System Condition

• The insulation vacuum of the magnet has been pumped down for multiple days and the vacuum level is below 8x10⁻⁶ Torr
• The U-Tube connection between the magnet and the fridge is installed and pumped down to below 1x10⁻³ Torr
• The QT transfer line and all 3 stingers, Dewars and cold boxes have been pumped down to below 1x10⁻³ Torr
• QT transfer line stinger is installed on the north riser of the magnet
• Both QT dewars are full
• Magnet is backfilled and magnet pressure is above the atmosphere
• Magnet shield is filled with LN2: If not, then follow Filling Magnet Shield with LN2
• Purity of the system (after roots, outside tank, inlet of HR3, magnet return) is close (within 0.03%) to to reference (100.43%)

Training: No special training is needed.

PPE:   Not needed

Risks: No Identified Safety Risks

Initial valve positions

Action needed before 1 hour

• Select a QT dewar to start the cooldown
• Bring the dewar pressure to 5 psi
• Note: This document will start the cooldown from the QT dewar A.

The following parameters should be monitored throughout the procedure

• Magnet pressure (Select PTMR3)
• Magnet bypass return flow (Select MagRetBypas Return)
• QT dewar levels
• QT dewar pressures
• Coil T, Coil B, Tank T, Tank B

Procedure

Cooling phase

1. Start the transfer from QT deawar A and monitor the magnet pressure
   • Open VJVA
   • Open VJVT
   • Close VPC
2. Change the mode to Liquify if needed.
3. When the magnet pressure reaches 5 psig, set the magnet return bypass valve to Auto Control with Flow and change the set point to 35 SLM.
4. It should maintain the following conditions in the magnet.
5. Maintain the magnet bypass return flow at 35 SLM.
6. Magnet pressure < 5 psi
7. Maintain the above magnet condition approximately for 5 days until the Coil T and Coil B temperatures reach ~40 K.
   
   

Fast Cooling and Filling phase

1. Turn off the Auto Control with Flow in the magnet return bypass valve level to the Full Open setting. Now the liquid is filling in at a higher flow rate.
2. Keep monitoring the magnet pressure, Coil T and Coil B temperature, and liquid level of the QT dewar.
3. Stop the fill if the level reaches ~45% (Magnet level will be full at 45% of the level probe) or any sudden change occurs during the transfer indicating a problem.
   • Open VPC
   • Close VJVT
   • Close VJV(A/B)
     
     
4. Set the magnet return bypass valve to Auto Control with PTMR3 and change the set value to 1 psig
5. Keep monitoring the magnet liquid level over time.