| 1105 | 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 55 mbar, then rises. Throughput = 42.2 mbar/min. Slightly lower than last time, 2021 May 5 |
| 1125 | Electrical checkout on DIB2+accessories (Cable 3). All looks good, though leaks to chassis are higher, I guess because humidity is high. Bias to chassis about 1.2 nS, FET-related connections to chassis (both polarities) 0.2-0.6 nS |
| 1130 | Electrical checkout on DIB1 (Cable 2). All looks good, again leaks to chassis are higher. Bias to chassis about 1.2 nS, FET-related connections to chassis (both polarities) 0.2-0.5 nS |
| 1135 | Open mixture to both sides of the fridge and cold LN2 Trap 1. |
| 1135 | Turbo on IVC = 8.6 nbar. With Turbo valved out for 1 minute, IVC = 63 nbar. |
| 1140 | Try Leak Detector on IVC, with Turbo still pumping in parallel. (We've been pumping out the helium for 1 hr 10 minutes.) LD = 282 pbarL/s. With Turbo valved out for a minute, LD → 1490 pbarL/s. Better than last time. Open Turbo valve to continue pumping IVC. |
| 1330 | IVC = 1320 pbarL/s |
| 1330 | Begin blowing out LN2. Main bath (G3) → 535 mbar+1atm |
| 1335 | IVC = 1300 pbarL/s, MB = 543 mbar+1atm |
| 1340 | IVC = 1280 pbarL/s, MB = 531 mbar+1atm |
| 1345 | IVC = 1250 pbarL/s, MB = 290 mbar+1atm and dropping. Close V1a for a second, G3 rises, proving we still have pressure in the feed. |
| 1350 | Stop LN2 blowout |
| 1350 | Fill LN2 cold trap bath |
| 1400 | remove hose from MB LN2 fill pipe, remove fill pipe from cyostat and put stopper in port, for MB pumpout |
| 1400 | IVC = 1220 pbarL/s |
| 1400 | Start pumping out main bath with scroll pump. Takes 9 minutes to fall to 1 mbar. |
| 1410 | IVC = 1220 pbarL/s |
| 1415 | Pressurize MB with helium to 160 mbar above 1 atm. |
| 1415 | IVC = 1170 pbarL/s |
| 1415 | 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 0.04 bar. Then pump out 1K Pot (needle valve closed) with Scroll Pump to 0.038 mbar on P2. Then close 1K Pot speedivalve and V4a. Open V1a again to monitor bath pressure. |
| 1430 | IVC = 1110 pbarL/s |
| 1435 | Let 63 μbar He exchange gas into IVC. |
| 1520 | Start initial LHe transfer |
| 1530 | Turn off 3He pump, we'll leave it off like last time. |
| 1530 | MC(Cernox)/Sorb = 79.1/138.7 K, IVC = 34 μbar, G1(fridge) = 607 mbar. G3(MB) = 492 mbar+1atm |
| 1540 | MC(Cernox)/Sorb = 70.3/117.7 K, IVC = 25 μbar, G1(fridge) = 602 mbar. G3(MB) = 256 mbar+1atm |
| 1545 | Start pressurizing Dewar (100L one) @ 3.75 PSI |
| 1555 | MC(Cernox)/Sorb = 61.1/78.4 K, IVC = 14 μbar, G1(fridge) = 575 mbar. G3(MB) = 337 mbar+1atm |
| 1615 | MC(Cernox)/Sorb = 50.6/9.3 K, IVC = 10 μbar, G1(fridge) = 481 mbar. MB = 10.2% / 337 mbar+1atm |
| 1630 | MC(Cernox)/Sorb = 41.1/7.0 K, IVC = 8.6 μbar, G1(fridge) = 468 mbar. MB = 22.1% / 400 mbar+1atm |
| 1645 | MC(Cernox)/Sorb = 30.6/6.6 K, IVC = 7.4 μbar, G1(fridge) = 463 mbar. MB = 48.4% / 361 mbar+1atm |
| | Refreshing to see that the IVC pressure is not increasing, like it was doing by this point in the last three cooldown attempts. |
| 1700 | MC(Cernox)/Sorb = 21.1/6.6 K, IVC = 7.4 μbar, G1(fridge) = 427 mbar. MB = 72.6% / 347 mbar+1atm |
| 1718 | End LHe transfer @ MB = 73.0% |
| 1730 | MC(Cernox)/Sorb = 12.9/5.5 K, IVC = 3.4 μbar, G1(fridge) = 526 mbar. |
| 1735 | MC(Cernox) = 11.8 K, IVC = 3.0 μbar |
| 1735 | 1K Pot = 4.47 K |
| 1743 | MC(Cernox) = 10.0 K, IVC = 2.5 μbar. Start pumping out IVC with Turbo pump. |
| 1750 | Turbo on IVC = 22 nbar |