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2023/10/25 (Wednesday)

Previous Day

* Lab in-personnel: Himangshu, Zach, Ping

1229 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 P2 by opening scroll pump valve. P2=0.020 mbar.

  1. Close scroll pump valve
  2. Check pressure in 1K Pot on P2 by opening the 1kpot speedivalve and V4A. Pump out with Scroll Pump connected to the 4He line.
  3. Close the 1kpot speedivalve, 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. Pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
  6. Once P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1242 Check pressure in 1K Pot by opening the 1kpot speedivalve and V4A. It seems like it get pumped out although V5A was closed(instantaneous reading similar to 32 mbar on P2, 0.05 atm on mechanical gauge). Pump out with Scroll Pump
1246 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).
1250 Pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
1256 P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1301 Once P2< 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 <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.
  6. Pump out with the scroll pump to < 1 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.
1345 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.
1356 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.
1405 Pressurize main bath and 1K Pot (both sides) with helium to 305 mbar+1atm 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.
1510 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.
1515 Inserted LN2 transfer stick, connected to the LN2 dewar with a hose, inserted the level resistor, disconnected the helium recovery line.

1520 Begin LN2 transfer
1500 MC(Cernox) = 296.0 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 654/726/0.60 mbar, Level resistor = 0.990 kΩ.
1538 MC(Cernox) = 279.0 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 655/720/0.095 mbar, Level resistor = 1.165 kΩ.
1541 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 17.17 mbar/min. Open V12a speedivalve again.
1600 MC(Cernox) = 216.0 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 657/719/0.2 mbar, Level resistor = 1.259 kΩ.
1615 MC(Cernox) = 182.0 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 657/719/0.3 mbar, Level resistor = 1.303 kΩ.
1617 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 30 mbar/min. Open V12a speedivalve again.
1630 MC(Cernox) = 161.95 K, Sorb = 202 K , IVC = 2.5 mbar, G2/G1/P1 (circulation) = 657/719/0.4 mbar, Level resistor = 1.322 kΩ.
1636 MC(Cernox) = 152.8 K, Sorb = 182.5 K , IVC = 2.5 mbar, G2/G1/P1 (circulation) = 657/718.5/0.45 mbar, Level resistor = 1.332 kΩ.
1637 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 53 mbar/min. Open V12a speedivalve again.
1647 MC(Cernox) = 139.8 K, Sorb = 156 K , IVC = 2.5 mbar, G2/G1/P1 (circulation) = 657/719/0.55 mbar, Level resistor = 1.346 kΩ.
1659 MC(Cernox) = 128.8 K, Sorb = 141 K , IVC = 2.5 mbar, G2/G1/P1 (circulation) = 658/718/0.65 mbar, Level resistor = 1.346 kΩ.
1700 No change in level resistor for a while. Stop LN2 transfer. Close LN2 Dewar valve. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1710 Close V6 and turn off 3He pump.

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