2019/05/24 (Friday)
| Status: | LN2 transfer yesterday. |
|---|---|
| 0905 | MC(Cernox) = 77.1 K, Sorb = 123.9 K, IVC = 1.6 mbar, G1 (fridge) = 617 mbar, DIB4 pD SQUID = 1.3 kΩ |
| 0906 | Close V12A + speedivalve and open V5 to pump mix from both sides of fridge to dump open to cold trap 1 |
| 0910 | Quick electrical check of phonon lines looks good. |
| Throughput test procedure, Cold Trap 1: |
- All mixture in dump, LN2 trap 1 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
| 0915 | Perform mixture throughput test at MC = 77 K using above procedure with 3He pump on. Let G1 rise to 557 mbar before Step 3, then it falls to 79 mbar, then rises. Throughput = 42.6 mbar/min. Even higher than last time. |
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| 0920 | Open V12A +speedivalve and V3 to again expose mix to both sides of fridge via trap 1. |
| 0921 | Begin pumping exchange gas out of IVC with scroll pump, then with turbo. |
| 0930 | Skip leak checking because we've done it already and the leak checker is broken. |
| 0934 | Make sure LN2 transfer stick is about 1/8“ above where it hits the bottom of the transfer cone. |
| 0935 | Start blowing out LN2. Main bath (G3) = 410 mbar (+1atm) and I can hear liquid pouring into the bomb dewar. |
| 0942 | Main bath (G3) = 392 mbar (+1atm) and pretty flat. |
| 0943 | Main bath (G3) starts to decrease to 360 mbar. |
| 0949 | Main bath (G3) = 215 mbar and falling. We're still getting a little liquid out of the transfer hose though. |
| 0956 | Main bath (G3) = 183 mbar and falling. Still getting LN2 spittle out of the transfer hose. 4He tank is nearly empty now, we'll just let it run out. |
| 1005 | He gas cylinder is empty. Close He gas wall valve behind IGH. Switch out He gas cylinder and purge the copper tubing line by opening a valve on it for a few seconds. |
| 1010 | Reopen the He gas wall valve behind the IGH. Seem to be only pushing gas out of the transfer tube. Close He gas wall valve, vent speedivalve, V2A and V5A to stop LN2 blowout officially. |
| 1017 | Top off LN2 cold trap from bomb dewar. |
| 1020 | Oh wait, I see now the LN2 blowout procedure says I should keep the He gas flowing until the transfer hose goes limp. Re-open the 4He gas wall valve, V2A and V5A. The transfer hose is blowing frosty gas, but no liquid and is still stiff. Maybe this is what I did wrong last time and did get the main bath purged enough? Though I think it just wouldn't have pumped down in that case… |
| 1025 | Main bath (G3) = 167 mbar and falling, transfer hose is stiff. |
| 1040 | Main bath (G3) = 151 mbar and falling, transfer hose is still stiff. |
| 1055 | Main bath (G3) = 140 mbar and falling slowly, transfer hose is still stiff. |
| 1115 | Main bath (G3) = 138 mbar, transfer hose is still stiff. |
| 1120 | Transfer hose is still stiff, but this has gone on long enough, we'll burn through another He cylinder if we keep this up! Stop pressurizing main bath. Wait for transfer hose to warm up. |
| 1146 | Start pumping out main bath with scroll pump. |
| 1202 | Main bath pressure is not going down. We must STILL have LN2 in there. |
| 1205 | Stop pumping on main bath. Pressurize main bath with He gas again. Re-seat transfer tube to sit all the way down in the transfer cone and re-attach transfer tube. G3 climbs to 370 mbar and transfer hose is blowing out cold gas and getting stiff again. |
| 1210 | He gas cylinder looks to be nearly half empty already, down to 900 psi from nearly 2000 psi when it was installed earlier. Maybe the pressure I'm using is too high and I'm being wasteful? Turn He cylinder regulator down a little. G3 falls to 340 mbar. |
| 1224 | Small LN2 dewar that we were blowing out into starts to overflow, switch to bomb dewar. So maybe the first time we just weren't able to blow out LN2 below the transfer cone and we were just blowing He gas through. |
| 1225 | Main bath (G3) = 350 mbar |
| 1230 | Main bath (G3) starts to fall |
| 1237 | Main bath (G3) = 122 mbar, LHe cylinder = 750 psi |
| 1247 | Transfer hose is getting flexible again, stop pressurizing main bath. LHe cylinder = 600 psi |
| 1254 | Start pumping out main bath with scroll pump. P2 falls below 1 mbar in 11 minutes |
| 1307 | Open 1K Pot speedivalve and needle valve (2 full turns) to pump Pot as well. Notice that the needle valve was hard to open initially. Had to use the allen key to get enough toque. Hopefully this doesn't mean it is icy down there. |
| 1310 | Close off scroll pump and pressurize MB and 1K Pot with helium to 150 mbar above 1 atm. |
| 1312 | Let's try to see if the 1K Pot has flow. Close V1A and the 1K Pot needle valve and speedivalve. Pump out the P2 volume, up to the 1K Pot speedivalve until P2 = a few mbar, then close off the pump. Now we have 125 mbar (+1 atm) in the main bath and 1K pot. Open 1K pot speedivalve, P2 goes above 1 bar, G3 is still 0.0 (less than 1 atm). Open 1K pot needle valve, this should let He into the 1K pot via the siphon. After a few minutes, G3 hasn't risen above 0.0, but we see the mechanical gauge on the 1K Pot rising (~ 1in Hg/sec), so there must be throughput through the 1K Pot. |
| 1315 | Start pumping out main bath and 1K Pot with scroll pump. |
| 1331 | Let 46 μbar He exchange gas into IVC. (Derek and Nick both confirm this reading a comical number of times.) |
| 1335 | Close off scroll pump and pressurize MB and 1K Pot with helium to 228 mbar above 1 atm. |
| 1342 | Set up webcam to take a photo of recovery meter every 1 min. Doing this with a cron job since we don't have the laptop right now. Not sure how to make it go faster than once a minute so this won't actually be helpful… |
| 1343 | Open main bath to recovery. |
| 1350 | Commence initial LHe transfer. |
| 1350 | MC(Cernox) = 77.3 K, Sorb = 150 K, IVC = 40 μbar, G1(fridge) = 609 mbar. G3(MB) = 471 mbar. |
| 1357 | Stop webcam cron job. Call Nick's webcam automater script like this to save an image every ~ 2 sec: python /home/mast/cdms/webcam webcamAutomater.py -delay_min 0.033 -total_time_hr 3 -save_images -update_website |
| 1400 | MC(Cernox) = 77.3 K, Sorb = 149 K, IVC = 460 nbar, G1(fridge) = 608 mbar. G3(MB) = 392 mbar. Gah, not again! Why does the IVC pressure keep falling like this during LHe transfers? |
| 1405 | Turn on LHe dewar heater to 4 PSIg |
| 1415 | MC(Cernox) = 76.9 K, Sorb = 138 K, IVC = 250 nbar, G1(fridge) = 597 mbar. G3(MB) = 230 mbar. |
| 1430 | MC(Cernox) = 75.4 K, Sorb = 119 K, IVC = 220 nbar, G1(fridge) = 587 mbar. G3(MB) = 206 mbar. |
| 1440 | MC(Cernox) = 74.4 K, Sorb = 109 K, IVC = 190 nbar, G1(fridge) = 574 mbar. G3(MB) = 199 mbar. MB = -1.0% |
| 1441 | This transfer seems to be going slowly. Ohh, the dewar heater is switched on, but none of the lights are lit, so it's not getting power. Unplug and replug it, but no change. Unplug, check the fuse, it looks fine. Put the fuse back and replug, now it switches on. |
| 1450 | MC(Cernox) = 73.0 K, Sorb = 95.9 K, IVC = 120 nbar, G1(fridge) = 537 mbar. G3(MB) = 301 mbar. MB = 8.8% With the LHe level above the wide part of the IVC, I think we should be much colder as on 2018/05/15 when MC/Sorb were 55/28 K by MB=4%. Probably need to add more He exchange gas again. |
| 1500 | MC(Cernox) = 71.8 K, Sorb = 84.9 K, IVC = 120 nbar, G1(fridge) = 491 mbar. G3(MB) = 301 mbar. MB = 27.5% |
| 1501 | Close valve connecting pump manifold to IVC lines. Then let in just 740 ubar of He into the pump manifold. Then open that to the IVC. IVC pressure falls to 160 nbar. |
| 1505 | Repeat above procedure. Added 1.2 mbar into pump manifold. IVC falls to 340 nbar. |
| 1510 | MC(Cernox) = 70.0 K, Sorb = 71.3 K, IVC = 220 nbar, G1(fridge) = 479.1 mbar. G3(MB) = 384 mbar. MB = 46.9% |
| 1515 | Repeat above procedure. Added 860 ubar into pump manifold. IVC falls to 340 nbar. |
| 1520 | MC(Cernox) = 67.3 K, Sorb = 61.5 K, IVC = 300 nbar, G1(fridge) = 473 mbar. G3(MB) = 362 mbar. MB = 66.2% |
| 1523 | Repeat above procedure. Added 860 ubar into pump manifold. IVC falls to 860 nbar. |
| 1530 | MC(Cernox) = 63.8 K, Sorb = 28.2 K, IVC = 460 nbar, G1(fridge) = 473 mbar. G3(MB) = 362 mbar. MB = 82.6% |
| 1531 | Turn off LHe dewar heater. Last cooldown we had to keep adding exchange gas after the transfer and it burned up a lot of our bath. Hopefully we can keep transferring as we add exchange gas to get back on track temperature-wise and keep our bath full for 2 days. |
| 1535 | Close valve connecting pump manifold to IVC lines. Then let in 860 ubar of He into the pump manifold. Then open that to the IVC. IVC pressure falls to 1.2 μbar. |
| 1540 | MC(Cernox) = 60.0 K, Sorb = 8.3 K, IVC = 1 μbar, G1(fridge) = 467 mbar. G3(MB) = 299 mbar. MB = 92.3% |
| 1545 | Cease LHe transfer, MB=91.2% |
| 1550 | MC(Cernox) = 55.2 K, Sorb = 6.9 K, IVC = 1 μbar, G1(fridge) = 493 mbar. G3(MB) = 157 mbar. MB = 91.2% |
| 1551 | Close valve connecting pump manifold to IVC lines. Then let in 860 ubar of He into the pump manifold. Then open that to the IVC. IVC pressure falls to 6.3 μbar. |
| 1606 | MC(Cernox) = 47.0 K, Sorb = 7.2 K, IVC = 2.2 μbar, G1(fridge) = 492 mbar. G3(MB) = 167 mbar. MB = 86.3% |
| 1615 | MC(Cernox) = 42.9 K, Sorb = 7.0 K, IVC = 2.2 μbar, G1(fridge) = 493 mbar. G3(MB) = 163 mbar. MB = 84.4% At this rate, we won't hit 10 K till 19:00. |
| 1617 | Close valve connecting pump manifold to IVC lines. Then let in 1.9 mbar of He into the pump manifold. Then open that to the IVC. IVC pressure falls to 10 μbar. |
| 1623 | MC(Cernox) = 38.4 K, Sorb = 6.9 K, IVC = 8.6 μbar, G1(fridge) = 492 mbar. G3(MB) = 163 mbar. MB = 82.6% |
| 1630 | MC(Cernox) = 34.5 K, Sorb = 6.7 K, IVC = 8.6 μbar, G1(fridge) = 493 mbar. G3(MB) = 155 mbar. MB = 80.9% At this rate, we'll 10 K at 18:05. |
| 1655 | MC(Cernox) = 22.7 K, Sorb = 6.1 K, IVC = 7.4 μbar, G1(fridge) = 503 mbar. G3(MB) = 138 mbar. MB = 76.9% New prediction for 10 K is 17:53. |
| 1705 | Fill LN2 cold trap bath full. |
| 1730 | MC(Cernox) = 12.6 K, Sorb = 5.6 K, IVC = 1.9 μbar, G1(fridge) = 512 mbar. G3(MB) = 117 mbar. MB = 74.1% |
| 1737 | MC(Cernox) = 9.9 K, Sorb = 5.5 K, IVC = 1.6 μbar and falling, G1(fridge) = 515 mbar. G3(MB) = 115 mbar. MB = 73.9% Begin pumping on IVC with Turbo Pump. |
| 1740 | MC(Cernox) Temperature began falling faster initially, appears to be slowing down as expected. MC(Cernox) = 7.2 K, Turbo on IVC = 19 nbar |
| 1922 | Webcam on main bath meter has stopped working. Seems like the camera is connected to jiajin correctly, but the images it produces can't be opened. Not sure what has changed. Maybe just need to restart the camera… |
| 1940 | Actually, there seems to be a problem with writing files to chocula; can't even make a new text doc in vi without weird errors. Move the /home/mast/cdms/webcam directory, which actually lives at /data/chocula/mast/cdms , to /home/mast and put a symlink from /data/chocula/mast/cdms/webcam to /home/mast/webcam . That seems to work for now. |
| 2230 | MC(Cernox) = 4.5 K, MB = 71.1% |