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In this mode, the fridge level should be maintained above the 'Heat Exchanger Bottom' (see the Purple curve on the top-left graph of the screenshot below), and the separator is kept at cold with 20slm return flow. IMPORTANT: If you see the Heat-Ex Top resistance (purple curve) starts increasing, then reduce the number of turns on the fridge run-valve using the "Fridge Valve Panel" VI on the CCP


If the system is currently on Hold Mode, then you can follow the steps for Transitioning from the Hold mode to the Production Mode


Configuration / Things to maintain

MicrowavesON . (link a page with see Microwave Operation page for instructions how to adjust/control specifically for this modemaintain the polarization)
NMRTaking Data
FridgeAll roots pumps are running
Adjust fridge RUN/Bypass valve to keep the fridge LHe level
It should be on "Take Data" (check with the Target Expert on Shift if there are issues)
Fridge
  • The entire pump system should be running
    See Roots pumps PLC interface page
  • Maintain the fridge LHe level at the Heat-Ex Bottom by adjusting the fridge-run-valve. 
    See these links
    (a) Fridge Fill Procedure (you will have to plan ahead of time to set the separator flow to 20slm 30 mins before you expect to fill the fridge)
    (b) How to identify the fridge LHe level is at Heat-Ex Bottom
  • The fridge pressure should be below 1 Torr because all roots should be ON
MagnetEnsure the magnet has enough LHe
  • .
  • Discuss with the Target Expert when
to implement Switching from
MagnetEnsure the magnet has enough LHe.
Ensure Magnet LN2 level is above 50%, if not refill it.
QT System
  • Ensure the purifier LN2 level
is
  • and the magnet shield LN2 levels are above 50%, if not refill it.
    See Helium Liquefier (QT) System Summary page to identify where to look at for those LN2 levels.
  • Ensure both liquefiers
are producing
  • produce LHe with the rate of ~ 4 L/ hr (with an uncertainty +/- 0.3). If not, then contact the Target Expert on shift. You can use https://e906-gat1.fnal.gov/data-summary/e1039/target-par-preset/target-LHe-prod-rate.php
  • Check LCW outlet Temperatures from the cold-head compressors and ensure all those temperatures are below  95 F. If any of those are. > 100 F then, report to the Target Expert immediately and follow Target Expert's instructions.



Outlet Flows


Outlet Flow (in slm)Run Valve / Bypass ValveHow to check and control
Fridge       Nominal 45slm
(depends on the microwave power + beam)		Fridge Run valve → 1 turn0.5 turns
Bypass valve → CLOSED		How to control the Fridge Return flow
Separator       20 N/AHow to control the Separator Return flow
Magnet     ~7 (on pressure PID at 0.9 psi)N/A(link to a page)


Other useful instructions:

Steps for Transitioning from the Production Mode to the Hold Mode


A sample screenshot of the fridge in the Production Mode







################# I think the links below are too much information for the Target Operator manual, can be suitable for the target expert manual ####

Conditions:

  1. Fridge parameters & valve positions when the fridge is in Production Mode
  2. QT system conditions when the fridge is in Production Mode
  3. Magnet conditions when the fridge is in Production Mode
  4. Cryo-control (CCP) parameters / conditions when the fridge is in Production Mode
  5. Microwave parameters / conditions when the fridge is in Production Mode
  6. Target Lifter conditions when the fridge is in Production Mode
  7. UVA-NMR conditions when the fridge is in Production Mode