Design of a millimeter-wavelength FEL experiment employing a large diameter electron beam and a quasioptical cavity

Abstract Hardware is being developed for a free electron laser experiment that will test the first stage of a quasioptical design concept for a two-stage FEL. A unique feature of this experiment is the excitation of a TE 01 cylindrical waveguide mode using a large-diameter electron beam in a helical wiggler. A permanent-magnet helical wiggler is being developed for the experiment. The experimental system is described and the results of magnet design, electron orbit, and radiation calculations are presented.