2017/01/24 (Tuesday)
| Status: Initial LHe transfer yesterday. IVC turbopumping overnight. Some mixture is in fridge, open to LN2 Trap 1. Trap 2 is at room temperature after yesterday's cryocleaning. | |
| 0855 | MC(Cernox)/Sorb/1K Pot = 4.67/8.6/6.55 K, Turbo/IVC = 1.9/16 nbar, Fridge(G1) = 440 mbar. Main bath=69.5% Because of the leak at the stripline tube, we will pump continuously on the IVC during this run. Boiloff rate: a little faster than slow mode |
| 0905 | Measure Trap 2 contaminants at G1: 14.8 mbar, after 60 minutes of cryocleaning yesterday. Pump out Trap 2 with scroll pump. |
| 0915 | Put Trap 2 back into LN2 bath. Fill LN2 cold trap bath. note: Trap 2 is now cleaner than Trap 1. Trap 1 still has mixture in it. |
| 0920 | Open dump to Trap 1 (v9, v13a), let settle. Open v1 to let mix into LHe trap, let settle. Open condenser valve to let mixture into condenser side of fridge. |
| 0925 | Open 1K Pot speedivalve. Pressure on mechanical gauge on pot pumping lines rises to about 1/3 bar. This should be the He we let into the pot yesterday. Open v4a, mechanical gauge falls to about 0.23 bar. 1K Pot temperature falls below 5 K when speedivalve opened, falls again when v4a opened, then starts to rise back above 6 K |
| 0935 | Start 4He pump, open recovery valves for 4He pump, then open pump valve and v4a to start pumping on 1K Pot, needle valve still closed. 1K Pot falls to about 5 K, then rises again to around 6 K, pressure falls to 0.045 mbar. |
| 0935 | Open 1K Pot needle valve about 10 degrees. 1K Pot → 3.4 K / 2.8 mbar Open needle valve a few more degrees. 1K Pot → 3.2 K / 4 mbar. Open needle valve a few more degrees. 1K Pot → 3.0 K / 8 mbar. Open needle valve a few more degrees. 1K Pot → 2.7 K / 17 mbar. MC temperature dropping. Open needle valve a few more degrees. 1K Pot → 2.5 K / 26 mbar. |
| 0945 | MC(Cernox) = 3.2 K and falling. Fridge(G1/G2) = 475 mbar and falling. |
| 1040 | MC(Cernox) = 2.0 K, Fridge(G1/G2) = 80 mbar and falling, 1K Pot = 1.70 K / 26 mbar and oscillatory Still/ColdPlate = 2.4/3.2 K |
| 1045 | Still gate valve was not open, open it now. G1/G2 fall a bit, 1K Pot reacts a bit. |
| 1050 | Tweak 1K Pot needle valve open a little more before starting circulation. 1K Pot → 1.72 K / 38 mbar |
| 1050 | Close v9 with G2 reading 61 mbar, so 61 mbar left in dump. |
| 1055 | Start circulation through Trap 1, v6 = 12.6% |
| 1100 | v6 → 13.0%. Condenser(G1/G2) → 90 mbar (peak), MC(Cernox) → 1.90 K (and falling) |
| 1110 | v6 → 13.3%. Condenser(G1/G2) → 220 mbar (peak), MC(H35) → 1.67 K (and falling). Still/ColdPlate = 1.9/2.4 K |
| H35 thermometer shifted upward after switching to Still/ColdPlate then back. Had fallen to 1.62 K but then shifted up to 1.71 K. It's still falling but apparently more slowly. | |
| 1120 | H35 fell to 1.65 K but then increased to 1.69 K, then falling again. Perhaps these are oscillations as the phase separation begins. |
| 1120 | v6 → 13.6%. Condenser(G1/G2) → 290 mbar (peak), MC(H35) → 1.38 K (and falling), ColdPlate = 1.55 K, Still = 1.33 K / 5.5 mbar. |
| 1K Pot has been steady at 1.71 K / 36 mbar | |
| 1135 | v6 → 14.0%. Condenser(G1/G2) → 165 mbar (flat), MC(H35) → 830 mK (and falling), Tower = 811 mK, ColdPlate = 0.91 K, Still = 1.13 K / 3.4 mbar. |
| 1145 | v6 → 15.5%. Condenser(G1/G2) → 180 mbar (peak), Tower → 300 mK (and falling), ColdPlate = 440 mK, Still = 1.09 K / 0.65 mbar. |
| 1200 | v6 → 100%. Condenser(G1/G2) → 170 mbar (peak), Tower → 100 mK (and falling), ColdPlate = 197 mK, Still = 1.03 K / 0.14 mbar. |
| 1215 | Open v14 to pull mixture left in dump into circulation. G1/G2 140 → 220 mbar, then fall again. Still pressure maxes out but then falls to < 20 mbar. Tower 85→140 mK and rising. |
| 1238 | Tower=72.5mK, G1/G2= 116/118 mbar, P1=0.85, 1K pot =34 mbar/1.71K Close v14. |
| 1305 | Tower/MC/Coldplate = 68.1/37.4/198 mK, Still = 1.28(?) K / 0.110 mbar, G1/G2 = 115/120 mbar, 1K Pot = 1.71 K / 34 mbar. |
| 1350 | Tower/MC/Coldplate = 67.5/35.2/190 mK, Still = 1.1 K / 0.110 mbar, G1/G2 = 115/120 mbar, 1K Pot = 1.71 K / 34 mbar. |
| Tower seems to be cooling very slowly, lagging behind MC. Does silicon take longer to cool than germanium? | |
| 1500 | Tower/MC/Coldplate = 67.0/35.1/192 mK, Still = 1.2 K / 0.110 mbar, G1/G2 = 115/120 mbar, 1K Pot = 1.71 K / 36 mbar. Still thermometer is a little unstable. |
| 1550 | Fill LN2 cold trap bath |
| 1550 | Main bath = 58.5%. Boiloff rate since this morning is between slow- and fast-mode |