Optimization of free electron laser performance by dispersion-based beam-tilt correction

Abstract

Free electron lasers in the X-ray regime require a good slice alignment along the electron bunch to achieve their best performance. A transverse beam slice shift reduces this alignment and spoils projected emittance and optics. Coherent synchrotron radiation specifically for over-compression and transverse wakefields are major contributors to this. In the case of the large-bandwidth operation, based on a strictly monotonic energy chirp of the bunch, the here introduced correction additionally enhances the spectral bandwidth of the FEL pulse. Well-defined leaking of dispersion at places with a strictly monotonic longitudinal phase space can compensate a beam tilt. This work presents a way to characterize the beam tilt as well as a method to correct for it within a linear accelerator with at least one high dispersive section with corrector magnets.