SKEW HARMONICS SUPPRESSION IN ELECTROMAGNETS WITH APPLICATION TO THE ADVANCED LIGHT-SOURCE (ALS) STORAGE-RING CORRECTOR MAGNET DESIGN

An analytical expression for prediction of skew harmonics in an iron c ore combined function regular/skew dipole magnet due to arbitrarily po sitioned electromagnet coils is developed. A structured approach is pr esented for the suppression of an arbitrary number of harmonic compone nts to arbitrarily low values. Application of the analytical harmonic strength calculations coupled to the structured harmonic suppression a pproach is presented in the context of the design of the ALS storage r ing corrector magnets, where quadrupole, sextupole, and octupole skew harmonics were reduced to less than 1.0% of the skew dipole at the bea m aperture radius r = 3.0 cm.