2018/08/02 (Thursday)
| status: LN2 transfer yesterday. Overnight MC reached minimum of 77.2 K, crept up to 77.3 K first thing: pump out IVC and turn on leak detector so we can leak check while blowing out LN2. |
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| 0939 | MC(Cernox) = 77.3 K, Sorb = 131.1 K (max), IVC = 1.4 mbar, G1 (fridge) = 606 mbar |
| 0945 | Start to pump out IVC |
| 1030 | 77 K electrical check looks good. [image not archived: cool.svg] |
| 1037 | Mini-throughput check: close off Trap 2 and V3. Only V1, condenser speedivalve, still gate valve, and V9 open. Turn on 3He pump, then open V6 to 12.8%. This pumps mix out of the still side and we can see if the pressure goes down on the condenser side. P1 (still) falls to 8 mbar after a few minutes. G1 (condenser) falls, from 606 mbar to 430 mbar in 5 minutes, and continues to fall. Good, looks like we have throughput. |
| 1045 | Close V6, turn off 3He pump. Open trap 2 valves and V3 to let mix into fridge lines through trap 2. |
| 1220 | Stop pumping IVC with turbo and start leak detector on IVC. Background leak = 600 pbarL/s. |
| 1230 | Begin blowing out LN2. Main bath (G3) = 375 mbar above 1atm. Leak detector on IVC = 609 pbarL/s |
| 1235 | LD = 620 pbarL/s. Main bath = 427 mbar. |
| 1240 | LD = 626 pbarL/s. Main bath = 417 mbar. |
| 1250 | Main bath pressure starts falling |
| 1250 | LD = 612 pbarL/s. Main bath = 253 mbar. |
| 1255 | LD = 599 pbarL/s. Main bath = 132 mbar. |
| 1255 | LD = 586 pbarL/s. Main bath = 128 mbar. Stop pressurizing main bath |
| 1310 | Start pumping out main bath with scroll pump - oops, in a rush, forgot that you need to stopper the LN2 fill stick |
| 1310 | Start pumping out main bath with scroll pump. LD = 550 pbarL/s. Takes 20 minutes to fall to 1 mbar (we were opening the valve a little slowly) |
| 1322 | Start pumping mix to the dump in preparation for full throughput test. |
| 1325 | MB = 34 mbar and falling. LD = 500 pbarL/s. Leak did not fall any faster when we started pumping MB, further indication that there's no bath-to-IVC leak. |
| 1335 | LD = 452 pbarL/s |
| 1350 | Pressurize MB with helium to 360 mbar above 1 atm. Open 1K Pot speedivalve and needle valve (2 full turns) to repressurize pot as well. Notice MB pressure falls about 5 mbar. |
| 1350 | LD = 410 pbarL/s |
| 1400 | Let 63 μbar He exchange gas into IVC. |
| Throughput test procedure, Cold Trap 2: |
- All mixture in dump, LN2 trap 2 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12a+speedivalve and V3, open V1
- monitor G1
| 1355 | Perform mixture throughput test at MC = 77 K using above procedure with 3He pump on. Let G1 rise to 585 mbar before Step 3, then it falls to 81 mbar and starts to rise. Throughput = 45.0 mbar/min. |
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| 1403 | Trap 1 is still dirty from yesterday's cryocleaning. Let's empty that before we cool any further. Pump mix to dump. |
| 1428 | G2 = 733 mbar with all mix in the dump and 3He pump on |
| 1430 | 9.3 mbar in warm trap 1. Pump out trap 1 with scroll pump. |
| 1443 | Put LN2 trap 1 back in LN2 dewar. |
| 1445 | Open mixture from dump to cold LN2 Trap 2 to both sides of fridge. Turn off 3He pump. Fridge pressure(G1) reads 605.6 mbar. |
| 1447 | MC(Cernox) = 79.5 K, Sorb = 147.9 K, IVC = 74 μbar, G1(fridge) = 606 mbar. |
| 1500 | Begin initial LHe transfer |
| 1515 | MC(Cernox) = 76.4 K, Sorb = 133.2 K, IVC = 25 μbar, G1(fridge) = 599 mbar. |
| 1525 | MC(Cernox) = 66.4 K, Sorb = 100.1 K, IVC = 16 μbar, G1(fridge) = 587 mbar. |
| this is one of those times when the IVC pressure seems to be falling too fast. I think we concluded before that this was because the gauge got dirty. | |
| 1540 | MC(Cernox) = 57.3 K, Sorb = 53.5 K, IVC = 12 μbar, G1(fridge) = 538 mbar. Main bath = 0.5% |
| 1600 | MC(Cernox) = 47.8 K, Sorb = 7.8 K, IVC = 10 μbar, G1(fridge) = 481 mbar. Main bath = 11.8% |
| 1610 | MC(Cernox) = 42.2 K, Sorb = 7.2 K, IVC = 10 μbar, G1(fridge) = 475 mbar. Main bath = 18.6% |
| 1620 | Increase resistance range on bridge to 2.00 kΩ, so that the Cernox thermometer doesn't saturate and make us miss the pumpout point (10 K) |
| 1630 | MC(Cernox) = 27.9 K, Sorb = 6.5 K, IVC = 6.3 μbar, G1(fridge) = 468 mbar. Main bath = 37.5% |
| 1640 | Cernox hits 10 K - start pumping out IVC with turbo. Noticed that IVC had fallen to 0.86 μbar before we started pumping. |
| 1645 | MC(Cernox) = 4.7 K, Sorb = 5.3 K, Turbo on IVC = 3.4 nbar, G1(fridge) = 453 mbar. Main bath = 57.7% |
| 1707 | End LHe transfer @ MB = 71.6%. Ran out the Dewar. |
| 1710 | Fill LN2 cold trap bath |
| 1720 | MC(Cernox) = 4.4 K, Sorb/1K Pot = 5.4/4.3 K, Turbo on IVC = 1.4 nbar, G1(fridge) = 513 mbar. |