Nondestructive Diagnostics for Relativistic Picosecond Bunched Electron Beams

摘要

The duration and form of relativistic picosecond electron bunches in the DukeUniversity Mark III free electron laser have been nondestructively measured by monitoring the submillimeter radiation produced by the bunches as they pass by or through a rectangular waveguide. Unlike other methods, our technique produces negligible electron bunch perturbation and allows real time beam diagnostics to be performed simultaneously with free electron laser (FEL) operation. We have measured 2.l-ps full width at half maximum duration electron bunches, studied the effect of electron gun and FEL modifications on bunch duration, and observed electron bunch variations during bunch trains.