Design and Experiment of an Electron Optical System for a Ku-Band Tunable Continuous Wave Klystron

Continuous wave tunable klystron is a microwave amplifier widely used in satellite earth stations. This type of klystron has outstanding characteristics of high efficiency and long lifespan. This article proposes a design scheme of an electron optical system for Ku-band continuous wave tunable klystron. The klystron adopts a depressed collector to improve the overall efficiency of the device, and the collector area is cooled by forced air. The emission current density of the cathode and the temperature of the drift channel and collector in klystron during the rated operating condition directly affect the device lifespan. The distribution of electron trajectories is simulated using 2-D and 3-D electromagnetic calculation software, and a thermal analysis simulation of the klystron structure is conducted. A reliable klystron design scheme was obtained through the above process, and it is experimentally verified under the testing of a klystron sample tube. The DC electron beam transmission rate of the klystron exceeds 99%, and high-frequency output state beam transmission rate is above 97.5%. During the testing process, the klystron can maintain a stable working state. This study laid an important technical foundation for the development of Ku-band tunable klystrons.