2018/05/14 (Monday)
| Status: Discovered blockage at 77K on Saturday. Warmed up since then. Helium in IVC. Pumping out cryostat vacuum jacket overnight. Still and MC heaters on @ 20 mW | |
| 0900 | MC(Cernox) = 280.6 K |
| 0905 | Still = 0.85 mbar. Still gate valve was open to P1 during the warmup |
| 0910 | Check condenser pressure, not much. Pump out both sides of fridge with scroll pump |
| 0910 | Turbo on cryostat vacuum jacket = 8.6 nbar; cryostat vacuum jacket = 100 nbar with pump valved out. Stop pumping out jacket. |
| 0915 | Check pressure in warm LN2 Trap 2: 8.4 mbar. Pump out with scroll pump |
| 0915 | Check pressure in warm LN2 Trap 1: 9.8 mbar. Pump out with scroll pump |
| Throughput test procedure, Cold Trap 2: |
- All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13b, V12b+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12b+speedivalve and V3, open V1
- monitor G1
| 0940 | Perform mixture throughput test at MC = 281 K using above procedure with 3He pump off. Let G1 rise to 546 mbar before Step 3, then it falls to 39 mbar and rises steadily. Throughput = 6.4 mbar/min. Compare to September, it's a little lower this time. But pressure differential is lower too. |
|---|---|
| 0950 | Pump mixture out of fridge to dump |
| 1200 | Let 6.3 mbar He exchange gas into IVC |
| 1405 | Check pressure in 1K Pot: 24 mbar. Pump out with scroll pump. |
| 1430 | Pump out main bath to <1 mbar |
| 1435 | Pressurize main bath with He to 301 mbar above 1 atm |
| 1445 | Let mixture into fridge through cold LN2 Trap 2. Using all of the mixture: V9 is open. 3He pump off. |
| 1445 | MC(Cernox) = 281.5 K, Sorb = >249 K (max), IVC = 6.3 mbar, G1 (fridge) = 599 mbar, Old Level resistor = 0.990 kΩ, New level resistor = 2.143 kΩ |
| 1450 | Begin LN2 transfer |
| 1510 | MC(Cernox) = 274.1 K, IVC = 5.4 mbar, G1 (fridge) = 598 mbar, Old Level resistor = 1.099 kΩ, New level resistor = 2.219 kΩ |
| 1530 | MC(Cernox) = 236.0 K, IVC = 3.0 mbar, G1 (fridge) = 595 mbar, Old Level resistor = 1.207 kΩ, New level resistor = 2.843 kΩ |
| 1605 | MC(Cernox) = 165.9 K, IVC = 2.2 mbar, G1 (fridge) = 593 mbar, Old Level resistor = 1.300 kΩ, New level resistor = 2.967 kΩ |
| 1620 | MC(Cernox) = 148.6 K, IVC = 2.2 mbar, G1 (fridge) = 591 mbar, Old Level resistor = 1.320 kΩ, New level resistor = 2.991 kΩ |
| 1630 | MC(Cernox)/Sorb = 137.4/159.2 K, IVC = 2.2 mbar, G1 (fridge) = 590 mbar, Old Level resistor = 1.334 kΩ, New level resistor = 3.009 kΩ |
| 1645 | MC(Cernox)/Sorb = 127.5/142.8 K, IVC = 1.9 mbar, G1 (fridge) = 589 mbar, Old Level resistor = 1.337 kΩ, New level resistor = 3.018 kΩ |
| 1650 | MC(Cernox)/Sorb = 122.6/136.4 K, IVC = 1.9 mbar, G1 (fridge) = 589 mbar, Old Level resistor = 1.336 kΩ, New level resistor = 3.018 kΩ |
| 1655 | Stop LN2 transfer |
| Cryocleaning mixture | |
|---|---|
| 1000 | Start cleaning mixture through cold LN2 Trap 2, V6 = 12.8% |
| 1005 | Increase V6 to 13.0% to speed up circulation |
| 1020 | Increase V6 to 13.1% to speed up circulation |
| 1050 | Stop cryocleaning, Trap 2 50 minutes. |
| 1105 | Start cleaning mixture through cold LN2 Trap 1, V6 = 13.1% |
| 1110 | Increase V6 to 13.2% to speed up circulation |
| 1155 | Stop cryocleaning, Trap 1 50 minutes. |
| 1205 | Check pressure in warm Trap 2: 12.0 mbar. Pump out with scroll pump |
| 1215 | Start cleaning mixture through cold LN2 Trap 2, V6 = 12.9% |
| 1235 | Increase V6 to 13.0% to speed up circulation |
| 1310 | Stop cryocleaning, Trap 2 55 minutes. |
| 1325 | Check pressure in warm Trap 1: 12.2 mbar. Pump out with scroll pump |
| 1330 | Start cleaning mixture through cold LN2 Trap 1, V6 = 13.1% |
| 1340 | Increase V6 to 13.2% to speed up circulation |
| 1345 | Increase V6 to 13.3% to speed up circulation |
| 1415 | Stop cryocleaning, Trap 1 45 minutes. |
| 1425 | Check pressure in warm Trap 2: 4.5 mbar. Pump out with scroll pump |