| | overnight: Tower temp, 1K pot steady |
| 0908 | Tower/MC/Coldplate = 40.6/39.3/181 mK, Still = 1.1 K / 0.055 mbar / 1 mW, G1/G2 = 264/246 mbar, 1K Pot = 1.46 K / 4.5 mbar. MB = 39.4% |
| 0913 | Fill LN2 cold trap full. |
| 0920 | We're going to try cleaning the 4He cold trap. Maybe it is partially blocked and reducing our flow rate. Following procedure in sec 8.3.4 of K100 Operator's Handbook. |
| 0924 | Turn off Still heater. Close V6 to stop circulation. |
| 0931 | Close V12A and cold trap 1 speedivalve. Close condenser speedivalve. Open V5 to pump mix in condenser lines to G2 volume. Tower temps tarts to rise. |
| 0934 | G1/G2 = 2.4/251 mbar. P1 = 1.4 mbar. Tower = 187 mK |
| 0942 | G1 seems to be at it's minimum. G1/G2 = 0.7/253.6 mbar. P1 = 5.0 mbar. Tower = 290 mK and rising. |
| 0943 | Close V5. G1 → 1.4±0.1 mbar |
| 0945 | Procedure says to start pumping out the 4He cold trap next before warming it. I'm going to deviate from that and let it warm so we can see the pressure in G1 rise and get a sense of how much gunk it trapped before pumping it out. Remove 4He cold trap from main bath. G1 immediately rises to 73 mbar, then starts slowly rising. Maybe a little air got in one of the seals as I was lifting the trap out? Check both seals on 4He cold trap lines, they're pretty tight. |
| 0953 | G1/G2 = 81.8/254.0 mbar. P1 = 8.0 mbar. Tower = 374 mK |
| 1000 | Cold trap feels close to room temp now. G1/G2 = 83.1/254.3 mbar. P1 = 12.0 mbar. Tower = 398 mK |
| 1002 | Close V4A. Switch 4He pump from recovery to exhaust. Open V5a, V2a, V7, V2 to pump out 4He cold trap. |
| 1006 | G1/G2 = 2.0/252.6 mbar. P1 = 26 mbar. Tower = 423 mK. That seems as low as it will go. |
| 1008 | Close V2, V7, V2A, V5A. Switch 4He pump exhaust bask to recovery. Open V4A. P2 rises off scale, but quickly recovers to 3 mbar. |
| 1009 | G1/G2 = 4.1/252.7 mbar. P1 = 30 mbar. Tower = 444 mK. G2 decreased by 1.3 mbar while pumping out the 4He trap. Maybe there was a little leak past V12A and the cold trap speedivalve? |
| 1012 | Try to replace 4He cold trap in main bath. I'm struggling to get the 4He cold trap inserted fully into the bath. With about 5“ still protruding, it feels like I am hitting up against one of the fiberglass baffles and can't get the trap through the hole. I guess I'll just leave it as is. Hopefully it still gets cooled enough. |
| 1022 | G1/G2 = 0.8/255.0 mbar. P1 = 34 mbar. Tower = 464 mK. |
| 1025 | Open V12A and cold trap 1 speedivalve to let mix from the LN2 cold trap into the condenser line. G1/G2 → 242/225 mbar. |
| 1028 | I'm a little worried we got some air in the condenser line when I pulled out the 4He cold trap at 0945. Let's try and cycle the G1 volume through the LN2 cold trap a while before restarting circulation. Open V5 to cycle warm mix through cold trap 1. |
| 1030 | G1/G2 → 69/235. |
| 1032 | 1K pot seems to be running again: 1.47 K / 5.0 mbar. |
| 1039 | LN2 trap 1 line is frosted a little bit, but well below the o-ring seal. |
| 1040 | G1/G2 = 69.0/235.4 mbar. P1 = 38 mbar. Tower = 504 mK. |
| 1048 | Close V5. Hopefully 20 min of such cleaning is sufficient for the small amount of mix out here. G1/G2 = 244/225 mbar. |
| 1049 | Open Condenser speedivalve. G1/G2 drop to ~180 mbar. Open V6 → 12.8% |
| 1053 | G1/G2 = 192/179 mbar. P1 = 34 mbar. Tower = 502 mK. |
| 1055 | Put IGH into remote mode. At vuk-01, increase V6 → 13.0% Check on IGH manually, seems o have worked. |
| 1056 | On VNC session to vuk-01, increase V6 → 13.2% Check on IGH manually, seems o have worked. |
| 1100 | Increase V6 → 13.6% |
| 1110 | G1/G2 = 214/200 mbar. P1 = 2.2 mbar. Tower = 497 mK. |
| 1128 | G1/G2 = 193/180 mbar. P1 = 1.6 mbar. Tower = 472 mK. |
| 1130 | Increase V6 → 14.0% |
| 1145 | G1/G2 = 220/207 mbar. P1 = 0.6 mbar. Tower = 476 mK. |
| 1200 | G1/G2 = 239/224 mbar. P1 = 0.65 mbar. Tower = 452 mK. |
| 1216 | G1/G2 = 267/249 mbar. P1 = 0.65 mbar. Tower = 418 mK. |
| 1234 | G1/G2 = 290/270 mbar. P1 = 0.65 mbar. Tower = 395 mK. |
| 1256 | G1/G2 = 303/281 mbar. P1 = 0.70 mbar. Tower = 372 mK. |
| 1343 | G1/G2 = 309/286 mbar. P1 = 0.55 mbar. Tower = 270 mK. |
| 1356 | G1/G2 = 309/287 mbar. P1 = 0.55 mbar. Tower = 286 mK. Condenser pressure has flattened out and temp bounced back up from a min of 262 mK. Increase V6 → 14.2% |
| 1406 | Increase V6 → 14.4% |
| 1415 | G1/G2 = 329/305 mbar. P1 = 0.40 mbar. Tower = 290 mK. |
| 1423 | Start LHe transfer (MB = 31.0%) |
| 1430 | Increase V6 → 14.8% |
| 1440 | Condenser pressure falling since the transfer started and tower temp is coming down again. G1/G2 = 310/289 mbar. P1 = 0.26 mbar. Tower = 226 mK. |
| 1500 | Cease LHe transfer (MB = 91.2%), G1/G2 start to rise. |
| 1505 | G1/G2 = 324/301 mbar. P1 = 0.26 mbar. Tower = 164 mK. |
| 1517 | G1/G2 = 331/307 mbar. P1= 0.22 mbar. Tower = 132 mK. |
| 1528 | Increase V6 → 15.0% |
| 1538 | G1/G2 = 299/278 mbar. P1= 0.18 mbar. Tower = 115 mK. Increase V6 → 15.4% |
| 1545 | G1/G2 = 286/266 mbar. P1= 0.14 mbar. Tower = 112 mK. Increase V6 → 15.8% |
| 1607 | G1/G2 = 249/231 mbar. P1= 0.11 mbar. Tower = 89.7 mK. Increase V6 → 100% |
| 1620 | G1/G2 = 235/219 mbar. P1= 0.036 mbar. Tower = 75.2 mK. |
| 1640 | Fill LN2 cold trap full. |
| 1650 | G1/G2 = 234/219 mbar and flattened out. P1= 0.040 mbar. Tower = 53.8 mK. |
| 1840 | G1/G2 = 315/293 mbar and rising. P1= 0.040 mbar. Tower = 50.9 mK. Tower bottomed out at 46.5 mK now rising slightly. |
| 1844 | Set Still heat = 1.0 mW |
| 1924 | Tower bottomed out at 44.8 mK, but now 79.3 mK and rising. Turn off Still heat. Looks like the cold trap cleaning did not help things. |