2020/09/26 (Saturday)
- Lab in-person: Matt
- Virtual partner: 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 on. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Status | Did a partial warming to get helium out of the IVC. Initial LHe transfer yesterday. |
| 0925 | MC(Cernox)/Sorb/1K Pot = 10.8/10.0/>7 K. G1(fridge) = 575.5 mbar (3He pump off). Warmer than usual, it may take longer to get the 1K Pot to cool it down. |
| 1150 | Matt arrives in lab |
| 1150 | Matt Fritts body temperature = 98.1 F |
| 1155 | MC(Cernox)/Sorb/1K Pot = 10.8/10.2/>7 K. G1(fridge) = 576.8 mbar (3He pump off). |
| 1155 | Turbo on IVC = 3.4 nbar. With turbo valved out for 1 minute, IVC = 46 nbar. Not as good as last time, maybe just because the fridge is warmer. Open Turbo valve again, we'll keep pumping on IVC. |
| 1200 | MB = 70.6% |
| 1200 | Pump out line leading to 1K Pot with scroll pump. Then switch over to 4He pump. Turn on 4He pump then change pump exhaust to recovery and open valve to recovery lines. |
| 1210 | Fill LN2 cold trap bath |
| 1210 | Check pressure in 1K Pot: Mechanical gauge = 0.13 bar. 1K Pot temperature remains above 7 K. |
| 1220 | Pump out 1K Pot in steps, alternating between V4a and the 1K Pot speedivalve, opening V4a for short bursts only when the mechanical gauge read above a few inches. After 9 iterations leave V4a and 1K Pot speedivalve open. 1K Pot → 5.6 K / 0.65 mbar. Sorb falls too. Fridge pressure falls too. |
| 1220 | MC(H35)/Tower = 13.7/11.0 K. (Coldplate/Still = NaN/157 K. These don't have good calibrations here.) |
| 1225 | MC(Cernox)/Sorb = 10.8/7.0 K. G1(fridge) = 569 mbar. |
| 1225 | Open 1K Pot needle valve → 10°. 1K Pot → 4.9 K / 0.75 mbar. Sorb falls to 6.2 K |
| 1230 | Open 1K Pot needle valve → 20°. 1K Pot → 5.4 K / 0.75 mbar. Open 1K Pot needle valve → 30°. 1K Pot → 4.9 K / 0.9 mbar. Sorb → 5.9 K |
| 1235 | Open 1K Pot needle valve → 40°. 1K Pot → 5.5 K / 0.75 mbar. This is not looking good so far. But I don't remember how it behaves when the Tower is this warm. Close needle valve, then open 1K Pot needle valve → 50°. 1K Pot → 4.2 K / 1.1 mbar. |
| 1240 | Open 1K Pot needle valve → 60°. 1K Pot → 4.5 K / 1.0 mbar. Close needle valve, then open 1K Pot needle valve → 70°. 1K Pot → 5.4 K / 0.75 mbar. |
| 1240 | Close input valve to 4He pump, we'll see what happens. 1K Pot → 4.2 K / off scale on P2, around 0.04 bar on mechanical gauge. |
| 1245 | Start pumping 1K Pot again. 1K Pot → 4.6 K / 0.95 mbar. |
| MC temperature has fallen slightly, to 10.8 K. Considering that it's above 10 K, it may make sense to let a little helium into the IVC, in order to pull it back down toward 4 K, then (almost immediately) pump it out again. | |
| 1250 | Close 1K Pot needle valve. Then close 1K pot speedivalve. 1K Pot rises to 5.6 K (and continues to rise) |
| 1255 | Let some helium into IVC, up to 4 ubar but settles to 0.19. MC falls… When MC falls below 10 K, open Turbo valve to pump out IVC again. MC temperature continues to fall. 1K Pot had risen to 6.5, now settles at 6.0 K. Sorb = 7.6 K |
| 1300 | MC(Cernox) = 7.7 K and continues to fall. |
| OK - this sets us back one day, because the standard is to pump out exchange gas overnight before starting 1K Pot. So we should wait until tomorrow to continue. | |
| 1305 | MC(Cernox)/Sorb/1K Pot = 7.21/8.3/6.54 K. G1(fridge) = 564.1 mbar (3He pump off). |
| 1310 | Matt leaves lab. |
| 1335 | MC(Cernox) reaches minimum of 6.8 K, then starts rising… |
| 2010 | MC(Cernox) = 9.9 K. Crap! We'll probably need to add exchange gas again tomorrow, try to bring it back down. Let it get colder before pumpout, I guess. |
| 2235 | Matt Fritts body temperature = 97.8 F |