2023/05/02 (Tuesday)
- Lab in-personnel: Himangshu
| Status | Run 78 Preparation. Tower Installation complete. IVC closed, turbo pumping over the weekend |
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| 1248 | Check contents of warm LN2 Trap 1: 4.5 mbar (10.5 on G1). Pump out Cold Trap 1 with the scroll pump. |
| 1250 | G1 = 2.0 mbar, stop pumping on trap 1 |
| 1252 | Turbo on IVC = 54 nbar, with turbo valved out for a min = 1.0 ubar |
| Throughput test procedure, Cold Trap 1: |
- All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12a+speedivalve and V3, quickly open V1
- monitor G1
| 1323 | Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 600 mbar before Step 3, then it falls to 47.5 mbar on step 4 and starts to rise. Throughput = (67.5-52.6)/2 = 38.7 mbar/min. |
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| 1333 | We will skip the step to “Pump mixture back to dump:” since we are working with pumping out the 1k pot and Main Bath and then re-introducing the mixture into the fridge. We are circulating the mixture by opening the previously closed valves. Open V12a+speedivalve, V3. |
| 1336 | Pump out 1kpot and main bath: |
- Check pressure in 1K Pot on P2 by opening the 1kpot speedivalve (mechanical gauge goes from 30 to 29 mminHg) and V4A (P2 reads 29.95 mbar). Pump out with Scroll Pump connected to the 4He line.
- Close the 1kpot speedivalve, close the scroll pump valve.
| 1350 | Open V1A which opens up the line to the main bath (this will cause the line to expand as the gas fills it). P2 reads 150 mbar |
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| 1351 | Pump on Main Bath with scroll pump, making sure not to overload the scroll pump. |
| 1409 | Once P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2. |
| Flush the 1kpot and main bath: |
| 1410 | With the scroll pump pumping on the He-4 pump line, open V5A, V2A, and the vent speedivalve to evacuate the clear hose leading to the He gas line. |
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| 1423 | Once P2 falls to <1 mbar, close the He-4 pump line valve at the pump and turn off the He-4 pump or scroll pump. |
- Open the blue valve that connects gas line to IGH - gas is filling the main bath now.
- Once the mechanical gauge (connected to the 1kpot speedivalve) reaches 15mmHg, the bath is at ~0.5bar, stop flushing.
- Pump out with the scroll pump to < 1 mbar on P2, making sure not to overload the pump.
- Close the scroll pump valve and repeat steps 3 to 5 once more
| 1446 | Close the scroll pump valve . Pressurize main bath and 1K Pot (both sides) with helium to 101 mbar+1atm on G3, then close 1K Pot speedivalve and needle valve, V1a, V4a, V5a, V2a and vent speedivalve. |
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| Flow mixture through fridge: | |
| This step is skipped since we kept mixture in the fridge, but not circulating with V6. (Open V9, V13a, V12a+speedivalve, V1, condenser speedivalve, still gate, V3, let things settle.) | |
| 3He pump is ON, open V6 to 12.6% and close V3. | |
| 1515 | Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 11 mbar/min . Open V12a speedivalve again. |
| 1519 | MC(Cernox) = 296.2 K, Sorb = >249 K (max), IVC = 74 ubar, G2/G1/P1 (circulation) = 667/725/0.060 mbar |
| 1532 | Let 5.4 mbar He exchange gas into IVC, this is a bit more than one hose length (connected to the mechanical gauge on the turbo pump) |
| 1545 | Pump mixture to dump. Close V13a, open V3, open V6 more in steps (12.6 → 13 → 13.5 → 14 → 14.5 → 15 → 20 → 30) to 30% |
| 1602 | G1 = 0.8 mbar, P1 = 0.11 mbar. Stop pumping mixture to dump. Close V12a+speedivalve, close condenser speedivalve and still gate, close V1, close V3, close V6 |
| 1610 | V6 is fully closed, close V9, leaving 724.6 mbar in the dump. Turn off 3He pump |