Analysis of electromagnetic characteristics exhibited by high-power traveling-wave tubes based on a chain of coupled resonators beyond the boundary of the passband of the slow-wave system

The electrodynamic characteristics of a traveling-wave tube (TWT) are numerically and experimentally analyzed beyond the boundary of the transparency band. A high-power three-section TWT with a slow-wave system in the form of a chain of coupled resonators is used as an example to show that, at the low-frequency edge of the operating band, the loaded Q factor of the resonance corresponding to the pi-mode oscillations is reduced and that the frequency characteristics do not shift into the low-frequency region.