| Status | LN2 left in main bath overnight, with fridge temperature at 82 K this morning. After cryocleaning, coldtrap 1 was left open to P2 overnight while warming. |
| 0940 | With P2=1000 mbar after being open to the warm cold trap 1 (G1 around 2.5 mbar and isolated from coldtrap 1). Open P2 to scroll pump and pump out contaminate for 15 minutes until P2=30 ubar. As a precaution, close off valves leading to cold trap 1 and isolate scroll pump. Remember to pump on this cold trap for longer, once next round of cryocleaning is finished. |
| 0955 | Fill LN2 bath full (only cold trap 2 inside), and commence another round of cryocleaning through cold trap 2, since the mixture was apparently very dirty. |
| 1010 | IVC pressure reads 1.4 mbar. Commence pumping on IVC with scroll pump. |
| 1015 | Close Condenser Line Speedivalve. We don't want whatever's frozen in the He Cold Trap to heat up and flow into the cold Fridge Lines. |
| 1030 | IVC external pressure sensor reading 2.2E-3 mbar. Switch to pumping on IVC with turbo pump. |
| 1045 | Commence LN2 blowout. |
| 1050 | Switch to pumping on IVC with leak checker. Background leak rate: 4.8E-7 mbarL/s. |
| 1105 | Cease cryocleaning mixture. Commence pumping mixture to dump. |
| | During Electrical Check, some QET/Return lines had higher conductances to Ground (~2nS). The problem with the DIB2 Qi FET leaking to chassis was much improved: Qi Feedback to chassis 15 nS, Drain and Source very low. Otherwise everything looks as it did during the last 77K electrical check. |
| 1126 | End blowout. IVC leak rate remained constant around 3.3E-7 mbarL/s. |
| 1130 | Commence pumping on the IVC in preparation for flushing it with He gas. |
| | V6 close, ceasing pumping to dump. G2=796 mbar. Close V9, and turn off He3 pump. |
| 1134 | Remove cold trap 2 from LN2 bath and open to G1, which read 1.4 mbar. |
| 1350 | Stop pumping MB, fill MB with He gas up to >70 mbar rel on G3. No leak detected, leak rate held at 1.3E-7 mbarL/s. |
| 1400 | Coldtrap 2 read 3.4 mbar on G1. Before opening to coldtrap, G1 read 1.4 mbar. Open G1 volume to P2, and G1 falls to 2.1 mbar, and P2 rises to 1.1 mbar. Pump out cold trap 2 and cold trap 1 thoroughly with scroll pump. |
| 1415 | Trap 2 pumped down to 14 ubar on P2 fairly quickly but Trap 1 is only going down to 26 ubar. Is this an indication of a leak on the Trap 1 connections? |
| 1420 | Stop pumping Trap 1 but watch pressure on P2. Watching pressure climb, up to 0.35 mbar in one minute and continues to rise… |
| 1425 | … P2 still climbing, up to 1.1 mbar in 8 minutes. Tried closing P7 for a minute, climb seemed to stop. So maybe Trap 1 is leaky. |
| 1430 | Try opening Trap 2 to P2 with the pump valved out for comparison. P2 is also climbing but a little more slowly… |
| 1435 | … P2 climbs to 0.65 mbar in 8 minutes, and seems to be plateauing. So it is somewhat better. |
| 1445 | Place both LN2 cold traps back into their LN2 bath. |
| 1450 | Try a forward throughput test through LN2 Trap 2. P1 does not go up, staying around 7 ubar. But G1 does seem to go down… the P1 volume is much larger, maybe we shouldn't expect it to go up very fast? |
| 1455 | G1 on the condenser side goes down at around 1.2 mbar/minute initially, then slows down and stops decreasing. |
| 1510 | Pump mixture to dump. Close all valves except V1 to view LHe Trap pressure on G1, then remove LHe Trap from MB to warm up. |
| 1525 | LHe trap pressure on G1 has increased from 1.5 to 3 mbar, trap mostly warm. Pump out LHe trap contents with scroll pump. |
| 1540 | Try another forward throughput test through LN2 Trap 2, this time with a warm LHe Trap. Doesn't look much different from last time. Blockage must be in fridge. |
| | Pump mixture back to dump. |
| 1550 | Attempt standard throughput test. G1 drops to ~45mbar after opening V1, but doesn't rise. Definitely blocked. Begin pumping out fridge through still side to see if we can get G1 to go lower at all. |
| 1605 | P1: 14ubar, G1: ~45mbar, G2: 799mbar. Interesting that G2 is so close to 800mbar while there's still mixture on condenser side of fridge. Close V6 and open V5 to pump from other side of fridge. |
| 1620 | G1 will not drop below 1.3mbar. Close condenser line speedivalve and V1/V5. G1: 1.3mbar, G2: 800mbar, P1: 14ubar. Isolate dump by closing V9. Turn of He3 pump. All valves on IGH closed (including Gate and Condenser Line speedivalve). |
| | Assemble and perform electrical check on 150mm Si electrodes in clean room. See update note here. |
| 1640 | Add two hose-lengths of He gas to the Dewar jacket to speed warm up. Add 1.9 mbar of He exchange gas into IVC. |
| 1642 | Fridge temp: 82.5 K |
| 1735 | Fridge temp: 111 K |