| 1225 | Perform mixture throughput test at MC = 77 K using above procedure with 3He pump on. Let G1 rise to 540 mbar before Step 3, then it falls to 67 mbar, then rises. Throughput = 42.4 mbar/min. Slightly lower than last time, 2021 Feb 17 |
| 1230 | Open mixture to both sides of the fridge and cold LN2 Trap 1. |
| 1235 | Electrical checkout on DIB2+accessories (Cable 3). All looks good. Leaks to chassis from both Feedbacks, Drains, Sources in both directions all 0.08-0.16 nS, from the Biases and Side 2 0.11-0.16 nS. |
| 1240 | Try Leak Detector on IVC, with Turbo still pumping in parallel. (We've only been pumping out the helium for 35 minutes.) LD = 22 pbarL/s. With Turbo valved out for a minute, LD → 1700 pbarL/s. Open Turbo valve to continue pumping IVC. |
| 1250 | Electrical checkout on DIB1 (Cable 2). All looks good. Leaks to chassis from both Feedbacks, Drains, Sources in both directions all 0.11-0.17 nS, from the Biases 0.12 nS. |
| 1305 | Leak on IVC with Turbo pumping: 210 pbarL/s. With Turbo valved out for 1 minute → 1530 pbarL/s. |
| 1315 | IVC = 1660 pbarL/s. |
| 1315 | Begin blowing out LN2. Main bath (G3) → 710 mbar+1atm |
| 1325 | IVC = 1510 pbarL/s, MB = 712 mbar+1atm |
| 1330 | IVC = 1460 pbarL/s, MB = 376 mbar+1atm and falling, looks like it's about finished |
| 1335 | IVC = 1500 pbarL/s, MB = 210 mbar+1atm and flattening |
| 1335 | Stop LN2 blowout |
| 1340 | Fill LN2 cold trap bath |
| 1340 | remove hose from MB LN2 fill pipe and put stopper in pipe, for MB pumpout |
| 1340 | Start pumping out main bath with scroll pump. Takes 9 minutes to fall to 1 mbar. |
| 1400 | Pressurize MB with helium to 240 mbar above 1 atm. |
| 1400 | Isolate MB by closing V1a. Pump out line to the G3 volume with Scroll Pump. Isolate pump, then open 1K Pot speedivalve to check pressure: about 0.03 bar. Then pump out 1K Pot (needle valve closed) with Scroll Pump to 0.026 mbar on P2. Then close 1K Pot speedivalve and V4a. Open V1a again to monitor bath pressure. |
| 1415 | Turbo on IVC = 4.6 nbar. With Turbo valve out for a minute, IVC = 100 nbar |
| 1420 | Let 63 μbar He exchange gas into IVC. |
| 1435 | Begin initial LHe transfer |
| 1435 | MC(Cernox) = 77.7 K, Sorb = 141.5 K, IVC = 63 μbar, G1(fridge) = 623.1 mbar. G3(MB) = offscale mbar+1atm; MB = 5.9 PSI on wall gauge. |
| | note: Mike told me that he changed out a check valve from our outgoing line, and it wound up having a smaller diameter connection than what we had before. This might make the pressure back up more on our side when we do transfers. |
| 1450 | MC(Cernox)/Sorb/1K Pot = 75.4/135/>7 K, IVC = 25 μbar, G1(fridge) = 620.4 mbar. G3(MB) = 307 mbar+1atm. |
| | Pressure seems to have settled, maybe the high pressure was just because I pushed the transfer line down pretty fast. |
| 1455 | Start pressurizing 100L LHe Dewar with gas from the cylinder, 3.5 PSI |
| 1450 | MC(Cernox)/Sorb/1K Pot = 75.4/135/>7 K, IVC = 25 μbar, G1(fridge) = 620.4 mbar. G3(MB) = 307 mbar+1atm. |
| 1500 | MC(Cernox)/Sorb/1K Pot = 66.9/110/>7 K, IVC = 16 μbar, G1(fridge) = 607.6 mbar, MB = -1.0% / 355 mbar+1atm. |
| 1510 | MC(Cernox)/Sorb/1K Pot = 59.8/78/>7 K, IVC = 12 μbar, G1(fridge) = 573.3 mbar, MB = 2.4% / 463 mbar+1atm. |
| 1510 | Zach enters lab |
| 1515 | Matt exits lab |
| 1520 | MC(Cernox)/Sorb/1K Pot = 52.9/30/>7 K, IVC = 12 μbar, G1(fridge) = 531.0 mbar, MB = 5.9% / 477 mbar+1atm. |
| 1530 | MC(Cernox)/Sorb/1K Pot = 47.6/7.4/>7 K, IVC = 12 μbar, G1(fridge) = 488.2 mbar, MB = 11.9% / 426 mbar+1atm. |
| 1540 | MC(Cernox)/Sorb/1K Pot = 41.2/7.0/>7 K, IVC = 40 μbar, G1(fridge) = 483.5 mbar, MB = 19.9% / 400 mbar+1atm. |
| 1550 | MC(Cernox)/Sorb/1K Pot = 34.6/6.9/5.52 K, IVC = 74 μbar, G1(fridge) = 479.1 mbar, MB = 35.7% / 390 mbar+1atm. |
| 1600 | MC(Cernox)/Sorb/1K Pot = 27.4/6.6/5.29 K, IVC = 100 μbar, G1(fridge) = 475.6 mbar, MB = 53.2% / 379 mbar+1atm. |
| | IVC pressure rising, could be a faulty gauge though, but I will first use the scroll pump when pumping it out. |
| 1610 | MC(Cernox)/Sorb/1K Pot = 22.3/6.3/5.11 K, IVC = 120 μbar, G1(fridge) = 473.5 mbar, MB = 68.9% / 370 mbar+1atm. |
| 1620 | MC(Cernox)/Sorb/1K Pot = 17.7/6.1/4.92 K, IVC = 140 μbar, G1(fridge) = 468.5 mbar, MB = 78.6% / 413 mbar+1atm. |
| 1627 | Begin pumping on IVC with scroll pump then turbo. |
| 1632 | End LHe transfer @ MB = 66.7 |
| | Webcam was only set for 2 hours so not sure what the final recovery meter reading was. Projecting forward to 16:32 from the recovery rate near the end, estimate 428329.4 at the end of transfer; so we can guess about 428335 10 minutes after the end of transfer. |
| 1700 | At around 16:40 the turbo pump shut off and the ivc pressure rose to about 1 mbar. I turned on the scroll pump and closed off the turbo valve. It seems that there is a large leak, with scroll on IVC = 1 mbar currently. |
| 1740 | Stopped pumping on IVC a bit ago, IVC = 3mbar now. |