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Warm Up Procedure

  1. Pump mixture to dump.
    1. Close V13A/B. This stops circulation.
    2. Open V9.
    3. Open V5. You are now pumping on the fridge lines from both directions.
    4. Open V12A/B if they're not already, and open the speedivalve for cold trap 1.
  2. Stop 1 K pot.
    1. Close the large black speedivalve. There's no need to close the gold needle valve.
    2. Close V4A. Switch the yellow valve on the recovery line to “exhaust” and close the red valve on the recovery line. Turn off the 4He pump.
  3. Feel the main bath, just in case. Are there vibrations? If so, remove the black bung from the transfer port to release some pressure.
  4. Turn on the mixing chamber heater to 10 mW.
  5. Wait for the helium level to read -0.1%. Wait for half an hour after that.
  6. With all the helium out, you can now lower the dewar. Refer to the section on lowering the dewar. Right before you take out the screws to lower the dewar, stop the He recovery on the main bath by closing the top black valve on the recovery lines, and close the orange valve.
  7. When lowering the dewar, do not lower it all the way - leave it hanging 1-2 feet below the bottom of the IVC.
  8. Because the IVC is very cold, cover the IVC and the fridge lines with the plastic cover. Direct a fan towards the IVC and turn it on.
  9. Turn on the Hepa filter hose and direct it into the main bath. You can use a stool to support the hose.
  10. Standard procedure would be to fill the IVC with 10 mbar of N2 exchange gas once the mixing chamber temperature has passed 77 K during warm-up. However, we do not always follow this procedure. We do overpressurise the IVC with N2 gas before opening it up, once at room temperature.