Review of the theory of mode interaction in gyrodevices

The present paper contains a brief overview of the studies of mode and wave interaction in gyrodevices. The main part of it is devoted to the discussion of physical effects caused by mode interaction in the free-running and phase-locked gyrotron oscillators. Also, the problem of the stability of large-signal operation of gyro-forward-wave amplifiers with respect to excitation of parasitic backward waves is discussed.