2021/03/30 (Tuesday)
- Lab in-person: Matt
- Virtual partner: Zach
| Status | Run 74 in progress. Warmed the fridge to fix short and presumed thermal touch. Helium gas in cryostat vacuum jacket, partially pumped out. IVC open and 4K stage removed. LN2 Trap 2 needs to be cleaned, mixture needs to be cryocleaned. |
|---|---|
| 1000 | Matt enters lab. |
| Yesterday I couldn't recreate the DIB2 qI Feedback short, but it was clear that the SQUET flyover is pushed against the stripline connector shell - plan to improve the insulation there. Found two contacts at the 100 mK stage between 600 mK and 100 mK stages, those likely explain the cooling issues, I'll fix those. | |
| 1055 | Check contents of warm LN2 Trap 2: 31.1 mbar. Pump out with scroll pump. |
| 1100 | Check contents of warm LN2 Trap 1: 2.8 mbar. Pump out with scroll pump. |
| 1115 | Finish adjusting 100 mK stage - heat sinks set properly, tape not in contact with 600 mK rod. |
| 1145 | Finish attaching 4K stage to IVC |
| 1150 | Attach tower socket covers at three unused tower faces |
| 1200 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.3% |
| 1210 | Increase V6 → 12.6% to restart flow |
| 1225 | Increase V6 → 12.7% to speed up flow |
| 1235 | Increase V6 → 12.8% to speed up flow |
| 1300 | Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 590-725 mbar. Pump mixture to dump. Removed 7.9 mbar. |
| 1305 | Make a little bundle of kapton tape and tape it to the flyover cable of the SQUET for DIB2 where it hits the stripline connectire. Install both SQUETs. Put a piece of paper (copper tape backing) between SQUET flyover and stripline connector for good measure. |
| 1320 | Finish installing and screwing in SQUETs and plug in accessory wiring. |
| 1325 | Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.7% |
| 1330 | Increase V6 → 13.0% to restart flow |
| 1340 | Increase V6 → 13.1% to speed up flow |
| 1425 | Stop cleaning through Trap 2 after 60 min. G2 flow pressure was 585-790 mbar. Pump mixture to dump. Removed 6.7 mbar. |
| 1330 | Perform electrical check on DIB2. Looks ok, everything nominally the same as 2021 Jan 28 checkout. |
| 1335 | Perform electrical check on DIB1. Looks ok, everything nominally the same as 2021 Jan 28 checkout. |
| 1400 | Attach 4K heat sinks. Use kapton tape to tape the unused stripline to the bottom coils of the two used striplines. |
| 1415 | Prepare bottom of IVC and attach with 2 bolts to start |
| 1420 | Perform quick electrical checkouts on both DIBs, still looks ok. |
| 1445 | With IVC bolts partially tightened, start gently pumping out IVC with Scroll Pump. Continue tightening bolts. |
| 1455 | Scroll on IVC < 0.1 mbar. Switch to Turbo Pump. |
| 1525 | Turbo on IVC = 1 μbar. With Turbo valved out for 1 minute, IVC = 46 μbar. |
| 1530 | Attach leak detector to IVC, valve out Turbo: LD = 70,000 pbarL/s, quite high, we never check it this early really. Squirt helium liberally around IVC indium joint, see no increase in signal, but not sure I'd see a leak with the base so high. |
| 1550 | Check contents of warm LN2 Trap 1: 7.9 mbar. Pump out with Scroll Pump |
| 1555 | Check contents of mostly warm LN2 Trap 2: 6.7 mbar. Pump out with Scroll Pump |
| 1555 | Turbo on IVC = 0.63 μbar. With Turbo valved out for 1 minute, IVC = 22 μbar. |
| 1605 | Matt exits lab |
Tomorrow:
- retighten IVC bolts
- leak check IVC. If it looks good:
- put clean tent away
- raise MB
- ? pump out cryostat vacuum jacket more ?
- throughput check @ 300K
- proceed to LN2 transfer procedure
- after LN2 transfer is complete, connect pumping station to cryostat vacuum jacket to pump out overnight