Design of Side-coupled Absorption Cavity to Suppress the Oscillation of Sheet Beam Traveling Wave Tube

The stability of a sheet beam (SB) traveling wave tube (TWT) in Ka-band is investigated, in which the origin of self-oscillation and its impact on the high-power traveling wave tube are analyzed. To suppress the self-oscillations in the high-power device, the side coupling structure of the absorption cavity was designed with the absorption filtering method. The simulation results by electromagnetic simulation software show that the absorption cavities can efficiently suppress the self-oscillations generated by the traveling wave tube structure under the simulation condition of no input signal. Furthermore, in the condition with input signal, the single-stage Ka-band traveling wave tube with absorption cavities loaded can stably produce high power without instabilities.