High temporal resolution, single-shot electron bunch-length measurements

Abstract

A new technique combining the electro-optic detection method of the Coulomb field of an electron bunch with the single-shot cross-correlation of optical pulses is used to provide the single-shot measurements of the shape and length of sub-picosecond electron bunches. That technique has been applied at the Free Electron Laser for Infrared eXperiments (FELIX) facility for free-electron laser (FEL) showing bunches of around 600 fs, where the resolution is limited primarily by the electro-optic (EO) crystal thickness and the relatively low γ of the electrons. X-ray FELs require dense, relativistic electron bunches with bunch lengths significantly shorter than a picosecond. For operating and tuning those lasers, advanced electron bunch length monitors with sub-picosecond temporal resolution are essential. Ideally, non-destructive and non-intrusive monitoring of a single electron bunch should be available in real-time. A promising candidate for such monitors, and the subject of an on-going research and development project at the FELIX facility, is the determination of the electron bunch longitudinal-profile via electro-optic detection of the co-propagating Coulomb field. This chapter presents the results of the first application of the cross-correlator technique to longitudinal-profile electron bunch characterization.