| 1115 | G1: 2mbar, P1: 30ubar, G2: 0mbar. The fact that G2 is at 0mbar again is obviously strange. It does seem to be following a pattern, though. Anytime the dewar is lowered and the fridge begins warming up, G2 rises to a pressure of several mbar for some reason. Either a valve is leaky and the temperature rise in the fridge is causing pressure to be pushed into the volume occupied by G2, or something even stranger is happening. |
| | External pressure sensor attached to He3 pump exhaust lines reads 1.0mbar. |
| 1150 | Stop pumping on fridge lines. Add 908mbar of He gas through vent valve to G1 lines. P1 at 32ubar. Open V1. G1 drops to 74mbar within several seconds. |
| 1158 | P1: 55ubar, G1: 73mbar. |
| 1213 | P1: 0.12mbar, G1: 69mbar. |
| 1226 | P1: 0.18mbar, G1: 67mbar. Pump out He gas through V6 (and V13a and V11a). |
| 1245 | P1: 0.19mbar, G1: 64mbar. Open V2 and V3 to aid in pumping, which seems especially slow. |
| 1340 | Turbopump on IVC. P1: 85ubar, G1: 2.3mbar. Ready to perform “real” throughput test. Open vent valve, V2, V3, V11a, V13a in preparation. Open V7 to let in He gas until G1 reads 600mbar. Close V7. When G1 stabilizes at 573mbar, close V2, V3, and open V1. |
| | Throughput rate of 9mbar/min observed. This is lower than the warm throughput observed on January 6th (~17mbar/min). The helium cold trap may be slowing down the flow, which would explain the slow pumping out of the fridge lines. Commence pumping out He gas in order to perform another test. |
| 1455 | P1: 85ubar, G1: 2mbar, G2 is still at 0mbar. Close V6. |
| 1500 | P1: 75ubar, G1: 2mbar. Add He gas until G1 reaches 630mbar. G1 stabilizes at ~600mbar. Close V2, V3, open V1. |
| | Throughput rate of ~10mbar/min observed, so it appears to be the cold trap that is slowing down the flow and not some strange blockage. |
| 1510 | Pump He gas out through V6. |
| 1545 | External pressure sensor attached to He3 pump exhaust lines now reads 1.2mbar. Add He exchange gas to IVC. |
| 1600 | Pump and flush main bath. |
| 1630 | Commence LN2 transfer. External pressure sensor connected to He3 pump exhaust lines now reads 1.4mbar. |
| 1900 | Finish LN2 transfer. Mixing chamber temperature 85K. |
| 1930 | Mixing chamber temperature 80K. Pump out He exchange gas. Leave fridge lines turbopumping out over the weekend. |