2017/10/17 (Tuesday)
| Status: Tower installed, cryostat raised. Mixture has been cleaned a few times. Fridge pumped out yesterday. Traps clean, cold. | |
| 0755 | Turbo pump = 46 nbar, pumping on IVC. With valve closed IVC = 1.6 μbar. (7.4 μbar after 10 minutes) |
| 0800 | Close 1K Pot needle valve is closed, then pump out 1K Pot with scroll pump. |
| 0805 | Open fridge lines up to (cold) Trap 1, to cryopump out whatever air is left in the fridge. |
| 0805 | Let mixture into fridge through Trap 1. 3He pump off, V9, V13a, V12a+speedi, V3, V1, condenser & still valves all open. |
| 0815 | Begin pumping out main bath. P2 falls below 1 mbar in 5 minutes. |
| 0815 | Pump on IVC with Leak Detector |
| 0820 | Pressurize main bath with He to 125 mbar above 1atm on G3. |
| note | He gas is left in the Vent volume, the auxiliary right volume, the auxiliary left (G3) volume, and the P2 volume. |
| 0820 | LD signal has remained low, currently 4 pbarL/s |
| 0825 | Let 5.4 mbar He exchange gas into IVC |
| 0830 | Begin LN2 transfer. |
| 0835 | MC(Cernox) = 295.4 K, Sorb = >249 K (max), IVC = 5.4 mbar, G1 (fridge) = 606 mbar, Level resistor = 0.985 kΩ. |
| 0850 | MC(Cernox) = 293.5 K, Sorb = >249 K (max), IVC = 5.4 mbar, G1 (fridge) = 606 mbar, Level resistor = 0.990 kΩ. |
| 0910 | MC(Cernox) = 276.3 K, Sorb = >249 K (max), IVC = 4.6 mbar, G1 (fridge) = 606 mbar, Level resistor = 1.000 kΩ. DIB4 qI-qO = 13.12 nS. |
| 0945 | MC(Cernox) = 226.5 K, Sorb = >249 K (max), IVC = 4.0 mbar, G1 (fridge) = 605 mbar, Level resistor = 1.026 kΩ. DIB4 qI-qO = 13.13 nS. |
| 1000 | MC(Cernox) = 202.2 K, Sorb = >249 K (max), IVC = 4.0 mbar, G1 (fridge) = 605 mbar, Level resistor = 1.044 kΩ. DIB4 qI-qO = 13.13 nS. |
| 1005 | close LN2 Dewar valve a few turns to slow down transfer so it doesn't overfill during meeting. |
| 1110 | MC(Cernox) = 127.6 K, Sorb = 238 K, IVC = 2.2 mbar, G1 (fridge) = 603 mbar, Level resistor = 1.170 kΩ. DIB4 qI-qO = 11.00 nS. |
| 1120 | The DIB4 qI-qO (that's qB-qE) conductance has been decreasing. That's good, suggests no short between those channels. Do a check on all interchannel conductances: |
| Cross-channel continuity through qBias leads (all in nS) | |||||
|---|---|---|---|---|---|
| DIB1qI (qA) | DIB4qI (qB) | DIB1qO (qC) | DIB3qO (qD) | DIB4qO (qE) | |
| DIB1qI (qA) | - | - | - | - | - |
| DIB4qI (qB) | 10.3 | - | - | - | - |
| DIB1qO (qC) | 9.9 | 11.2 | - | - | - |
| DIB3qO (qD) | 10.6 | 10.9 | 10.7 | - | - |
| DIB4qO (qE) | 10.5 | 10.1 | 11.3 | 11.0 | - |
| note qObias is pin 11, qIbias is pin 15 on I/O cable | |||||
All are significantly lower than 13 nS, the conductance of the combined two bias resistors. So it looks like there are no shorts. (And no opens.)
| 1125 | MC(Cernox) = 117.9 K, Sorb = 213 K, IVC = 2.2 mbar, G1 (fridge) = 603 mbar, Level resistor = 1.218 kΩ. DIB1 qI-qO = 8.99 nS. |
|---|---|
| 1200 | MC(Cernox) = 99.6 K, Sorb = 157 K, IVC = 1.9 mbar, G1 (fridge) = 602 mbar, Level resistor = 1.296 kΩ. DIB1 qI-qO = 2.7 nS. |
| 1230 | MC(Cernox) = 90.2 K, Sorb = 132 K, IVC = 1.9 mbar, G1 (fridge) = 600 mbar, Level resistor = 1.317 kΩ. DIB1 qI-qO = 0.83 nS. |
| 1235 | Level resistor = 1.320 kΩ. Stop LN2 transfer. |
| 1255 | MC(Cernox) = 85.4 K, Sorb = 124 K, IVC = 1.6 mbar, G1 (fridge) = 600 mbar, DIB1 qI-qO = 0.42 nS. |
| 1305 | Mini-throughput check: close off Trap 1 and V3. Only V1, condenser speedivalve, still gate valve, and V9 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. P1 (still) falls to 3 mbar after a few minute. G1 (condenser) falls, from 600 mbar to 500 mbar in a couple minutes, and continues to fall. Good, looks like we have throughput. G2 (dump) slowly rising. |
| 1320 | MC(Cernox) = 82.6 K, Sorb = 123 K, IVC = 1.6 mbar, DIB1 qI-qO = 0.23 nS. |
| 1320 | Begin pumping exchange gas out IVC |
| 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 V126
- monitor G1
| 1350 | Perform mixture throughput test at MC = 82.8 K using above procedure. Let G1 rise to 550 mbar before Step 3, then it falls to 64 mbar and begins to rise. Throughput: 35.2 mbar/min. Higher than Run 64 but that's expected since we're colder this time. |
|---|---|
| 1355 | Begin blowing out LN2. G3 around 430 mbar - close helium cylinder regulator valve a bit to reduce this to around 300 mbar. |
| 1405 | Electrical checkout: all looks OK. Previous short in DIB4 qO-qI now gone. |
| Cross-channel continuity through qBias leads (all in nS) | |||||
|---|---|---|---|---|---|
| DIB1qI (qA) | DIB4qI (qB) | DIB1qO (qC) | DIB3qO (qD) | DIB4qO (qE) | |
| DIB1qI (qA) | - | - | - | - | - |
| DIB4qI (qB) | 0.36 | - | - | - | - |
| DIB1qO (qC) | 0.21 | 0.25 | - | - | - |
| DIB3qO (qD) | 0.44 | 0.50 | 0.48 | - | - |
| DIB4qO (qE) | 0.31 | 0.51 | 0.21 | 6.5 | - |
| note qObias is pin 11, qIbias is pin 15 on I/O cable | |||||
| 1450 | Blowing out LN2 - hose is going limp, but G3 hasn't fallen much. We'll stop the pressure so the hose will warm enough to remove from the transfer stick, then try pumping out the MB. |
|---|---|
| 1500 | Open 1K Pot needle valve a little to let He gas into 1K Pot. (But if it turns out the LN2 isn't all out of the bath, we should pump out the 1K Pot again.) |
| 1505 | There's a problem with the blowout - the pressure in the Main Bath is high, but there's almost no gas coming out of the transfer stick. The transfer stick or the tube in bath must be clogged. |
| 1510 | Removing the transfer stick, pressure is released. That probably means that the tube inside the Main Bath that extends to the bottom is clogged. |
| 1515 | Replace stick and try blowing He gas into it. Remove stopper from the neighboring port. When He is flowing, more gas comes out of port, and when it's pinched off less gas comes out. So it doesn't seem like it's clogged. |
| 1520 | Restart the LN2 blowout, but this time use more pressure. Running with G3 = 420 mbar. Hose gets frosty. The previous pressure, G3 (main bath) = 250 mbar, was too low I guess. |
| 1525 | G3 (main bath) falls quickly, 420→190 mbar. So looks like we're about finished. Check cylinder - it's not empty. |
| 1535 | Stop blowing out LN2. |
| 1540 | Begin pumping out Main Bath with scroll pump. |
| 1550 | P2 falls below 1 mbar, so Main Bath is indeed empty. |
| 1550 | Also pump out 1K Pot again. |
| 1600 | Fill Main Bath with He to 110 mbar above 1atm on G3. Also fill 1K Pot with He. |
| 1600 | Turbo pump = 4.6 nbar pumping on IVC. IVC = 0.14 μbar with valve to pump closed for a couple minutes. |
| 1605 | Let 63 μbar He exchange gas into IVC. |
| 1622 | Begin initial LHe transfer |
| 1630 | Open mixture from Dump through Trap 1 (cold) to Condenser and Still. |
| 1630 | MC(Cernox) = 82.1 K, Sorb = 132.0 K, IVC = 63 μbar, G1(Fridge) = 609 mbar. |
| 1645 | MC(Cernox) = 79.6 K, Sorb = 127.3 K, IVC = 54 μbar, G1(Fridge) = 608 mbar. |
| 1650 | MC(Cernox) = 77.6 K, Sorb = 122.6 K, IVC = 46 μbar, G1(Fridge) = 608 mbar. |
| 1705 | MC(Cernox) = 67.5 K, Sorb = 95.0 K, IVC = 25 μbar, G1(Fridge) = 596 mbar. |
| Like in Run 64 and the run before that, the IVC pressure is decreasing faster than it should just from the ideal gas law. It's not as extreme as in the last run though. But we may want to consider “topping it off” again if it gets too low. | |
| 1720 | MC(Cernox) = 56.1 K, Sorb = 57.6 K, IVC = 19 μbar, G1(Fridge) = 570 mbar. |
| 1740 | MC(Cernox) = 40.6 K, Sorb = 5.8 K, IVC = 12 μbar, G1(Fridge) = 479 mbar. |
| 1800 | MC(Cernox) = 27.3 K, Sorb = 5.4 K, 1K Pot = 4.27 K, IVC = 10 μbar, G1(Fridge) = 465 mbar. MB = 3.0%! |
| 1815 | MC(Cernox) = 18.8 K, Sorb = 5.3 K, 1K Pot = 4.23 K, IVC = 10 μbar, G1(Fridge) = 463 mbar. MB = 14.0% |
| 1830 | Start pumping out IVC with turbo pump (Thermometer went out of range - mistakenly thought temp had dropped below 10K so started pumping out IVC. Realized pumping started around 14.4K once range was adjusted. Oops.). MC(Cernox) = 14.2 K, Sorb = 5.3 K, 1K Pot = 4.27 K, IVC = 7.4 nbar, G1(Fridge) = 460 mbar. MB = 26.0% |
| 1840 | MC(Tower) = 9.79 K, Sorb = 5.7 K, 1K Pot = 4.49 K, IVC = 2.6 nbar, G1(Fridge) = 460 mbar. MB = 42.4% |
| 1850 | MC(Tower)/Sorb/1K Pot = 9.83/6.0/4.77 K, Fridge(G1) = 459.7 mbar, MB = 67.4% |
| 1933 | MC(Tower)/Sorb/1K Pot = 11.26/6.6/5.18 K, Fridge(G1) = 510 mbar, End LHe transfer: MB = 87.2% |