A method for determining oscillation area in microwave tubes

Abstract

Oscillations in high-frequency tubes are regular and important problems for their use and development. The limitations of the Bers-Briggs criteria, generally applied to uniform systems, are avoided here by a method based directly on the differential equations that describe the electronic device. One must then find the parameters and the boundary conditions that are appropriate to determine the different types of operation or instabilities. This method is general enough to be used on a wide range of tubes (Traveling Wave Tubes, Gyrotrons, Free Electron Laser, ...). An original criterion for characterization of the build-up of oscillation is applied to traveling wave tubes with a good match to the results obtained by experiments.