Theory of multimode oscillation in a gyromonotron

The study of mode competition in gyrotrons essentially allows for a simplification in consequence of the gyrotropy of the electron current and the axial symmetry of the working space in these instruments. For the case when the width of the resonance curves and the spacing of the natural frequencies of the modes are small in comparison to the line of cyclotron resonance, it is shown that stable, single-frequency oscillations correspond to a 'soft' oscillation excitation regime, while in 'rigid' self-excitation, stable, biharmonic regimes are possible.