2019/10/03 (Thursday)
| Status: Warming up after leak seen from bath to IVC, Softened Vacuum Jacket | |
| 0904 | MC(Cernox) = 290 +/- 2 K, cryostat vacuum jacket = 1.6 mbar. |
| 0913 | Close cryostat vacuum jacket valve. Connect pump manifold to IVC. Pump down manifold to ~1e-2 mbar with scroll pump, then open valves to IVC to check IVC pressure. IVC pressure reads >1 bar even though we only added 0.1 bar at 130 K. Could be the leak from the main bath is bad enough it leaked to 1 atm. Or we could have frozen some water in the IVC when we accidentally opened it to atmosphere on Monday. |
| 0924 | Try opening manual valve to IVC pressure relief valve. Don't feel any gas escaping or entering this way. The relief valve is rated for 1/3 psi = 20 mbar, so we're probably right at 1 atm. |
| 0930 | Notice that G1 = 77 mbar, IGH monitor shows it rising steadily from 70 mbar yesterday. It was at 4.5 mbar on Friday |
| 0945 | Drop the dewar. |
| 0950 | Start pumping on IVC with scroll pump in preparation for leak checking. The pressure begins to fall immediately, but the scroll pump doesn't complain at all. This is not what we expect if the whole IVC volume is at 1 bar. Notice that the Pfeiffer display is a little weird. It capitalizes the U and there's an extra symbol like: “pressUre [”. Not sure if that means anything or if it just had a stroke. Changing the display value and returning to pressure fixed it, odd. |
| 0959 | Turbo pressure on IVC = 2.2 ubar. |
| 1109 | Turbo pressure on IVC = 540 nbar. Move scroll pump to leak detector and power on. Baseline rate reads Leak Rate = 1.8e-9 mbarL/s |
| 1111 | Open leak detector valve to Turbo and IVC, Leak Rate = 1.1e-7 mbarL/s. |
| 1113 | Valve off Turbo, Leak Rate = 1.4e-6 mbarL/s. Begin squirting He through fine nozzle at the different IVC seals. |
| 1130 | No Leaks detected there above the baseline above. Power down leak detector and begin flushing IVC with N2 one tube length at a time until it reaches a bar. |
| 1131 | Tighten all of the IVC seals besides the bottom just to be safe. |
| 1142 | Realize the Pfeiffer gauge isn't quite working right with N2 near 1 atm. Going by the mechanical gauge, add N2 gas until IVC pressure is a little over 1 atm. |
| 1300 | Begin de-install. |
| 1400 | Found that all of the kapton band-aids that secure the thermometer wire to the outside of the MC can had either one side come loose or had fallen off completely. Some of them were touching both the MC and 100 mK cans.   |
| 1440 | Remove tower from fridge and place in anti-chamber. |