2019/04/24 (Wednesday)
| Status | Tower installed, IVC closed (screws not fully tightened). LN2 traps, 4He trap, fridge all pumped out. 1K Pot needle valve closed. Cryostat vacuum jacket pumped out. Mixture needs to be cleaned. |
|---|---|
| 0940 | IVC = 3.0 mbar. Start pumping it out with scroll pump. |
| 1005 | Scroll pump on IVC = 54 μbar. Switch to turbo pump. Turbo pump on IVC = 1.0 μbar. |
| 1020 | Turbo pump on IVC = 340 nbar. |
| 1050 | Change oil in leak detector rough pump using Leybonol LVO 100 mineral oil. |
| 1140 | Turbo pump on IVC = 160 nbar. |
| 1140 | Try leak detector after oil change. Seems to be working. With port blanked off, background <1 pbarL/s. |
| 1150 | Leak detector on IVC: 5.9 pbarL/s. That's with the Turbo valved out, pumping pressure has risen to 8.6 μbar. Open turbo valve again to pump some more |
| 1215 | IVC = 13 pbarL/s. (Turbo valved out again.) |
| 1230 | Leak check IVC at top of fridge and the indium joints. Looks good. Leak signal stayed around 37 pbarL/s. |
| 1310 | Raise main bath |
| 1310 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.7% |
| 1310 | Increase V6 → 12.9% to restart flow |
| 1320 | Increase V6 → 13.1% to restart flow |
| 1415 | Stop cleaning through Trap 1 after 65 min. G2 flow pressure was 575-740 mbar. Pump mixture to dump. Removed 12.2 mbar |
| 1450 | Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.9% |
| 1455 | Increase V6 → 13.2% to restart flow |
| 1515 | Increase V6 → 13.3% to restart flow |
| 1555 | Stop cleaning through Trap 2 after 65 min. G2 flow pressure was 575-610 mbar. Pump mixture to dump. Removed 7.5 mbar |
| 1615 | Trap 1 is warm I think. Check contents: 13.7-1.5 = 12.2 mbar on G1. Immerse trap in lukewarm water for a few minutes: pressure does not increase. Pump out with 4He pump. |
| 1650 | Prepare to leak test our recovery system. Request from Paul Crowell is to pressurize our bath and recovery system, including the recovery gas gauge (with the valve to the external system closed). Do not include 4He pump recovery line. The system should hold a few PSI at least overnight. |
| 1650 | Pump main bath with scroll pump to less than 1 mbar. |
| 1655 | Pressurize main bath to 388 mbar above atm on G3. |
| 1655 | Close main recovery valve to external recovery system. Open main bath recovery valve. G3 falls to 300 mbar above 1 atm, and continues to fall… Recovery meter moves from 246401.5 to 246401.68. |
| 1700 | Turbo on IVC = 63 nbar. |
| 1700 | Main bath (G3) = 181 mbar +1atm, recovery meter = 246401.73 |
| 1705 | Main bath (G3) = 138 mbar +1atm, recovery meter = 246401.78 this is roughly consistent with the idea that we are leaking somewhere past the meter, because it all seems to be registering on the recovery meter. This could be a leak in our lines up to the main valve, or it could be a leak through the valve and actually going to the external recovery. |
| 1710 | Main bath (G3) = 114 mbar +1atm, recovery meter = 246401.80 |
| 1710 | Close the recovery valve between our system and the meter. This is above and to the right of the meter. Put more helium into main bath, up to 356 mbar +1atm on G3. (note - this is equivalent to about 5 PSI. But the main bath gauge only reads 2 PSI.) |
| 1715 | Main bath (G3) = 352 mbar. It's falling slowly. We'll let it go overnight. Start logging pressure to file /data/chocula/k100/k100_log/20190424_pressure. |
| 1745 | Main bath (G3) = 328 mbar. Turbo on IVC = 54 nbar. |