2021/06/11 (Friday)
- Lab in-personnel: Matt, Scott
| Status | Run 74 in progress. First cooldown after IVC rebuild. Initial LHe transfer yesterday. |
|---|---|
| 0955 | MC(Cernox)/Sorb/1K Pot = 5.41/8.5/6.78 K |
| MC reached a minimum of 5.25 K around 11:30pm and has drifted steadily upward overnight. Contrast this to the last three cooldown attempts where it fell rock hard to 4.4 K and stayed there. Good indication that now the fridge is not thermally connected to the bath, i.e. no appreciable He gas in the IVC. | |
| 1050 | Turbo on IVC = 4.0 nbar. With Turbo valved out for one minute, IVC = 22 nbar. Open Turbo valve again to continue pumping IVC. |
| 1100 | MB = 54.9% / 145 mbar+1atm |
| 1100 | MC(Cernox)/Sorb/1K Pot = 5.42/8.5/6.75 K. G1(fridge) = 557 mbar (3He pump off). |
| 1110 | 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. |
| 1120 | Check pressure in 1K Pot: Mechanical gauge = 0.33 bar. (Note: V4a was closed during this check.) 1K Pot temperature dips to below 5 K |
| 1130 | 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. |
| 1140 | MC(Cernox)/MC(H35)/Tower = 5.41/5.41/8.59 K. (Coldplate/Still = 2.523/2.739 kΩ = 10.4/5.34 K. These don't have good calibrations here.) |
| 1140 | Sorb = 4.1 K. G1 (fridge) = 523 mbar and falling. 1K Pot = 3.27 K / 1.2 mbar |
| 1145 | Open 1K Pot needle valve → 10°. 1K Pot → 2.7 K / 14 mbar. Open 1K Pot needle valve → 20°. 1K Pot → 2.3 K / 30 mbar and oscillating. |
| 1150 | MC(H35) → 3.32 K, G1(Fridge) → 420 mK |
| 1155 | Open 1K Pot needle valve → 30°. 1K Pot → 2.1 K / 34 mbar, oscillating. |
| 1200 | Fill LN2 cold trap bath |
| 1205 | Open 1K Pot needle valve → 40°. 1K Pot → 1.73 K / 60 mbar, oscillating. |
| 1210 | 1K Pot = 1.67 K / 30 mbar, drifting downward. MC(H35) = 2.27 K, G1 (fridge) = 90.6 mbar. |
| 1225 | 1K Pot = 1.58 K / 11 mbar, drifting downward. MC(H35) = 2.09 K, G1 (fridge) = 61.0 mbar. |
| Maybe need to open the 1K Pot valve more, but let's wait to see if the pressure shoots up as we cool below the lambda point. Right now the MC temperature is flattening out so we're probably approaching the lambda point. | |
| 1230 | 1K Pot spikes! looks like the lambda point. MC = 2.065 K 1K Pot → 1.71 K / 55 mbar, oscillating |
| 1305 | MC(H35)/Tower = 1.93/6.17 K. Coldplate/Still = 3.222/3.216 kΩ =? 3.45/2.50 K. Sorb = 4.0 K (flat - is this minimum? don't remember) |
| 1348 | Begin LHe transfer @ MB = 50.3% |
| 1420 | End LHe transfer @ MB = 86.2% |
| 1445 | MC(H35)/Tower = 1.82/6.02 K. Coldplate/Still = 3.266/3.276 kΩ =? 3.26/2.37 K. Sorb = 4.0 K (flat - is this minimum? don't remember) |
| 1450 | 1K Pot = 40° / 1.65 K / 32±1 mbar |
| 1550 | 1K Pot = 40° / 1.65 K / 32±1 mbar. MC(H35) = 1.82 K, G1 (fridge) = 42.3 mbar. |
| 1550 | Close V3 and V9, leaving 44 mbar (G2) in the dump. Turn on 3He pump. |
| 1555 | Start circulation through Trap 2. V6 → 12.0%. Condenser = 46 mbar, no increase yet nor decrease in temperature. Probably 12.0% is not open yet. |
| 1600 | V6 → 12.4%. No change yet. V6 → 12.8%. Condenser peaks at 50 mbar. MC starts falling a little. |
| 1605 | V6 → 13.2%. Condenser peaks at 116 mbar. MC falling quickly, → 1.59 K |
| 1610 | V6 → 13.6%. Condenser peaks at 164 mbar. P1(Still) falls, → 16 mbar. MC → 1.30 K |
| 1K Pot pressure fluctuated a bit | |
| 1615 | V6 → 14.0%. Condenser rises slowly, takes a while to peak. Still → 3.2 mbar. MC → 0.90 K and falling - a few kinks in the cooling curve but generally falling, looks like we powered through the Al s/c transition. |
| 1625 | Condenser peaks at 115 mbar. MC → 0.70 K |
| 1625 | V6 → 14.4%. Condenser peaks at 116 mbar. Still → 1.8 mbar. MC → 0.48 K |
| 1635 | V6 → 15.0%. Condenser peaks at 110 mbar. Still → 0.9 mbar. MC → 0.32 K |
| 1645 | V6 → 100%. Condenser peaks at 104 mbar. Still → 0.1 mbar. MC → 42 mK |
| 1840 | MC(H35) = 33.0 mK and pretty flat, Still = 0.085 mbar, G1/G2 = 71/82 mbar. |
| 1840 | Open V14 to let the remaining mix out of the dump and into circulation. P1(Still) peaks at 30 mbar then falls again. MC(H35) peaks at 72 mK. Condenser peaks at 97 mbar. |
| 1900 | MC(H35) = 36.8 mK, Still = 0.850 mbar, G1/G2 = 68/79 mbar. |
| 1900 | Close V14 |
| 1925 | MC(H35) = 33.1 mK, Still = 0.085 mbar, G1/G2 = 71/82 mbar. |
| 1925 | 1K Pot = 40° / 1.65 K / 30 mbar |