Investigation of a 12-cavity rising-sun relativistic magnetron with diffraction output using particle-in-cell simulation

A 12-cavity rising-sun relativistic magnetron with diffraction output (MDO) driven by transparent cathode is investigated with three-dimensional particle-in-cell simulation. It is shown that its electronic efficiency can be as high as 78% with gigawatt level of radiation power when applied voltage is 400 kV. The peak efficiency around 70% of the 12-cavity rising-sun relativistic MDO occurs at the voltage (V≈400kV±50kV). In simulations all deep cavities are continued axially along the wall of a conical horn antenna whose cross section exceeds cutoff for the radiated wave and all shallow cavities are tapered to the output. When choosing the depth ratio of the cavities as 0.84, an output power of 1.8 GW for 12-cavity rising-sun relativistic magnetron MDO with 400 kV applied voltage can be obtained. Also, when increasing the transparent azimuthal thickness and optimizing the length of transparent cathode, the axial leakage current can be reduced by 50%.