Stability of Excitation of Traveling Waves in Gyrotrons With Low-Relativistic Electron Beams

A number of application require compact low-power gyrotrons with relatively low operating currents. In order to provide the start of such gyrotrons, one should use long-length operating cavities with high diffraction Q-factors, and, therefore, with significant losses of the radiated wave power due to Ohmic heating of the cavity wall. In this paper, we demonstrate that in low-voltage gyrotrons there is a possibility for stable operation at higher order axial modes possessing relatively low diffraction Q-factors. An enhanced efficiency of the beam-wave interaction is provided due to the excitation of such modes in the traveling-wave-tube regime.