Dielectric slow-wave structures for the generation of power at millimeter and submillimeter wavelengths

Several new types of coupling structures, designed to extract energy from a megavolt electron beam at a harmonic of the frequency used to modulate the beam current, are considered. In particular, the advantages of a slow-wave device over a right cylindrical cavity are indicated. The slow-wave coupling device may be resonant or nonresonant; the latter corresponds to a Cerenkov radiator. Power measurements at the twelfth harmonic of the fundamental modulating frequency provide good correlation with the theoretical power output expected. The design of a submillimeter coupling device is described, and the theoretical pulsed power obtainable is shown to be at the milliwatt level for a harmonic current density of 74 ma/cm².