Experimental Validation of Current Distribution in Intense Relativistic Electron Beams From a Coaxial Dual-Ring Cathode

This article presents a comprehensive simulation study and the first experimental investigation of a coaxial nested dual-ring cathode (CNDC) for dual-frequency high-power microwave (HPM) generation. Operating under a low solenoidal guiding magnetic field of 0.6 T, the CNDC successfully emitted and transmitted dual-ring intense relativistic electron beams (IREBs) with high transmission efficiencies. The experimental results closely validated the predictions of particle-in-cell (PIC) simulations, with total emission currents measured at approximately 15.8 kA, aligning well with the 15.6 and 15.5 kA predicted by the 2-D and 3-D simulations, respectively. Furthermore, the experimentally observed beam current distribution between the outer and inner rings closely adhered to design expectations, demonstrating the stability and reliability of the CNDC for dual-frequency HPM applications.