COHERENCE EFFECTS IN FEL RADIATION GENERATED BY SHORT ELECTRON BUNCHES

In the last few years there has been a growing interest in the study o f coherent radiation from short electron bunches. The possibility of r ealizing compact FEL devices in the far-infrared and millimeter wave r egions utilizing small to medium size radio-frequency (RF) accelerator s has stimulated a number of theoretical and experimental investigatio ns to clarify basic physics issues in this process. Coherent emission experiments will be reviewed in this paper. Measurements on the tempor al and spectral characteristics of the coherent emission from a single bunch and on the coherence between consecutive bunches will be presen ted along with an analysis of the influence of coherence on the dynami cs of the laser.