H-plane loaded and phase velocity tapered SWS for improved performance of TWT THz sources

摘要

The design optimization and simulation for high performance of two types of slow wave structures (SWS) for micro-electro-mechanical system (MEMS) terahertz (THz) sources are presented, e.g., THz staggered double vane (SDV) traveling wave tube (TWT) working at center frequency of 220 GHz, H-plane and E-plane loaded (HEL) rectangular TWT working at center frequency of 400 GHz. The structures are able to realize a larger interaction impedance, thereby resulting in higher gain and improved output power of the devices. To further enhance the energy transferring between the electron beam and THz wave, the maximum length of the interaction section can be extended using the phase velocity tapering technique, where the spent electron beam energy can be reused by resynchronizing the phase velocity of the THz signal with electron velocity at the second section of the TWT. As an achievement, improved power of more than 50% is achieved over the operated bandwidth for both designs. The designs have considered the LIGA fabrication for these vacuum MEMS THz sources.