Mechanism of bright halo defects induced by electric field distortion on microchannel plate surface

Localized bright halo defects critically impair the performance of third-generation image intensifiers, presenting as central dark zones surrounded by luminous rings. While conventional black spot defects stem from contaminants, the distinct spatial pattern of halos suggests complex electron interactions with microchannel plate (MCP) contaminants. Initial hypotheses attributing halos to electron diffraction are invalidated by the significant scale mismatch between contaminant sizes (>5 μm) and photoelectron de Broglie wavelengths (∼1 nm at 2 eV). This study establishes a new mechanism: halo formation arises from electric field distortion around surface contaminants, leading to electron focusing. We validate this model through experimental electron-gun testing on contaminated MCPs, theoretical analysis of halo dimensions, and COMSOL Multiphysics simulations of electron trajectories. The consistent agreement across approaches confirms electric field distortion as the root cause. This work provides the first quantitative model of halo defect formation, advancing MCP reliability understanding for night vision systems.