Direct Generation of Switchable Circularly Polarized High-Power Microwaves via Virtual Cathode Diocotron Instability in a Relativistic Magnetron

The first experimental demonstration of direct generation of circularly polarized high-power microwaves (HPMs) with switchable rotation direction was proposed. A novel approach, the diocotron instability of virtual cathode (VC) in relativistic magnetrons (RMs), was carried out for stable and efficient generation. Through particle-in-cell (PIC) simulations, we analyzed the key to stable generation, which lies in two criteria: 1) matching the number of electron spokes split by diocotron instability with the azimuthal periodicity of the resonant mode, and 2) balancing VC formation and dissipation through appropriate external quality factor. Finally, experimental results demonstrate switchable left/right-handed circular polarization with 39.5% power conversion efficiency and 1.19 GW output power via magnetic field reversal, and the microwave pulsewidth is extended to 82 ns, closely matching the 100 ns voltage pulse duration.