Free-electron laser beam instrumentation and diagnostics

Abstract

Beam instrumentation and diagnostics for FEL user facilities have to provide single-shot and shot-to-shot information about all relevant beam parameters such as beam charge, transmission, transverse beam position and profile as well as beam energy and energy spread, bunch compression, bunch length, and arrival time. The diagnostics systems have to be designed such that they support accelerator set-up and commissioning as well as user operation. Non-invasive monitors are used in beam-based feedbacks that stabilize the photon yield for user experiments. This article provides a layout of beam diagnostics for an FEL user facility and describes the technical realization of the most important beam instrumentation devices, including examples of the latest achievements.