Electron beam measurement technologies and techniques in free electron lasers

Measurement techniques for electron-beam parameters are reviewed. The development of a variety of diagnostic methods to characterize the electron beam from an RF linear accelerator, which is used to drive in a free-electron laser (FEL), is summarized. The FEL´s electron-beam length is in the microsecond range and consists of many picosecond micropulses separated by nanoseconds. This extreme range of time scale requires complex measurement systems. The focus is on electron spectrum and emittance measurement techniques