[FFA_CEBAF_Collab] correction strength requirements

[Jay Benesch]

Colleagues, 

I vaguely remembered that no meeting is scheduled after waiting in the zoom room.   I was going to ask a question today: How much correction capability is required of the external "picture frame" aka Panofsky magnets?  I threw together a design with 23 cm square clear bore and low current density in the conductor, 1 A/mm^2.  Dipole 70 G.  Quad 5.5 G/cm aka 55 mT/m.  Current density could easily be increased to get 100 G, ~1% of permanent magnet dipole.  Quad is another matter.   What's a reasonable target?  

Bore is relatively large because there needs to be mounting and alignment gear for the permanent magnets inside it.  Even if the correctors are ~10 cm shorter than the permanent magnets (PM), so alignment is handled in 5 cm at each end, there will still need to be a rigid support under the PM within the corrector.   Likely a box beam of some sort for stiffness. 

Jay