Multiphysics Characteristics of a 600 W Broadband Ka-Band Pseudo-Periodic Helix Traveling Wave Tube

A pseudo-periodic helix slow wave structure (SWS) is proposed to provide high output power with wide bandwidth in Ka-band. The support rods with curved metal provide flat dispersion and high interaction impedance, while a pseudo-periodic SWS suppresses backward oscillation and improves output power. The simulation results show that the traveling wave tube (TWT) with this pseudo-periodic helix SWS produces an average output power of more than 600 W in the frequency range from 26 to 36 GHz with beam voltage and beam current of 11.287 kV and 0.3 A, respectively, with a maximum output power of 700 W at 31 GHz, corresponding to a maximum gain of 42.8 dB and an electronic efficiency of 20.5%. The multiphysics analysis reveals the influence of the high-frequency losses on the temperature distribution in the operating condition. The results indicate that the maximum temperature in the last 15 circles is concentrated at the end of the pseudo-period helix SWS with a peak temperature of 304 °C, resulting in better heat dissipation performance, easier structural fabrication, and less deformation.