2016/07/13 (Wednesday)
| Status | Initial LHe transfer yesterday. Turbopumping IVC overnight. Cf source on fridge for overnight activation (but no warning sign on door). |
|---|---|
| 0815 | MC(Cernox) = 20 K, Sorb = 15.8 K, G1 (fridge) = 460 mbar, MB = 76.4% |
| MC, Sorb and G1 have all been slowly climbing overnight | |
| 0820 | IVC = 1.9 nbar pumping pressure, 12 nbar with pump valved out. Isolate turbopump from IVC. |
| 0825 | Tower = 20.2 K, MC(H35) = 27.5 K, Still = 23.8 K, Coldplate = 34.6 K, MC sensor = 2.359 kΩ (no calibrated reading on vi), 1K Pot > 7 K |
| above temperatures taken with excitation = 63.2 μV. Some of the thermometers vary a lot at higher excitations, e.g. Still = 80 K (!) at excitation 200 μV. H35 is 35 K at 200 μV. | |
| 0850 | remove Cf source from fridge and return it to safe |
| 0900 | Temperatures are disappointingly high. Is there additional heat from somewhere? Oops - actually the still heater was left on since a few days ago, at 100 mW. Turn off still heater now. |
| 0905 | pump out vent volume and auxiliary right-side and left-side volumes with scroll pump. Pump out 1K Pot with scroll pump. Close valve at pump. |
| 0910 | Still = 20.1 K, a little improved since turning off the heater. (This may be another slow cooldown). |
| 0915 | Fill LN2 cold trap bath. Where is the l-shaped fill tube??? Couldn't find it, LN2 was last used to fill the HPGe dewar and left attached to it. I just shoved the hose in the hole in the top of the LN2 trap bath, guess that works. |
| 0920 | Open 1K Pot needle valve a little more than 90 degrees. 1K Pot temperature falls to < 4 K. Sorb also falls. |
| 0925 | Close needle valve again, then pump on 1K Pot with scroll pump. 1K Pot falls to 1.9 K then rises again. Sorb falls to 4 K then rises to > 8K. Still falls to 11 K. |
| 0935 | Open needle valve then close again then pump again. Still temp and fridge pressure fall strongly, → 3.8 K / 210 mbar. Continue to pump until 1K Pot temperature begins to rise again. |
| 0940 | Switch to pumping 1K Pot with 4He pump. Switch 4He exhaust valve to recovery. Open needle valve a little over 90 degrees. |
| Pot temperature falls, Still temperature and fridge pressure begin falling again (had risen after the pot emptied). | |
| 0945 | 1K Pot = 1.73 K / 40 mbar, Still/Coldplate/MC(H35)/Tower = 3.5/30.3/26.9/19.8 K, Fridge(G1) = 204 mbar. Sorb <4K |
| 1000 | 1K Pot starts oscillating, pressure oscillating strongly, 400-1000 mbar, 1.785-1.795 K |
| 1005 | 1K Pot = 1.79 K / 600 mbar, Still/Coldplate/MC(H35)/Tower = 2.9/20.6/26.1/19.1 K, Fridge(G1) = 167 mbar |
| 1010 | Close 1K Pot needle valve by several degrees to let pot settle. 1K Pot → 1.74 K / 55 mbar |
| 1030 | 1K Pot = 1.73 K / 50 mbar, Still/Coldplate/MC(H35)/Tower = 2.4/3.4/24.5/17.9 K, Fridge(G1) = 123 mbar |
| 1145 | 1K Pot = 1.73 K / 50 mbar, Still/Coldplate/MC(H35)/Tower = 2.2/3.0/16.2/11.9 K, Fridge(G1) = 85 mbar (flat) |
| 1150 | Open the V12a speedivalve (V12a still “closed”) to let more mix into fridge. G1 goes up to >150 mbar. 1K Pot remains steady. Still temperature goes up a little, to 2.5 K |
| 1155 | When G1 reaches 200 mbar, 1K Pot pressure starts to go up. Close V12a speedivalve again to let it settle. G1 falls to >175 mbar. G2 (dump) fell from 600 to 550 mbar. |
| After a minute G1 falls to 160 mbar then starts rising again | |
| 1200 | 1K Pot = 1.72 K / 45 mbar, Still/Coldplate/MC(H35)/Tower = 2.3/3.5/11.1/8.3 K, Fridge(G1) = 171 mbar |
| 1205 | Let some more mix into fridge through V12a(1%) and speedivalve, until 1KPot > 100 mbar, then close again. G1 peaks at 225 mbar then falls below 150 mbar. G2 (dump) falls to 510 mbar. |
| MC falls quickly below 4 K | |
| 1210 | 1K Pot = 1.72 K / 40 mbar, Still/Coldplate/MC(H35)/Tower = 2.0/3.3/3.0/3.8 K, Fridge(G1) = 132 mbar |
| 1225 | Gradually open V12A to 7.0% before any dramatic increase in G1 or P2 is seen. P2 rises to 110mbar, then gradually begins decreasing. |
| 1K Pot = 1.74K / 50.0 mbar, Still/Coldplate/MC(H35)/Tower = 2.1/2.8/2.7/2.8 K, Fridge(G1) = 134 mbar. | |
| 1240 | Gradually keep opening V12A. G1 stops going up, so open V12A to 100%. |
| 1K Pot = 1.71K / 38.0 mbar, Still/Coldplate/MC(H35)/Tower = 1.8/-/2.5/2.3 K, Fridge(G1) = 70 mbar and dropping. | |
| 1315 | 1K Pot = 1.70K / 34.0 mbar, Still/Coldplate/MC(H35)/Tower = 1.85/2.32/2.28/2.10 K, Fridge/dump(G1/G2) = 60/63 mbar, steady. |
| 1320 | Turn on 3He pump, pushing mix from back of pump into dump/fridge. Fridge pressures and still temperature go up a bit then stabilize |
| 1330 | Still = 1.88 K, G1/G2 = 60/63 mbar. Close V9, leaving 63 mbar mixture in dump. Close V3. |
| 1330 | Start circulation. At V6 = 12.8% see response, G1/G2 go up a few mbar. |
| at V6 = 13.2%, strong drop in Still temperature and increase in G2, small spike in 1K Pot | |
| 1345 | 1K Pot = 1.69K / 30.0 mbar, Still/Coldplate/MC(H35)/Tower = 1.73/2.11/1.98/1.86 K, G1/G2 = 87/106 mbar. |
| 1400 | With V6 = 13.4%, P1 (still pressure) falls into readable range. |
| 1405 | V6 = 13.4%, Still = 1.43 K / 1000 mbar, G1/G2 = 110/140 mbar, Coldplate/MC(H35)/Tower = 1.78/1.68/1.62 K, 1K Pot = 1.68K / 26.0 mbar |
| 1425 | V6 = 13.8%, Still = 1.47 K / 26 mbar, G1/G2 = 115/140 mbar, Coldplate/MC(H35)/Tower = 1.69/1.44/1.44 K, 1K Pot = 1.67K / 22.0 mbar |
| 1500 | V6 = 14.5%, Still = 1.13 K / 2.6 mbar, G1/G2 = 105/120 mbar, Coldplate/MC(H35)/Tower = 0.94/0.48/0.79 K, 1K Pot = 1.64K / 16.0 mbar |
| 1505 | Open V6 100% |
| 1530 | V6 = 100%, Still = 1.06 K / 0.17 mbar, G1/G2 = 90/105 mbar, Coldplate/MC(H35)/Tower = 0.22/0.18/0.65 K, 1K Pot = 1.63K / 13.0 mbar |
| 1535 | Open V14 to let remaining mixture from dump into circulation. G1/G2 increase to 125/160 mbar. P1 maxes out but then drops quickly below 50 mbar. Small increase in 1K Pot. |
| 1600 | V14 open, Still = 1.10 K / 0.75 mbar, G1/G2 = 90/105 mbar, Coldplate/MC(H35)/Tower = 0.22/0.19/0.64 K, 1K Pot = 1.61K / 9.5 mbar |
| 1640 | V14 open, Still = 1.03 K / 0.28 mbar, G1/G2 = 90/100 mbar, Coldplate/MC(H35)/Tower = 0.21/0.175/0.61 K, 1K Pot = 1.59K / 8.0 mbar |
| 1645 | Close V14. The 1K Pot has been steadily decreasing so open the needle valve a few degrees further. |
| 1650 | 1K Pot = 1.72 K / 40 mbar. Still = 0.20 mbar. MC(H35) = 167 mK and falling. |
| 1710 | Fill LN2 cold trap full. 1K Pot = 1.70K / 32 mbar. Looks like it's still decreasing at the same rate as before. Should be ok overnight. |
| The He Recovery line for the 1K Pot Pump exhaust was not open (the yellow valve was turned to “recovery”, but the actual red recovery valve was closed, so pressure had been building up all day). Open the recovery valve, and the pressure doesn't seem to have built up too high. Regardless, the exhaust is now being recovered. | |
| 1730 | Put Cf source on fridge for overnight activation. |