A Coaxial High Power Output Cavity Operating in Hybrid TM₀₁-TM₀₂ Modes for Repetitive Operation

An output cavity operating in hybrid TM01-TM02 modes is investigated for the sake of producing repetitive high power microwaves (HPMs) in coaxial electromagnetic structures. To suppress anode plasma formation, the generated microwave is changed to be extracted inwards, so that the intense electron beam can be collected on the outer conductor, which makes beam collector cooling feasible practically in this topology. The issue of radio frequency breakdown is addressed by using a large extraction waveguide, and particularly the external quality factor required for optimal beam wave interaction is achieved by adjusting mode coupling. The design is examined in an X-band triaxial klystron amplifier by particle-in-cell simulation, which shows HPM with a power of 2 GW can be generated with an efficiency of about 36%.