Electron-beam position monitoring and feedback control in Duke Free-Electron Laser Facility

This paper addresses data acquisition and feedback control of electron-beam positions in the Duke University Free-Electron Laser Facility. The control system consists of a distributed system of VME-based hardware and processors connected through a network to host workstations. The host workstations provide graphical data presentation to the user and are also used for high-level supervisory control. The electron-beam profile is controlled by electromagnetic forces generated by passing currents through the coils of correction magnets distributed around the ring. A desired control objective is to move the stored electron beam to specific locations in the vacuum chamber and to stabilize the orbit in the presence of disturbances. The technical details of implementing the data acquisition and control scheme and their integration with the existing control system modules are presented along with experimental results