Linear theory of rectangular helix slow-wave structure for traveling wave tube

Linear gain properties of a rectangular helix traveling wave tubes (TWT) loaded a solid sheet electron beam are investigated. The working dispersion equation was obtained by the self-consistent field theory, and then small signal gain of it was computed. The numerical results show that, the small signal gain and the bandwidth increase as the beam current increasing; while the beam voltage affects small signal gain not strongly, and the gain increases and the bandwidth decreases with the increases of the width of the structure whether structure parameters a and L or ψ and L are fixed, which reveals that this kind of structure is a wide-band or high gain amplifier by choosing proper value of the slow-wave structure and the beam parameters. So this structure has potential applications in compact TWTs.