Investigation on S-band long pulse relativistic klystron amplifier

This paper presents the progress on design and adjustment of cavities, experiments of beam-current modulation and microwave extraction for an S-band long-pulse-intense-current relativistic klystron amplifier. Modulation of long-pulse intense relativistic electron beams and self-exciting oscillation of output microwave are described in detail. The cause of self-exciting oscillation and its results is also introduced. The self-exciting oscillation was suppressed to a certain extent by taking relevant adjustments. In experiments, a hollow electron beam of 550 kV, 4 kA and 210 ns generates an electron beam with modulated current of 3.2 kA and pulse width of 150 ns after optimization and adjustment of the parameters of cavities. More than 580 MW RF power with a duration of 140 ns is obtained. T