With the development of pulse power technology and plasma physics, high-power microwave technology has developed rapidly, giving rise to various types of high-power microwave sources. Among them, the relativistic magnetron stands out as one of the most promising high-power microwave sources due to its high power conversion efficiency, compact structure, and tunable frequency. At present, the investigations of the relativistic magnetron mainly focus on microwave generation mechanisms, operation characteristics and radiation characteristics at relatively low frequency bands, such as L-band and S-band. The operating characteristics of the relativistic magnetron at higher frequencies are scarcely studied.

A Ku-band coaxial relativistic magnetron (RM) is designed in this paper to broaden working frequency range of this type of high-power microwave (HPM) source, further expanding its application scope.

A coaxial magnetron structure with 18 inner cavities is applied in this tube. A particle-in-cell (PIC) simulation has been carried out with the coaxial-axial output.

The high power microwave with power of 108 MW was detected at 14.613 GHz with a power conversion efficiency of about 43% when the applied voltage was 180 kV, the current was 1.4 kA, the inducing magnetic field was about 0.4 T, and the mode of output microwave in coaxial waveguide is TE₀₁ mode.

The simulation results show that the presented tube has a relative high conversion efficiency with low guiding magnetic field and more compact structure, which is convenient for decreasing the volume and weight of the system.