Controlling chaotic dynamics in a multiple cavity klystron oscillator driven by an external signal

Among sources of chaotic microwave radiation, a delayed feedback multiple cavity klystron oscillator is one of the most promising due to high power level and high efficiency. It has been shown that increasing either beam current or feedback level leads at first to self-modulation instability and then to a transition to chaos after a sequence of period doubling bifurcations. In this paper, we present the results of an experimental study of a multiple cavity klystron oscillator driven by an external signal. In the experiment, a medium power S-band five-cavity klystron, with double-gap cavities operating in π-mode, was used. It was shown that driving the multiple cavity klystron oscillator with an external harmonic signal provides an efficient control of oscillations and allows one to obtain various regimes: single frequency, multi-frequency or chaotic ones.