This paper investigates the properties of traveling wave-beam interaction in a rectangular helix traveling-wave-tube(TWT) for a solid sheet electron beam.The 'hot' dispersion equation is obtained by means of the self-consistent field theory.The small signal analysis,which includes the effects of the beam parameters and slow-wave structure(SWS) parameters,is carried out by theoretical computation.The numerical results show that the bandwidth and the smallsignal gain of the rectangular helix TWT increase as the beam current increases;and the beam voltage not obviously influences the small signal gain.Among different rectangular helix structures,the small-signal gain increases as the width of the rectangular helix SWS increases,however,the bandwidth decreases whether structure parameters a and L or ψ and L are fixed or not.In addition,a comparison of the small-signal gain of this structure with a conventional round helix is made.The presented analysis will be useful for the design of the TWT with a rectangular helix circuit.
