2021/12/02 (Thursday)
- Lab in-personnel: Himangshu, Matt
| Status | Beginning Run 75. LN2 transfer two days ago; there's a delay on LHe so we put a little more LN2 in yesterday to keep it at 77K. Throughput and electrical checks yesterday, both OK. |
|---|---|
| Today there is still a delay on LHe, maybe tomorrow. I'd like to leak-check the IVC so we'll push out the LN2 today anyway, then transfer LN2 back into the main bath. | |
| 1040 | Turbo on IVC = 4.6 nbar. With turbo valved out for 1 minute IVC = 100 nbar. |
| 1045 | MC(Cernox)/Sorb = 77.3/131.0 K |
| 1055 | Leak Detector on IVC with Turbo pumping in parallel = 20 pbarL/s. With Turbo valved out IVC = 110 pbarL/s. |
| 1105 | IVC = 135 pbarL/s |
| 1110 | Begin blowing out LN2 |
| 1110 | IVC = 141 pbarL/s |
| 1120 | IVC = 134 pbarL/s |
| 1135 | IVC = 152 pbarL/s |
| 1135 | G3(MB) has fallen from 600 mbar+1atm to 171, looks like it's finished…. |
| 1140 | Stop blowing out LN2. |
| 1140 | IVC = 185 pbarL/s |
| 1150 | IVC = 149 pbarL/s |
| 1150 | MC(Cernox)/Sorb = 77.3/132.1 K |
| Sorb has gone up a little. We'll re-transfer LN2, but we need to fill our Dewar first. Maybe we can try pouring some in from the top. | |
| 1200 | Fill LN2 cold trap bath |
| 1425 | MC(Cernox)/Sorb = 77.5/143.0 K |
| Temperatures have crept up a bit. Ready to start LN2 transfer again. We'll see whether we will need exchange gas or whether it will cool OK without. | |
| 1430 | Let's flow mixture through the fridge again during this LN2 transfer. Let mixture from dump through cold LN2 Trap 1 to fridge, both sides. Then isolate the sides and circulate with V6 open partially and mix open to dump. V9, V13b, V12b+speedi, V1, Condenser speedi, Still gate valves open, 3He pump on. Open V6 to 12.6%. |
| 1430 | Level resistor = 1.124 kΩ |
| 1435 | P1(Condenser) → 0.7 mbar |
| 1435 | Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 61.6 mbar/min. Open V12a speedivalve again. |
| 1435 | Begin LN2 transfer |
| 1440 | MC(Cernox)/Sorb = 77.6/144.0 K. Level resistor = 1.203 kΩ. |
| 1510 | MC(Cernox)/Sorb = 77.7/145.4 K. Level resistor = 1.275 kΩ. Sorb is still rising but more slowly, maybe it will turn around. |
| 1535 | MC(Cernox)/Sorb = 77.9/144.3 K. Level resistor = 1.318 kΩ. Sorb falling now. |
| 1555 | MC(Cernox)/Sorb = 77.9/142.1 K. Level resistor = 1.326 kΩ. |
| We don't have to do a leak check tomorrow because we've already done it. So there's really no drawback to putting some exchange gas in the IVC, since the only reason to pump it out thoroughly is for the leak check. | |
| 1600 | Let 0.46 mbar He exchange gas into IVC. Sorb drops quickly but MC temperature rises at first. Then MC recovers. |
| 1605 | MC(Cernox)/Sorb = 78.0/137.0 K. Level resistor = 1.327 kΩ. |
| 1610 | Stop LN2 transfer. Close LN2 Dewar valve. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port. |
| 1610 | Close V6 and turn off 3He pump. |