2018/05/12 (Saturday)
| Status: Transferred LN2 yesterday. | |
| 1149 | Begin pumping on IVC with scroll pump. |
| 1155 | Turbo pressure reached below 1e-1 mbar, switch over to turbo pump and turn off scroll pump. |
| note: both full dewars are still available. | |
| 1415 | MC(Cernox)/Sorb = 77.2/124.0 K, G1 (fridge) = 207 mbar, Old Level resistor = 1.224 kΩ, New level resistor = 2.993 kΩ |
| 1415 | Turbo on IVC = 3.4 nbar |
| 1420 | Electrical check on DIB4: looks good, still has short from qI to chassis but otherwise good. |
| 1425 | Electrical check on DIB1: looks good |
| 1430 | Electrical check on DIB3: looks good, same issues as last time(SQUID A open) except now Feedback D reads high, 8 MΩ. Not a connected channel so no problem. |
| 1440 | Leak on IVC = 763 pbarL/s with turbo valved out |
| 1440 | Start blowing out LN2 |
| 1440 | IVC leak = 785 pbarL/s, Main bath = 458 mbar above 1 atm, New level resistor = 2.986 kΩ |
| 1445 | IVC leak = 750 pbarL/s, Main bath = 448 mbar above 1 atm, New level resistor = 2.995 kΩ |
| 1450 | IVC leak = 706 pbarL/s, Main bath = 438 mbar above 1 atm, New level resistor = 2.995 kΩ |
| 1450 | Try Mini-throughput check: close off Trap 1 and V3. Only V1, condenser speedivalve, still gate valve open. Turn on 3He pump, then open V6 to 12.8%. This pumps mix out of the still side and we can see if the pressure goes down on the condenser side. Increased V6 to 13.0% to bring down P1. G1 (condenser) started out at 206 mbar, not falling. Increase V6→ 13.5%. Still pressure falls below 1 mbar, condenser not falling, or falling very slowly, 0.1 mbar/min. Fucking blockage. |
| 1455 | IVC leak = 671 pbarL/s, Main bath = 434 mbar above 1 atm, New level resistor = 2.994 kΩ |
| 1505 | IVC leak = 623 pbarL/s, Main bath = 435 mbar above 1 atm, New level resistor = 2.990 kΩ |
| 1510 | IVC leak = 600 pbarL/s, Main bath = 438 mbar above 1 atm, New level resistor = 2.989 kΩ |
| Throughput test procedure, Cold Trap 1: |
- All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12a+speedivalve and V3, open V1
- monitor G1
| 1510 | Perform mixture throughput test at MC = 77 K using above procedure, but leaving some mixture in dump. Let G1 rise to 231 mbar before Step 3, then it falls to 13.5 mbar, doesn't rise. Throughput < 0.04 mbar/min. |
|---|---|
| 1515 | IVC leak = 587 pbarL/s, Main bath = 330 mbar above 1 atm (falling), New level resistor = 3.001 kΩ |
| 1520 | IVC leak = 587 pbarL/s, Main bath = 159 mbar above 1 atm, New level resistor = 2.983 kΩ |
| 1523 | IVC leak = 579 pbarL/s, Main bath = 155 mbar above 1 atm, New level resistor = 2.968 kΩ Stop blowing out LN2 |
| 1530 | Perform another mixture throughput test at MC = 77 K as before but with all the mixture. Let G1 rise to 592 mbar before Step 3, then it falls to 33.5 mbar, then sits there. Throughput < 0.04 mbar/min |
| 1535 | Pump out main bath with scroll pump. Falls to <1 mbar in 10 minutes. |
| 1545 | Pump shitty mixture to dump |
| 1550 | Fill main bath with nitrogen gas |
| 1555 | IVC leak = 500 pbarL/s, never budged. |
| 1555 | Let 10 hose-lengths of He into IVC. MC temperature rises a little. |
| 1615 | Let 2 hose-lengths of He into cryostat vacuum jacket. Cryostat vacuum jacket → 0.63 mbar |
| 1615 | Turn on MC and Still heaters to 20 mW each |
| 1620 | MC(Cernox)/Sorb = 78.7/135.7 K, New level resistor = 2.898 kΩ |
| 1630 | MC(Cernox)/Sorb = 79.6/141.4 K, New level resistor = 2.838 kΩ |
| 1645 | MC(Cernox)/Sorb = 82.8/153.3 K, New level resistor = 2.772 kΩ |
| 1650 | MC(Cernox)/Sorb = 83.7/158.2 K |
| 1650 | Start logging IGH data to I:\K100\temperature_20180512.txt. Open still gate valve. We can monitor any release of pressure as the fridge warms. |
| 1840 | MC(Cernox) = 114.3 K |
| 2040 | MC(Cernox) = 144.0 K |
| warming time constant around 11.2 hours, predicted to hit 273 K by 6pm tomorrow |