ANALYSIS OF THE BEAM BUNCHING PRODUCED BY A FREE-ELECTRON LASER

A high-power microwave Free Electron Laser (FEL) experiment has been p erformed to study the inherent electron beam bunching that occurs in t he FEL interaction. An induction linac delivered a 1 kA, 2.2 MeV elect ron beam to a FEL amplifier. In the process of amplifying the input si gnal of frequency 35 GHz to power levels of the order of 10 MW, the el ectron beam was bunched by the ponderomotive force. In this paper we d escribe the FEL experiment and the optical technique that was used to observe the bunches. Their properties as functions of the basic FEL pa rameters are discussed. (C) 1996 American Institute of Physics.