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2024/11/21 (Thursday)

Previous Day

  • Lab in-personnel: Himangshu
Status Run 82 In Preparation. Pumped out fridge lines. Pumped out 1k pot and Main Bath. Saw a slight pressure built up in Main Bath. Leak checking shows no leaks. Waited a day to if pressure in main bath goes up.
Leak is in the copper line going to recovery system. Donot have a regulator valve to close of that side when not in use.
Swapped the regulator in turbo pump line to have a new valve on the recovery line. It can be turned off while using main bath and then switched on when using recovery system.
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.
1244 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.
1251 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.
1258 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.
We won't flow mixture through the fridge as I would like to do another cryocleaning today
– 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.
– P1(Condenser) → 0.05 mbar. (forgot to close V3 right away)
– Turbo on IVC = 12nbar
– Try closing V12a+speedivalve. G1 falls as it should, showing we have throughput. Falls at 10 mbar/min . Open V12a+speedivalve again.
1450 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 MC(Cernox) = 296.6 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = –/–/– 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.

1520 Begin LN2 transfer
1530 MC(Cernox) = 296.4 K, IVC = cant read, G2/G1/P1 (circulation) =– mTorr, Level resistor = 1.039 kΩ.
1547 MC(Cernox) = 283.7 K, IVC = – mbar, G2/G1/P1 (circulation) =— mTorr, Level resistor = 1.141 kΩ.
1601 MC(Cernox) = 261 K, IVC = – mbar, G2/G1/P1 (circulation) = — mTorr, Level resistor = 1.252 kΩ.
1602 Stop LN2 transfer. Close LN2 Dewar valve. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.

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