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2021/05/04 (Tuesday)

Previous Day

  • Lab in-person: Matt
  • Virtual partner: Zach
Status Run 74 in progress. Warmed up after second occurrence of IVC leak during initial LHe transfer. Tightened all IVC bolts yesterday. IVC pumping overnight. Cryostat Vacuum Jacket pumped out.
1110 Matt enters lab
1115 Check contents of warm LN2 Traps 1/2: 5.3/4.5 mbar. Pump out with Scroll Pump.
1125 Check fridge pressures: LHe trap/Condenser/Still = 1.4/0.1/0.12 mbar. Pump out with scroll pump.
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
1130 Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 545 mbar before Step 3, then it falls to 41 mbar and starts to rise. Throughput = 6.4 mbar/min.
1140 Turbo on IVC = 8.6 nbar. With Turbo valved out for 1 minute IVC = 140 nbar.
1140 Leak detector on IVC with Turbo valved out for 1 minute: 7.3 pbarL/s
1140 Check pressure in 1K Pot: 24 mbar on P2, 0.013 atm on mechanical gauge. Pump out with Scroll Pump
1140 With 1K Pot speedivalve and needle valve closed, pump on Main bath with scroll pump. Once P2 < 2 mbar, open 1K pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1145 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.
1150 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.
1200 Pressurize main bath and 1K Pot (both sides) with helium to 284 mbar +1atm on G3, then close 1K Pot speedivalve and needle valve.
1205 As on 2021 Apr 27, 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% - this is enough to see an increase in Condenser pressure. Increase V6 → 12.9%, Still pressure starts to fall.
1215 P1(Still) = 0.5 mbar. G1(Condenser) = 748.0 mbar.
1215 Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 11.7 mbar/min . Open V12a speedivalve again.
1220 Let 6.3 mbar He exchange gas into IVC (a little higher than the standard 5.4)
1225 MC(Cernox) = 287.0 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 680/749/0.55 mbar, Level resistor = 0.987 kΩ.
1230 Begin LN2 transfer
1230 LN2 Dewar pressure is low. Pressurize with N2 through the vent port. Dewar → 8.0 PSI.
1240 MC(Cernox) = 287.2 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 681/749/1.4 mbar, Level resistor = 0.990 kΩ.
1240 LN2 Dewar = 9.5 PSI
1250 MC(Cernox) = 283.6 K, Sorb = >249 K (max), IVC = 6.3 mbar, G2/G1/P1 (circulation) = 682/748/2.4 mbar, Level resistor = 1.004 kΩ.
1300 MC(Cernox) = 275.3 K, Sorb = >249 K (max), IVC = 4.6 mbar, G2/G1/P1 (circulation) = 682/748/3.6 mbar, Level resistor = 1.008 kΩ.
1300 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 12.7 mbar/min. Open V12a speedivalve again.
1315 MC(Cernox) = 251.7 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 683/747/6.0 mbar, Level resistor = 1.027 kΩ.
1315 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 14.7 mbar/min. Open V12a speedivalve again.
1330 MC(Cernox) = 224.2 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 683/747/16.0 mbar, Level resistor = 1.068 kΩ.
1330 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 18.1 mbar/min. Open V12a speedivalve again.
1345 MC(Cernox) = 190.9 K, Sorb = >249 K (max), IVC = 2.5 mbar, G2/G1/P1 (circulation) = 682/745/90 mbar, Level resistor = 1.130 kΩ.
1345 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 22.8 mbar/min. Open V12a speedivalve again.
1400 MC(Cernox) = 158.8 K, Sorb = >249 K (max), IVC = 2.2 mbar, G2/G1/P1 (circulation) = 679/742/off-scale mbar, Level resistor = 1.217 kΩ.
1400 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 31.1 mbar/min. Open V12a speedivalve again.
1415 MC(Cernox) = 141.6 K, Sorb = 239.6 K, IVC = 2.2 mbar, G2/G1 (circulation) = 677/738 mbar, Level resistor = 1.263 kΩ.
1415 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 38.0 mbar/min. Open V12a speedivalve again.
1430 MC(Cernox) = 128.1 K, Sorb = 197.2 K, IVC = 2.2 mbar, G2/G1 (circulation) = 672/733 mbar, Level resistor = 1.293 kΩ.
1430 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 44.5 mbar/min. Open V12a speedivalve again.
1445 MC(Cernox) = 117.3 K, Sorb = 166.8 K, IVC = 1.9 mbar, G2/G1 (circulation) = 665/726 mbar, Level resistor = 1.312 kΩ.
1445 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 49.9 mbar/min. Open V12a speedivalve again.
1500 MC(Cernox) = 108.9 K, Sorb = 148.4 K, IVC = 1.9 mbar, G2/G1 (circulation) = 657/718 mbar, Level resistor = 1.323 kΩ.
1500 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 51.5 mbar/min. Open V12a speedivalve again.
1510 MC(Cernox) = 104.6 K, Sorb = 140.7 K, IVC = 1.9 mbar, G2/G1 (circulation) = 651/713 mbar, Level resistor = 1.327 kΩ.
1510 Stop LN2 transfer. Close both LN2 Dewar valves and N2 gas supply valve on wall. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1510 Close V6 and turn off 3He pump.
1515 Matt exits lab

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