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2023/01/31 (Tuesday)

Previous Day

  • Lab in-personnel: Himangshu, Zach, Carson
Status Run 77 preparation
Setup Fridge closed, pumping on IVC, preparing for cooldown
1210 Turbo on IVC = 8.6 nbar, with turbo valved out for a min = 120 nbar
1215 Check contents of warm LN2 Trap 1: 0.5 mbar (3.6 on G1). Pump it out with the scroll pump.
1222 Insert cold trap 1 into the LN2 bath, begin filling with LN2
1230 Pump out fridge lines:
  1. Make sure mixture is isolated in the dump.
  2. Check fridge pressures by opening condenser speedivalve+V1 and still gate valve: LHe trap+Condenser(G1)/Still(P1) = 4.7/0.7 mbar.
  3. Connect scroll pump to He-4 pump line, turn it on.
  4. Open pump line valve, V5A, V2A, V7, V2, wait a minute, then open V3.
  5. You're now pumping on the fridge lines. Wait until P1 and G1 flatten out.
  6. Close condenser speedivalve and still gate valve, V1, V3, V2, V7, V2A, V5A and close and turn off the scroll pump.
1252 G1 fell to about 1 mbar then rose to now 1.6 mbar, P1 still falling to 0.38 mbar now.
1300 Perform a quick leak check, no issues seen
Throughput test procedure, Cold Trap 1:
  1. All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
  2. Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
  3. Close V12a+speedivalve and V3, open V1
  4. monitor G1
1310 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 62 mbar on step 4 and starts to rise. Throughput = 7.2 mbar/min.
1325 Pump mixture back to dump:
  1. Close V13A then turn on the 3He pump.
  2. Open V12A+speedivalve, V3.
  3. Open V6 initially to 11%, then further in steps to 30%, making sure G2 doesn't rise too quickly.
  4. Continue pumping until G1 stabilizes at a minimum value (typically a few mbar) and P1 is less than 0.1 mbar.
  5. Stop pumping on cold trap 1, close V12a and speedivalve.
  6. Stop pumping on fridge, close still gate valve, condenser speedivalve, V1, V3.
  7. Close V6, then when V6 is fully closed, close V9.
Pump out 1kpot and main bath:
  1. Check pressure in 1K Pot on P2 by opening the 1kpot speedivalve and V4A. Pump out with Scroll Pump connected to the 4He line.
  2. Close the 1kpot speedivalve, close the scroll pump valve.
  3. Open V1A which opens up the line to the main bath (this will cause the line to expand as the gas fills it).
  4. Pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
  5. Once P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1340 Check pressure in 1K Pot by opening the 1kpot speedivalve and V4A: 32 mbar on P2, 0.05 atm on mechanical gauge. Pump out with Scroll Pump
1348 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).
1350 Pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
1400 G1 = 1.7 mbar, P1 = 0.28 mbar and stable
1400 Isolate LN2 Trap 1 which is now pumped out to dump (close V12a and speedivalve)
1405 Stop pumping out fridge (close Still Gate valve, Condenser speedivalve, V1, V3)
1406 Close V6, then when V6 is fully closed, close V9, leaving G2(Dump) = 709.5 mbar
1410 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:
  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 the blue valve that connects gas line to IGH - gas is filling the main bath now.
  4. Once the mechanical gauge (connected to the 1kpot speedivalve) reaches 15mmHg, the bath is at ~0.5bar, stop flushing.
  5. Pump out with the scroll pump to < 1 mbar on P2, making sure not to overload the pump.
  6. Close the scroll pump valve and repeat steps 3 to 5 once more
  7. 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.
1500 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.
1515 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.
1525 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.
1535 As on 2021 Nov 30, 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.
1548 P1(Condenser) → 0.065 mbar.
1550 Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 12 mbar/min . Open V12a speedivalve again.
1555 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)
1610 MC(Cernox) = 296.2 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 655/730/0.085 mbar, Level resistor = 0.975 kΩ.
1642 Can't find part to connect the LN2 transfer stick to the hose
1700 Pump mixture to dump. Close V13a, open V3, open V6 more in steps up to 30%
1720 G1 = 1.6 mbar, P1 = 0.06 mbar. Stop pumping mixture to dump. Close V12a+speedivalve, close condenser speedivalve and still gate, close V1, close V3, close V6
1725 V6 is fully closed, close V9, leaving 713.9 mbar in the dump. Turn off 3He pump

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