2020/09/14 (Monday)
- Lab in-person: Matt
- Virtual partner: Derek
| 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 overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Status: | Warming up to deal with cryo problems: 1K Pot partial blockage, helium in IVC. Stopped circulation and 1K Pot pumping last night. |
| 0830 | MB = 2.6% |
| 0845 | Tower = 1.6 K, slowly rising. |
| Shortly after stopping pumping on the 1K Pot, the 1K Pot pressure (as seen on G3) rose to 200mbar+1atm. 1K Pot rose to 4K by 00:46 - just then pressure rose again, to 360 mbar+1atm, then settled down again to around 200mbar+1atm. Before 04:00 the 1K Pot temperature started rising again and the pressure rose a little for a short time then fell to 170 mbar+1atm and stayed there as the temperature rose off scale (>7K). 1K Pot pressure stayed constant after that - presumably the same pressure as the Main Bath. | |
| Sorb was at about 5.5 K while 1K Pot was at 4K. Then when Pot started rising, Sorb did too, maxxing at 9.7 K, then started slowly falling. | |
| G1(condenser) fell to a 50 mbar when the 1K Pot got to 4K, then began rising. | |
| 0905 | Condenser(G2) = 365 mbar, rising. |
| 0905 | Open V1a. This opens the 1K Pot pumping line to the main bath, both measured at G3. G3 does not change, so yes as suspected the Pot is at the MB pressure now. |
| 0915 | Tower/Sorb = 1.6/9.3 K. Condenser = 374 mbar. MB+1Kpot = 166mbar+1atm. |
todo:
- let He into IVC
- start monitoring recovery with webcam
- soften cryostat vacuum jacket
- pump out mixture from fridge? could maybe wait, this can mostly be done remotely (leaving it in may help it warm up)
- fill LN2 trap, since we still have mixture in the trap
- disconnect 4He Pump exhaust from reco, then we can turn off 4He pump
- consider leaving both 1K Pot manual valves open, along with V1a - this leaves Main Bath and Pot connected. Should keep Pot full of clean helium at safe pressure.
- switch to Cernox thermometer
| 1110 | Matt arrives in lab |
|---|---|
| 1110 | Tower/Sorb = 1.7/9.2 K. Condenser = 460 mbar. MB+1Kpot = 168 mbar+1atm. |
| 1115 | Turbo on IVC = 4.6 nbar. With Turbo valved out for 1 minute, IVC = 54 nbar. Let a little He into IVC. IVC → 0.14 ubar. After a second small blast: IVC falls to 54 nbar again. A little reaction in 1KPot+MB pressure (G3), rising. Maybe slight reaction in Sorb too. |
| 1120 | Close valves to IVC. Then let 0.19 mbar He into turbo pump manifold. Then open IVC valves to let this into IVC. This causes quick rise in Tower temperature, 1.75→2.1 K, then a quick fall → 1.85 K. IVC settles to 74 nbar. |
| 1130 | Fill LN2 cold trap bath |
| 1130 | Switch 4He outlet to EXHAUST and close its recovery system valve. Close valve to 4He pump inlet and turn off 4He Pump. |
| 1130 | MB = -0.8%. Recovery rate = 13.5 cuft/hour |
| 1140 | Isolate IVC then switch Turbo station hose to Cryostat Vacuum Jacket port, pump out manifold |
| 1145 | Tower/Sorb = 1.83/9.0 K. Condenser = 473 mbar. MB+1Kpot = 175 mbar+1atm. |
| 1150 | Let 3.4 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vaccum Jacket → 0.063 mbar. Recovery meter speeds up. 1KPot+MB pressure increases. |
| 1153 | MB = -1.0% (minimum). Recovery rate = 327 cuft/hour |
| 1159 | Recovery = 379800 cuft / 287 cuft/hour |
| 1200 | Turn on MC/Still heaters → 20/30 mW |
| 1205 | Tower temperature rising quickly with heaters on, now 3.0 K. Condenser pressure and Sorb temp were falling during boiloff, now rising. |
| 1210 | Switch to Cernox thermometer |
| 1210 | MC(Cernox)/Sorb = 3.30/8.3 K. Condenser = 495 mbar. MB+1Kpot = 236 mbar+1atm. |
| 1210 | Recovery = 379843 cuft / 245 cuft/hour |
| 1215 | MC temperature, Condenser pressure rising quickly. Sorb temperature falling. |
| 1220 | Open V3 to connect Still and Condenser sides of fridge. G1(fridge) pressure increases 660→720 mbar |
| 1220 | MC(Cernox)/Sorb = 3.73/5.3 K. G1(fridge) = 758 mbar (rising). MB+1Kpot = 218 mbar+1atm. |
| 1220 | Recovery = 379875 cuft / 173 cuft/hour |
| 1230 | Recovery = 379901 / 133 cuft/hr |
| 1235 | MC(Cernox)/Sorb = 3.96/8.7 K. G1(fridge) = 853 mbar. MB+1Kpot = 211 mbar+1atm. |
| 1240 | Open V4 for several seconds to let some mixture into the dump. G1(fridge) falls 850→700 mbar. MC temperature falls 3.96→3.74 K then starts rising again. |
| 1240 | Recovery = 379923 / 124 cuft/hr |
| 1250 | MC(Cernox)/Sorb = 3.99/12.4 K. G1(fridge) = 885 mbar. MB+1Kpot = 193 mbar+1atm. |
| 1250 | Open V4 for several seconds to let some mixture into the dump. G1(fridge) falls 890→750 mbar. MC temperature falls 4.02→3.88 K then starts rising again. |
| 1255 | Matt leaves lab |
| 1255 | MC temperature starts rising quickly |
| 1300 | Recovery = 379960 / 98 cuft/hr |
| 1320 | MC(Cernox)/Sorb = 8.7/14.8 K. G1(fridge) = 944 mbar. MB+1Kpot = 193 mbar+1atm. |
| 1320 | Close V13a and open V9. Now reading Dump at G2. Dump(G2) = 379 mbar. Note that 3He pump is on. Open V5. Now pumping mix out of fridge and LN2 Cold Trap 1 to Dump. |
| 1330 | Recovery = 380001 / 60 cuft/hr |
| 1340 | MC(Cernox)/Sorb = 10.3/18.1 K. G1/P1(fridge) = 1.6/2.2 mbar. G2(dump) = 732 mbar. MB+1Kpot = 179 mbar+1atm. |
| 1355 | MC(Cernox)/Sorb = 11.1/19.8 K. G1/P1(fridge) = 1.2/0.7 mbar. G2(dump) = 732.3 mbar. |
| 1400 | Close V5. Open V6→13%. Switching to V6 for pumpout. |
| 1400 | Recovery = 380030 / 47 cuft/hr |
| 1405 | P1 has fallen lower with V6 open Increase V6 → 20% |
| 1410 | MC(Cernox)/Sorb = 12.1/21.6 K. G1/P1(fridge) = 1.3/0.04 mbar. G2(dump) = 734.1 mbar. |
| 1410 | Close V12a, isolating LN2 Trap 1. Note: V12a Speedivalve is still open. |
| 1420 | MC(Cernox)/Sorb = 12.7/22.8 K. G1/P1(fridge) = 1.2/0.022 mbar. G2(dump) = 735.0 mbar. |
| 1420 | Close V1, V3, V6. No longer pumping out fridge. Fridge isolated but Condenser speedivalve and Still gate valve open. |
| 1430 | Recovery = 380052 / 27 cuft/hr |
| 1450 | G2(dump) = 738.2 mbar. Still creeping up. |
| 1500 | Recovery = 380063 / 14 cuft/hr |
| 1525 | G2(dump) = 738.9 mbar and pretty flat. Barometric pressure = 29.3 inHg, temperature 76 F, gives sea-level pressure 30.1 inHg. Corrected dump pressure = 743.9 mbar. Expected: 710.8 mbar (measured Mar 15) plus 40.2 mbar (added Aug 17) = 751.0 mbar. A little lower. |
| 1525 | MC(Cernox)/Sorb = 26.6/41.2 K. |
| 1530 | Close V9 to isolate Dump, turn off 3He pump |
| 1530 | Recovery = 380069 / 9 cuft/hr |
| 1600 | MC(Cernox)/Sorb = 26.6/41.2 K. |
| 1600 | Recovery = 380070 / 5.1 cuft/hr. Gets a lot slower after this - looks like this is when the bath finishes boiling off. |
| 1610 | Matt Fritts body temperature 97.2 F |
| 1700 | Recovery = 380074 / 3.3 cuft/hr |
| 1800 | Recovery = 380077 / 2.2 cuft/hr |
| 1900 | Recovery = 380078 / 1.4 cuft/hr |
| 2000 | Recovery = 380079 / 0.73 cuft/hr |
| 2020 | MC(Cernox)/Sorb = 56.2/115.3 K. |
| 2100 | Recovery = 380080 / 0.66 cuft/hr |
| 2130 | MC(Cernox)/Sorb = 62.9/135 K. |
| 2200 | Recovery = 380080.7 / 0.57 cuft/hr |