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2018/03/04 (Sunday)

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Status: LN2 transfer yesterday.
1230 MC(Cernox) = 77.05 K, Sorb = 122.4 K, IVC = 4.9 mbar, G1 (fridge) = 214 mbar
1240 Mini-throughput check: close off Trap 1 and V3. Only V1, condenser speedivalve, still gate valve, and V9 open. Turn on 3He pump, then open V6 to 12.8%. This pumps mix out of the still side and we can see if the pressure goes down on the condenser side. G1 (condenser) started out at 214 mbar (most mix is still in dump), then started falling at about 6.4 mbar/s. Note: this
1245 Open mixture that's still in dump up to Cold Trap 1.
1250 Fill LN2 cold trap bath
1250 Pump mixture out of fridge to dump/Trap 1
Throughput test procedure, Cold Trap 1:
  1. All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
  2. Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
  3. Close V12b+speedivalve and V3, open V1
  4. monitor G1
1300 Perform mixture throughput test at MC = 77 K using above procedure. Let G1 rise to 582 mbar before Step 3, then it falls to 81 mbar, then begins to rise. Throughput 47.7 mbar/min. Significantly higher than Run 66.
1325 Perform electrical check. On DIB2, the short that we saw on qI before at 77K is back, but it has a much higher resistance. Qi_feedback-chassis = 7.5 nS. Chassis-qI_drain or source = 15 nS. So the short is on the order of 70 MOhm, instead of the 1 MOhm we saw before. Hopefully we can live with this.
1345 MC(Cernox) = 77.0 K, Sorb = 122.5 K, IVC = 1.9 mbar, G1 (fridge) = 608 mbar, Level resistor = 1.213 kΩ.
1355 MC(Cernox) = 77.0 K, Sorb = 120.9 K, IVC = 1.9 mbar, G1 (fridge) = 607 mbar, Level resistor = 1.339 kΩ.
1414 MC(Cernox) = 77.0 K, Sorb = 119.0 K, IVC = 1.9 mbar, G1 (fridge) = 605 mbar, Level resistor = 1.339 kΩ.
1431 MC(Cernox) = 77.0 K, Sorb = 118.2 K, IVC = 1.9 mbar, G1 (fridge) = 603 mbar, Level resistor = 1.339 kΩ.
1433 Stop LN2 transfer.

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