2019/05/21 (Tuesday)
| Status: | 1K pot clogged at 4K, warming back up. Helium exchange gas in cryostat jacket and IVC. |
|---|---|
| 0135 | MB = 60.4% |
| 0535 | MB = 49.7% |
| 0905 | Fill LN2 cold trap full. |
| 0906 | MC(Cernox) = 4.17 K, Sorb/1K Pot = 5.2/4.2 K, MB = 40.3% |
| 0916 | Right now we're pumping cold trap 1 and both sides of the fridge to the dump. G1/P1 = 1.4/0.017 mbar. Close V1 and V3 to just pump on cold trap 1 for a bit. |
| 0920 | G1 flat at 1.5 mbar. Close V12A + speedivalve to isolate cold trap 1. Open V1 and V3 to pump on both sides of fridge. |
| 0925 | Cryostat vacuum jacket = 0.4 μbar, way down from the 34 μbar that was in there yesterday. |
| 0935 | Let 2.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 54 μbar |
| 0940 | MB = 38.9%. Recovery rate = 74 sec/sqft |
| 0941 | Vacuum jacket has fallen to 30 μbar |
| 0945 | Let 2.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 63 μbar |
| 0946 | MB = 38.3%. Recovery rate = 50 sec/sqft |
| 0948 | Vacuum jacket has fallen to 40 μbar |
| 0949 | MC(Cernox) = 4.19 K (on Lakeshore bridge. vi says 4.25 K) Tower is starting to warm. |
| 0958 | Vacuum jacket has fallen to 12 μbar |
| 1000 | Let 2.5 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 86 μbar |
| 1001 | MB = 35.9%. Recovery rate = 32 sec/sqft |
| 1002 | Vacuum jacket has fallen to 34 μbar |
| 1005 | Turn on MC and Still heaters to 20 mW each. MC(Cernox) → 4.5 K. |
| 1008 | MB = 34.4%. Recovery rate = 18 sec/sqft |
| 1010 | Vacuum jacket has fallen to 19 μbar |
| 1030 | MB = 28.0%. Recovery rate = 16 sec/sqft, MC(Cernox) = 4.5 K |
| 1043 | We'd previously seen P2 increase when sealed off, indicating a leak somewhere in that line [when/how much??]. Yesterday we pumped out that volume when shutting down the 1K Pot pumping by closing the 1K Pot speedivalve, V4A, and the valve at the 4He pump. Since then, the pressure in P2 hasn't changed a ton, only increasing from 0.04 mbar to 0.13 mbar in the last 10 hours. |
| 1045 | MB = 22.0%. Recovery rate = 15 sec/sqft, MC(Cernox) = 4.6 K Hose from bath to recovery is a lil frosty. |
| 1100 | MB = 17.7%. Recovery rate = 18 sec/sqft, MC(Cernox) = 4.6 K |
| 1140 | MB = 7.2%. Recovery rate = 17 sec/sqft, MC(Cernox) = 4.6 K |
| 1200 | MB = 1.4%. Recovery rate = 17 sec/sqft, MC(Cernox) = 4.6 K |
| 1225 | MB = -1.0%. Recovery rate = 16 sec/sqft, MC(Cernox) = 4.8 K |
| 1226 | MC(Cernox)/1K Pot/Sorb = 4.8/5.6/7.0 K. All rising steadily. |
| 1234 | Vacuum jacket = 19 μbar |
| 1235 | Let 2.5 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum jacket → 63 μbar |
| 1240 | MC(Cernox)/1K Pot/Sorb = 5.0/6.2/7.8 K. |
| 1241 | Dump pressure basically flat. Stop pumping to dump. Close all IGH valves. |
| 1300 | Dump pressure (G2) = 718.7 mbar with 3He pump on. Current air pressure is 1017.6 mbar, so corrected dump pressure is 718.7 + (1017.6-1013.25) = 723.1 mbar |
| 1335 | MC(Cernox) = 10.7 K |
| 1350 | Take cold trap 1 out of LN2 bath to warm up. |
| 1510 | MC(Cernox) = 42.8 K |
| 1530 | MC(Cernox) = 46.6 K, Vacuum jacket = 0.12 mbar |
| 1600 | MC(Cernox) = 53.3 K, Vacuum jacket = 0.14 mbar |
| 1715 | MC(Cernox) = 67.0 K, Vacuum jacket = 0.16 mbar |
| 2010 | MC(Cernox) = 96.5 K |