Characteristic of X-band coaxial double-gap output cavity of klystron amplifier

With 3D full electromagnetic particle-in-cell code, an X-band coaxial double-gap output cavity of klystron amplifier has been designed and simulated. It is found that the microwave extraction power and efficiency is increased by employing the coaxial double-gap output cavity. The relation between output power and modulation depth of current, and the relation between output power and the distance from electron beam outer radius to drifting wall are obtained. Furthermore, the relation between output power and DC transitional angle is presented. A 1.2 GW averaged power over the oscillator period is generated by simulation with 600 kV electron beam voltage, 5 kA current, 100% modulation depth of current and 1 T leading magnetic field density. The peak frequency is 9.37 GHz and the efficiency i