220GHz High Power Terahertz Wave Generation Based on Miniaturized Vacuum Cerenkov Device

New micromachining techniques now provide the technology to fabricate vacuum electron devices with dimensions suitable for operation in terahertz region. In this paper, results of theoretical and numerical simulation studies of a MW-class, large diameter terahertz wave generator based on the Cerenkov principle are presented. The device consists of a miniaturized foilless diode as well as an oversized rectangular slow wave structure (SWS) which could support surface wave and provide a strong beam-wave coupling. With the method of Particle-in-cell simulation, we investigated the operating characteristics of a prototype 0.22 THz oscillator. It is found that the steady-state, single-frequency operation in the overmoded situation could be realized by the property of surface wave, and the unique voltage tunable capability proves that the device performs as a forward wave oscillator.