2017/09/22 (Friday)
| Status: Successful 98K throughput, initial LHe transfer yesterday. | |
| 1055 | MC(Tower)/Sorb/1K Pot = 4.70/8.3/6.41 K, Fridge(G1) = 587 mbar, MB = 70.7%. |
| 1055 | Turbo = 3.0 nbar, IVC = 30 nbar. Stop pumping on IVC. |
| 1100 | Fill LN2 cold trap bath |
| 1100 | Connect 4He pump to 1K Pot pumping line, turn on pump, open the two valves connecting pump exhaust to recovery |
| 1130 | Electrical checkout at 4K, specifically cross-channel resistances: |
| Cross-channel continuity through qBias leads (all in nS) | |||||
|---|---|---|---|---|---|
| measurements at 92K / 4K | |||||
| DIB1qI (qA) | DIB4qI (qB) | DIB1qO (qC) | DIB3qO (qD) | DIB4qO (qE) | |
| DIB1qI (qA) | - | - | - | - | - |
| DIB4qI (qB) | 13 / 12.90 | - | - | - | - |
| DIB1qO (qC) | 1.1 / 0.07 | 0.7 / 0.06 | - | - | - |
| DIB3qO (qD) | 7 / 5.40 | 7 / 5.44 | 1.0 / 0.07 | - | - |
| DIB4qO (qE) | 13 / 12.96 | 13 / 13.00 | 0.7 / 0.06 | 7 / 5.44 | - |
| note qObias is pin 11, qIbias is pin 15 on I/O cable | |||||
This reinforces the notion that qA, qB, and qE are all shorted to one another.
It also suggests that the other two channels are connected and not shorted, since their conductivities have decreased with cooling, by about the same ratio.
| 1135 | Pump out P2 and G3 volumes, then isolate pump and open 1K Pot speedivalve. Mechanical gauge shows about 0.23 bar. 1K Pot temperature dips from 6.4 K to 4.7 K then rises back to >6 K. |
|---|---|
| 1140 | Open valve to 4He pump to start pumping on 1K Pot, needle valve closed. Another temporary dip in 1K Pot temperature. |
| 1145 | 1K Pot needle valve closed. 1K Pot → 6.5 K / 0.04 mbar Open 1K Pot needle valve about 10 degrees. 1K Pot → 3.3 K / 4.5 mbar Open needle valve a few more degrees. 1K Pot → 2.8 K / 10.0 mbar Open needle valve a few more degrees. 1K Pot → 2.4 K / 24.0 mbar. MC temperature falls below 4 K. Open needle valve a few more degrees. 1K Pot → 2.1 K / 36.0 mbar. |
| 1200 | Tower = 3.33 K, 1K Pot = 2.10 K / 36 mbar, Fridge(G1) = 430 mbar |
| 1210 | Tower = 2.95 K, 1K Pot = 1.71 K / 34 mbar, Fridge(G1) = 280 mbar |
| 1220 | Tower = 2.37 K, 1K Pot = 1.62 K / 24 mbar, Fridge(G1) = 112 mbar |
| 1230 | Tower = 2.12 K, 1K Pot = 1.56 K / 11 mbar, Fridge(G1) = 65.4 mbar |
| 1233 | Open needle valve a few more degrees. Wait a few minutes to settle, Tower = 2.07 K, 1K Pot = 1.81 K / 1 in Hg (which is about 33 mbar), Fridge(G1) = 61.5 mbar |
| 1251 | Close needle vale a few degrees (equal to previous open tweak). Tower = 2.03 K, 1K Pot = 1.68 K / 75 mbar, Fridge(G1) = 60.1 mbar |
| 1310 | Tower = 1.99 K, 1K Pot = 1.70 K / 85 mbar, Fridge(G1) = 57.6 mbar |
| 1405 | Tower = 1.90 K, 1K Pot = 1.69 K / 70 mbar, Fridge(G1) = 48.7 mbar |
| 1430 | Tower = 1.89 K, 1K Pot = 1.69 K / 70 mbar, Fridge(G1) = 47.4 mbar |
| 1435 | Close V9 leaving 48.6 mbar in dump. Close V3. Turn on 3He pump, which will push a little more mix into condenser. Fridge pressures rise a little then fall again. |
| 1435 | MC(H35)/Coldplate/Still = 1.91/2.97/2.19 K |
| 1440 | Start circulation through Trap 1. V6 → 12.8%. Condenser peaks at 160 mbar. 1K Pot pressure spike. MC falls to 1.65 K. |
| 1445 | V6 → 13.2%. Condenser peaks at 126 mbar. MC → 1.51 K. |
| 1435 | Tower/Coldplate/Still = 1.50/2.14/1.66 K |
| 1450 | V6 → 13.5%. Condenser peaks at 133 mbar. Still → 55 mbar. MC → 1.55 K. |
| 1500 | V6 → 13.8%. Condenser peaks at 130 mbar. Still → 5 mbar. MC → 1.25 K. |
| 1505 | 1K Pot = 1.69K, 60 mbar. Pretty steady. |
| 1505 | Tower/Coldplate/Still = 1.10/1.28/1.23 K. MC(H35) = 1.16 K. |
| 1510 | V6 → 14.2%. Condenser flattish at 133 mbar. Still → 3.6 mbar. MC → 0.92 K. |
| 1515 | V6 → 15.0%. Condenser → 136 mbar. Still → 1.6 mbar. MC → 0.81 K. |
| 1515 | Tower/Coldplate/Still = 0.73/0.72/1.14 K. MC(H35) = 1.16 K. |
| 1515 | V6 → 100%. Condenser peaks at 134 mbar. Still → 0.22 mbar. MC → 0.31 K. |
| 1515 | Tower/Coldplate/Still = 0.32/0.52/1.18 K. MC(H35) = 1.16 K. |
| 1540 | Condenser = 103 mbar, Still = 0.16 mbar, MC(H35)/Tower/Coldplate = 77/140/312 mK |
| 1545 | Condenser = 86 mbar, Still = 0.13 mbar, MC(H35)/Tower/Coldplate = 56/110/284 mK. MC looks like it's flattening out. |
| 1615 | Condenser = 83 mbar, Still = 0.13 mbar, MC(H35)/Tower/Coldplate = 52/71/293 mK. |
| 1620 | Open V14 to let the rest of the mixture from the trap into circulation. Condenser peaks at 115 mbar, Still peaks at 60 mbar, Tower rises to 111 mK. |
| 1625 | Condenser has settled down to 76 mbar, Still 4 mbar and falling exponentially, Tower = 78 mK and falling. |
| 1640 | Condenser = 81 mbar, Still = 0.85 mbar, Tower = 70 mK. Close V14. |
| 1645 | Fill LN2 cold trap bath |
| 1645 | Tower/MC/Coldplate = 68.9/52/308 mK, Still = 1.16 K / 0.130 mbar, G1/G2 = 80/90 mbar, 1K Pot = 1.69 K / 60 mbar. MB = 61.0% |