2019/09/20 (Friday)
| Status: IVC sealed and pumping overnight. Have cryocleaned mixture 11 times so far. Mixture open to both cold LN2 traps. | |
| 0850 | Turbo pumping pressure on IVC = 140 nbar. With pump valve out, IVC = 7.4 ubar (after several minutes). |
| 0855 | Fill LN2 cold trap bath |
| 0900 | Pump mixture from cold LN2 Traps 1&2 to dump. |
| 1015 | Our Pfeiffer leak detector forepump was rebuilt this summer, but when we finally tried to start it again it does not turn. Trying to run the leak detector with the scroll pump used as the forepump now. |
| 1040 | Start pumping IVC with leak detector (LD), valve out turbo pump. Leak settles around 5 pbarL/s. |
| 1100 | Leak check passed, no sudden increases in leak rate during He spray test. |
| 1150 | Check warm LN2 Cold Trap 1: 6.3 mbar. Pump out trap with scroll pump. |
| 1200 | Check warm LN2 Cold Trap 2: 2.7 mbar. Pump out trap with scroll pump. |
| 1200 | Removed 6.3 mbar from Trap 1 after overnight passive mixture cleaning. Removed 2.7 mbar from Trap 2 after overnight passive mixture cleaning. |
| 1210 | Check fridge pressures: LHe trap/Condenser/Still = 3.0/0.2/0.068 mbar. Pump out with scroll pump. |
| 1230 | Raise main bath |
| 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
| 1240 | Perform mixture throughput test at MC = 300 K using above procedure with 3He pump off. Let G1 rise to 525 mbar before Step 3, then it falls to 37 mbar and starts to rise. Throughput = 5.4 mbar/min. |
|---|---|
| 1250 | 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. |
| 1305 | Close off scroll pump, then pressurized bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar. |
| 1310 | Close off scroll pump, then pressurized bath and 1K Pot (both sides) to about 0.5 bar with helium. Then pump it out again with scroll pump to < 1 mbar. |
| 1325 | Pressurize main bath and 1K Pot (both sides) with helium to 300 mbar +1atm on G3, then close 1K Pot speedivalve and needle valve. |
| 1330 | Turbo on IVC = 120 nbar. With turbo valved out for a few minutes, IVC = 4.6 ubar. |
| 1335 | Let 5.4 mbar He exchange gas into IVC |
| 1345 | As on 2019 May 18 during last run (Run 70), we will flow mixture through the fridge during LN2 cooldown. Dump is open to cold LN2 Trap 2 and fridge: V9, V13b, V12b+speedi, V1, Condenser speedi, Still gate valves open. Turn on 3He pump. Now open V6 to 12.8%. |
| 1350 | Circulation pressures settle to G2/G1/P1 = 654/723/0.45 mbar |
| 1350 | MC(Cernox) = 299.0 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 655/723/0.3 mbar, Level resistor = 0.995 kΩ |
| 1400 | Begin LN2 transfer |
| 1405 | MC(Cernox) = 297.9 K, Sorb = >249 K (max), IVC = 4.6 mbar, G2/G1/P1 (circulation) = 657/726/1.5 mbar, Level resistor = 1.099 kΩ |
| 1410 | MC(Cernox) = 293.0 K, Sorb = >249 K (max), IVC = 4.6 mbar, G2/G1/P1 (circulation) = 658/726/2.6 mbar, Level resistor = 1.140 kΩ |
| 1415 | Close V12b speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 12.9 mbar/min. Open V12b speedivalve again. |
| 1420 | MC(Cernox) = 276.5 K, Sorb = >249 K (max), IVC = 3.4 mbar, G2/G1/P1 (circulation) = 658/726/4.5 mbar, Level resistor = 1.230 kΩ |
| 1430 | MC(Cernox) = 247.3 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 659/725/8.0 mbar, Level resistor = 1.232 kΩ |
| 1430 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 16.0 mbar/min. Open V12b speedivalve again. |
| 1445 | MC(Cernox) = 203.0 K, Sorb = >249 K (max), IVC = 3.0 mbar, G2/G1/P1 (circulation) = 658/725/50.0 mbar, Level resistor = 1.186 kΩ |
| LN2 Dewar has run dry. I guess that's why the Level Resistor resistance got lower. | |
| 1455 | MC(Cernox) = 181.9 K, Sorb = 236 K, IVC = 3.0 mbar, G2/G1/P1 (circulation) = 657/723/(off scale) mbar, Level resistor = 1.185 kΩ |
| 1500 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 30.2 mbar/min. Open V12b speedivalve again. |
| 1505 | MC(Cernox) = 168.6 K, Sorb = 216 K, IVC = 2.2 mbar, G2/G1 (circulation) = 657/722 mbar, Level resistor = 1.184 kΩ |
| 1530 | MC(Cernox) = 141.5 K, Sorb = 181 K, IVC = 1.9 mbar, G2/G1 (circulation) = 651/716 mbar, Level resistor = 1.185 kΩ |
| 1545 | MC(Cernox) = 130.5 K, Sorb = 171 K, IVC = 1.9 mbar, G2/G1 (circulation) = 647/711 mbar, Level resistor = 1.186 kΩ |
| 1600 | Restart LN2 transfer with freshly filled Dewar Sorb temperature starts falling faster. |
| 1615 | MC(Cernox) = 113.3 K, Sorb = 148 K, IVC = 1.6 mbar, G2/G1 (circulation) = 637/698 mbar, Level resistor = 1.352 kΩ |
| 1625 | Close V12b speedivalve for 2 minutes to assess throughput. G1 falls at 45.3 mbar/min. Open V12b speedivalve again. |
| 1640 | MC(Cernox) = 101.9 K, Sorb = 125 K, IVC = 1.6 mbar, G2/G1 (circulation) = 624/684 mbar, Level resistor = 1.352 kΩ |
| 1640 | Stop LN2 transfer. |
| 1650 | Close V6 to stop circulating mixture. Turn off 3He pump. |