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2024/09/05 (Thursday)

Previous Day

  • Lab in-personnel: Himangshu
Status Mixture in fridge with 3He pump off, 4He pump off
1251 Fill LN2 cold trap bath from 5L dewar.
1256 MC(Cernox)/Sorb/1K Pot = 4.75/–/–, G1/G2 = 455/445 mbar, MB = 71.7%
1257 Turbo on IVC = 86 nbar. With Turbo valve out for 1 minute IVC = 100 nbar
1400 Close IVC valves on top of the fridge
– P2 is up again after Himangshu pumped out the 1kpot on saturday, need to swap back to the scroll pump and redo it
1300 Pump out line leading to 1K Pot with scroll pump (V4a open, V1a closed, 1kpot speedivalve closed). Then switch the line over to the 4He pump. Turn on 4He pump and make sure the pump exhaust is connected to recovery and open valve to recovery lines.
1425 Check pressure in 1K Pot by opening the 1kpot speedivalve with V4a closed: Mechanical gauge = 200 mbar on G3.
1425 Pump out 1K Pot by slowly opening V4a then the manual valve at the 4He pump until it just starts to make noise, once it quiets down somewhat open it up a little more. continue this until the valve is fully open.
Leaving mixture in the fridge when starting 1K pot. P2 = 1 mbar
1315 Open 1K Pot needle valve → 15° (half the unit on the needle marks). 1K Pot → – K / 10 mbar.
Temp dropping slightly, MC(cernox) = 4.7 K
1430 Open 1K Pot needle valve → 30° () 1 unit mark). 1K Pot → – K / 50 mbar.
1500 Temps start to drop, mixture pressure starts to drop
1520 MC(H35) temp drops, flattens at around 2.4 K
1331 We will keep 1K pot needle valve at close to 30 deg since P2 is already ~ 30 mbar(we try to keep it in this range in earlier runs)
1527 MC(Cernox)/Sorb/MC(H35) = 2.35/–/2.60, 1K Pot = – K / 30 mbar. G1 (fridge+dump) = 150 mbar. Still: 2.35 K, Coldplate: 3.08 K
1350 MC(Cernox)/Sorb/MC(H35) = 2.15/–/2.09, 1K Pot = – K / 15 mbar. G1 (fridge+dump) = 60 mbar.
1630 MC stuck at 2.34 K. making a 10K pumpout procedure from here
Stop pumping on the 1K pot. Close needle valve, 1K pot valve, V4A and He4pump manual valve

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