2018/07/05 (Thursday)
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) | |
| 2400 | Tower = 35.9 mK, G1/G2 = 321/290 mbar , Still = 0.050 mbar / 1 mW. 1K Pot = 1.38 K / 2.0 mbar. It won't last till morning. |
| 0047 | Open 1K Pot needle valve about 10 degrees. 1K Pot peaks at 2.15 K and falls / >1000 mbar. |
| overnight: 1K Pot pressure never fell below “1000 mbar” (except for a period between 3:30 and 4:30 am, but it was still high). 1K Pot temperature remained above 1.7 K. Condenser pressure remained in control so things are basically working, but Tower temperature is elevated. Should close the needle valve a little when we get in this morning. |
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| 0730 | Tower = 51.3 mK, G1/G2 = 473/424 mbar , Still = 0.080 mbar / 1 mW. 1K Pot = 1.76 K / “1000” mbar. |
| 0740 | Reduce Still heat from 1 mW to 0.1 mW. Tower temperature and circulation pressures fall. Tower settles at 45.9 mK |
| 0935 | Close 1K Pot needle valve a few degrees. 1K Pot temperature goes up instead of down, 1.76→1.9 K, and pressure still pegged. But Tower temperature starts to fall. 1K Pot pressure is low on mechanical gauge. But 4He pump is straining a bit, vapor coming out of it. |
| 0940 | Close 1K Pot needle valve a few degrees more. Little change. |
| 0945 | Close 1K Pot needle valve about 10 degrees more. Pot temperature goes down a little, → 1.87 K |
| 0950 | Close 1K Pot needle valve about 10 degrees more. Pot temperature → 1.83 K |
| 0955 | Close 1K Pot needle valve about 10 degrees more. Pot temperature → 1.78 K and falls slowly. |
| 1005 | Close 1K Pot needle valve about 10 degrees more. Pot temperature spikes up to 1.83 K but then falls to 1.78 K |
| 1010 | Close 1K Pot needle valve about 10 degrees more. Pot temperature → 1.73 K, pressure falls into readable range on P2 |
| 1020 | Tower = 44.8 mK. Turn Still heater up to 1 mW again. |
| 1025 | 1K Pot = 1.73 K / 260 mbar. Pressure falling slowly. |
| 1030 | 1K Pot = 1.73 K / 300 mbar, kind of hanging there Close 1K Pot needle valve about 10 degrees more. 1K Pot → 1.71 K / 110 mbar |
| 1035 | Condenser pressure = 456 mbar, starts falling |
| 1035 | MB = 32.3% |
| 1040 | Fill LN2 cold trap bath |
| 1K Pot is still pretty warm, condenser pressure still high-ish (450 mbar), Tower temperature still high-ish (47 mK). Might want to stop circulation and start over. | |
| 1040 | 1K Pot = 1.70 K / 80 mbar, kind of hanging there Close 1K Pot needle valve about 10 degrees more. 1K Pot → 1.66 K / 38 mbar. Condenser = 429 mbar, falling. |
| 1045 | 1K Pot = 1.63 K / 26 mbar. G1/G2 = 423/376 mbar, now flat. Tower = 50.5 mK and actually increasing, that's bad. Still = 0.065 mbar. |
| 1050 | Increase Still heater 1→2 mW. Still → 0.075 mbar, Tower 52→51.4 mK. |
| 1210 | Reduce Still heat 2→1 mW |
| 1210 | Tower = 61.4 mK (yuk), G1/G2 = 436/388 mbar , Still = 0.060 mbar / 1 mW. 1K Pot = 1.51 K / 6.0 mbar. Pot behaving pretty normally now but base sucks, condenser pressure high. |
| 1210 | Close V6 to stop circulation. Still pressure rises, Condenser falls, Tower rises. |
| 1220 | Close 1K Pot needle valve, then close 1K Pot speedivalve to stop pumping on pot. |
| 1220 | Just noticed that we have not been pumping on the IVC since we warmed above 4K last week. IVC = 34 nbar |
| 1230 | Still off-scale, Condenser = 265 mbar and falling, Tower = 0.74 K, 1K Pot = 2.6 K. IVC = 34 nbar. |
| 1305 | Condenser = 152 mbar and falling, Tower = 1.4 K, 1K Pot = 3.9 K. IVC = 34 nbar |
| 1305 | Open V3 to let Condenser side open to Still side. Condenser pressure falls, indicating that equilibrium had not yet been reached - might suggest poor throughput. Condenser → 88 mbar. |
| 1310 | Turn on MC heater to 20 mW. Tower temperature rises. |
| 1325 | Condenser = 214 mbar and rising, Tower = 2.9 K. 1K Pot = 4.1 K, flat. IVC still flat at 34 nbar. |
| 1340 | Condenser = 353 mbar and rising, Tower = 3.2 K. IVC = 34 nbar. |
| 1345 | Turn Still heater up to 20 mW |
| 1353 | Start LHe transfer @ MB = 28.2% |
| 1400 | Condenser = 655 mbar and rising, Tower = 3.8 K. IVC = 25 nbar. IVC went down, surprisingly - maybe because we started the transfer? |
| Starting the transfer seems to have stopped the rise of the Tower temperature and the Condenser pressure. | |
| 1420 | Condenser = 680 mbar and flattish, Tower = 3.78 K and flattish. IVC = 15 nbar, even lower. |
| 1445 | Tower = 3.9 K, then suddenly starts climbing, to 5.3 K in 5 minutes. IVC → 63 nbar. |
| 1450 | Stop LHe transfer @ MB = 88.8% |
| 1455 | Condenser = 859 mbar and flattish, Tower = 5.46 K and flattish. IVC = 74 nbar. Start pumping out IVC with turbo pump. |
| 1500 | Tower = 5.6 K, Condenser = 893 mbar. Turn off MC and Still heaters |
| 1520 | Tower = 4.46 K and settling, Condenser = 903 mbar. Turbo on IVC = 2.5 nbar |
| 1520 | Open 1K Pot speedivalve to start pumping on pot. Pot dips to 1.9 K then rises back to 3.7 K. Pressure falls to 0.4 mbar. Condenser pressure falls to 743 mbar, Tower temperature falls to 3.8 K. |
| 1525 | Open 1K Pot needle valve → 10 degrees. 1K Pot → 3.35 K / 4.5 mbar Open 1K Pot needle valve → 20 degrees. 1K Pot → 2.98 K / 6.0 mbar |
| 1535 | Open 1K Pot needle valve → 30 degrees. 1K Pot → 2.76 K / 9.5 mbar Open 1K Pot needle valve → 40 degrees. 1K Pot → 2.28 K / 19 mbar |
| 1540 | Condenser = 431 mbar, Tower = 3.39 K, both falling |
| 1540 | 1K Pot = 1.70 K / 19 mbar (pressure steady but temperature falling) |
| 1550 | Condenser = 131 mbar, Tower = 2.60 K, both falling |
| 1550 | 1K Pot = 1.54 K / 11 mbar |
| 1550 | Open 1K Pot needle valve → 50 degrees. 1K Pot → 1.54 K / 11 mbar (not much change) Open 1K Pot needle valve → 60 degrees. 1K Pot → 1.55 K / 12 mbar (not much change) |
| 1555 | Condenser = 84 mbar, Tower = 2.38 K, levelling out |
| 1555 | Close V3 |
| 1555 | Start circulation through Trap 1. V6 → 12.8%. Condenser peaks at 170 mbar. Tower falls to 2.23 K. 1K Pot kinda flat… |
| 1600 | Open 1K Pot needle valve → 70 degrees. Not much change. |
| 1605 | V6 → 13.2%. Condenser rises above 200 mbar. 1K Pot spike → 1.71 K / off-scale, settles at 1.68 K / 75 mbar. Tower → 2.14 K. |
| 1615 | Condenser finally started falling after reaching max 210 mbar. Tower = 1.99 K |
| 1620 | V6 → 13.5%. Condenser eventually peaks at 350 mbar. Tower → 1.68 K. 1K Pot = 1.38 K / 75 mbar and steady. |
| 1640 | V6 → 13.8%. Condenser peaks at 405 mbar. Tower → 1.41 K. Still → 8 mbar. |
| 1650 | V6 → 14.2%. Condenser peaks at 420 mbar. Tower → 1.29 K. Still → 3.2 mbar. |
| 1655 | Fill LN2 cold trap bath |
| 1655 | V6 → 15.0%. Condenser peaks at 420 mbar. Tower → 1.30 K (wavering). Still → 0.55 mbar. |
| 1710 | V6 → 100%. Condenser rises to 405 mbar quickly, then continues to rise more slowly but steadily. Tower → 1.31 K, flattish. Still → 0.095 mbar. |
| not sure what to make of this. The condenser has risen to 417 mbar and keeps climbing linearly. Tower seems stuck around 1.3 K. Still is pretty low. | |
| this is a little different from the usual cooldown because no mixture was left in the dump, we started with all of it. | |
| 1720 | Tower finally starts cooling again… |
| 1725 | Tower = 1.15 K and falling. Condenser = 423 mbar and no longer rising. |
| 1730 | Tower = 1.07 K and falling. Condenser = 422 mbar |
| 1740 | Still = 0.080 mbar. Turn on Still heater → 1.0 mW |
| 1900 | Tower = 0.99 K and seems to be oscillating with a ~3 min period. Condenser = 432 mbar. Still = 0.085 mbar. 1K Pot = 1.68 K / 55 mbar. |
| 1900 | Increase Still heater 1 → 5 mW |
| 1955 | Tower rose to 1.09 K, now down to 1.04 K. Condenser has risen to 484 mbar and continues to rise. Still has only risen a little, 0.110 mbar. Doesn't look good. |
| 1955 | Decrease Still heater → 0.1 mW |
| 2348 | Tower = 0.92 K and oscillating, Condenser = 423 mbar, 1K Pot = 1.67 K / 45 mbar. Try closing to V6=13.4% |