2020/08/19 (Wednesday)
- Lab in-person: Matt
- Virtual partner: Zach and Michael
| 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 off overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Status: Added more 4He to the mixture two days ago, fridge couldn't cool below 0.4 K. Suspect He in IVC. Stopped circulation yesterday and letting LHe bath boil off. | |
| 0930 | MC = 7.87 K. G1/G2 (fridge and dump) = 594/541 mbar. IVC = 74 nbar. MC/Still heaters are on at 20/30 mW. |
| These values are mostly unchanged from last night. It seems that the system is in equilibrium, cooled by the bath and warmed by the heaters. | |
| 0940 | Matt Fritts body temperature 98.0 °F |
Plan:
- Let some He into Cryostat Vacuum Jacket.
- Allow fridge to warm further. Monitor IVC pressure.
- When warm enough (? >10K ?) pump out IVC.
- Pump out Cryostat Vacuum Jacket.
- Do an Initial LHe Transfer with standard procedure.
| 1020 | Matt enters lab |
|---|---|
| 1025 | MC(Cernox) = 6.98 K. Sorb = 9.6 K. IVC = 74 nbar. |
| 1025 | MB = -1.0% |
| 1030 | Isolate IVC then connect turbo pump manifold to cryostat vacuum jacket port |
| 1040 | Let 2.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vaccum Jacket → 0.074 mbar. Recovery meter speeds up. G3 (1K Pot pressure) increases 160→310 mbar+1atm. Fridge pressure decreases a little. Sorb increases to 10.3 K. MC(Cernox) flat. |
| Note: 1K Pot Needlevalve partially open, 1K Pot Speedivalve open, V4a closed. So G3 reads 1K Pot pressure which is close to bath pressure. | |
| 1050 | Connect turbo pump manifold to IVC port in the usual configuration, pump out line. |
| 1053 | He recovery meter = 363700 cuft, rate = 221 cuft/hour |
| 1055 | IVC = 190 nbar. Definitely an increase. |
| 1105 | He recovery meter = 363737 cuft, rate = 147 cuft/hour |
| 1110 | MC(Cernox)=6.72 K, going down. Sorb = 10.8 K, rising. IVC = 160 nbar. |
| 1115 | Turn off MC and Still Heaters. We'll see how low the MC temperature falls. After 5 minutes MC(Cernox) falls to 5.86 K, IVC falls to 120 nbar. |
| 1120 | He recovery meter = 363773 cuft, rate = 124 cuft/hour |
| 1130 | MC(Cernox)=5.72 K, looks flat. Sorb = 11.6 K, rising. IVC = 120 nbar. |
| 1130 | Turn MC/Still Heaters back on, to 20/30 mW. MC temp rises, IVC pressure goes back to 160 nbar. |
| 1134 | He recovery meter = 363800 cuft, rate = 107 cuft/hour |
| 1155 | MC(Cernox)=7.79 K, now rising steadily. Sorb = 13.1 K, rising. IVC = 340 nbar, apparently also rising - good. |
| 1200 | He recovery meter = 363839 cuft, rate = 73 cuft/hour |
| 1200 | MC(Cernox)=8.57 K, Sorb = 14.5 K. IVC = 630 nbar. |
| 1210 | Isolate IVC, hook up Turbo Pump Manifold to Cryostat Vacuum Jacket, pump out lines, check Jacket pressure: 16 ubar. Begin pumping out Cryostat Vacuum Jacket with Turbo Pump. |
| 1210 | He recovery meter = 363851 cuft, rate = 71 cuft/hour |
| 1215 | Turbo on Jacket = 120 nbar. With Turbo valved out for 1 minute, Jacket = 8.6 ubar. |
| 1220 | He recovery meter = 363861 cuft, rate = 49 cuft/hour |
| 1225 | Turbo on Jacket = 40 nbar. With Turbo valved out for 1 minute, Jacket = 1.9 ubar. |
| 1230 | MC(Cernox)=9.95 K, Sorb = 17.0 K. These seem to be leveling out now that the jacket is getting pumped out. |
| 1230 | Turn off MC and Still Heaters for now. |
| 1230 | He recovery meter = 363867 cuft, rate = 25 cuft/hour |
| 1240 | Turbo on Jacket = 22 nbar. With Turbo valved out for 1 minute, Jacket = 0.46 ubar. |
| 1240 | He recovery meter = 363871 cuft, rate = 17 cuft/hour |
| 1245 | MC(Cernox)=10.0 K, Sorb = 17.1 K, both pretty flat. |
| 1300 | Turbo on Jacket = 14 nbar. With Turbo valved out for 1 minute, Jacket = 0.30 ubar. |
| 1300 | He recovery meter = 363875 cuft, rate = 9.6 cuft/hour |
| 1305 | Stop pumping out Cryostat Vacuum Jacket |
| 1315 | Connect Turbo Pumping Station to IVC. IVC = 16 ubar. |
| 1315 | Begin pumping out IVC with Turbo Pump |
| OOPS - noticed the valve on top of the Turbo Pump Station was closed - this means I was not pumping on the IVC, and that I probably let air from the large line into the IVC. (although maybe not - I thought I heard the loudness of the scroll pump, meaning I did pump out the line…) Will this cause problems? Unclear. We can hope that that air just froze onto the walls. If it formed a frost layer on the fridge parts that could cause a problem. |
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| 1325 | Start pumping out IVC with Turbo Pump |
| 1330 | Turbo on IVC = 30 nbar. With Turbo valved out for 1 minute IVC = 220 nbar |
| 1335 | Leave turbo valve closed. MC(Cernox)/Turbo = 10.6/17.8 K. Turn on MC/Still Heaters to 20/30 mW |
| 1340 | MC(Cernox)/Turbo = 10.9/18.1 K, IVC = 220 nbar. |
| 1340 | Start pumping IVC with Turbo again. Leaving MC/Still Heaters on. |
| 1345 | Turbo on IVC = 14 nbar. With Turbo valved out for 1 minute IVC = 140 nbar |
| 1345 | MC(Cernox)/Turbo = 11.4/18.8 K (MC/Still Heaters = 20/30 mW) |
| 1355 | Turbo on IVC = 12 nbar. With Turbo valved out for 1 minute IVC = 140 nbar |
| 1355 | Turn off MC/Still Heaters. MC temperature was increasing linearly, now levels out. Resume IVC pumping. |
| I'll start transfer soon. Looking at last initial LHe transfer, with MC(Cernox) at 12 K, the exchange gas pressure was down to 2.5 ubar. So it makes sense to add that much transfer gas, and as usual start pumping out again when MC hits 10 K. | |
| 1420 | Turbo on IVC = 12 nbar. With Turbo valved out for 1 minute IVC = 140 nbar |
| 1420 | Tried to add 2.5 ubar He transfer gas to IVC. This is actually causing MC(Cernox) to cool. And it keeps falling below 2.5 ubar. |
| 1430 | Start pumping out IVC again with Turbo, turn on MC/Still Heaters to 20/30 mW again. |
| 1430 | Close 1K Pot Speedivalve, open V1a to monitor MB pressure. |
| 1435 | Got IVC back down to 140 nbar. Let's start the transfer without exchange gas and pump on the IVC. If it looks like it needs exchange gas we can add it during the transfer maybe. |
| 1435 | Turn off MC/Still Heaters |
| 1440 | MC(Cernox) = 11.7 K, Sorb = 20.3 K, Turbo on IVC = 4.6 nbar, G1(fridge) = 611.3 mbar. G3(MB) = 152 mbar+1atm. |
| 1443 | Begin LHe transfer |
| 1450 | MC(Cernox) = 11.7 K, Sorb = 19.7 K, Turbo on IVC = 2.2 nbar, G1(fridge) = 582 mbar. G3(MB) = 228 mbar+1atm. |
| 1455 | MC(Cernox) = 11.7 K, Sorb = 6.9 K, 1K Pot = 5.3 K, Turbo on IVC = 1.9 nbar, G1(fridge) = 535 mbar. G3(MB) = 325 mbar+1atm. |
| 1500 | Stop pumping on IVC. |
| 1505 | Let about 1 ubar He into IVC, watch MC - starts falling. When it hits 10.0 K, start pumping out IVC with Turbo. |
| 1510 | MC(Cernox) = 7.8 K, Sorb = 5.4 K, 1K Pot = 4.3 K, Turbo on IVC = 3.4 nbar, G1(fridge) = 457 mbar. G3(MB) = 397 mbar+1atm. MB = 37.0%. |
| 1515 | MC(Cernox) = 7.2 K, Sorb = 5.4 K, 1K Pot = 4.3 K, Turbo on IVC = 2.5 nbar, G1(fridge) = 453 mbar. G3(MB) = 387 mbar+1atm. MB = 53.5%. |
| 1525 | MC(Cernox) = 6.9 K, Sorb = 5.4 K, 1K Pot = 4.3 K, Turbo on IVC = 2.2 nbar, G1(fridge) = 451 mbar. G3(MB) = 371 mbar+1atm. MB = 76.7%. |
| 1525 | Fill LN2 cold trap bath |
| 1530 | MC(Cernox) = 6.7 K, Sorb = 5.4 K, 1K Pot = 4.3 K, Turbo on IVC = 2.2 nbar, G1(fridge) = 446 mbar. G3(MB) = 366 mbar+1atm. MB = 89.0%. |
| 1533 | Finish LHe transfer @ MB = 91.3% |
| 1555 | MC(Cernox)/Sorb/1K Pot = 6.3/5.3/4.2 K, Turbo on IVC = 3.0 nbar, G1(fridge) = 510 mbar. G3(MB) = 153 mbar+1atm. |
| 1610 | Matt leaves lab |