2018/04/30 (Monday)
| Pumping out cryostat vacuum jacket for last two days. Main bath raised, IVC pumped out. | |
| 0905 | Turbo = 5.4 nbar, Cryostat vacuum jacket = 100 nbar. Stop pumping out cryostat vacuum jacket |
| 0915 | Pump out fridge lines |
| 0950 | Check IVC pressure: 2.2 mbar. Pump out with scroll, then turbo |
| 1000 | Turbo = 140 nbar. Valve out turbo and pump IVC with leak detector: leak = 100 pbarL/s. Better than Saturday. |
| 1115 | Turbo = 54 nbar. Valve out turbo and pump IVC with leak detector: leak = 102 pbarL/s. |
| 1125 | Squirt-test for leaks at top of fridge. The KF flange on the stripline elbow shows the most leak. Signal increases by 20-50 pbarL/s with smallish squirts to this flange. |
| 1425 | Let mixture from 3He pump through cold LN2 Trap 1 into fridge lines, both sides. (Most mixture still in dump.) Leak detector on IVC - no increase in signal (leak = 96 pbarL/s). |
| 1430 | Check pressure in 1K Pot: 26 mbar on P2, about 0.1 bar on mechanical gauge above IGH. Pump out with scroll pump. |
| 1435 | Pump out main bath with scroll pump to <1 mbar on P2. |
| 1450 | Pressurize main bath with helium to 292 mbar above 1atm on G3. No increase in IVC leak, about 96 pbarL/s. |
| 1450 | Open 1K Pot speedivalve to pressurize it with helium also. |
| 1455 | Let 5.4 mbar He exchange gas into IVC |
| 1455 | MC(Cernox) = 297.0 K, Sorb = >249 K (max), IVC = 5.4 mbar, G1 (fridge) = 216 mbar, Level resistor = 0.983 kΩ. |
| 1500 | Begin LN2 transfer. |
| 1505 | MC(Cernox) = 296.8 K, Sorb = >249 K (max), IVC = 5.4 mbar, G1 (fridge) = 216 mbar, Level resistor = 1.033 kΩ. |
| 1525 | MC(Cernox) = 280.3 K, Sorb = >249 K (max), IVC = 4.0 mbar, G1 (fridge) = 213 mbar, Level resistor = 1.114 kΩ. |
| 1545 | MC(Cernox) = 243.0 K, Sorb = >249 K (max), IVC = 3.0 mbar, G1 (fridge) = 211 mbar, Level resistor = 1.210 kΩ. |
| 1605 | MC(Cernox) = 199.6 K, Sorb = >249 K (max), IVC = 2.5 mbar, G1 (fridge) = 209 mbar, Level resistor = 1.307 kΩ. |
| 1625 | MC(Cernox) = 163.9 K, Sorb = 199.3 K, IVC = 2.5 mbar, G1 (fridge) = 207 mbar, Level resistor = 1.337 kΩ. |
| 1640 | MC(Cernox) = 146.2 K, Sorb = 167.4 K, IVC = 1.9 mbar, G1 (fridge) = 206 mbar, Level resistor = 1.338 kΩ. |
| 1640 | Stop LN2 transfer |
| 1700 | MC(Cernox) = 129.4 K, Sorb = 144.3 K, IVC = 1.9 mbar, G1 (fridge) = 206 mbar |
| Cryocleaning mixture | |
|---|---|
| 0910 | Check warm LN2 Trap 2: 6.5 mbar. Pump out with scroll pump. Check warm LN2 Trap 1: 8.0 mbar. Pump out with scroll pump. |
| 0930 | Start cryocleaning mixture through cold LN2 Trap 2, V6 = 12.9% |
| 0935 | Increase V6→13.0% to speed up flow |
| 0945 | Increase V6→13.1% to speed up flow |
| 1030 | Stop cryocleaning through LN2 trap 2, pump to dump. |
| 1055 | Start cryocleaning mixture through cold LN2 Trap 1, V6 = 13.1% |
| 1100 | Increase V6→13.2% to speed up flow |
| 1110 | Increase V6→13.3% to speed up flow |
| 1140 | Increase V6→13.4% to speed up flow… too much, close V14 and reduce V6→13.2% to bring pressure down, then open V14 again. Adjust V6 to get the flow right. |
| 1155 | Stop cryocleaning through LN2 trap 1, pump to dump. |
| 1210 | Check pressure in warm LN2 Trap 2: 5.9 mbar. Pump out with scroll pump. |
| 1220 | Start cryocleaning mixture through cold LN2 Trap 2, V6 = 13.2% |
| 1235 | Increase V6→13.3% to speed up flow |
| 1250 | Increase V6→13.4% to speed up flow |
| 1335 | Stop cryocleaning through LN2 trap 2, pump to dump. |
| 1400 | Check pressure in warm LN2 Trap 1: 15.9 mbar. Pump out with scroll pump. |
| Cryocleaning log | |||
|---|---|---|---|
| date | trap | duration (minutes) | contaminants removed (mbar) |
| Apr 27 | 2 | 60 | 6.5 |
| Apr 27 | 1 | 60 | 8.0 |
| Apr 30 | 2 | 60 | 5.9 |
| Apr 30 | 1 | 60 | 15.9 |
| Apr 30 | 2 | 75 | 2.4 |