Design considerations for submillimeter-wave reflex klystrons

The problems facing the development of klystrons for use at submillimeter wavelengths are reviewed. Analytical formulas for reentrant cavity resonance, starting conditions, output power, and oscillation buildup are presented. This paper describes methods of calculating cavity Q-factor, output coupling, focusing potentials, electron paths, and heating effects. The scaling of output power with frequency is derived. Examples of techniques that might be used to realize a working device are presented.