2019/04/10 (Wednesday)

Previous Day

Status	Began warmup yesterday. Mixture in fridge and dump. Mixture pumped out of LN2 traps, traps warm. 1K Pot needle valve open. Main bath boiling away.
0945	G1 (dump/fridge) = 339 mbar. Tower/1K Pot/Sorb = 2.7/>7/9.9 K. MB = 4.4%
1025	Recovery = 1 cuft/223 seconds. Pretty steady overnight.
1045	Turbo on IVC = 1.6 nbar. IVC = 16 nbar with pump valved out.
1050	Let some helium gas into the IVC, less than a tube length. Tower temperature spikes to 3.2 K then falls again, IVC settles at 19 nbar. I guess it condensed.
1055	Let more helium gas into IVC, total about 1 tube length. Tower climbs to 3.6 K. Fridge pressure rises rapidly. IVC settles at 630 nbar. Sorb and 1KPot temperatures fall.
1105	Tower/1K Pot/Sorb = 3.8/4.2/5.3 K, G1(dump/fridge) = 580 mbar and rising. IVC = 540 nbar.
1110	Let more helium gas into IVC, part of a second tube length. Tower temperature climbs faster. IVC settles at 7.4 μbar.
1125	Tower/1K Pot/Sorb = 4.23/4.4/5.5 K, G1(dump/fridge) = 630 mbar. IVC = 7.4 μbar. MC(Cernox) = 4.24 K.
1130	MB = 2.2%
1135	Recovery = 1 cuft/211 seconds
1140	Isolate IVC with 7.4 μbar. Connect pump manifold to cryostat vacuum jacket port.
1150	Recovery = 1 cuft/197 seconds Looks like recovery rate began climbing after letting exchange gas into IVC.
1150	MC(Cernox)/1K Pot/Sorb = 4.27/4.79/6.0 K, G1(dump/fridge) = 637 mbar.
1155	Isolate dump, turn on 3He pump, open V9. G2(dump) = 508 mbar.
1200	Start pumping mix to fridge from dump, on both sides (V3 open). V6 = 13.0%. G1(fridge) falling, G2(dump) rising. MC/1K Pot/Sorb temperatures fall but then recover.
1205	MC(Cernox)/1K Pot/Sorb = 4.27/4.70/5.9 K, G1(fridge)/G2(dump) = 195/657 mbar. Increase V6→13.5%. Fridge pressures change more quickly, temperatures dip again.
1210	MC(Cernox)/1K Pot/Sorb = 4.26/4.71/5.9 K, P1(fridge)/G2(dump) = 1.8/717.8 mbar.
1210	Recovery = 1 cuft/223 seconds Slowing down again. Maybe because of outside activity.
1220	MC(Cernox)/1K Pot/Sorb = 4.28/4.80/6.0 K, P1(fridge)/G2(dump) = 0.18/720.6 mbar. Increase V6→20.0%.
1225	MB = 1.2%
1230	MC(Cernox)/1K Pot/Sorb = 4.28/4.81/6.0 K, P1(fridge)/G2(dump) = 0.045/722.5 mbar. Increase V6→100.0%.
1305	Recovery = 1 cuft/224 seconds Still slow. The boost from letting exchange gas into the IVC was temporary.
1310	MC(Cernox)/1K Pot/Sorb = 4.29/4.88/6.1 K, P1(fridge)/G2(dump) = 0.018/725.6 mbar.
1320	MB = -0.1%
1325	MC(Cernox)/1K Pot/Sorb = 4.30/4.89/6.1 K, P1(fridge)/G2(dump) = 0.017/726.8 mbar.
1355	MC(Cernox)/1K Pot/Sorb = 4.28/4.87/6.1 K, P1(fridge)/G2(dump) = 0.017/727.9 mbar.
1400	Close off fridge and 4He trap, by closing Condenser speedivalve, Still gate valve, and V1. No significant drop in pressures so fridge was almost certainly empty.
1410	MC(Cernox)/1K Pot/Sorb = 4.28/4.88/6.1 K, G2(dump) = 728.2 mbar.
1412	MB = -0.7%
1420	Let 2.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. After 5 minutes, recovery = 1 cuft/13 seconds, MC/1K Pot/Sorb rising.
1430	MC(Cernox)/1K Pot/Sorb = 4.44/5.11/6.4 K, G2(dump) = 728.9 mbar. Recovery = 1 cuft/14 seconds. MB = -1.0% (minimum).
1440	MC(Cernox)/1K Pot/Sorb = 4.58/5.53/7.0 K, G2(dump) = 729.1 mbar. Recovery = 1 cuft/18 seconds.
1450	MC(Cernox)/1K Pot/Sorb = 4.71/5.83/7.4 K, G2(dump) = 729.1 mbar. Recovery = 1 cuft/24 seconds.
	Barometric pressure = 30.00“ (source is https://w1.weather.gov/data/obhistory/KMSP.html.) G2 = 729.1 mbar. Corrected dump pressure = 731.8 mbar. A few mbar lower than Run 68 but a few mbar higher than Run 67.
1500	MC(Cernox)/1K Pot/Sorb = 4.93/6.22/7.9 K, G2(dump) = 729.0 mbar. Recovery = 1 cuft/26 seconds.
1505	Dump pressure basically flat. Stop pumping to dump. Close all IGH valves, turn off 3He pump.
1515	MC(Cernox)/1K Pot/Sorb = 5.40/>7/9.0 K, Recovery = 1 cuft/28 seconds.
1530	MC(Cernox)/Sorb = 5.94/10.0 K, Recovery = 1 cuft/34 seconds.
1545	MC(Cernox)/Sorb = 6.81/11.1 K, Recovery = 1 cuft/38 seconds.

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