Preliminary experimental verification of a metamaterial-based all-cavity axial extraction relativistic magnetron

This paper presents a preliminary experimental study on a metamaterial-based all-cavity axial extraction relativistic magnetron, previously discussed in our earlier work [Pi et al., Appl. Phys. Lett. 126, 141701 (2025)]. The experiment was conducted under laboratory conditions, with a measured input of 439 kV (voltage) and 4.33 kA (current), and a guiding magnetic field of 0.3 T. High-power microwaves with a power of 495 MW, a pulse width of 61 ns, and a frequency of 1.393 GHz were generated, achieving an efficiency of 25.5%. Measurements of the microwave radiation pattern, spectrum, and neon lamp glow pattern confirmed that the output microwave was predominantly in the TM01 mode. These results validate the miniaturization potential of the metamaterial structure and the reliability of particle-in-cell (PIC) simulations for experimental guidance. The stable pulse width and operating frequency demonstrate the stability of the device in mode selection and control. Discrepancies were observed in center frequency and efficiency between simulation and experiment, which may be partly due to differences in the power supply system compared to the ideal input in the PIC simulation. Further experiments and simulation refinements will address these discrepancies.