UMN CDMS Wiki archive
start › cdms › k100 › run_diary › 20220318

2022/03/18 (Friday)

Previous Day

  • Lab in-personnel: Giulia, Matt
Status Run 76 beginning. First LN2 transfer revealed IVC leak (used wrong indium wire). Redid seal yesterday, also fixed broken source mover connection. Pumping out cryostat vacuum jacket overnight and IVC in parallel overnight. MC and Still heaters are on.
0840 Turn off MC and Still heaters (should have done that earlier)
1020 Turbo on CVJ+IVC = 74 nbar.
1035 With Turbo valved out for 1 minute (and IVC isolated), CVJ = 740 nbar
1040 With Turbo valved out for 1 minute (and CVJ isolated), IVC = 740 nbar
1050 Check contents of warm LN2 Trap 1, then pump out with scroll pump. 0.7→2.6→1.7 mbar.
1055 Check contents of warm LN2 Trap 2, then pump out with scroll pump. 0.5→5.6→1.9 mbar.
1100 Check fridge pressures: LHe trap/Condenser/Still = 1.0/0.0/0.005 mbar. Pump out with scroll pump.
Throughput test procedure, Cold Trap 1:
  1. All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
  2. Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2.
  3. Close V12a+speedivalve and V3, open V1
  4. monitor G1
1135 Perform mixture throughput test at MC = 300 K using above procedure with 3He pump on. Let G1 rise to 538 mbar before Step 3, then it falls to 42 mbar and starts to rise. Throughput = 6.1 mbar/min.
1140 Check pressure in 1K Pot: 8.5 mbar on P2, 0.0 atm on mechanical gauge. Pump out with Scroll Pump
1235 With 1K Pot speedivalve and needle valve closed, pump on Main Bath with scroll pump. Once P2 < 2 mbar, open 1K Pot speedivalve and needle valve (5 turns) to pump out 1K pot volume to < 1 mbar on P2.
1240 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.
1245 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.
1250 Pressurize main bath and 1K Pot (both sides) with helium to 475 mbar+1atm on G3, then close 1K Pot speedivalve and needle valve.
1250 As on 2022 Mar 14, we will flow mixture through the fridge during LN2 cooldown. Let mixture from dump through cold LN2 Trap 1 to fridge, both sides. Then 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. Open V6 to 12.6%.
1300 P1(Condenser) → 0.08 mbar.
1300 Try closing V12a speedivalve. G1 falls as it should, showing we have throughput. Falls at 10.8 mbar/min. Open V12a speedivalve again.
1300 Turbo on CVJ+IVC = 63 nbar. Close CVJ valve. Note: we'll keep the hose connected to the CVJ for now.
1305 With Turbo valved out for 1 minute, IVC = 630 nbar
1305 Let 5.4 mbar He exchange gas into IVC.
1310 MC(Cernox) = 295.5 K, Sorb = >249 K (max), IVC = 5.4 mbar, G2/G1/P1 (circulation) = 669/737/0.11 mbar, Level resistor = 0.981 kΩ.
1315 Begin LN2 transfer. Dewar pressure is very low (we just filled it today…) so we'll have to pressurize it.
1315 Start pressurizing N2 Dewar with N2 gas from the wall. Gauge on Dewar reads around 8.0 PSI. Gauge on N2 cylinder regulator = 8.7 PSI.
1330 Transfer seems slow. Increase N2 regulator pressure → 10.0 PSI. Gauge on Dewar → 9.8 PSI.
1400 MC(Cernox) = 261 K, Sorb = >249 K (max), IVC = 4.0 mbar, G2/G1/P1 (circulation) = 676/736/0.22 mbar, Level resistor = 1.025 kΩ.
1400 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 14.7 mbar/min. Open V12a speedivalve again.
1430 MC(Cernox) = 192 K, Sorb = >249 K (max), IVC = 2.5 mbar, G2/G1/P1 (circulation) = 673/736/0.40 mbar, Level resistor = 1.135 kΩ.
1430 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at ~22 mbar/min. Open V12a speedivalve again.
1500 MC(Cernox) = 140 K, Sorb = 225.5 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 673/735/1.6 mbar, Level resistor = 1.273 kΩ.
1500 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 39.9 mbar/min. Open V12a speedivalve again.
1530 MC(Cernox) = 117 K, Sorb = 161.4 K, IVC = 2.2 mbar, G2/G1/P1 (circulation) = 673/734/3.4 mbar, Level resistor = 1.307 kΩ.
1530 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 51.5 mbar/min. Open V12a speedivalve again.
1600 MC(Cernox) = 101 K, Sorb = 133.0 K, IVC = 1.6 mbar, G2/G1/P1 (circulation) = 673/734/4.5 mbar, Level resistor = 1.324 kΩ.
1600 Close V12a speedivalve for 2 minutes to assess throughput. (Condenser pressure G1 should fall.) G1 falls at 60.0 mbar/min. Open V12a speedivalve again.
1610 Stop LN2 transfer. Close LN2 Dewar valves. Pull out Level Resistor and put stopper in port. Put ping-pong ball on MB exhaust port.
1615 Close V6 and turn off 3He pump.
1625 Electrical check on all 3 cables @ MC(Cernox) = 93 K. All look good!
At this temperature some interchannel resistances are readable, ~ 10 MOhm. Others read open. No logical pattern really for which ones are open.
1715 MC(Cernox)/Sorb = 82.9/123.4 K
1325 Finish soldering Coldplate thermometer wires to new Dsub-25 connector (Channel 3). Test with the new LakeShore scanner - it's reading, good.
1445 Finish soldering Still thermometer wires to new Dsub-25 connector (Channel 1). Test with the new LakeShore scanner - it's reading, good.
1515 Cover ends of unused wires with electrical tape. As noted before, some of these probably lead to Sorb and 1KPot thermometers and Still and MC heaters. Don't want to short them.
1545 As on the previous cable, solder ground straps between outer cable shield and connector chassis.
2230 MC(Cernox) = 77.2 K. It's been pretty flat since 1900.
2230 IVC = 1.6 mbar. Start pumping out IVC with scroll pump. At 0.1 mbar switch to turbo pump.

Next Day