Novel source of the chaotic microwave radiation based on the gyrotron backward-wave oscillator

First experimental studies of the nonstationary phenomena in powerful K-band gyrotron backward-wave oscillator with external reflector are presented. Variation of the self-modulation frequency from 69 to 112 MHz and transition to the chaotic oscillations with spectrum width 100 MHz were obtained due to the tuning of the guiding magnetic field. These results are in a good agreement with simulations, which demonstrate a strong influence of the guiding magnetic field on the system dynamics.