2016/06/08 (Wednesday)
| Setup | DIB1/2 → cables → Dsub filters → DCRC55/50. DCRCs powered. |
|---|---|
| taking 30-min data series overnight of charge bias sweeps. Last flash at ???? | |
| Overnight two big things went wrong. |
* The MIDAS website crashed again during the +2V data, which was the next set of data to be taken after we left for the night.
- After restarting the website and the Sequencer this morning, the Qbias was still set to +2 (presumably it was biased all night), and the sequencer still has ~1750s left of the series to take data.
- This means the sequence essentially paused itself while the server was down, so we don't have to “rerun” any data necessarily.
- I paused the sequencer at this point to deal with the second thing that went wrong overnight.
* The 1K Pot had run dry leading to a temperature spike at approximately 0145 this morning.
- The Tower held at base temperature for another hour while G1/G2 rose from ~125mbar to ~875mbar, and P1 rose from ~0.05mbar to 0.50mbar during that time.
- At ~0250 this morning, the pressure increase then entered a regime of slower increase until the circulation pressures maxed out the gauges at 1000mbar at ~0600 this morning.
- At ~0250 this morning, the Tower temperature began to rise, reaching a local max of 1.3K at ~0600. The temperature then slowly rose to ~1.5K when I came in and found it like that.
- At ~0250 this morning, P1 (still pressure) fell from its elevated 0.5mbar to 0.35mbar and remained approximately there until ~0600, at which point P2 spiked to 1.70mbar, then fell gradually back to ~0.45mbar where I found it this morning.
| 0945 | Open needle valve an eighth of a turn to let LHe into 1K Pot. 1K Pot temperature rises, and 1K Pot temperature immediately falls from the 5K it was at. Open V9 to let some of the mixture in the lines into the dump to alleviate high pressures. |
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| G2 quickly drops and G1 after approximately 10 seconds also drops. G1/G2 drop to ~650mbar after 10 seconds. Close V9 and G1/G2 continue steadily decreasing. | |
| 0950 | Fill LN2 cold trap full. |
| 1020 | 1K Pot temperature has dropped to a nice 1.69K and a pressure of 28.0mbar, though it is still steadily decreasing. G1/G2 have stabilized at 126/117mbar. P1 is steady at 0.038mbar. |
| The Tower temperature is also slowly rising, perhaps to low levels of mixture. Begin throttling V14 to gradually let mixture back into circulation while making sure G1/G2 do not rise above 300mbar. | |
| 1045 | P2 (1K Pot pressure) has dropped to 17mbar already. Open the needle valve another 16th of a turn to let in more LHe. The P2 pressure rises to 1000mbar while the 1K Pot temperature rises from 1.68K to 1.95K, then begins dropping back 1.83K where it's settled for the time being. P2 is still reading off scale at 1000mbar. |
| 1150 | Still throttling V14. Tower temperature has fallen to 450mK and still dropping steadily. P2 has dropped to 14.0mbar. May have to open the needle valve again in an hour or two. |
| 1400 | Can now leave V14 open without G1/G2 rising above 300mbar while we pump out the rest of the mixture from the dump. Tower temperature currently 135mK and dropping. P2 has fallen to 5.5mbar, so it will need to be opened more before leaving for the day. |
| Now that the fridge is in hand, time to figure out why the MIDAS server was crashing last night. Set ODB SeriesInfo setting to “test”, reapply +2V Qbias, then stop the paused sequencer script and rerun the same script to see how long we can run for. | |
| 1440 | P2 (1K Pot pressure) has fallen to 2.4mbar. Open needle valve another 16th of a turn. P2 begins rising. |
| 1445 | P1 has reached a minimum of 0.50mbar. Close V14 to isolate the dump and continue circulation. |
| 1510 | Commence LHe transfer (35.1%). |
| 1600 | After making it through two Flash & Takes and starting a third flash & cooldown, the sequencer has run without issue. Stop the current sequence immediately, so we can start it up after the transfer is over. |
| 1605 | Fill LN2 cold trap full. JK refill LN2 dewar upstairs. |
| 1610 | Cease LHe transfer (91.8%). |
| 1620 | Let pressure out of main bath. |
| 1620 | Start 22 hours of 30 min background series bias sweeps at +/+1 V to +/+13 V and -/-1 V to -/-9 V in increments of 1 V with 30s flash and 25min cooldown in between. Triggering on DIB1 Qo at 40ADC bins. 1000 randoms before and after. |
| 1625 | MC/Tower/Cold Plate: 33.7mK/ 44.8mK/ 182mK. Still: 1.16K/0.11mbar. 1K Pot: 1.48K/4.0mbar. |
| 1725 | 1K Pot pressure at 4.4mbar. Open 1K Pot needle valve an eighth of a turn in preparation for leaving it overnight. 1K Pot temperature rises to 1.88K before beginning to decrease. |
| 1735 | Fill LN2 cold trap fo' REALsies. |