Simulation study on beam current modulation of C-band wide-gap triaxial klystron

The wide-gap klystron and triaxial klystron are the recent developments of the conventional relativistic klystron amplifier, which can effectively improve the output power and efficiency especially at high frequency. The wide-gap triaxial klystron takes advantages of the two kinds of klystrons mentioned above. 2D particle-in-cell simulation on the electron beam transportation of the C-band wide-gap klystron is presented. In order to obtain stable beam transportation, both the radially asymmetrical cavity structure and cautious position choice of the grounding rod located before the input cavity are necessary. Under a diode voltage of 440 kV and an input power of 200 MW at 5.0 GHz, a maximum fundamental integral modulation current of 11.8 kA is obtained with the modulation depth of 88% and