2018/07/26 (Thursday)
| status: circulation and 1K Pot suspended, mixture in fridge, IVC closed off. MC/Still heaters on @ 20/20 mW. Investigating helium in IVC | |
| overnight: Tower temperature settling downward, from to ~8.5 K. Sorb flat. | |
| 0932 | Tower = 8.7 K and decreasing, IVC = 40 nbar. |
| 0933 | Fill LN2 cold trap full. |
| 1010 | Main bath = “-1.0%” |
| 1220 | Tower = 8.56 K, Sorb = 11.5 K, IVC = 40 nbar. |
| 1222 | Insert LN2 transfer stick into bath. IVC pressure spikes rises to 54 nbar, then falls to 46 nbar. Sorb rises to 12.3 K. Tower unaffected. Remove LN2 transfer stick. |
| 1230 | Pump mix to dump. Close V13A, Open V5 and V3 to pump on both sides of fridge. |
| 1241 | G1 = 3.0 mbar, P1 = 4.0 mbar. Close V1 and V3 to pump on just the cold trap. |
| 1305 | G1 = 1.0 mbar. Close V12A and the cold trap 1 speedivalve. Open V1 and V3 to pump on fridge lines. |
| 1315 | Close valves to IVC so we can disconnect the pump manifold to let gas into the cryostat vacuum jacket. But failed to close one of the valves, so let a bunch of air into the IVC. (Valve knob was blocked by metal hose). Recovery meter starts spinning very quickly. Tower shoots to 37 K. Sorb shoots to 90 K |
| 1335 | Pump out IVC with scroll, then turbo pump. |
| 1340 | Tower = 35 K and flat, IVC = 34 nbar (pumping), Sorb = 82.3 K |
| 1405 | Tower = 35 K, IVC = 46 nbar (pumping), Sorb = 77.4 K. Sorb falling, Tower falling slowly. |
| 1410 | Close Turbo pump valve. IVC = 0.25 ubar. |
| 1440 | Close IVC (for real). Switch over to connect pump manifold to cryostat vacuum jacket. Pump down pumping lines. Close Turbo pump valve. |
| 1445 | Open vacuum jacket valve, vacuum jacket pressure = 0.2 ubar. Add one clear hose length of He (at 2.5 psi) to vacuum jacket. |
| 1500 | Vacuum jacket pressure settles to 46 ubar |
| 1501 | Add another clear hose length of He to vacuum jacket. |
| 1520 | Vacuum Jacket Pressure settles to 46 ubar again Add another clear hose length of He to the vacuum jacket. |
| 1540 | Vacuum jacket pressure settles to 120 ubar, then slowly increases 160 ubar |
| 1550 | Tower = 39 K and rising |
| 1600 | Switch pump manifold back to IVC. Pump out lines, close off turbo pump. Open IVC valves at top of fridge to watch IVC pressure. |
| 1605 | Tower = 46.2 K, IVC pressure = 1.4 mbar, sorb = 73.2 K |
| 1607 | We're still pumping fridge lines to dump. G1 = 1.7 mbar, P1 = 0.26 mbar, G2 = 733.5 mbar and flat Stop pumping mixture out of fridge. Isolate fridge, close IGH valves. Turn off 3He pump. Also close V4A and turn off 1K Pot pump. |
| 1616 | Tower = 49.1 K, IVC pressure = 3.0 mbar, sorb = 79.2 K |
| 1716 | Tower = 51.9 K, IVC pressure = 5.4 mbar, sorb = 100.1 K |