2016/07/12 (Tuesday)
| Status | Cooling to 77K overnight. Leaving mixture in fridge. Yesterday there was throughput at <200 K. |
|---|---|
| 0815 | MC(Cernox) = 78 K, Sorb = 127 K (slowly increasing), IVC = 0.86 mbar. G1/G2 = 647/603 mbar |
| Strangely P2 increased overnight, now reading 1000 mbar. Pump this out with 4He pump. | |
| 0830 | Begin blowing out LN2 from MB, into LN2 cold trap bath. Did not bother to pump out IVC for leak checking, we've already checked. |
| 0835 | Adjust He cylinder regulator to get G3 (MB pressure) down to 325 mbar. |
| Currently the Still gate valve, Condenser speedivalve, V1, V12a+speedivalve, and V13a are open, 3He pump is off. So mixture is open from dump to pump and through cold trap 1 to the condenser and through to the still pumping line. | |
| 0845 | Close V13a and turn on 3He pump. Then open V6 to 14%. We are now pumping on the still side of the fridge to dump to test throughput - condenser side pressure should start to decrease. |
| 0850 | G1 (condenser) = 630 mbar and falling at -6 mbar/min. Looks like throughput. |
| 0855 | Stop LN2 blowout, hose is limp |
| 0905 | Begin pumping on MB with scroll pump. |
| note of interest: P2 falls below the maximum 1000 mbar value when the mechanical gauge on the recovery reads about 1/3 bar. | |
| 0920 | after about 11 minutes of pumping on the MB, P2 has fallen only to 45 mbar, with the mechanical MB gauge at ~130 mbar. Probably there is still LN2 in the bath… |
| 0925 | Fill MB with He gas, reseat the transfer tube in the funnel, then restart LN2 blowout. |
| 1020 | Cease LN2 blowout again. Hose is limp and G3 reads only ~65mbar overpressure. Commence pumping out Main Bath with scroll pump. |
| 1025 | Fill LN2 cold trap full. |
| 1110 | We're still pumping the mixture out of the still to the dump. G1(condenser) has been falling steadily, now 211 mbar |
| 1115 | Close V6. P1 (still) pressure starts to increase as the still side is filled from the condenser side. |
| 1117 | Open V5 to pump condenser and trap 1 contents to dump |
| 1130 | Cease pumping out Main Bath (P2 below 0.5mbar). Pump out 1K Pot, then backfill with He gas. Flush Main Bath with He gas in preparation for LHe transfer. |
| 1130 | Close V12a+speedivalve, open V6 to 16%. Now pumping fridge to dump from both condenser and still sides (V1 and V5 are open). Dump (G2) = 795.0 mbar |
| 1140 | Perform reverse throughput test with following procedure: |
- All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
- Close V12a and V3, open V1
- monitor G1
| 1145 | Throughput looks good. G1 reaches maximum of 620 mbar before Step 3, then falls to minimum of 90 mbar, then rises at 50 mbar/min |
|---|---|
| 1210 | Turbopump IVC exchange gas down from 860 μbar to 46 μbar |
| 1249 | Commence LHe transfer (-1%) |
| 1310 | Sorb = 140.5 K, starts to fall. |
| 1315 | MC(Cernox) = 79 K, Sorb = 139 K, IVC = 46 μbar, G1= 598 mbar |
| note | Still and Condenser valves have been left open since throughput test, V1 is also open. So there is some mix sitting in fridge, the rest is in the dump and Trap 1 and the pump (V13a and V9 open, 3He pump off). |
| 1320 | Open V3 so both sides of fridge are open to G1. G1 goes up somewhat. |
| 1335 | MC(Cernox) = 75 K, Sorb = 120 K, IVC = 14 μbar, G1= 569 mbar |
| 1345 | MC(Cernox) = 70 K, Sorb = 99 K, IVC = 12 μbar, G1= 511 mbar |
| 1355 | MC(Cernox) = 65 K, Sorb = 77 K, IVC = 10 μbar, G1= 427 mbar |
| 1435 | MC(Cernox) = 48 K, Sorb = 7.5 K, IVC = 5.4 μbar, G1= 239 mbar (leveling) |
| 1440 | MC(Cernox) = 45 K, Sorb = 7.4 K, IVC = 5.4 μbar, G1= 236 mbar, MB = 4.5% |
| 1510 | MC(Cernox) = 33 K, Sorb = 6.9 K, IVC = 1.4 μbar, G1= 231 mbar, MB = 14.9% |
| 1545 | MC(Cernox) = 16 K, Sorb = 6.4 K, IVC = 0.74 μbar, G1= 222 mbar, MB = 33.9% |
| 1600 | MC(Cernox) = 14 K, Sorb = 6.3 K, IVC = 0.63 μbar, G1= 216 mbar, MB = 45.5% |
| 1630 | MC(Cernox) = 10.6 K, Sorb = 6.2 K, IVC = 0.46 μbar, G1= 211 mbar, MB = 76.5% |
| 1637 | MC(Cernox) = 10.1K, commence turbopumping out IVC. |
| 1648 | End LHe transfer (92.7%). Since the He recovery system has been fixed, we will experiment with not letting pressure out of the Main Bath to see if our hold time is unaffected. |
| 1650 | Fill LN2 cold trap full. |
| 1710 | Top off HPGe crystal dewar (weighed 41 kg this morning). |
| Place Cf source on fridge for overnight activation. |