Frequency Tuning in a Subterahertz Gyrotron With a Variable Cavity

According to calculations, electromechanical frequency tuning by 8% relative to a central frequency of 316 GHz can be provided in a high-power gyrotron with a slit and variable cavity. A monoaxis helical electron beam (configuration of large orbit gyrotron) is proposed for the use in such an oscillator instead of the conventional polyaxis beam, which was used in earlier long-wavelength prototypes. This modification increases gyrotron efficiency and frequency tuning range, as well as stability of the generation regime. A mechanism for the precise parallel movement of the cavity halves and mode converter, which transforms an azimuthally standing cavity mode into a wavebeam, have been designed. Peculiarities of frequency tuning associated with the coupling of the operating and parasitic modes in the slit cavity have been studied.