Real time harmonic closed orbit correction

Abstract We discuss several schemes for improving the stability of the closed orbit, by implementing a feedback system based upon harmonic analysis of both the orbit movements and the correction magnetic fields. The harmonic feedback system corrects the Fourier components of the orbit nearest to the betatron tune. Such a system may provide a significant improvement in orbit stability for all beamlines, using simpler electronics than required for an array of local bump feedback systems. Experiments based upon these schemes are in progress at the NSLS.