Investigation on a novel axially extracted relativistic metamaterial Cherenkov oscillator

This paper proposes an axially extracted relativistic metamaterial Cherenkov oscillator employing a non-uniform slow wave structure. It aims to address issues in the incompatibility of magnets with miniaturization and the instability of operating mode under high beam current conditions. Compared to traditional radial extraction, introducing an axial extraction structure reduces the radial loading volume of the magnet. Additionally, the non-uniform periodic structure lowers the π-mode’s external quality factor (Q-factor), mitigating mode competition risks. Particle-in-cell simulation results demonstrate that the device achieves an output microwave power of 870 MW with 35% conversion efficiency under an acceleration voltage of 500 kV and a beam current of 5 kA. Additionally, it has a center frequency of 1.51 GHz with a pure frequency spectrum. The simulation study verifies the advantages and stable operation potential of the proposed device.