Suppression of parasitic oscillation in X-band long pulse multi-beam relativistic klystron amplifier

An X-band multi-beam relativistic klystron amplifier is designed to increase the output microwave power and the operating frequency of the amplifier tube, and an experimental study is performed on the long pulse accelerator. The parasitic oscillation of relativistic klystron amplifier is explored in particle-in-cell code and experiment, and the results indicate that the parasitic oscillation is mainly excited by retrograde electrons. Special measures are introduced in the device to suppress the retrograde electrons and avoid parasitic oscillation. Output power of 0.98 GW is obtained in the experiment, the microwave frequency is 9.405 GHz, the pulse width is 95 ns, and the amplifier gain is about 43 dB.