2021/12/06 (Monday)
- Lab in-personnel: Himangshu, Matt
| Status | Beginning Run 75. Initial LHe transfer three days ago. Haven't started 1K Pot yet. |
|---|---|
| 1100 | MC(Cernox)/1K Pot/Sorb = 5.29/6.65/8.4 K, G2/G1 (fridge+trap1+dump) = 500/554 mbar, 3He pump off. |
| 1100 | Pump out line leading to 1K Pot with scroll pump. Then switch over to 4He pump. Turn on 4He pump then change pump exhaust to recovery and open valve to recovery lines. |
| 1105 | Check pressure in 1K Pot: Mechanical gauge = 0.33 bar. (Note: V4a was closed during this check.) 1K Pot temperature dips briefly to below 5 K |
| 1110 | Pump out 1K Pot in steps, alternating between V4a and Speedivalve. Throttle valves to keep pressure at P2 below around 10 mbar. After several iterations, leave both valves open. |
| 1115 | MC(Cernox)/MC(H35)/Tower/Goldman = 5.30/6.55/8.55/5.31 K. (Coldplate/Still = 2.502/2.652 kΩ = 21.0/6.75 K. These don't have good calibrations here.) |
| 1125 | Sorb = 4.2 K. G1 (fridge) = 535 mbar and falling. 1K Pot = 3.36 K / 1.0 mbar |
| 1125 | Open 1K Pot needle valve → 15°. 1K Pot → 2.7 K / 16 mbar. Open 1K Pot needle valve → 30°. 1K Pot → 2.3 K / 32 mbar. |
| 1130 | Open 1K Pot needle valve → 40°. 1K Pot → 1.9 K / 60 mbar. |
| 1135 | MC(Cernox)/MC(H35) = 3.08/3.50 |
| 1140 | Tower/Goldman = 3.23/2.87 K. |
| 1155 | 1K Pot = 1.65 K / 24 mbar, drifting downward. MC(H35) = 2.53 K and falling, G1(fridge) = 81 mbar and falling. |
| 1205 | 1K Pot spikes when MC(H35) falls below 2.4 K. 1K Pot → 1.71 K / 60 mbar, oscillating |
| 1220 | Fill LN2 cold trap bath |
| 1220 | Tower/Goldman = 1.95/1.97 K. |
| 1335 | 1K Pot = 1.71 K / 60±5 mbar. MC(H35) = 2.10 K, G1(fridge) = 48 mbar. |
| 1335 | Close V3 and V9, leaving 36 mbar (G2) in the dump. Turn on 3He pump. |
| 1340 | Start circulation through Trap 1. V6 → 12.6%. Condenser peaks at 153 mbar. MC(H35) → 1.64 K, falling fast. 1K Pot spikes to 1.76 K / 500 mbar, then recovers. P1 (still) → 28 mbar. |
| 1345 | V6 → 13.0%. Condenser(G1) peaks at 121 mbar. MC(H35) → 1.40 K. Still(P1) → 12 mbar. |
| 1350 | V6 → 13.4%. Condenser(G1) peaks at 125 mbar. MC(H35) → 1.29 K. Still(P1) → 5.5 mbar. |
| 1355 | Tower/Goldman = 1.21/1.18 K. |
| 1355 | MC(H35) rises from 1.22 to 1.25 K then falls again, also Condenser pressure rises a little then falls. This is maybe the Al transition. Wait no, I still had the Goldman thermometer plugged in, but either way, the temperature is fluctuating. |
| 1355 | V6 → 13.8%. Condenser(G1) peaks at 132 mbar. MC(H35) → 1.24 K. Still(P1) → 4.0 mbar. |
| 1400 | MC(H35) = 1.03 K and falling fast, looks like we're through the Al transition. |
| 1405 | V6 → 14.5%. Condenser(G1) peaks at 126 mbar. MC(H35) → 0.65 K. Still(P1) → 2.4 mbar. |
| 1410 | V6 → 15.0%. Condenser(G1) doesn't really rise. MC(H35) → 0.36 K. Still(P1) → 1.3 mbar. |
| 1415 | Tower/Goldman = 0.47/0.27 K. Goldman thermometer is surprisingly low… But switching to MC(H35), it's currently reading 0.24 K, so close to Goldman… |
| 1420 | V6 → 100%. Condenser(G1) peaks at 109 mbar. MC(H35) → 140 mK. Still(P1) → 0.22 mbar. |
| 1425 | MC(H35) = 100 mK. Still(P1) = 0.20 mbar. |
| 1430 | MC(H35) = 50 mK. Still(P1) = 0.16 mbar. |
| 1430 | Tower/Goldman = 267/74 mK. Again, Goldman is much closer to MC than Tower is. Which do we believe? Dunno. |
| 1445 | MC(H35) = 36.1 mK, falling slowly. Still(P1) = 0.14 mbar. |
| 1445 | Tower/Goldman = 210/60.6 mK. |
| 1450 | Open V14 to let the remaining mix out of the dump and into circulation. P1(Still) peaks at 65 mbar then falls again. MC(H35) peaks at 77 mK. Condenser peaks at 103 mbar. |
| 1515 | Still = 0.85 mbar |
| 1515 | Close V14 |
| 1520 | MC(H35) = 31.9 mK. Still(P1) = 0.13 mbar. G1/G2 = 73/73 mbar. |
| 1520 | Tower/Goldman = 181/55.9 mK. (Goldman = 47.90 kOhm.) |
| 1535 | MC(H35) = 30.2 mK, Still = 0.130 mbar / 0 mW, G1/G2 = 73/75 mbar. 1K Pot = 40° / 1.71 K / 50±3 mbar |
| 1540 | Tower/Goldman = 195/55.9 mK. (Goldman = 47.97 kOhm.) These haven't fallen in the last 20 min, in fact Tower is reading higher. |
| 1630 | MC(H35) = 30.2 mK, Still = 0.130 mbar / 0 mW, G1/G2 = 73/73 mbar. 1K Pot = 40° / 1.70 K / 50±3 mbar. All stable. |
| 1630 | Tower/Goldman = 221/57.6 mK. (Goldman = 46.11 kOhm.) These are rising - odd. |