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2024/01/23 (Tuesday)

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  • Lab in-personnel: Himangshu, Ping
Setup Fridge closed, pumping on IVC, preparing for cooldown
1006 Turbo on IVC = 54 nbar, with turbo valved out for a min = 540 nbar
1008 Check contents of warm LN2 Trap 1: 9.5 mbar (2.6 on G1 after pumped out). Pump it out with the scroll pump.
1013 Insert cold trap 1 into the LN2 bath, begin filling with LN2
1020 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) = 6.5/0.38 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.
1024 G1 rise to 6.5 mbar and falling, P1 is stable at 0.4 mbar.
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
1040 Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 520 mbar before Step 3, then it falls to 40 mbar on step 4 and starts to rise. Throughput = 5 mbar/min.
1043 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( when we 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.
1156 Close V6, then when V6 is fully closed, close V9, leaving G2(Dump) = 632.5 mbar
1159 Check pressure in 1K Pot by opening the 1kpot speedivalve and V4A: 36 mbar on P2, 0.05 atm on mechanical gauge. Pump out with Scroll Pump
1202 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).
1207 Pump on Main Bath with scroll pump, making sure not to overload the scroll pump.
1208 G1 = 1.1 mbar, P1 = 0.02 mbar and stable
1211 P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1214 P2 reads < 1 mbar. Close V1A and 1K pot speedivalve (blocks off the MB and 1K pot, needle valve still open)
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 clear hose now, once G3 is above 100 mbar, open V1A and 1K pot speedivalve.
  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.
1327 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.
1337 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.
1343 Close off scroll pump. Pressurize main bath and 1K Pot (both sides) with helium to 285 mbar+1atm on G3, then close 1K Pot speedivalve and needle valve, V1a, V4a and vent speedivalve. Turn on the scroll and pump out the line and then close V2a, V5a
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.
1451 P1(Condenser) → 0.065 mbar.
1550 Try closing V12a+speedivalve. G1 falls as it should, showing we have throughput. Falls at 9.5 mbar/min . Open V12a speedivalve again.
1530 MotorCoils: X1= 160.8 ohm, X2= 183.6 ohm, Y1= 264 ohm, Y2= 193.5 ohm, Xendstop=, 501.6 ohm, Yensdtop=30.3 ohm
1530 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)
1530 MC(Cernox) = 296.5 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 585/651/0.05 mbar, Level resistor = 0.988 kΩ.
1530 Inserted LN2 transfer stick, connected to the LN2 dewar with a hose, inserted the level resistor, disconnected the helium recovery line.

1540 Begin LN2 transfer
1555 MC(Cernox) = 295.4 K, Sorb = >249 K (max), IVC = 4.6 mbar, G2/G1/P1 (circulation) = 587/652/0.055 mbar, Level resistor = 0.994 kΩ. MotorCoils: X1= 158.1 ohm, X2= 176.1 ohm, Y1= 219.2 ohm, Y2= 190.6 ohm, Xendstop= 500.8 ohm, Yensdtop=31.4 ohm
1600 Close V12a+speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 9 mbar/min. Open V12a speedivalve again.
1615 MC(Cernox) = 275.8 K, Sorb = >249 K (max), IVC = 4.0 mbar, G2/G1/P1 (circulation) = 655/726/1.000 mbar, Level resistor = 1.01 kΩ. MotorCoils: X1= 147.0 ohm, X2= 191.6 ohm, Y1= 206.2 ohm, Y2= 178.9 ohm, Xendstop= 502.2 ohm, Yendstop=30.0 ohm
1632 MC(Cernox) = 250.5 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 589/652/0.07 mbar, Level resistor = 1.025 kΩ. MotorCoils: X1= 137.9 ohm, X2= 158.7 ohm, Y1= 196.2 ohm, Y2= 169.3 ohm, Xendstop= 496.5 ohm, Yendstop=46.9 ohm
1645 MC(Cernox) = 227 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 588/652/0.085 mbar, Level resistor = 1.051 kΩ. MotorCoils: X1= 128.8 ohm, X2= 157.0 ohm, Y1= 186.5 ohm, Y2= 160.1 ohm, Xendstop= 460.0 ohm, Yendstop = 90.2 ohm
1648 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 13.75 mbar/min. Open V12a speedivalve again.
1700 MC(Cernox) = 199 K, Sorb = >249 K (max), IVC = 2.5 mbar, G2/G1/P1 (circulation) = 588/652/0.11 mbar, Level resistor = 1.091 kΩ. MotorCoils: X1= 118.4 ohm, X2= 139.3 ohm, Y1= 175.7 ohm, Y2= 149.3 ohm, Xendstop= 480.3 ohm, Yendstop = 83.4 ohm
1715 MC(Cernox) = 174.9 K, Sorb = >249 K (max), IVC = 2.2 mbar, G2/G1/P1 (circulation) = 588/652/0.15 mbar, Level resistor = 1.143 kΩ. MotorCoils: X1= 108.5 ohm, X2= 125.8 ohm, Y1= 157.3 ohm, Y2= 139.2 ohm, Xendstop= 463.1 501.6 ohm, Yendstop = 34.9 ohm
1730 MC(Cernox) = 152 K, Sorb = >249 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 587/651/0.22 mbar, Level resistor = 1.211 kΩ. MotorCoils: X1= 99.1 ohm, X2= 116.5 ohm, Y1= 147.4 ohm, Y2= 129.4 ohm, Xendstop and Yendstop rapidly fluctuating, could not record a value
1745 MC(Cernox) = 137 K, Sorb = 220 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 588/651/0.28 mbar, Level resistor = 1.252 kΩ. MotorCoils: X1= 92.1 ohm, X2= 109.5 ohm, Y1= 139.7 ohm, Y2= 121.9 ohm, Xendstop= 467.5 ohm, Yendstop = 30.5 ohm
1746 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 30.55 mbar/min. Open V12a speedivalve again.
1800 MC(Cernox) = 124 K, Sorb = 190 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 588/651/0.36 mbar, Level resistor = 1.283 kΩ. MotorCoils: X1= OL ohm, X2= 118.6 ohm, Y1= 136.0 ohm, Y2= 113.9 ohm, Xendstop= 469.1 ohm, Yendstop rapidly fluctuating, could not record a value
1815 MC(Cernox) = 113 K, Sorb = 160 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 588/651/0.4 mbar, Level resistor = 1.304 kΩ. MotorCoils: X1= OL ohm, X2= 95.0 ohm, Y1= 129.6 ohm, Y2= 107.3 ohm, Xendstop = OL ohm, Yendstop = 88.3 ohm
1830 MC(Cernox) = 106 K, Sorb = 150 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 588/651/0.45 mbar, Level resistor = 1.314 kΩ. MotorCoils: X1= OL ohm, X2= 82.0 ohm, Y1= 111.2 ohm, Y2= 102.2 ohm, Xendstop= OL ohm, Yendstop = 133.2 ohm
1845 MC(Cernox) = 99.9 K, Sorb = 140 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 588/651/0.5 mbar, Level resistor = 1.324 kΩ. MotorCoils: X1= OL ohm, X2= 77.8 ohm, Y1= 106.7 ohm, Y2= 97.7 ohm, Xendstop= OL ohm, Yendstop = 124.2 ohm
1850 Stop LN2 transfer. Close LN2 Dewar valve. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1850 Close V6 and turn off 3He pump.

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