Generation of millimeter waves with a racetrack microtron

A 6-MeV racetrack microtron has been used to generate millimeter radiation with a Fabry-Perot radiator having no dielectric medium. The electron beam is injected at an angle to the axis of the Fabry-Perot in order to achieve interaction with the transverse electric field in the cavity. Radiation is coupled out of the cavity in the zero order of a reflection grating used as one end plate. Radiation resistances of the order of one kilohm are obtained at 4 mm. A corresponding submillimeter design is shown.