Hold Mode

In this mode, you will need to coordinate with the Target Expert on shift regarding the planned duration of time spent in this mode.
This mode will be alternated with the Production Mode during normal operations with microwaves to keep up with the LHe production from the QT system.

Configuration / Things to maintain

Microwaves	OFF
NMR	Usually, it should be on "Take Data" (check with the Target Expert on Shift)
Fridge	Only the Backing Pump (Rotary Vane pump) should be running, and the rest of the roots pumps should be OFF Maintain the fridge LHe level between 50% and Heat-Ex Bottom. In other words, let the fridge level drops down to 50% and then refill it up to Heat-Ex Bottom by opening the run-valve (then close it). The fridge pressure should be on PID control at 100 Torr (see the table below) Adjust the fridge RUN/Bypass valve between 0.5 turns (for a slow fill) or 2 turns (for a relatively quick fill), and close it when the fridge fill is complete and continue to monitor the fridge level and refill when the level reaches back to 50%. See this link: How to open/close the fridge run-valve
Magnet	Ensure the magnet has enough LHe. Discuss with the Target Expert when to implement Switching from Production Mode to Hold Mode Ensure Magnet LN2 level is above 50%, if not refill it.
QT System	Ensure the purifier LN2 level is above 50%, if not refill it. Ensure both liquefiers are producing LHe with the rate of ~ 4 L/ hr.

Outlet Flows

		How to check and control
Fridge	8 slm (should be on the PID controlled for maintaining 100 Torr by Auto Control with Pressure) →	How to control the Fridge Return flow
Separator	20 slm	How to control the Separator Return flow
Magnet	~7 (on pressure PID at 0.9 psi)	(link to a page)

Transitioning from the Hold mode to the Production Mode

Space shortcuts

Page tree

#################

Conditions