the gate valve can be opened and process started.
