Suppression and diode spurious oscillation in wide-gap klystron amplifier

The diode spurious oscillation in wide-gap klystron amplifiers was studied by using a three-dimensional high frequency program and particle-in-cell softwave. Due to the cut-off of the high-order mode TM31 in the diode region at 6.18 GHz, the diodes together formed a resonant cavity and a strong electric field was generated in the anode-cathode gap, which resulted in intense electron beam modulation. According to simulation results, some improvements were brought forward to optimize the diode structure. The diode spurious oscillation was eliminated ultimately.