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2024/07/23 (Tuesday)

Previous Day

* Lab in-personnel: Himangshu, Zach

1214 IVC closed and pressure valve closed. CVJ pumped out and valve closed. Main Bath is up(fridge closed)
—- Pump out 1kpot and main bath:

- Get to baseline on G3 by opening scroll pump valve and V4A. G3 at 0 mbar.

  1. Close scroll pump valve and V4A
  2. Check pressure in 1K Pot on G3 by opening the 1kpot speedivalve. Open V4A and slowly pump out with Scroll Pump by opening the scroll pump valve slowly connected to the 4He line.
  3. Close the 1kpot speedivalve and V4A. close the scroll pump valve.
  4. Open V1A which opens up the line to the main bath (this will cause the line to expand as the gas fills it).
  5. Open V4A and pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
  6. Once P2 < 2 mbar,close V1A and open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 10e-1 mbar on P2.
1224 Check pressure in 1K Pot by opening the 1kpot speedivalve. G3 went up, but below the 1st least count mark. Pump out with Scroll Pump
1231 Close 1kpot speedivalve, close scroll pump valve, open V1A which opens up the line to the main bath (this will cause the line to expand as the gas fills it). G3 reads 950 mbar
1237 Open V4A and pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
1250 P2 < 2 mbar, close V1A. Open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 10e-1 mbar on P2.
1252 Once P2< 10e-1 mbar. Close V4A and scroll pump valve.
Flush the 1kpot and main bath:
  1. 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.
  2. Once P2 falls to <10^-1 mbar, close the He-4 pump line valve and turn off the He-4 pump or scroll pump.
  3. Open V1A, V4A, V5A, V2A.
  4. Open the blue valve that connects gas line to IGH - gas is filling the main bath now.
  5. Once the mechanical gauge (connected to the 1kpot speedivalve) reaches 15mmHg, the bath is at ~0.5bar, stop flushing. Close V5A.
  6. Pump out with the scroll pump to < 4 mbar on P2, making sure not to overload the pump.
  7. Close the scroll pump valve and repeat steps 3 to 5 once more
  8. Close the scroll pump and pressurize the main bath and 1K Pot with helium to a few 100 mbar+1atm on G3, then close 1K Pot speedivalve and needle valve.
  9. Close V1A, V4A, V5A, V2A.
1310 Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar on P2.
1323 Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar on P2.
1348 Pressurize main bath and 1K Pot (both sides) with helium to 1000 mb on G3, then close 1K Pot speedivalve and needle valve, V1a, V4a, V5a, V2a.
1422 We will flow mixture through the fridge during LN2 cooldown. Let mixture from dump through cold LN2 Trap 1 to fridge, both sides. Then isolate the sides and circulate with V6 open partially and mix open to dump. V9, V13a, V12a+speedi, V1, Condenser speedi, Still gate valves open, 3He pump on. Open V6 to 12.6%.
Flow mixture through fridge:
  1. Open V9, V13a, V12a+speedivalve, V1, condenser speedivalve, still gate, V3, let things settle.
  2. Turn on 3He pump, after a min, open V6 to 12.6% and close V3.
1426 P1(Condenser) → 0.05 mbar. (forgot to close V3 right away)
1427 Turbo on IVC = 12nbar
1430 Try closing V12a+speedivalve. G1 falls as it should, showing we have throughput. Falls at 10 mbar/min . Open V12a+speedivalve again.
1439 Let 6.3 mbar He exchange gas into IVC, this is a little less than one hose length (connected to the mechanical gauge on the turbo pump)
1455 We found that the valve to the recovery system was OPEN the whole time. This might be the reason why Zach has to redo pumpout the MAIN BATH twice. We will pump out the Main Bath again to make sure no dirty gas/particles enter from the recovery line(Mike mentioned that we cannot pump on the recovery system due to check valves on the line) and pressurize the Main Bath+1K pot
1506 Pressurize main bath and 1K Pot (both sides) with helium to120 mbar+1atm on G3, then close 1K Pot speedivalve and needle valve, V1a, V4a, V5a, V2a.
1450 MC(Cernox) = 296.4 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 647/716/0.040 mbar, Level resistor = 0.990 kΩ.
1450 Inserted LN2 transfer stick, connected to the LN2 dewar with a hose, inserted the level resistor, disconnected the helium recovery line.

1503 Begin LN2 transfer
1510 MC(Cernox) = 294.8 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 590/610/410 mTorr, Level resistor = 0.999 kΩ.
1515 MC(Cernox) = 292 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 590/610/410 mTorr, Level resistor = 1.025 kΩ.
1517 Close V3 for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls slightly over time. Open V3 again.
1542 MC(Cernox) = 230.4 K, IVC = 3.0 mbar, G2/G1/P1 (circulation) = 590/610 mbar / 650 mTorr, Level resistor = 1.150 kΩ.
1545 Close V3 for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls slightly over time. Open V3 again.
1612 MC(Cernox) = 164.8 K, IVC = 2.5 mbar, G2/G1/P1 (circulation) = 590/610 mbar / 2000 mTorr, Level resistor = 1.285 kΩ.
1615 Close V3 for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls slightly over time. Open V3 again.
1634 MC(Cernox) = 137.8 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 590/610 mbar / atm, Level resistor = 1.218 kΩ (was over 1.3 but has dropped)
1636 LN2 dewar is now empty, stop LN2 transfer. Close LN2 Dewar valve. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1638 Close V2 and turn off 3He pump.

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