Design of a Conic Helix Slow-Wave Structure for TWT BWO Immunity and High Efficiency

A serious problem that limits the peak power of the conventional helix TWT is represented by the oscillation of the backward wave (BWO) [1]–[4]. In this paper, a pseudo-periodic helix as a slow-wave structure aiming to improve the performance of conventional periodic helix X-band TWT in terms of electronic efficiency and immunity to backward wave oscillation (BWO) is designed. The simulation results of the pseudo-periodic interaction structure, carried out by CST studio 2019, are compared with the simulated parameters of a periodic helix TWTs. The TWT based on pseudo-periodic helix slow-wave structure (SWS) shows a BWO immunity increased by 5% points and an electronic efficiency increased by 4% points respect to the conventional helix TWT. Indeed, the conic helix TWT offers an outstanding combination of small size, light weight, good linearity, high reliability, large bandwidth, high efficiency, and high BWO immunity.