Effect of complex surface morphologies on secondary electron yield characteristics of polyimide films based on Geant4

The Secondary Electron Yield (SEY) of polyimide (PI) films critically impacts spacecraft surface charging and reliability. Using Geant4-MicroElec simulations, we investigated the SEY characteristics of PI films for primary electrons (25–2000 eV) at incident angles of 0°–85°. To simulate surface changes from atomic oxygen (AO) erosion, we modeled “cylindrical groove” and “pyramidal groove”. Results align with experimental data, showing SEY peaks increase and shift to higher energies at larger incident angles. Importantly, both groove structures effectively suppress secondary electron escape due to absorption. Notably, the pyramidal groove structure increases the effective primary electron incident angle and shifts the SEY peak energy toward higher levels, making this structure more representative of the complex surface topography observed after actual AO erosion. This study enables accurate SEY prediction for complex surfaces, guiding passive potential control and the structural design of spaceborne PI materials.