2020/09/25 (Friday)
- Lab in-person: Matt
- Virtual partner: Zach, Ruiren
| Setup | Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Status | Doing a partial warming to get helium out of the IVC. Circulation and 1K Pot stopped. No gas in cryostat vacuum jacket, main bath still boiling down. Pumping on IVC and heaters, LEDs off - now warming up unassisted. 1K Pot manual valves both open. |
| 0000 | MC(Cernox)/Sorb = 13.9/28.0 K |
| 0016 | Recovery = 384273.4 / 10.7 cuft/hr |
| 0116 | Recovery = 384283.5 / 10.2 cuft/hr |
| 0216 | Recovery = 384293.3 / 9.8 cuft/hr |
| 0316 | Recovery = 384302.5 / 9.2 cuft/hr |
| 0400 | MC(Cernox)/Sorb = 14.9/38.1 K |
| 0416 | Recovery = 384311.6 / 9.1 cuft/hr |
| 0516 | Recovery = 384320.4 / 8.8 cuft/hr |
| 0616 | Recovery = 384329.3 / 8.9 cuft/hr |
| 0716 | Recovery = 384337.4 / 8.1 cuft/hr |
| 0800 | MC(Cernox)/Sorb = 16.4/46.6 K |
| 0816 | Recovery = 384346.4 / 9 cuft/hr |
| 0916 | Recovery = 384363.8 / 17.4 cuft/hr This is oddly high. But looking at the G3 pressure, which is tracking the MB, it seems that it was climbing to a max up to 08:35 then suddenly dropped. So maybe the recovery system pressure was high, blocking our side up until 8:35, when there was a sudden release. |
| 1016 | Recovery = 384372.4 / 8.6 cuft/hr |
| 1116 | Recovery = 384381 / 8.6 cuft/hr |
| 1200 | MC(Cernox)/Sorb = 18.0/53.1 K |
| 1216 | Recovery = 384389.0 / 8.0 cuft/hr (I think) |
| 1316 | Recovery = 384395.3 / 6.3 cuft/hr (I think) |
steps for LHe transfer today
- fill LN2 Cold Trap Bath
- turn on 3He pump (otherwise just leave mixture as is, both sides of fridge open to dump and LN2 Trap 1)
- pump out 1K Pot (first close needle valve and pump out line to pump. Isolate pot. Then open MB to G3.)
- check turbo pressure, IVC pressure
- add He exchange gas to IVC, amount appropriate to MC temperature (e.g 18 K → 4.6 ubar, see Sep 18)
- start initial LHe transfer. Start pumping out IVC at 10K as usual
| 1340 | Matt enters lab |
|---|---|
| 1345 | Fill LN2 cold trap bath |
| 1355 | Close 1K Pot needle valve. Then pump out the 1K Pot through the speedivalve using the 4He pump, pumping out the line first in steps, keeping the load on the pump low by opening v4a and 1K Pot Speedivalve alternately for short times, keeping P2 below a few mbar. Pump 1K Pot down to 0.16 mbar. Close 1K Pot Speedivalve. Close V4a and 4He Pump valve, turn off 4He Pump. |
| 1405 | Open V1a to monitor MB pressure on G3 |
| 1405 | MC(Cernox)/Sorb = 19.2/57.7 K |
| 1405 | Turbo on IVC = 6.3 nbar. After closing off pump for 1 minute, IVC = 100 nbar. |
| 1415 | Let some helium exchange gas into IVC. Settles to 0.54 ubar. This causes MC and Sorb temperatures to rise. That's interesting. I expected them to fall toward 4K, because there is still some LHe in the MB. They must now be more in thermal contact with the top of the fridge. |
| 1416 | Recovery = 384396.7 / 2.6 cuft/hr |
| 1432 | Recovery = 384396.9 / 0.9 cuft/hr |
| So recovery rate has gone down a lot, looks like maybe the bath is about gone. | |
| 1435 | MC(Cernox)/Sorb = 28.4/65 K |
| 1445 | Let 4.0 μbar He exchange gas into IVC. |
| 1510 | MC(Cernox)/Sorb = 35.2/74 K. IVC = 7.4 ubar (it has crept up, probably means the IVC is now well above 4K) |
| 1519 | Begin initial LHe transfer |
| 1520 | MC(Cernox) = 37.0 K, Sorb = 76.4 K, IVC = 2.5 μbar, G1(fridge) = 618.0 mbar. G3(MB) = 333 mbar+1atm. |
| 1530 | MC(Cernox) = 34.8 K, Sorb = 68.6 K, IVC = 1.2 μbar, G1(fridge) = 603 mbar. G3(MB) = 238 mbar+1atm. |
| 1540 | MC(Cernox) = 28.9 K, Sorb = 46.9 K, IVC = 0.86 μbar, G1(fridge) = 560 mbar. MB = 21.9% / 395 mbar+1atm. |
| 1550 | MC(Cernox)/Sorb/1K Pot = 20.7/5.3/4.21 K, IVC = 0.40 μbar, G1(fridge) = 519 mbar. MB = 45.7% / 377 mbar+1atm. |
| 1600 | MC(Cernox)/Sorb/1K Pot = 12.4/5.3/4.26 K, IVC = 0.25 μbar, G1(fridge) = 475 mbar. MB = 72.2% / 357 mbar+1atm. |
| 1607 | MC(Cernox)/Sorb/1K Pot = 10.0/5.5/4.40 K, IVC = 0.30 μbar Start pumping out IVC with Turbo Pump |
| 1611 | End LHe transfer @ MB = 92.4% |
| 1635 | MC(Cernox)/Sorb/1K Pot = 10.8/6.9/5.47 K, Turbo on IVC = 2.2 nbar, G1(fridge) = 557 mbar. MB = 92.2% / 129 mbar+1atm. |
| not sure why temperatures are rising. MC temperature seems to have started rising when I started pumping the IVC. | |
| 1650 | Matt leaves lab |
| 12:00:24 | 78.65 |
| 12:16:24 | 80.95 |
| 12:57:24 | 86.05 |
| 13:16:24 | 87.25 |
| 14:16:24 | 88.66 |
| 14:32:24 | 88.9 |
| 14:45:24 | 89.07 |
| 15:09:24 | 89.35 |
| 15:12:31 | 89.37 |