A Free Electron Laser Experiment

An experiment has been performed in which microwaves are generated by the interaction of a helical magnetic wiggler field with an electron beam. This Free Electron Laser can be operated in either the stimulated Raman or stimulated Compton regime by changging the electron beam density. The high repetition rate, and long pulse length of the electron beam facilitate diagnostics and the characterization of the device. To date, the device has been operated in the superradiant and oscillator Raman scattering mode. Preliminary results show an increase of 20 db in the oscillator mode with respect to the superradiant mode. The variations in the spectrum with wiggler field amplitude and electron beam density are shown.