2019/09/27 (Friday)
| Status: Leak checked yesterday, seems to be coming from somewhere outside the fridge lines. Warming, MB is has boiled off, performing MB leak checks today. | |
| 1155 | MC(Cernox)/Tower/Sorb = 15.7/16.1/31.1 K, G1(fridge) = 3.3 mbar, 1K Pot = 7 K / 0.3 mbar |
| 1158 | Turbo on IVC = 74 nbar |
| 1200 | Start up leak detector |
| 1205 | Had webcam set up to watch recovery, forgot to set up light…oops. There is only information from this morning. Recovery = 3153xx |
| 1208 | Leak Detector baseline (valved off) Leak Rate = 1.1e-9 mbarL/s |
| 1208 | Open valve on leak detector, Leak Rate = 1.0e-3 mbarL/s |
| 1210 | Valve off turbo, Leak Rate = 1.2 e-2 mbarL/s still as bad as previously. |
| 1215 | Reopen turbo valve, valve off leak detector and shut down for now |
| 1218 | Turbo on IVC = 100 nbar |
| 1420 | Begin pumping down main bath by opening 4a and 1a and attaching the scroll pump to the MB line in the back. |
| 1440 | G3 and P2 are both off scale, gauge on MB line reads 28/30 with 30 being vacuum. |
| 1444 | Both G3 and P2 are still off scale, tower temperature has dropped slightly to 14.0 K, there may still be liquid in the MB. |
| 1455 | P2 is now on scale, reading 65 mbar and falling, tower = 13.3 K |
| 1510 | P2 = 18 mbar, disconnecting scroll pump to begin leak checking procedure, Tower = 14 K, MC = 13.1 K |
| 1515 | P2 rose to 300 mbar, isolate MB and pump out remaining line, connecting N2 to vent to fill the MB. |
| 1530 | The N2 seems to be flowing fine, but G3 and P2 are both on scale which shouldn't be the case. What could be wrong? MB isn't staying pressurized. |
| 1535 | Close of MB, G3 rises to about 700 mb, drops to below zero when 1a closed. |
| 1540 | Close 4a, P2 doesn't seem to budge despite the lines filling, what is happening? |
| 1548 | Ahh, turns out we made a mistake here, the N2 is likely liquefying in the MB. Closing of N2 flow and vent. Going to try to leak check it anyway. Tower = 18.8 K, MC = 19.3 K |
| 1550 | Attach scroll pump back to Leak detector. |
| 1557 | Start up scroll pump and leak detector |
| 1603 | Leak detector baseline Leak Rate = 1.3e-9 mbarL/s, MC = 20.6 K |
| 1605 | Open Leak detector to turbo and IVC, Leak Rate = 1.8e-7 mbarL/s, much lower than before, MC = 21.1 K |
| 1607 | Valve off turbo, Leak Rate = 4.4e-6 mbarL/s, MC = 20.8 K. Would try squirting some He into the MB, but it is under pressured right now. |
| 1610 | Stop leak check, leave turbo pumping on IVC = 12 nbar |
| 1612 | Don't want to leave the MB under vacuum with LN2 inside, going to fill it with He |
| 1619 | Fill MB through vent, P2 off scale, G3 reads 100 mbar. Take out stopper on top of LHe transfer port, leave it resting (so it doesn't over pressurize when the LN2 in the MB boils off). MB was over-pressured when I removed the stopper. |
| 1620 | MC(Cernox)/Tower/Sorb = 22.0/21.9/58.4 K, G1(fridge) = 4.5 mbar, 1K Pot = off scale |
| 1623 | Leave turbo on IVC = 3.0 nbar |