...
We fill the fridge to Heat-Ex Top for the Cold Hold Mode and close the Run and Bypass valves. To reduce LHe consumption in the fridge nose, set the GV bypass opening at 8.1% at the lowest opening to keep the fridge pressure flat. Set the Separator flow at 11slm.
Keep monitoring the target parameters, say Insert#7, Insert #8, Annealing A, and Annealing B. Where Insert #7 and Insert# 8 are the Cernox (CX-1030) sensors on the Top and Bottom cup of the target insert. Where Annealing A and Annealing B are the metal temperature in the fridge, monitor these four target parameters. Where Insert#7 and Insert# 8 are in resistance (Ohm) and Annealing A and Annealing B are in temperature (K). Please see a screenshot below for these target parameters:
...
Below is the conversion table for the Cernox (CX-1030) from temperature resistance
...
.
- Run and Bypass valves are closed.
- Separator Flow set at 7slm
- The GV bypass can be set at 8% or fully open. It does not matter what the GV bypass opening is.
If you see the target parameters, Insert #7 and Insert #8 start lowering down to around 132 Ohms, which is around 50K, then open the Run valve at 0.55 or 0.65 turns to get the liquid in the fridge nose. Keep monitoring the resistance of sensors; it should start increasing after opening the Run valve. Wait for 30 minutes. If the temperature exceeds ~80K (lower than 101 Ohm), open the run valve at two turns, set the separator flow at 30slm, and call the target expert.
Please follow this page to put the fridge in the Cold Hold Mode: Cryo-control parameters / conditions when the fridge is in Hold Cold Mode - Wiki Post Portal - Confluence (virginia.edu)You can see the Fridge Parameters on the Strip Charts Fridge 2x3 (fnal.gov):