Monte Carlo Simulation of High-energy Particle Irradiation Effects on Ta2O5 Optical Coatings
摘要
We employed Monte Carlo simulations via Geant4 to model the interactions of 60Co gamma rays (1.25 MeV), electrons (0.1–10 MeV), and protons (0.5–10 MeV) with Ta2O5 optical coatings. By analyzing secondary electron generation and energy deposition, we found that 1.0 MeV electrons and protons produce 67.5 and 67 secondary electrons per particle, respectively, compared to 116 from 1.25 MeV gamma rays in thick targets. Boltzmann-function fitting revealed depth-dependent ionization equivalence: 0.582 gamma photons match the secondary electron yield of a 1.0 MeV electron, and 0.577 gamma photons match a 1.0 MeV proton. These results establish a framework to convert ground-based gamma-ray test data to space environment scenarios, accounting for critical differences in penetration depth-protons deposit energy within 10 µm (coating layers), while gamma rays penetrate >100 mm into substrates. This provides a theoretical basis for evaluating radiation effects using existing 60Co facilities, enabling reliable predictions of optical component durability in complex space environments.