Eigenvalue and transmission characteristics of a Disc-loaded interaction structure for a Gyro-TWT amplifier

Abstract

The present work is dedicated to developing the analysis of an axially periodic disc-loaded interaction structure, in the fast-wave regime, incorporating the factors of practical relevance that would be useful in designing wideband gyro-TWTs. The field expressions and the electromagnetic boundary conditions relevant to a disc-loaded waveguide are introduced. The structure model is field-analyzed for the dispersion relation. The eigenvalue characteristics of the disc-loaded circular waveguide excited in azimuthally symmetric TE01 mode is then plotted to study the effect of the parameters, namely, the dischole radius and the structure periodicity on these characteristics. Novel expressions for the power loss and power transmission through the structure have been derived starting from the first principles. Finally, attenuation characteristics of the structure excited in TE01 mode have been analyzed. As a special case of the ratio of ‘disc hole radius to waveguide radius (r D /rw)’ equal to unity; typically for L/rw=0.50, T/rw=0.01; it can be observed that our result always converges to the case of smooth wall cylindrical waveguide establishing the validity of our analysis.