ELSA, a Proposed Stretcher and Post Accelerator for the Bonn 2.5 GeV Electron Synchrotron

ELSA (Electron Stretcher and Accelerator) operates in two different modes. Up to the maximum energy of the synchrotron it works at a constant magnetic field. The electrons from the synchrotron which runs at 50 Hz repetition rate are injected, stored and ejected at a constant rate. In this operation mode the macroscopic duty cycle is 95% at least. In the case of post acceleration which is possible up to 3.5 GeV the duty cycle is reduced to 70%. The intensity in this operation mode is 6% of that in the stretcher mode. Higher intensities are available at lower duty cycle. ELSA mainly is designed to feed a tagged photon facility.