2016/10/14 (Friday)
| Status: Initial LHe transfer yesterday, turbopumping IVC overnight. Mixture has been cleaned through Trap 1 and is in dump. 3He pump was left on overnight pumping from Trap 1 to dump, not ideal but probably doesn't matter. |
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| 0820 | Remove Cf source from the IVC and return source to safe |
| 0825 | MC(Cernox)/Sorb/1K Pot = 15/16/>7 K, Turbo (on IVC) = 2.5 nbar, MB = 47.1% Temperatures increased to around 19/17 K until 11pm then began to fall again |
| 0830 | Fill LN2 cold trap |
| 0840 | Let mix into fridge: close all valves but v9, then turn off 3He pump. Open v13b, v12b+speedi, and v1 to let mix into LN2 Trap 2 and the LHe trap, let it cool for a bit |
| 0845 | Turn on 4He pump, open pump valve and v4a. |
| 0850 | G1/G2 = 750/680 mbar. Open condenser valve to let mixture into fridge. G1/G2 start falling steadily, Sorb falls quickly to below 14 K After 10 minutes, G1/G2 = 710/640 mbar and falling (suggesting there's throughput from condenser to still), Sorb = 8.6 K and falling. |
| 0855 | Close 4He pump valve, then open 1K Pot speedivalve. P2 rises off scale, pressure on mechanical gauge on pot pumping lines rises to about 0.1 bar, so there was some gas in the pot. |
| 0900 | Open recovery valves for 4He pump, then open pump valve to start pumping on 1K Pot, needle valve still closed. 1K Pot falls to 5.7 K / 0.7 mbar. |
| 0905 | Open 1K Pot needle valve about 10 degrees. 1K Pot → 3.6 K / 5.4 mbar. Open needle valve additional 5 degrees. 1K Pot → 3.2 K / 9.5 mbar. Open needle valve additional 5 degrees. 1K Pot → 2.9 K / 24 mbar. Open needle valve additional 5 degrees. 1K Pot → 2.1 K / 70 mbar. |
| 0910 | G1/G2 falling more quickly now that 1K Pot is started, → 605/550 mbar. Sorb = 4.0 K (I think this is bottom of scale) |
| 0920 | MC(Cernox) = 14.2 K, G1/G2 = 490/445 mbar and falling, 1K Pot = 1.9 K / 70 mbar and flat |
| 0935 | MC(Cernox) = 9.7 K, G1/G2 = 370/335 mbar and falling, 1K Pot = 1.8 K / 60 mbar |
| 0945 | MC(Cernox) = 5.1 K, G1/G2 = 230/220 mbar and falling, 1K Pot = 1.7 K / 40 mbar. Tweak 1K Pot open a few more degrees |
| 0950 | Close valve to turbo pump. IVC = 8.6 nbar |
| 1145 | Looking back at pressures, P2 jumped to 1000mbar at 0951 and stayed there until it was noticed now. The 1K Pot temperature jumped from 1.71K to 1.84K when this occured, but was otherwise stable. The pressure on the mechanical gauge was low, a small fraction of a bar. It must have still been at an acceptable level, but still high enough to be in the inaccurate regime of the P2 gauge. |
| Close the needle valve ~1/16th of a turn. P2 drops and settles around 100mbar. 1K Pot temperature has settled around 1.77K. | |
| G1/G2 have stabilized at 82/76 mbar. MC (Cernox) = 2.2K, Tower = 2.3K. Turn on He3 pump and wait to let G1/G2 stabilize. | |
| 1155 | Still/Coldplate = 1.9/2.7 K. Coldplate temperature seemed to be rising slowly during measurement (resistance falling) so it could be we still have a problem with this thermometer as we did in the last run. |
| 1155 | G1/G2 stable at 82/77 mbar. Close V9, open V6 to 12% to begin circulation. |
| 1200 | V6 → 13.0% |
| 1210 | V6 → 13.4%. G1/G2 → 140 mbar and rising. Spike in 1K Pot pressure then back to 130 mbar / 1.8 K. MC(Cernox) = 2.1 K and falling. Still = 1.81 K. After 5 minutes G1/G2 pass peak of 160 mbar then fall again to 125 mbar and continue to drop |
| 1215 | V6 → 13.7%. G1/G2 → 200 mbar and rising. Spike in 1K Pot pressure then back to 120 mbar / 1.8 K. Tower = 1.7 K and falling. Still = 1.45 K. After 2 minutes G1/G2 pass peak of 220 mbar then fall again to 200 mbar and continue to drop. P1 (still pressure) falls into readable range. |
| 1220 | V6 → 13.9%. G1/G2 → 150 mbar and start to fall. 1K Pot steady at 110 mbar / 1.8 K. Tower = 1.3 K and falling. Still = 1.20 K / 10 mbar. Coldplate = 1.37 K, looks maybe reasonable now |
| 1230 | V6 → 14.2%. G1/G2 → 160 mbar peak. Small spike in 1K Pot pressure. Tower = 1.16 K and falling. Still = 1.12 K / 4.5 mbar. Coldplate/MC(H35) = 1.07/1.09 K |
| 1240 | V6 → 14.4%. G1/G2 → 150 mbar. 1K Pot = 1.8 K / 130 mbar. Tower = 0.85 K and falling. Still = 1.11 K / 3.2 mbar. Coldplate/MC(H35) = 0.79/0.71 K |
| 1245 | V6 → 14.7%. G1/G2 = 150 mbar. 1K Pot = 1.8 K / 140 mbar. Tower = 0.56 K and falling. Still = 1.10 K / 2.2 mbar. Coldplate/MC(H35) = 0.84/0.47 K |
| 1255 | V6 → 15.0%. G1/G2 = 150 mbar. 1K Pot = 1.8 K / 120 mbar. Tower = 0.34 K and falling. Still = 1.12 K / 1.5 mbar. Coldplate/MC(H35) = 0.92/0.35 K Why is coldplate getting warmer? |
| 1300 | V6 → 100%. G1/G2 → 155 mbar. 1K Pot = 1.8 K / 150 mbar. Tower = 0.25 K and falling. Still = 1.01 K / 0.22 mbar. Coldplate/MC(H35) = 0.32/0.13 K Coldplate looks happy now |
| 1310 | Tower/MC/Coldplate = 67/59/202 mK, Still = 1.09 K / 0.120 mbar, G1/G2 = 125/130 mbar, 1K Pot = 1.77 K / 120 mbar. |
| 1320 | Tower/MC/Coldplate = 44/42/197 mK, Still = 1.09 K / 0.095 mbar, G1/G2 = 105/105 mbar, 1K Pot = 1.77 K / 130 mbar. |
| 1340 | With G2 at 105 mbar, open V14 to let mixture from the dump into circulation. Leave V14 open until G2 rises to 190 mbar (P2 rose to ~200 mbar), then close V14 to let pressures decrease. |
| 1353 | G2 back down to 105 mbar. Open V14. G1/P1/P2 all rise initially, though begin dropping soon after. Leave V14 open. |
| 1420 | V14 open. Tower/MC/Coldplate = 40.1/37.8/197 mK, Still = 1.07 K / 0.55 mbar, G1/G2 = 105/105 mbar, 1K Pot = 1.77 K / 110 mbar. |
| 1425 | Close V14 |
| 1440 | P2: 125 mbar. 1K Pot temp = 1.77K. Close needle valve to cool 1K Pot. Targeting P2 pressure of 40mbar. |
| 1455 | Tower/MC = 38.7/37.0 Still = 0.11 mbar, G1/G2 = 100/105 mbar, 1K Pot = 1.73 K / 45 mbar. |
| 1459 | Commence LHe transfer (34.3%) |
| 1540 | End LHe transfer (91.3%) |
| 1600 | Tower/MC/Coldplate = 38.2/36.3/196 mK, Still = 1.09 K / 0.085 mbar, G1/G2 = 95/100 mbar, 1K Pot = 1.70 K / 36 mbar. Still thermometer is not as stable as usual, varying around 0.05 K |
| 1700 | Set up for baking. LEDs are connected from DIB1 and DIB4 (none on DIB3). We are hooking up DCRC 1/2/3 (aka 55/33/50) to DIBs 1,3,4. |
| 1715 | Test LEDs to ensure current signs are correct (+0.6mA). Fridge temperature reaches 0.5K when all four LEDs are enabled. Start 12 hour bake of tower. |
| 1725 | Fill LN2 cold trap full. |
| 1735 | MB = 90.5%. Note that we are seeing what happens when we don't release pressure after a fill. Hopefully after drilling the holes in the ports we will have fixed the Taconis oscillations and our boiloff rates will be good without the need to release pressure. |
| 1750 | Found an ethernet port that gives POE for the third DCRC (somehow we'd run out) by swapping two cables at the outlet near the door (switching the Windows machine cable with the white cable leading to top of DAQ desk). |