2018/04/03 (Tuesday)
| Setup: DIB1/2 → SL 43/41 → 3.2 MHz filters → cables 3/1 → DCRC50(3)/55(1). | |
| Status: Stopped circulation and 1K Pot yesterday. LN2 traps pumped out. Mixture open to fridge and dump. 1K Pot needle valve open. | |
| 0900 | Tower = 1.87 K mK, Condenser/Dump = 252 mbar, 1K Pot > 7 K, Sorb = 9.8 K, Main bath = 5.0% |
| 1005 | Remove Traps 1 and 2 from LN2 bath to let them warm up. |
| 1005 | Close turbo pump valve to stop pumping on IVC. |
| 1005 | Turn on MC heater and Still heater to 20 mW each. Tower temperature rises. |
| 1010 | Close V4 and V14 to isolate dump. V1 and V3 open. Trapping the mixture in the fridge while heating. |
| 1010 | Tower = 2.7 K and rising, G1(fridge) = 278 mbar and rising. IVC = 16 nbar. |
| 1035 | Tower = 4.1 K, G1(fridge) = 1000 mbar. Wasm't in the lab at the time, shouldn't have let it climb so high |
| 1100 | Open V4 to release pressure in fridge to dump |
| 1105 | Tower/Sorb = 5.9/7.7 K and rising, G1(fridge/dump) = 625 mbar, IVC = 19 nbar |
| 1110 | Start pumping fridge to dump, V6 = 13.0%. Tower/sorb temperatures fall. |
| 1115 | MC(Cernox)/1K Pot/Sorb = 6.9/4.2/5.3 K, P1(fridge) = 0.9 mbar, G2(dump) = 722 mbar. Open V6 to 100% |
| 1120 | MC(Cernox)/1K Pot/Sorb = 7.0/4.7/6.0 K, G1/P1(fridge) = 0.3/0.17 mbar, G2(dump) = 724 mbar. |
| 1125 | MC(Cernox)/1K Pot/Sorb = 7.0/5.9/7.5 K, G1/P1(fridge) = 0.2/0.065 mbar, G2(dump) = 726 mbar. |
| 1130 | MC(Cernox)/1K Pot/Sorb = 7.0/6.6/8.5 K, G1/P1(fridge) = 0.3/0.040 mbar, G2(dump) = 726 mbar. |
| 1135 | MC(Cernox)/1K Pot/Sorb = 7.0/>7/9.2 K, G1/P1(fridge) = 0.3/0.030 mbar, G2(dump) = 727 mbar. |
| 1135 | Stop pumping mixture out of fridge. Isolate fridge, close IGH valves. Turn off 3He pump. |
| Dump reached 728.0 mbar and was still climbing before closing V9. Snowy day today so barometric pressure is low, 29.88 inHg, so corrected dump pressure = 726.6 mbar. Compare Run 66, the corrected dump pressure after pumping it out was 737.7 mbar. In Run 65 it was 738.8 mbar. So we may have lost some during this run, when the fridge failed and overpressurized. | |
| 1140 | Stop MIDAS programs and disconnect power from DCRCs. |
| 1155 | IVC = 34 nbar. Let He into IVC. MC/Sorb temperatures start falling. Trying to put about 2 μbar in but it seems to keep condensing, falls to 0.12 μbar when I close the valve. Maybe it's a little premature, maybe parts are still below 4 K. |
| 1205 | MC(Cernox)/1K Pot/Sorb = 5.0/5.7/7.3 K |
| 1210 | Tower/MC(Cernox)/Coldplate/Still/1K Pot/Sorb = 4.8/4.9/13.8/11.7/5.3/6.8 K, IVC = 0.12 μbar |
| 1215 | Turn off MC and Still heaters. |
| 1220 | Tower/MC(Cernox)/Coldplate/Still/1K Pot/Sorb = 4.3/4.3/12.0/7.6/5.4/6.8 K, IVC = 0.074 μbar |
| 1225 | Turn on MC and Still heaters, 20 mW each. |
| 1235 | Tower/MC(Cernox)/Coldplate/Still/1K Pot/Sorb = 4.8/4.9/12.4/10.4/5.3/6.7 K, IVC = 0.10 μbar |
| 1240 | Main bath = 0.4% |
| 1315 | Main bath = -0.2% |
| 1315 | MC(Cernox)/1K Pot/Sorb = 4.9/5.3/6.7 K, IVC = 0.10 μbar, same as 12:35 |
| 1345 | Main bath = -0.5%. |
| 1405 | MC(Cernox)/1K Pot/Sorb = 4.9/5.3/6.7 K, IVC = 0.12 μbar |
| 1410 | Try again to add He gas to IVC. Open valve enough to hold pressure around 2 μbar for several minutes, then close it again. Temperatures drop. |
| 1420 | Tower/MC(Cernox)/Coldplate/Still/1K Pot/Sorb = 4.6/4.7/12.8/9.7/4.97/6.3 K, IVC = 0.46 μbar |
| 1430 | Disconnect pump manifold from IVC and connect it instead to the cryostat vacuum jacket. Main bath ⇐ -1.0% (minimum) |
| 1435 | Pump out line leading to cryostat vacuum jacket down to 34 μbar. Open valve to cryostat vacuum jacket, pressure falls to 4 μbar. |
| 1450 | Recovery = 1 sqft/235 seconds |
| 1500 | Let 1.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. After a couple minutes, recovery = 1 sqft/25 seconds, MC/1K Pot/Sorb rising. |
| 1505 | MC(Cernox)/1KPot/Sorb = 4.8/5.0/6.3 → 4.9/5.2/6.7 K, Main bath outer surface = 22.4 C, recovery = 1 sqft/16 seconds. |
| 1515 | MC(Cernox)/1KPot/Sorb = 4.9/5.4/6.9 K, Main bath outer surface = 22.3 C, recovery = 1 sqft/22 seconds. |
| 1530 | MC(Cernox)/1KPot/Sorb = 5.1/5.7/7.3 K, Main bath outer surface = 22.0 C, recovery = 1 sqft/28 seconds. |
| 1555 | MC(Cernox)/1KPot/Sorb = 5.4/6.3/8.1 K, Main bath outer surface = 21.8 C, recovery = 1 sqft/47 seconds. |