First Observation of the Chaotic Oscillations in the K-Band Gyro-BWO

Summary form only given. In the paper the results of the theoretical and experimental studies of the non-stationary dynamics of the sub-relativistic K-band gyro-BWO with external reflections are presented. The gyro-BWO is an attractive source of powerful microwave signals due to frequency tunability, which can be realized by varying the magnetic field or the beam voltage. From the other hand, in comparison with conventional Cherenkov BWO, cyclotron emission does not require slow-wave system with period less than the wavelength. For reducing the bifurcation currents, corresponding to the transition to the non-stationary regimes, the delayed feedback, formed by the additional reflector installed at the output waveguide section was used. The transition to the periodic and chaotic oscillations regimes were obtained by the variation of the guiding magnetic field. According to theoretical considerations the gyro-BWO dynamics strongly depends on the phase of the reflecting signal, which determined by the operation frequency and, thus, by the value of the guiding magnetic field. For example, the phase variation could change the self-modulation frequency, which was observed experimentally. The maximum output power of chaotic oscillations amounted 100 W at the central frequency near the 24.6 GHz and spectrum width of about 100 MHz. It should be noted, that gyro-BWO has a potential of increasing the operating frequency and output power with relatively high efficiency of 10-20%