The BAF octupole magnets are 50cm long with a 8.125" (206mm) aperture to accomodate the 8" beampipe. The Opera-3D simulation of the octupole magnet as designed yields a very pure octupole field. A particular feature of the design is the relatively small cross section of the magnet coils, see the 2D-flux pattern. This design minimizes saturation effects in the steel and thus improves the field quality, while still providing sufficient field integral for the highest momentum beam transported down the beamline. The harmonic field analysis of the field measurements in one of the octupole magnets show that the design goal for higher multipoles, < 0.5% at 3" (7.6mm) radius, was easily met (note that the measurements were done at a radius of 3.125"). 


Magnet characteristics: