...
- In the 1st row and 1st column, the strip chart is related to the chip resistor, which we installed in different locations on the fridge. The purpose of these chip resistors is to track the level of liquid helium in the fridge. When the liquid is at a certain level, say Heat-Ex Bottom (Ohm), it should show 1400 or 1450 Ohm resistance. Usually, we fill the fridge to the Heat-Ex Top (Ohm) and leave it there. But, during a regular, sustainable polarization study, we must keep the Heat-Ex Bottom (Ohm) level.
- The strip chart in the first row and the second column relate to the fridge nose level (in percentage) and the two valves, the Run and Bypass valves, which we usually use to fill the fridge. We can use a Bypass valve when we have to fill the fridge quite quickly. But during sustainable polarization, to replenish the liquid level in the fridge, we have to use a Run valve to keep the level at Heat-Ex Bottom (Ohm).
- The strip chart in the first row and the third column is related to the total consumption or the boil-off at the cryostat. The Main (SLM) target parameter shows the evaporation from the fridge while filling it by opening the Run or Bypass valve. The Separator (SLM) target parameter shows the separator flow we are getting from the magnet reservoir via a U-tube to fill the fridge. The MagRetBypass (SLM) target parameter shows the boil-off from the magnet reservoir. The Total (SLM) shows the sum of the three target parameters.
- The strip chart in the second row and the first column are related to fridge pressure. The Fridge/1000 (Torr) target parameter shows the fridge pressure more accurately when it is above 100 torr. Still, the Fridge/100 (Torr) target parameter shows the fridge pressure more accurately when it is under 100 torr. Suppose the fridge pressure is above 100 torr. In that case, the Fridge/1000 (Torr) target parameter is reliable, and the fridge temperature to the Fridge/1000 (K) target parameter is in the second row and second column. Suppose the fridge pressure is under 100 torr. In that case, the Fridge/100 (Torr) target parameter is reliable, and the fridge temperature to the Fridge/100 (K) target parameter is in the second row and second column.
- The second row and third column show the CAD model of the fridge.
Please read the entire procedure first and then proceed to start filling the fridge:
Please follow the steps to fill the fridge:
...
13. Close the bypass valve.
a. Usually the software interlock sets it at 0.5 1 turns automatically.
b. Anyway you set it at 0.0 turns manually.
...
In the above picture, click on Point 1 top open the Fridge_Valve VI, according to Step 12, when the Heat-Ex Top resistor goes to 1400 Ohms the interlock becomes red and set the bypass valve at 0.5 1 turns automatically.
After that, you can fully close the bypass valve by inserting 0 at point 4 and press Enter.
...