| Status: | Fridge cooling toward 4K overnight. Turbo-pumping IVC overnight. Trap 1 at room temperature overnight. |
| 0800 | MC(Cernox) = 24.9 K, Sorb = 20 K, IVC = 8.6e-7 mbar pumping, 4.6e-6 mbar with pump valved out. Isolate IVC. |
| 0810 | Trap 1 reached 5 mbar on P2. Pump out Trap 1. |
| 0815 | Put LN2 Cold Trap 1 bath and fill bath. Trap 2 is also clean and in bath. |
| 0820 | Tower = 25.7 K, MC(H35) = 19.6 K, Still = 18.4 K, Coldplate = 37.0 K, MC sensor = 2.332 kΩ (no calibrated reading on vi), 1K Pot > 7 K |
| 0830 | Open 1K Pot needle valve 90 degrees. No response in Sorb or 1K Pot temperatures |
| 0840 | Pump out lines leading to 1K Pot, then isolate pump. Close needle valve then open 1K Pot speedivalve - pressure on mechanical gauge on 1K Pot pumping line rises to about 1/4 bar. Open needle valve until this rises again, over 90 degrees. Sorb and 1K Pot temperatures fall quickly as pot fills with LHe. Pressure rises to 136 mbar relative on G3 (MB overpressure). |
| 0842 | Sorb = 5.3 K, 1K Pot = 4.1 K |
| 0845 | Let mixture through cold trap into fridge, through V9 (3He pump is off), V13a, Trap 1 speedivalve (V12a closed), V1, and condenser valve. |
| 0850 | Still = 16.3 K and falling. |
| 0900 | Sorb/1K Pot/Still/Coldplate/MC(Cernox)/Tower = 5.4/4.2/14.3/37/24.5/25.4 K. So Still is cooling significantly, CP/MC/Tower down slightly. |
| 0905 | G1/G2 (Condenser/Trap) = 670/645 mbar. G1 is still rising, G2 is still falling. |
| 0910 | Close V13a to leave some mixture in the dump. G1(Condenser) = 700 mbar, G2(Dump) = 644 mbar |
| 0915 | Set 1K Pot needle valve to about 50 degrees. Start pumping on 1K Pot with 4He pump. Opening and closing V4a so as not to put too much strain on pump. Open 4He Pump exhaust to recovery. |
| 0920 | Close 1K Pot needle valve completely, then leave V4a open to pump on pot. Trying to be a little more gentle. |
| 0925 | Sorb = 4K (minimum?), 1K Pot = 1.6 K / 8.0 mbar, Still = 4.2 K, Condenser pressure falling, now at 234 mbar. |
| 0930 | 1K Pot fell to < 1 mbar. Open 1K Pot needle valve to 45 degrees. 1K Pot → 1.7 K / 36 mbar. |
| 0932 | Open V13a to let more mix into fridge. Monitoring 1K Pot pressure. It doesn't go up much (50 mbar). |
| 0935 | Open V12a to 1.5% - now G1 starts to rise, 1K Pot pressure rises to 400 mbar. Close V13a. Begin letting mix in through V13a in controlled fashion to regulate 1K Pot pressure. |
| 0940 | On 5th cycle pot pressure stops increasing. Leave V13a open to let mixture into condenser. |
| 0945 | Still/Coldplate/MC(Cernox)/Tower = 4.3/35/24.1/24.9 K. CP/MC/Tower cooling slowly. |
| 0945 | 1K Pot = 1.7 K / 60 mbar. G1/G2 = 490/490 mbar and falling steadily. Open V12a completely. Causes brief surge in condenser and 1K Pot pressures. |
| 1000 | 1K Pot = 1.8 K / 75 mbar, oscillating. G1/G2 = 440/400 mbar. Close 1K Pot needle valve 5 degrees narrower. Oscillations calm down. |
| 1005 | Still/Coldplate/MC(Cernox)/Tower = 3.8/31/23.6/24.4 K |
| 1015 | 1K Pot = 1.7 K / 38 mbar, oscillating slightly. G1/G2 = 375/340 mbar. |
| 1015 | Open Still gate valve. Causes a surge in 1K Pot temperature. This is somehow a result of the sudden decrease in pressure on the still side. MC temperature decreases a little more rapidly. 1K Pot temperature settles back after 5 minutes. 1K Pot pressure is now more stable. |
| 1020 | Still/Coldplate/MC(Cernox)/Tower = 3.6/27/23.1/23.8 K |
| 1025 | 1K Pot = 1.7 K / 40 mbar. G1/G2 = 400/360 mbar and falling slowly. |
| 1030 | Close V9 leaving 356 mbar in dump. Then turn on 3He pump, which pushes mixture from back of pump into condenser. Surge in 1K pot temperature and pressure and G1/G2, also brief decrease in Still temperature. Then things stabilize quickly. |
| 1035 | 1K Pot = 1.7 K / 40 mbar. G1/G2 = 350/320 mbar and falling. |
| 1040 | Start circulation. At V6 = 13% response seen - 1K Pot surge to 2.2 K / 240 mbar, circulation pressures rise from 300 to 500 mbar, Still temperature falls a little. |
| 1045 | Circulation pressures falling again, G1/G2 = 400/380 mbar. 1K Pot = 2.1 K / 40 mbar, temperature slowly falling. Still temperature flat at 3.1 K. Start opening V6 more in increments of a few tenths of a percent. |
| 1050 | Still/Coldplate/MC(Cernox)/Tower = 2.9/26/21.1/21.9 K |
| 1055 | At V6 = 13.3%, circulation pressures started climbing steadily and didn't fall. At close to 1 bar, stop circulation by closing V6 to 12%. Circulation pressures falling again. |
| 1100 | Start circulation again with V6 = 13.2%. Circulation pressures stabilize at around 600 mbar. Still at around 3.1 K. |
| 1120 | 1K Pot = 2.1 K / 38 mbar, temperature falling. G1/G2 = 330/325 mbar and falling. |
| 1145 | Still/Coldplate/MC(Cernox)/Tower = 2.5/18/18.9/19.3 K |
| 1150 | 1K Pot = 1.7 K / 22 mbar. G1/G2 = 135/125 mbar. All quite stable. |
| 1155 | Increase V6 to 13.5%. 1K Pot and circulation surge but come back down and stabilize quickly. |
| 1210 | Still/Coldplate/MC(Cernox)/Tower = 2.1/21/17.5/17.9 K |
| 1215 | Increase V6 to 14.0% |
| 1225 | Circulation pressures running away again, reduce V6 to 13.0%. Pressures begin to fall. |
| 1245 | After a few minutes pressures increased again and hit 1 bar. Closed V6 to 10% and opened V9 to release pressure into dump. |
| 1255 | MC fall quickly to below 4 K |
| 1300 | Close V9 again isolating 373 mbar of mixture in dump. |
| 1305 | Still/Coldplate/MC(Cernox)/Tower = 2.5/3.6/3.1/4.9 K. G1/G2 = 200/185 mbar and falling. |
| 1310 | Start circulation again, V6 = 13.2% |
| 1315 | Increase V6 to 13.5% because circulation pressure still falling. Still → 1.8 K |
| 1325 | Still down to 1.6 K, starting to level out. G1/G2 = 105/120 and level. Increase V6 to 13.7%. |
| 1336 | P1 (Still) pressure falls into readable range |
| 1355 | Still = 1.47 K / 400 mbar, Coldplate/MC(Cernox)/Tower = 1.9/6.6/7.1 K (MC and Tower higher??) G1/G2 = 125/140 mbar. 1K Pot = 1.7 K /36 mbar |
| 1400 | V6 → 14%. Still pressure falls a lot, Still temperature decreases a bit, 1K Pot and circulation pressures not affected much. |
| 1405 | V6 → 14.5%. Still → 1.19 K / 4 mbar |
| 1406 | Surge in Still/Circulation/1K Pot to 1000/450/230 mbar, then back down. |
| 1410 | Still = 1.49 K / 22 mbar, Coldplate/MC(Cernox)/Tower = 1.8/2.6/4.5 K (MC and Tower much lower), G1/G2 = 140/170 mbar and falling. 1K Pot = 1.6 K /28 mbar and falling. |
| 1415 | V6 → 15%. There are oscillations in MC temperature and circulation pressure, possibly superfluid/normal fluid transition forming. |
| 1435 | V6 → 100%. Still = 0.60 mbar. MC(H35) = 1.2 K |
| 1440 | Some oscillations in MC temperature and Still pressure. MC not going any lower than 1.2 K. |
| 1445 | Begin opening and closing V14 to let more mix from dump into circulation. Throttle to prevent circulation pressures from going too high. |
| 1510 | MC = 1.25 K, not falling. Tower = 3.6 K. I'm concerned that this tower has a thermal short between 4K stage and other stages… |
| 1515 | Still = 1.33 K / 1.2 mbar, Coldplate/MC(H35)/Tower = 1.5/1.4/3.6 K, G1/G2 = 600/580 mbar and creeping up. 1K Pot = 1.75 K / 45 mbar and falling. |
| 1535 | 1K Pot pressure, circulation pressure, and still pressure are all oscillating in phase. Something is producing a strain on the fridge. |
| 1540 | Switch to one-shot mode, close V13a and open V9. Circulation pressures keep creeping up, can't maintain this. |
| 1515 | Still = 1.14 K / 0.22 mbar, Coldplate/MC(H35)/Tower = 1.5/1.3/3.4 K, G1/G2 = 24/373 mbar. 1K Pot = 1.6 K / 6 mbar. |
| 1555 | Still = 1.14 K / 0.14 mbar, Coldplate/MC(H35)/Tower = 1.4/1.2/3.25 K, G1/G2 = 8/420 mbar. 1K Pot = 1.7 K / 22 mbar. |
| 1620 | Still = 1.20 K / 0.09 mbar, Coldplate/MC(H35)/Tower = 1.4/1.2/3.0 K, G1/G2 = 3/505 mbar. 1K Pot = 1.7 K / 32 mbar. |
| 1635 | Close V6 to end the one-shot, open V13a to let mixture back into fridge. |
| 1640 | Turn off 3He pump |
| 1730 | Fill LN2 cold trap full. |