A Method for Reducing the Second Harmonic Level in Wideband Traveling Wave Tubes

摘要

To reduce the second harmonic level and enhance the efficiency and stability against backward-wave self-excitation of wideband helical traveling-wave tubes containing a screen with longitudinally conducting edges, it is suggested that the gap between edge ends and a helix in the output section be gradually increased toward the energy output, the helix pitch being constant or slightly varied for optimizing the efficiency. It is shown that the increase in the gap reduces the second harmonic level and enhances the efficiency and the start current of backward-wave self-excitation.