Research on the double-sided surface flashover characteristics of the irregular ceramic insulator in high-power electron guns

With the development of electronic guns toward high voltage, large capacity, and miniaturization, the surface flashover of ceramic insulators has become a key problem that leads to insulation damage, limits equipment performance, and reduces system reliability. In this paper, surface flashover experiments were conducted on irregular ceramic insulator, and the phenomenon of surface flashover discharge was observed on the double-sided surface. It was found that the inner surface of the ceramic insulators with this structure is more prone to flashover discharge by application of optical diagnostics, indicating that the weak point of insulation is the inner surface of the insulator. Through simulations of the electric field distribution and flashover discharge processes on insulator surfaces, three critical factors are identified to significantly influence flashover development: the enhanced electric field at the cathode triple junction, the strong normal component of the surface electric field, and the groove structures. The inner surface exhibits stronger field intensification at the cathode triple junction, generating more primary electrons. Concurrently, the parallel electric field components near the cathode triple junction promote the emission of secondary electrons. In contrast, the outer surface's groove configuration suppresses discharge by altering electron trajectories. These combined effects make the inner surface more vulnerable to flashover occurrence. The research in this article has important scientific and engineering significance for the safe and stable operation of electronic guns and the improvement of technical level.