Particle simulation and optimization design of X-band quasi-periodic RF cavity for high power microwave source

A novel resonator of quasi-periodic structure is put out in the paper. The interaction between the beam and the microwave field in the cavity is theoretically investigated with 2.5 dimensional particle simulation code. With this type of structures, theoretically beam-microwave interaction efficiency can reach 52%. An X-band quasi-periodic structure cavity is designed, its working frequency is 9.4 GHz. With the voltage 700 kV, current 6.6 kA and magnet field 4.4 T in the simulation, the output power is 1.67 GW, the frequency 9.4 GHz and interaction efficiency about 36%. Driven by Sinus-700 accelerator in the experiment, microwave power is 1.3 GW, the frequency is 9.4 GHz, pulse duration is about 26 ns, and the efficiency is 26%.