2017/09/30 (Saturday)
| Status: stopped circulation yesterday. 3He pump is off, small amount of mixture left in it. Mixture open between dump, Trap 1 (cold), still&condenser - V13a, V12a, V4, V3, V1, condenser & still valves open. 1K Pot speedivalve closed, needle valve open. 4He pump off and isolated. MB was below 20% last night, should be below 0% now (though likely still some in the bottom). | |
| 1120 | G1/G2 (trap+dump+fridge) = 215/185 mbar, rising steadily overnight. MC(Cernox) = 2.1 K, slow rise overnight. 1K Pot > 7K (max). Sorb = 11.8 K. IVC = 22 nbar. |
| 1125 | Close 1K Pot needle valve, isolating pot with He gas inside. |
| 1145 | Finish pumping Cold Trap 1 to dump. Remove both traps from bath to let them warm up. |
| 1145 | Start pumping mixture out of fridge (both sides) to dump. Might still be too cold to get it all out. Sorb, Still, MC temperatures fall. So mixture is still condensed. G1 (fridge) fell quickly to 60 mbar, now falling more slowly. G2 (dump) rises to 330 mbar, rising slowly. |
| 1150 | V6 12.8→14.0%, to speed up pumpout. Pressures change more quickly but cooling effect also enhanced. |
| 1205 | G1/P2 (fridge) = 0.9/0.22 mbar, G2 (dump) = 382 mbar, MC(H35)/Still/Sorb = 1.13/1.54/8.9 K. G2 rising very slowly. Fridge still too cold to pump out efficiently. |
| 1210 | Close V6 to stop pumping on fridge. Then turn on MC heater and Still heater to 20 mW each. |
| 1220 | G1(fridge, now isolated and being heated) has risen to 40 mbar. MC(H35) has risen to 2K. |
| 1220 | Let 1 hose-length of He gas into IVC. Much quicker warmup and increase in fridge pressure. G1(Fridge) → 400 mbar and rising. MC(Cernox) → 4.6 K. IVC → 34 μbar. |
| 1225 | With fridge at 650 mbar and rising, open V6 to 13.0% to start pumping to dump again. |
| 1230 | MC(Cernox)/Sorb = 4.7(flat)/8.1(rising) K. |
| 1230 | G1(fridge)/G2(dump) = 105(falling)/735(rising) mbar. Open V6 to 14% to speed up pumpout. |
| 1230 | Turn off MC and Still heaters, shouldn't need them. MC temperature falls a little. |
| 1235 | G1/P1(fridge) = 1.6/0.4 mbar, falling. G2(dump) = 767 mbar, rising very slowly. Open V6 to 25%. |
| 1240 | MC(Cernox)/Sorb = 4.64(flat)/8.3(flat) K. |
| 1245 | G1/P1(fridge) = 0.9/0.03 mbar, P1 still falling a little. G2(dump) = 767.5 mbar, nearly flat. |
| 1300 | G1/P1(fridge) = 1.0/0.02 mbar, P1 essentially flat. G2(dump) = 768 mbar. Isolate fridge, close IGH valves, turn off 3He pump. |
| 1300 | MC(Cernox)/Sorb = 4.67(slow rise)/8.5(slow rise) K. Good, we've retrieved the mix with the fridge still below H2 boiling point. This time we'll be able to pump any H2 in the LHe cold trap out. Not to dump of course, pump out to air. |
| 1310 | Check fridge port - definitely significant pressure, still LHe down there. |
| 1315 | Let 3-inch hose length of He gas into cryostat vacuum jacket. Recovery meter starts turning swiftly. MC and Sorb temperatures rise. |
| 1315 | He recovery = 1 cuft / 6 seconds |
| 1320 | He recovery = 1 cuft / 7 seconds. So it's not getting faster, probably OK to leave it like this. Recovery hose a little frosty, Cu warming coil only a little frosty. |
| 1320 | MC(Cernox)/Sorb = 6.10/14.1 K, both rising |
| 1330 | MC(Cernox)/Sorb = 8.34/18.4 K, both rising. He recovery = 1 cuft / 11 seconds. Cryostat somewhat cool to the touch. IVC = 63 μbar (up from 34) |
| Probably could stand to put extra gas in the cryostat jacket, but I'll leave it for now. Maybe tomorrow (or Monday) it will be warm enough to put N2 in instead of He. Easier to pump out N2 and not as bad if you don't get it all out. | |
| 1335 | Start new temperature logging file, I:\K100\temperature_20170930.txt |
| 1925 | MC(Cernox) = 98.7 K |