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QT Dewar level: Liq B = Warm, pumped, and purged. Flushed out level sensors.
- [MV02 should be set to restrict flow to allow only 100 ~60 SLM; if it is, then the pressure should be able to be regulated in the dewar]. If you cannot adjust that due to NM4 hall restriction due to beam operations, skip step 2.
- The inlet flow should be around 60 slm, and the outlet should be 60 slm. At Open VJVA/B and VPC ahead of time at the beginning of the dewar A/B cooldown, open VJVA/B and VPC ahead of time.
- Dewar setting should be on AUTO+Liquefy mode. Set the outlet flow at 20slm. The gas will flow through the cold head and pass through the dewar neck. It will take a few hours to cooldown the dewar.. The entire flow should be going out through VPC. You can monitor this flow by looking at FMR.
Note: If the heaters come on due to set pressure when the dewar is warm in the beginning, it's fine. Once the dewar starts cooling down, adjust the pressure to keep the heaters off.
4. Run the system for about four hours.
5. Then switch it to normal modemodes, like 20slm (outlet) and , AUTO+Liquefy, and dewar, set pressure at 6.5 psi, and leave it there until it starts liquefying.
6. Monitor the dewar temperature as it drops [TIDA/B]. Once it get to around 10K reduce the outlet flow. Once the level starts to fluctuate between 0.2 and 1.9L liquid is starting to accumulate [I need to take pictures of the strip charts, showing 7K and the liquefier level starting to fluctuate.]
7. The final step is to set the outlet flow at 2slm to let it start to liquefy over the next several hours. Every few hours you should check on it and see that the production rate is making sense (should be close to 4L/h). 5.