...

• The magnet already contains LHe, i.e. the magnet LHe level > 0%.
• The fridge valves (i.e. run and bypass valves) are fully closed.
• You can access and control the QT HMI and the Cryo Control Panel (CCP).
• You can access the strip charts on the data-summary page, particularly these preset pages;
  
  • Transfer-Line Cool Down:  https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/cool_down.php
  • LHe Transfer:  https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/transfer.php

Tentative procedure for filling from two Dewars

1. You will see an alarm when Tank B at 4.6 K, at that time set the Dewar B pressure to 3psi and leave the Dewar A pressure as it is (6.5 psi).
2. Monitor the magnet level reaching the seam.
3. Switch the Magnet level probe to "CONT".
4. At right before the fill, open the run valve to 3 turns for 3 mins and put it back to 0.8 turns.
5. Start pre-cooling by opening VJVB.
6. When TX1 reaches ~100 K, then open Mag return bypass fully, open VJVT, and close VPC.
7. Switch the Dewar B to Manual mode and set FC501 B to 45slm, and monitor FMR.
8. Monitor until the Dewar B level reaches 12 L, and then open VJVA to pre-cool until it reaches 9 L.
9. Close VJVB. Now you are filling from A. Magnet Pressure may have a pressure spike. After the pressure spike set Dewar B to Manual mode and set FC501A to 45slm.
10. Switch LQ-B to Auto + Liquefy mode, and set the Dewar pressure back to 6.5 psi.
11. Adjust the flow to keep FMR below 480slm, PC1 below 1.1 psi, and magnet pressure below 2.5 psi.
12. At the end of the fill, Open VPC, Close VJVA, and VJVT.
13. Switch LQ-A to Auto + Liquefy mode, and set the Dewar pressure back to 6.5 psi.
14. Set the Magnet Bypass to pressure PID to 0.9 psi.
15. Switch the Magnet level probe back to "HOLD" mode.

Procedure for filling from a Single Dewar(Since 03/29/2024)

Note: Select the Dewar that you are going to use to fill (Liq should contain at least 200 L of Helium), and then change Dewar Set pressure to 3 psi at least 3 hours before the fill.

1. Change the liquefier mode to "Auto +Idle" mode, if it is not.
2. Download Magnet_LHe_Fill_Checklist.docx file, fill in all the "initial parameters" and get ready to fill the rest of the fields during the fill.
3. Start to cool down the transfer line by opening VJVA/B (ensure VPC is already opened). This is the start time of the transfer.
4. Wait until TX1  reaches ~100 K. While you are waiting, connect to the CCP and get ready to open the Magnet Return Bypass Valve when TX1 is ~100 K.
   Also note that you will have to perform Steps 5, 6, 7 relatively quickly.
   Meanwhile, ensure the mode of the other liquefier is on  "Auto+Idle". If not, set it to "Aut+Idle" mode. **
5. When TX1  is ~100 K, thenpress the "Full Open" button on "MagRetBypass_Main.vi" in CCP, to open the MagRetBypass valve fully, and wait until you can see it is fully open on CCP panel.
6. Open VJVT and close VPC.
7. Switch the liquefier that you are filling, to "Manual + Idle" mode, and open SV501 solenoid valve, and after that set FC501 to 45slm.
8. Monitor the pressure difference (between magnet and delivery Dewar) using the "LHe Transfer page", and ensure it keeps increasing towards 3.0 psi.
   Ensure the FMR value doesn't exceed 480slm (~470slm would be ideal) and if it is increasing above 500slm, then reduce the "FC501" by a couple of 'slm' and continue to monitor.
9. Once the pressure difference reaches ~3.0 psi, then reduce the flow on FC501 to 40slm, and continue to monitor using https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/transfer.php
10. You may need to reduce (increase) it if the pressure difference is increasing-faster (reducing) while monitoring the FMR.
11. Keep monitoring the fill parameters: Magnet level, Delivery Dewar level, Pressure difference, FMR
12. Maintain the pressure differential above 3 psi and below 3.3 psi, by adjusting FC501A/B if necessary (after setting FC501A/B to 40slm is usually smooth until the end of the fill, but pay attention in-case you have to change it)
13. Monitor everything, until the magnet level reaches 50%, and then observe a level-spike that confirms that you have filled the magnet up to the top level (145 L).
    In case you don't have enough liquid in the delivery dewar, you can stop before seeing the level-spike.
14. Open VPC,  Close VJVA/B.  Open VPC.  , Close VJVT.
    
    1. This is the end time of the transfer.  Record the time, the magnet level, and the Liq level.
15. Enable the auto control of the MagRetBypass valve.  Change the set point to 0.9 psi.
16. Change the Liq mode to "Auto+ Liquefy" mode:
    1. Change the Dewar Set pressure to 6.5 psi.
    2. Set the outlet flow is 40 SLM. Note: you will need to pay attention to this Liquefier for the next ~1 hr until you change this to 2 slm step-by-step while monitoring the Dewar pressure (follow Steps #17, #18).
       If the Dewar pressure is keep increasing beyond the Set pressure (6.5 psi), then you will need to increase this outlet flow to 60slm. When you change this, always confirm on the Liquefier screen's FCA/B whether it's flowing what you set to. If not, you will have to quickly press "Idle" button and then press "Liquefy" button immediately after.
    3. The Liquefier Compressors' coldhead heaters should be OFF, but it's better to confirm that on the "Helium Compressors" screen.
       If they are ON, please turn them off one-by-one (double tap/click on each button for heaters).
    4. If you change the mode of the other liquefier in step #4, then change it back to Liquefy mode.
17. Wait until the Liquefier's Dewar pressure (PT503) gets slightly below 6.5 psi, and then check the actual inlet flow (FC501 A/B I) to the liquefier is above 40 SLM (FC501 A/B Q will be 60 slm).
    This indicates that you can change the Outlet Flow Set point to a lower value like 30slm (follow the next steps over the next ~40 mins).
    Note: Ensure the Dewar pressure doesn't go above 9 psig. If it is rising, you should change the Outlet Flow Set point to 60slm and wait until the Dewar pressure is between 6-7 psi.
18. Repeat step #17 with outlet flows = 20, 10, 5slm, and and then to 2 SLM when the cold-head temperatures are below 5.5 K.
19. Confirm that the Liq pressure stays around the set point (6.5 slm).
20. Calculate the transfer efficiency using initial and final levels in the magnet and the Liquefier Dewar.
21.  Post the filled Magnet_LHe_Fill_Checklist.docx file on uva-elog including the date of the fill as part of the file name (for example: Magnet_LHe_Fill_Checklist_03-29-2024.docx or .pdf file)
    If you don't have access to the uva-elog, then please send this file to the Target Expert on shift.

...