Orbit Feedback using X-ray Beam Position Monitoring at the Advanced Photon Source

Abstract

The Advanced Photon Source (APS) was commissioned in 1995 as a third-generation x-ray user facility. At that time orbit control was performed exclusively with broadband rf beam position monitors (BPMs). Since then, emphasis has been placed on incorporating x-ray beam position monitors into the orbit control algorithms. This has resulted in an order of magnitude improvement in long-term beam stability vertically, using x-ray BPMs (X-BPMs) on bending magnet beamlines. Additional processing will allow similar improvements horizontally, once systematic effects associated with variable insertion device (ID) x-ray beams are properly compensated. Progress to date and upgrade plans will be presented, with an emphasis on the details of the required digital signal processing.