Equivalent Circuit Analyses and Methods to Enhance Bandwidth of Klystron Reentrant Cavities

Abstract

Klystron is used as an amplifier at microwave frequency range. Klystrons use cylindrical or rectangular reentrant cavities in their interaction structure. Characteristics of reentrant cavity can be defined using parameters such as resonant frequency, characteristic shunt impedance and quality factor, which can be computed either using 3D electromagnetic field solver or using equivalent circuit analysis. An equivalent circuit analysis is often preferred to quickly arrive at initial dimensions of the cavity as well as to analyse the effect of various dimensional variations on the cavity parameters. Equivalent circuit analysis for the calculation of these parameters is available in the literature for cylindrical reentrant cavity with single beam-tunnel and single constituent material. However, practical cavities are normally made with dissimilar materials and have multiple beam-tunnels as in the case of multiple-beam klystron. A new formulation has been proposed for accounting the effects of single and multiple beam-tunnels in the calculation of cavity gap capacitance... newline