2018/07/18 (Wednesday)
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) | |
| overnight: 1K Pot failure around 10pm last night (we'll look at the logs for more detail of the failure and conditions preceeding it). Nick caught it at 11:30 pm and suspended circulation; at that time the Condenser pressure had risen above 800 mbar. | |
| 0810 | V6 closed, V14 open, so pump is pumping on nothing, dump-trap1-condenser path open. Tower = 2.4 K, 1K Pot = 2.5 K / 1 mbar. G1/G2 = 207/184 mbar. |
| 0810 | Close 1K Pot needle valve, then close 1K Pot speedivalve. 1K Pot → 3.5 K. Sorb rises above 4 K. |
| 0815 | Turbo on IVC = 2.5 nbar. Close valve to turbo pump, if we decide to warm above 4K we can see how much helium comes out. |
| 0930 | Tower = 2.8 K, IVC = 30 nbar. |
| 0931 | Fill LN2 cold trap |
| 1125 | 1K Pot >7K. Sorb = 11.5 K |
| 1125 | Tower = 3.1 K and rising, IVC = 30 nbar. G1/G2 = 414/375 mbar and rising. |
| 1125 | Turn on MC heater → 20 mW, increase Still heater 6→20 mW. Tower temperature rises more quickly. Sorb temperature rises too. |
| 1130 | Turn off MIDAS DAQ programs and unplug DCRCs 1&3. |
| 1145 | Tower = 3.5 K and flattening a bit, G1/G2 =495/448 mbar and rising quickly than before, Sorb now falling, peaked at 12.5 K now 9.6 K |
| 1155 | Tower temperature suddenly starts rising quickly, 3.6 → 5.4 K, IVC 30→63 nbar. 1K Pot falls to 6 K |
| 1200 | Tower = 5.4 K and plateauing, G1/G2 = 548/497 mbar and rising steadily, IVC = 63 nbar, Sorb = 7.7 K and falling. 1K Pot = 6K |
| 1250 | Tower = 5.5 K, G1/G2 = 576/523 mbar, Sorb = 7.5 K, all flat. IVC = 74 nbar |
| 1250 | Close V14 and V13A, open V9 and V5. This pumps on the Condenser and LN2 Trap 1 to dump. Sorb temp falls a little, Tower/1K Pot flat. |
| 1315 | Tower = 5.5 K, Sorb = 7.6 K, flat. G2 (dump) = 695 mbar and rising, G1 (condenser + Trap1) = 9.7 mbar and falling. IVC = 63 nbar. |
| 1320 | Open V3 to pump on Still side too. G2 peaks to 60 mbar then falls. |
| 1350 | Tower = 5.5 K, Sorb = 7.8 K, flat, G2 (dump) = 730 mbar, looks flat. G1 (condsenser+trap1) = 1.5 mbar, Still = 0.6 mbar. IVC = 63 nbar. |
| On July 6 we warmed the tower to 7.5 K under I think the same conditions, here we're stuck at 5.5 K. Is something anchoring the temperature? | |
| 1400 | Try turning off both MC heater and Still heater, see where it settles |
| 1430 | Tower settled to 4.4 K. So it does seem anchored. Turning off heaters also seems to have caused Sorb/1K Pot temperature to rise, now Sorb = 10.9 K, 1K Pot > 7 K. IVC has fallen to 40 nbar. |
| 1435 | Turn Still heater back on to 20 mW this caused Tower to rise slightly to 4.8 K and caused Sorb to fall, 10.9→9.5 K |
| 1505 | Turn MC heater back on to 20 mW Tower → 5.5 K, Sorb falls again, → 7.7 K, 1K Pot falls → 6 K |
| 1525 | IVC = 74 nbar |
| 1536 | Start LHe transfer @ MB = 49.6% |
| Starting transfer caused Sorb/1K Pot to peak to 9.0/6.9 K then fall to 5.4/4.2 K | |
| 1610 | End LHe transfer @ MB = 93.6% |
| After end of transfer Sorb rises to 5.9 K | |
| 1705 | Fill LN2 cold trap full. |
| 1725 | Close V12a+speedivalve, V1, V3, V5, no longer pumping to dump. Dump(G2) = 732 mbar. Close V9, turn off 3He pump. |
| 1725 | Tower/Sorb/1K Pot = 5.7/5.4/4.2 K, all flat. MC/Still = 20/20 mW. IVC = 63 nbar. |