A high-efficiency klystron with distributed interaction

This paper describes a theoretical and experimental investigation of a special form of a three-cavity klystron amplifier having shorted sections of a slow-wave structure as resonators. Although the behavior basically is similar to that of a narrow-gap klystron, improved performance is obtained due to distributed interaction and higher cavity characteristic impedance. Higher efficiency and larger gain-bandwidth product, as predicted by theory, were observed experimentally with a pulsed S-band distributed klystron operated at a maximum beam voltage of 22 kv and a beam current of 3.5 amperes. Saturation efficiencies of approximately 50 per cent at 18 db gain and 2 per cent half-power bandwidth, and small-signal gain of 40 db at 0.5 per cent bandwidth, were measured. Small-signal behavior is in good agreement with the space-charge-wave theory. At large-signal levels, experimental results and simplified kinematic theories agree qualitatively.