Multiple square beam hole slow wave structure at W band

A folded waveguide travelling wave tube (FWTWT) with 36 periods of slow wave structure (SWS) and multiple square beam holes is presented. Characteristics of the SWS including dispersion properties, interaction impedance and beam wave interactions are analyzed for W band using CST PC for a beam voltage of 16kV, and a beam current of 35mA. A flat gain of 27dB is predicted over a bandwidth of 93-102 GHz for the design with multiple beam holes, compared to 15dB for the one with single beam hole of equivalent area.