Design and Measurement of the Sextupole Magnet for the APS Storage Ring

L.R. Turner, K.M. Thompson, S.H. Kim, K. Kim
Advanced Photon Source, Argonne National Laboratory

A prototype sextupole magnet has been designed, constructed, and measured for the storage ring of the Advanced Photon Source. The design approaches very closely to 120° rotation symmetry, in order to minimize all forbidden multipole components. The core is made of three identical stacks of laminations, each lamination consisting of two poles and the return yoke joining them. The antechamber of the thick aluminum vacuum chamber fits between two neighboring stacks. Computations and measurements of the sextupole strength B and multipole field components, both in the central region and integrated in the beam direction, show that the magnet meets the requirements for positron beam dynamics

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