2019/09/07 (Saturday)
| Status: warming up. Mixture in fridge and dump. No mixture in LN2 Cold Traps. Small amount of He gas in IVC and cryostat vacuum jacket. 1K Pot needle valve open. | |
| 0326 | Recovery meter = 312300 cuft |
| 0655 | Tower/1K Pot/Sorb = 4.95/6.32/8.0 K. G1(fridge+dump) = 620 mbar. MB = -0.1%. Recovery meter = 312389 cuft. Recovery rate = 0.0074 cuft/second (1 cuft/136 seconds) |
| 0705 | Start pumping mixture to dump: isolate dump by closing V4 and V14, then connect Still and Condenser by opening V3 (V1 also open), then open V6 to 12.8% to pump from both sides of fridge to dump. Forgot to open V9 at first, G2 (pump outlet) pressure went pretty high - then opened V9 to let mixture into dump. Increase V6 every few minutes to speed up pumping. |
| 0720 | Recovery meter = 312400 cuft |
| 0730 | Increase V6 to 25%. |
| 0745 | Tower/1K Pot/Sorb = 5.25/6.82/8.6 K, P1(fridge)/G2(dump) = 0.015/713.2 mbar. |
| 0750 | Increase V6 to 100%. |
| 0815 | Tower/1K Pot/Sorb = 5.58/7.0(max)/9.2 K, P1(fridge)/G2(dump) = 0.009/714.4 mbar. |
| 0850 | Tower/Sorb = 6.05/9.8 K, P1(fridge)/G2(dump) = 0.011/714.8 mbar. |
| Barometric pressure = 30.10“ (source is https://w1.weather.gov/data/obhistory/KMSP.html.) G2 = 714.8 mbar. Corrected dump pressure = 720.9 mbar. Around 10 mbar less than Run 69. |
Ptrue[mbar] = Pdisplay[mbar] + ( Pbar[inHg] - 29.92 ) * 33.86
| 0900 | Stop pumping out fridge: close V6. |
|---|---|
| 1055 | Close V9 to isolate dump. Turn off He-3 pump. |
| Leaving open V1, V3, Still gate valve, Condenser speedivalve. Can monitor whatever boils off at G1. | |
| 1058 | Recovery meter = 312500 cuft. Recovery rate = 0.0076 cuft/second (1 cuft/131 seconds) |
| 1100 | Tower/Sorb = 9.07/14.5 K |
| Saw a boiloff from the fridge between around 11:00-11:45. G1 rose from about 1 to 6 mbar. Boiloff abruptly stopped with a corner in the boiloff rate. Tower temperature rose from 9→10 K at this time, Sorb rose from 10→16 K. H2 boils at 22 K, but of course pressure is lower than 1 atm. At 6 mbar looks like the sublimation point is around 12-13 K. | |
| 1300 | Recovery rate starts falling. About 20 minutes later Tower warming rate starts increasing. |
| 1400 | Recovery meter = 312566 cuft. Recovery rate = 0.0031 cuft/second (1 cuft/322 seconds) |
| 1800 | Recovery meter = 312587 cuft. Recovery rate = 0.00046 cuft/second (1 cuft/36 minutes) |
| 2100 | Recovery meter = 312591 cuft. Recovery rate = 0.00023 cuft/second (1 cuft/72 minutes) |
| 2200 | Tower/Sorb = 52/116.5 K. (Not sure the Tower thermometer calibration is good here, should switch to Cernox when we get back to the lab.) G1(fridge) = 10.5 mbar and pretty flat. |