• Magnet Fill with Slow Pre-cooling

Pre-cooling:

1. Enable the Flow PID control of the Magnet Return Bypass at 65 slm.

2. Open VJVA/B,open VJVT and close VPC.

Note: Liquifier A/B should be on Liquify mode. If at the time of starting the slow pre-cooling the Liquifier A/B is on Idle mode, start the slow pre-cooling and when 4L are consumed on the Liquifier then change it to Liquify mode.

Proceed to fill the magnet anytime after the transfer lines are cold. The system is sufficiently cold once the Tank T temperature decreases after opening VJVT (about 4 hours). The figure below shows an example of the Tank T behavior during a slow pre-cooling.

Image Added

Filling:

1. Open the MagRetBypass valve fully by pressing the "Full Open" button on "MagRetBypass_Main.vi" in CCP and wait until you can see it is fully open on the CCP panel. The magnet pressure will start decreasing. The FMR will spike momentarily.

2. After the FMR has stabilized, set the Liquifier A/B to "Manual + Idle", open SV501A/B (inlet valve), and set FC501A/B at 45 SLM. Ensure the outlet valve SVNA/B is closed and the cold heads of the Liquifier are off.

3. When the magnet level reaches 48%, open VPC, close VJVA/B, close VJVT.

4. Set the Liquifier A/B back to "Auto+ Liquefy".

5. Enable the Pressure PID auto control of the MagRetBypass valve at 0.9 psi.

Post-filling:

Monitor the Liquifier A/B pressure until the cold-head temperatures are below 5.5 K and ensure the Liquifier A/B pressure doesn't go above 9 psi:

1. If the Liquifier A/B pressure rises, change the outlet Flow to 60slm on "Settings" and wait until the Dewar pressure is between 6-7 psi and the inlet flow is not zero.

2. Repeat step 1 reducing the flow by 10 slm until reaching 2 slm. If the pressure increases when the flow is reduced, change it back to the previous value.

Note: Always confirm on the Liquifier screen whether the outlet flow on FCA/B gives what you set it to. If not, press quickly the "Idle" button and then the "Liquefy" button immediately after.

Use this .docx file (download and edit) to collect data during the fill:  

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