Electron irradiation-induced metal particle perturbation of the surface electric field on polyimide (PI) is the core cause of insulation failure in solar array drive assemblies (SADA) of a spacecraft. This paper investigates PI insulation components with surface-adhered metal particles

and reveals the electric field distortion mechanism under the coupled effects of electron irradiation and metal particles through Geant4-COMSOL co-simulation and experiments. The study demonstrates that: deposited irradiation electrons within the PI cause the electric field at the electrode-insulator-vacuum “triple junction” to reach 1.1×108 V/m

with the electric potential exhibiting a symmetrical “peak” distribution; metal particles exacerbate distortion through charge trapping and geometric field enhancement

forming new distortion zones and elevating the electric field at the original triple junction. Analysis of metal particle parameter effects on the electric field indicates: (1) As particle size decreases

the tip effect dominates field distortion

causing the electric field intensity at the contact point to surge to 1.69×108 V/m; (2) Linear particles

due to their “double-tip” polarization characteristic

increase the electric field distortion rate at the triple junction by 91.8%

significantly higher than the 45.5% for flake particles and 18.2% for spherical particles; (3) Closer proximity of particles to the electrode results in higher local electric field intensity; when particles tightly contact the electrode

geometric discontinuity causes the maximum electric field intensity to surge to 9.89 times that of the particle-free condition. The research results provide a theoretical basis and key technical support for the radiation-resistant design of spacecraft insulation components

metal particle contamination protection

and discharge risk assessment.