2018/06/07 (Thursday)
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) | |
| overnight: 1K pot ran dry, tower at 1.1 K. Also, LabView programs are all frozen and stopped logging at around 2100 last night. | |
| 1K Pot was down to 1.4 mbar by 23:30. At 01:30 it dropped quickly to 0.7 mbar, temperature climbed, peaked at 5.25 K at 3:00, then fell to 3.7 K by 9:30. At 1:30 circulation pressures began to climb, reached 800 mbar at 02:15, then rose more slowly, hit 1 bar at 05:15. | |
| 0930 | G1>999.9 mbar, G2 = 968 mbar. Open V9 to release pressure back into the dump. |
| 0935 | Tower = 1.1 K, Still = 0.045 mbar, G1/G2 = 574/523 mbar, 1K pot = 3.3 K / 0.70 mbar, MB = 36.4% |
| 0935 | Close 1K pot needle valve. Close V6. |
| 0940 | Open needle valve to 30 degrees. 1K Pot → 2.9 K / 7 mbar. G1 = 569 mbar open needle valve +10 degrees. 1K Pot → 2.2 K / 7 mbar. G1 = 558 mbar. open needle valve +10 degrees. 1K Pot → 1.62 K / 14 mbar. G1 = 540 mbar. |
| 0945 | 1K Pot = 1.61 K / 10 mbar. G1 = 505 mbar. |
| 0950 | 1K Pot = 1.76 K / 8 mbar. G1 = 461 mbar. open needle valve +10 degrees. 1K Pot → 1.66 K / 8.0 mbar. G1 = 446 mbar. |
| 0955 | open needle valve +10 degrees. 1K Pot → 1.60 K / 17 mbar. G1 = 416 mbar. |
| 1010 | 1K Pot = 1.55 K / 8.5 mbar. G1 = 334 mbar. |
| 1035 | 1K Pot = 1.49 K / 5.5 mbar. G1 = 197 mbar. open needle valve +10 degrees. 1K Pot → 1.54 K / 8.5 mbar. G1 = 194 mbar. |
| 1100 | 1K Pot = 1.57 K / 11 mbar. G1 = 134 mbar. |
| 1315 | 1K Pot = 1.46 K / 4.5 mbar. G1 = 43 mbar. open needle valve +10 degrees. 1K Pot → 1.59 K / 13 mbar. |
| 1320 | Close V9 leaving 37.1 mbar in dump. |
| 1320 | Start circulation through Trap 1. V6 → 12.8%. Condenser peaks at 95 mbar. Tower = 1.62 K. |
| 1325 | V6 → 13.2%. Condenser peaks at 140 mbar. Tower → 1.54 K. |
| 1345 | V6 → 13.6%. Condenser peaks at 215 mbar. Tower → 1.35 K. Still pressure falls into readable range. |
| 1412 | V6 → 14.0%. Condenser peaks at 295 mbar. Tower → 1.0 K. |
| 1440 | V6 → 14.5%. Condenser keeps falling. Tower → 0.73 K. |
| 1450 | V6 → 100%. Condenser steadying at 116 mbar. Tower → 0.56 K. |
| 1510 | Still = 0.05 mbar (low!). |
| 1515 | Open V14 to let the rest of the mixture from the trap into circulation. Condenser peaks at 198 mbar, Still peaks at 45 mbar |
| 1550 | Still = 0.40 mbar, close V14 |
| 1555 | 1K pot = 1.48 K/ 5.5 mbar open needle valve +10 degrees. 1K Pot → 1.65 K / 20.0 mbar. G1 = 120 mbar. |
| 1602 | Start LHe transfer (MB = 26.9%) |
| 1605 | Tower/MC/Coldplate = 96.5/88.9/246 mK, Still = 1.20 K / 0.050 mbar, G1/G2 = 121/112 mbar, 1K Pot = 1.57 K / 15 mbar. |
| 1645 | Tower = 46.4 mK, Still = 0.050 mbar, G1/G2 = 110/103 mbar, 1K Pot = 1.51 K / 7.5 mbar. |
| 1740 | Tower = 37.2 mK, Still = 0.050 mbar, G1/G2 = 105/97 mbar, 1K Pot = 1.47 K / 5.5 mbar. open needle valve +15 degrees. |
| 1745 | Fill LN2 cold trap bath |
| 1910 | Tower = 42.4 mK |
| 2345 | Tower = 42.6 mK |
| LabView | |
|---|---|
| 0930 | All LabView programs are frozen. Temperature logs (from both H35 on LakeShore and omni_logger vi's) indicates they froze at 2102 last night. Logged data looks good up until then. |
| 0955 | Struggling to get LabView programs running again, they were all frozen and firefox had a warning about a script that wasn't responding. Also, Keithley electrometer is in a state that seems like it was power cycled. Close firefox and stop fridge temp vi and omni_logger vi. They took a few minutes to stop. Then, the IGH vi's started working again. Closed omni_logger, turn off Keithley and HP multimeter. When I try to start the fridge temp vi, I get the error “VISA: The connection for the given session has been lost.” |
| 1000 | The original error was thrown by the sub-vi LSCI 370 Serial Write. This seemed to ot be able to write to the GPIB bus. I can still communicate manually with the LakeShore using the LabView Measurement and Automation Explorer Communicate with instrument tool. |
| 1015 | Tried unplugging all but the LakeShore from GPIB, power cycling LakeShore, and un/re plugging the GPIB usb adapter, but none fixed the problem. Close all LabView programs and restart LabView. That did the trick! |
| 1040 | Post mortem: It's hard to understand what went wrong. Somehow GPIB communications with the LakeShore bridge seem to have gotten screwed up. Perhaps running the Keithley and HP multimeter vi's (via omni_logger), which also communicate via GPIB was the problem? Maybe several of them were trying to talk at the same time? It is strange though that it would work for some days before failing. I also thought that LabView VISA system, which coordinates GPIB use, was smart enough to deal with this as well as GPIB's build-in handshake and readiness protocols. Additionally, the issue seemed to be with writing to the GPIB bus. |