2019/10/29 (Tuesday)
| Status: Mixture cryocleaned 4 times. IVC leak-checked at 300K. Beginning 2nd attempt at Run 71 cooldown. | |
| 0920 | Turbo pump on IVC = 22 nbar. IVC = 860 nbar with turbo valved out for several minutes. |
| 0920 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.9% |
| 0930 | Increase V6 → 13.0% to restart flow |
| 0940 | Increase V6 → 13.1% to restart flow |
| 0950 | Increase V6 → 13.2% to speed up flow |
| 1015 | Main bath raised and secured. Fridge insert was slightly misaligned from fridge frame. To fix this, we first put in the small screws part way to attach fridge insert to dewar. Then we loosened the fridge insert mount screws which set the insert radial position, so the insert was free(ish) to rotate. Then put in medium and large screws to attach dewar to frame. Finally we tightened the small screws attaching insert to dewar and re-tightened fridge insert mount screws. |
| 1025 | Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 555-805 mbar. Pump mixture to dump. Removed 8.7 mbar. |
| 1055 | Check warm LN2 Cold Trap 1: 8.7 mbar. Pump out Trap 1. |
| 1100 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.9% |
| 1105 | Increase V6 → 13.1% to restart flow |
| 1120 | Increase V6 → 13.2% to restart flow |
| 1125 | Increase V6 → 13.3% to speed up flow |
| 1200 | Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 560-670 mbar. Pump mixture to dump. Removed 9.1 mbar. |
| 1215 | Check fridge pressures: LHe trap/Condenser/Still = 2.5/0.6/0.6 mbar. Pump out with scroll pump. |
| Throughput test procedure, Cold Trap 2: |
- All mixture in dump, LN2 trap 2 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13b, V12b+speedivalve, V3. Wait for G1 to be close to G2.
- Close V13a+speedivalve and V3, open V1
- monitor G1
| 1230 | Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 580 mbar before Step 3, then it falls to 43 mbar and starts to rise. Throughput = 6.6 mbar/min. |
|---|---|
| 1245 | Pump mixture out of fridge and cold LN2 Trap 2 to dump. |
| 1245 | With 1K Pot speedivalve and needle valve closed, pump on Main bath with scroll pump. Once P2 < 100 mbar, open 1K pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2. |
| 1250 | Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar. |
| 1300 | Close off scroll pump, then pressurize bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar. |
| 1305 | Pressurize main bath and 1K Pot (both sides) with helium to 365 mbar +1atm on G3, then close 1K Pot speedivalve and needle valve. |
| 1310 | Check warm LN2 Cold Trap 1: 9.1 mbar. Pump out Trap 1. a little worrying that this is not coming down. I tightened the o-ring connections on the Still pumping line above the GHS. Maybe that will help. I guess I'll try LN2 transfer anyway. |
| 1310 | Turbo on IVC = 19 nbar. With turbo valved out for a few minutes, IVC = 540 nbar. |
| 1315 | Let 5.4 mbar He exchange gas into IVC |
| 1325 | As on 2019 Sep 20 during previous Run 71 cooldown, we will flow mixture through the fridge during LN2 cooldown. Let mixture from dump through cold LN2 Trap 2 to fridge, both sides. Then we'll 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. Now open V6 to 12.8%. |
| 1330 | Circulation pressures settling to G2/G1/P1 = 647/722/20 mbar |
| 1335 | MC(Cernox) = 296.8 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 647/723/9.0 mbar, Level resistor = 0.983 kΩ |
| 1340 | Begin LN2 transfer |
| 1350 | MC(Cernox) = 296.4 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 646/723/38 mbar, Level resistor = 0.997 kΩ |
| 1350 | Close V12b speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 11.8 mbar/min. Open V12b speedivalve again. |
| 1355 | MC(Cernox) = 293.5 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 647/723/75 mbar, Level resistor = 1.009 kΩ |
| 1405 | MC(Cernox) = 279.2 K, Sorb = >249 K (max), IVC = 4.0 mbar, G2/G1/P1 (circulation) = 647/722/(off scale) mbar, Level resistor = 1.020 kΩ |
| 1415 | MC(Cernox) = 259.9 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 647/721/(off scale) mbar, Level resistor = 1.065 kΩ |
| 1415 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 13.8 mbar/min. Open V12b speedivalve again. |
| 1430 | MC(Cernox) = 248.2 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 645/719/(off scale) mbar, Level resistor = 1.128 kΩ |
| 1430 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 18.4 mbar/min. Open V12b speedivalve again. |
| 1445 | MC(Cernox) = 182.9 K, Sorb = >249 K (max), IVC = 2.5 mbar, G2/G1/P1 (circulation) = 643/715/(off scale) mbar, Level resistor = 1.193 kΩ |
| 1445 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 24.6 mbar/min. Open V12b speedivalve again. |
| 1505 | MC(Cernox) = 152.5 K, Sorb = 224.4 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 638/709/(off scale) mbar, Level resistor = 1.251 kΩ |
| 1505 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 29.0 mbar/min. Open V12b speedivalve again. |
| looks like the LN2 Dewar is almost empty | |
| 1515 | Pause transfer, disconnect LN2 Dewar to refill it. |
| 1530 | MC(Cernox) = 128.5 K, Sorb = 170.2 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 628/698/(off scale) mbar, Level resistor = 1.177 kΩ |
| 1530 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 41.1 mbar/min. Open V12b speedivalve again. |
| 1605 | MC(Cernox) = 108.3 K, Sorb = 150.1 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 611/680/(off scale) mbar, Level resistor = 1.172 kΩ |
| 1605 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 41.0 mbar/min. Open V12b speedivalve again. |
| 1615 | Restart LN2 transfer with freshly filled Dewar |
| 1625 | MC(Cernox) = 100.4 K, Sorb = 144.9 K, IVC = 1.9 mbar, G2/G1/P1 (circulation) = 603/671/(off scale) mbar, Level resistor = 1.267 kΩ |
| 1625 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 39.3 mbar/min. Open V12b speedivalve again. |
| 1645 | MC(Cernox) = 93.6 K, Sorb = 134.2 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 593/659/(off scale) mbar, Level resistor = 1.284 kΩ |
| 1705 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 33.2 mbar/min. Open V12b speedivalve again. |
| 1708 | MC(Cernox) = 88.4 K, Sorb = 127.8 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 585/649/(off scale) mbar, Level resistor = 1.292 kΩ |
| 1730 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 26.7 mbar/min. Open V12b speedivalve again. Seems like we're losing throughput. |
| 1736 | MC(Cernox) = 84.1 K, Sorb = 123.7 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 575/639/(off scale) mbar, Level resistor = 1.302 kΩ |
| 1745 | MC(Cernox) = 83.0 K, Sorb = 122.8 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 572/636/(off scale) mbar, Level resistor = 1.305 kΩ |
| 1746 | Stop LN2 transfer. Put Ping-pong ball on MB exhaust port. Close V6 and stop circulation pump. |