Digital orbit feedback control for SPEAR

A digital orbit feedback system is being developed for SPEAR to improve electron beam stability at photon beam sourcepoints. The first phase implementation of this system operates at 1 minute intervals and stabilizes the horizontal and vertical orbit position to 50 /spl mu/m RMS at beam position monitors. The vertical global system works in tandem with local 50 Hz analog photon beam steering systems to stabilize photon beam position and angle. We are now developing the second phase system which will execute a unified global/local, 30-50 Hz vertical orbit feedback algorithm digitally. In this paper, we discuss design and performance of orbit monitoring, signal processing, and orbit correction components for the digital feedback systems.