QW Wien quadrupoles (200 kV upgrade)

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JLab QW Air core quad

New Wien quadrupoles have been designed to operate at higher 200 kV energy but also with improved magnetic and mechanical design.

Design
Performance
Background
  • These quads are used to compensate the dipole focusing of the Wien filters.
  • There is one installed on the 6-way cross upstream/downstream of each Wien filter.
  • They were designed to fit on top of existing 6-way viewer cross (1.5" pipe w/ 2-3/4" flanges).
  • In order to maximize the field strength they were designed w/ as small an ID as possible 2-3/4". However, this means they're captured by the flanges which are welded on after the coils are assembled. We'd love to eliminate this, to have a quad coil that would pass over the 2-3/4" flange.
  • Their length is about 4.9", the length of the 6-way cross. They could be longer, however, the 6-way cross abuts an 8" zero-reducer flange on the Wien filter, so a longer coil could not be perfectly symmetric on the 6-way cross. But, that's OK. A great way to recover field strength, I guess.
Pre-existing drawings
QW info
  • Present operating limit is 3A
  • Field measurements may exist, need to look
  • Jay should have a model of the quads, a good starting place, here's info from him:
On 3/5/2020 2:42 PM, Jay Benesch wrote:
> IR of QW model 1.375".  Cross section 0.3" radial by 0.22" azimuthal. 
> 4.92" overall length.  35 AT in my 1A model, not 36 T.  0.55 G-cm 
> dipole, 22.57 G, both evaluated at 1 cm radius.  With 1 A and 36 T, 
> 23.21 G quadrupole at 1 cm radius.
What to consider in a new design?
  • Larger ID air-core quad that could fit over 2-3/4" flange
  • Longer quad to provide more field strength (required values under study; appears we need at least 33% increase over existing QW @ 3A)
  • Quads have to be bakeable to 250C; as they're still captured when vacuum assembly made-up before beam line bake out
  • Operate w/ <10 A idea, so can use existing trim cards (like those presently used)
Darmstadt triplet
B. Steiner et al., Recent Simulation Results of the Polarized Electron injector (SPIN) of the S-DALINAC [1] (media:200204_Triplet.pdf)
J. Benesch, Modeling the Darmstadt quad triplet JLAB-TN-19-025
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