A Repetitive Ku-Band Coaxial Relativistic Klystron Amplifier Packaged With Permanent Magnets

A compact Ku-band coaxial relativistic klystron amplifier (RKA) with permanent magnets is proposed for the sake of producing repetitive high-power microwaves (HPMs) in this article. The improved input and output mode converters are designed to load the input signal at the end of this device to ensure the integrity of permanent magnets. Besides, the intense relativistic electron beam (IREB) is changed to be collected on the outer collector, which makes collector cooling feasible in the proposed device. The typical experimental results show that the Ku-band HPM with a power of 540 MW is generated, corresponding to a gain of 48 dB and an efficiency of 29%, when the guiding magnetic field is around 0.45 T produced by the permanent magnets. The result of continuous operation for 30 s at a repetition rate of 35 Hz indicates that the proposed coaxial RKA has the capability of operating at a high repetition rate.