Conversion efficiency in axial monotrons

A comparative study is given on the bunching mechanisms which develops in transit-time tubes with RF-field bunching, often referred to as monotrons. Uniform and stepped wise longitudinal electric-field profiles are discussed, and it is shown that the two-fold enhancement in the conversion efficiency of a monotron operating in the ¿ mode-instead of the longitudinally uniform TM
₀₁₀
mode for which the efficiency is limited to 20 percent-arises from a phase synchronization process due to the action of RF electric fields of reversed signs in each partition of the bisected cavity.