2018/06/12 (Tuesday)
| 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) | |
| 0345 | Tower = 96 mK, Still = 0.100 mbar, G1/G2 = 421/390 mbar, 1K Pot = 1.85±0.10 K / 1.7 mbar. Tower temperature was around 100 mK for several hours but now starting to fall… This coincided with a small increase in the 1K pot pressure from 0.9 mbar to 2 mbar and sudden increase in 1K pot pressure from stable 1.36 K to relatively unstable 1.8±0.10 K |
| 0415 | Tower = 84 mK, lowest it has been in last 12+ hours, and falling. Good sign I guess. (Maybe we had a partial blockage and it came loose. Sure, why not?) |
| 0615 | Tower = 67 mK, still falling |
| 0820 | Tower = 61 mK, still falling |
| 0838 | Tower/MC/Coldplate =60.3/58.9/190 mK, Still = 1.26 K / 0.10 mbar, G1/G2 = 353/329 mbar, 1K Pot = 1.6±0.1 (somewhat unstable) K / 2.2 mbar. MB = 73.8% |
| 0844 | Open 1K pot +10 degrees. P2 → 8 mbar and starts to decay, 1K pot temperature stabilizes at 1.55 K and slowly decreases |
| 0906 | 1K pot spontaneously jumps and oscillates around 1.57 K / 12 mbar. Tower = 59.6 mK |
| 0924 | Tower = 60.3 mK, G1/G2=348/323 mbar, 1K pot = 1.54 K / 8.5 mbar. Still heater = 3.5 mW, P1 = 0.10 mbar |
| 0925 | Let's play with the Still heating and see if that helps things. Turn Still heater off. |
| 0930 | P1 falls to 0.045 mbar, Tower rises to 63.1 mK. |
| 0931 | Turn Still heater back on to 3.5 mW |
| 0936 | P1 → 0.045 mbar, Tower → 55.3 mK and decreasing, G1/G2 → 322/300 mbar |
| 0938 | 1K pot is slowly falling as usual to 1.52 K / 7 mbar |
| 0951 | Tower bottomed out at 48.2 mK, now P1 → 0.10 mbar, Tower → 50.2 mK G1/G2 → 332/308 mbar, 1K pot = 1.49 K / 5.0 mbar. Increase Still heating to 5.0 mW |
| 0955 | Tower temp starts to increase to 53 mK, P1 rises to 0.12 mbar. Turn Still heater back to 3.5 mW |
| 0956 | Fill LN2 cold trap. |
| 1000 | All Linux machines freeze. :/ |
| 1010 | Anthony suggested stopping/starting circulation could loosen the suspected partial fridge blockage. Let's try that. G1/G2 = 321/295 mbar. Close V13A to stop circulation gently. |
| 1015 | G1/G2 = 215/406 mbar, reopen V13A. G1/G2 → 334/313 mbar. That didn't seem to do anything. But we didn't really change the pressure at the impedance that much. |
| 1026 | Tower = 65.3 mK |
| 1030 | Let's try a more drastic circulation restart by pumping the mix to the dump from both sides of the fridge like we're going to warm up, then restarting circulation from scratch. Close V13A, open V9, open V5. G1/G2 → 6.6/80 mbar, Tower → 120 mK |
| 1034 | Close V5, V9. Close V6 fully. G1/G2 = 12.9/120 mbar. G2 rising presumably as cold mix comes to room temp. |
| 1040 | Watch V6 stepper motor as it is closing. Notice that the motor shifts slightly each step because the screws that attach the motor to the valve body are loose. This may be the source of some of the V6 valve slop. Tighten those screws with an allen key. |
| 1042 | Restart circulation by opening V13A, V14 and opening V6 → 12.4%. G1/G2 →95/96 mbar, P1 → >1000 mbar, Tower → 0.99 K |
| 1047 | V6 → 13%. G1/G2 →95/96 mbar, P1 → >1000 mbar, Tower → 0.99 K |
| 1052 | V6 → 13.5%. G1/G2 → 284/265 mbar, P1 → 32 mbar, Tower → 1.59 K |
| 1110 | G1/G2 flat at 285/265 mbar |
| 1115 | V6 → 14.0%. G1/G2 → 473/439 mbar, P1 → 5 mbar, Tower → 1.21 K. 1K pot oscillates a little around 1.4K / 3 mbar |
| 1132 | Close needle valve and immediately open back up to same position +10 degrees. P2 → >1000 mbar then eventually settles to 6.5 mbar with no oscillations |
| 1158 | G1/G2 = 538/497 and flattening out. P1 = 4.0 mbar, Tower = 1.24 K. I don't think we're getting any circulation now. Dang, we might have fully blocked it with the circulation restart… |
| 1230 | G1/G2 = 439/406 and slowly falling. P1 = 2.8 mbar. Tower = 1.25±0.2 K |
| 1233 | Still heater may not be helping things at this point. Turn off Still heater. P1 → 1.1 mbar, Tower → 1.05±0.2 K |
| 1238 | V6 → 14.4%. G1/G2 → 356/330 mbar and decreasing, P1 → 0.50 mbar, Tower → 1.0±0.1 K |
| 1244 | V6 → 14.8%. G1/G2 → 310/288 mbar and decreasing, P1 → 0.40 mbar, Tower → 0.90±0.1 K |
| 1503 | G1/G2 → 242/256 mbar and decreasing, P1 → 0.40 mbar, Tower → 0.90±0.1 K |
| 1305 | V6 → 15.2%. G1/G2 → 201/187 mbar and decreasing, P1 → 0.26 mbar, Tower → 0.57±0.05 K |
| 1309 | Close 1K pot needle valve and immediately reopen to same position + 10 degrees. |
| 1319 | 1K pot = 1.58 K / 13 mbar |
| 1320 | V6 → 100%. G1/G2 → 127/121 mbar and decreasing, P1 → 0.090 mbar, Tower → 249 mK |
| 1430 | G1/G2 → 106/101 mbar and decreasing, P1 → 0.036 mbar, Tower → 155 mK. Close V14. |
| 1435 | 1K pot = 1.38 K / 1.9 mbar. Open 1K pot needle valve +10 degrees. |
| 1500 | G1/G2 → 100/97 mbar and decreasing, P1 → 0.034 mbar, Tower → 121 mK, 1K pot = 1.44 K / 3.8 mbar. Seems to be cooling okay and it's encouraging that the fridge pressures are far down from what they were this morning. |
| 1503 | Let's try helping it out with Still heating. Turn on Still heater to 3.5 mW. P2 → 0.11 mbar, G1/G2 → rising, Tower → cooling faster |
| 1554 | G1/G2 → 303/283 mbar and starting to flatten out slowly, P1 → 0.10 mbar, Tower → 36.2 mK, 1K pot = 1.40 K / 2.5 mbar. Alright, we're back to base, but we still have a 1K pot that keeps running dry. |
| 1556 | Open 1K pot needle valve +10 degrees. |
| 1614 | G1/G2 → 326/304 mbar, P1 → 0.10 mbar, Tower → 43.9 mK, 1K pot = 1.49 K / 5.0 mbar. Tower has risen slightly. |
| 1650 | Maybe air is leaking down the 1K pot needle valve shaft when we turn it. Enclose needle valve in ziploc bag filled with He from the wall line. Open 1K pot needle vale +10degrees through bag. |
| 1654 | Fill LN2 cold trap full. |
| 1700 | Tower → 55.0 mK |
| 1827 | G1/G2 = 333/312 mbar, P1 = 0.10 mbar, Tower → 59.5 mK, 1K pot = 1.38 K / 2.4 mbar. Ziploc trick didn't seem to help. |
| 2134 | G1/G2 = 336/313 mbar, P1 = 0.10 mbar, Tower → 55.1 mK, 1K pot = 1.38 K / 2.0 mbar. |
| 2326 | G1/G2 = 437/403 mbar, P1 = 0.11 mbar, Tower → 70.4 mK, 1K pot = 2.33 K / 1.4 mbar. Crap, looks like the 1K pot is failing. |
| 2347 | Open 1K pot needle valve +20 degrees. G1/G2 start to fall, 1K pot temp → 1.62 K / 22 mbar |
| 2350 | 1K pot pressure is already falling below 20 mbar. Open 1K pot needle valve +10 degrees. P2 rises to 100 mbar, decays down to 40 mbar over couple minutes, then runs away to >1000 mbar. 1K pot temperature is oscillating around 1.8 K |
| 0001 | P2 finally falls into readable range. It's falling steeply and oscillating slightly. |
| 0003 | G1/G2 = 413/381 mbar, P1 = 0.10 mbar, Tower → 77.6 mK, 1K pot = 1.71 K / 85 mbar (and falling). |
| 0017 | P2 has fallen to 20 mbar and is not oscillating. This still doesn't seem stable and likely won't last the night. Close V6 to stop circulation. |
| 0022 | Open V9 and V3, turn off 3He pump. |