Energetic Particle and Ray Irradiation Effects in HfO₂ Optical Thin Film Materials

HfO 2 optical materials are extensively employed in the fabrication of high-power laser thin film components due to their high refractive index, elevated dielectric constant and thermal stability. However, their performance degradation under space radiation — primarily from energetic particles — remains poorly understood, with ground-based [Formula: see text]Co [Formula: see text]-ray experiments failing to replicate the complex ionization dynamics of space environments. In this study, we employ the Monte Carlo method to investigate the irradiation effects of [Formula: see text]Co [Formula: see text]-rays, electrons and protons on HfO 2 , material, establishing quantitative equivalence models that link secondary electron yields to particle type and energy. We demonstrate that 0.469 photons of 1.25[Formula: see text]MeV [Formula: see text]Co [Formula: see text]-rays induce ionization equivalent to 1[Formula: see text]MeV electrons and 0.483 [Formula: see text]-photons match the effect of 1[Formula: see text]MeV protons. The depth-dependent secondary electron distribution follows a Boltzmann function, enabling a theoretical framework to extrapolate [Formula: see text]Co [Formula: see text]-ray data for predicting space radiation effects. This work resolves the long-standing discrepancy between laboratory tests and in-space conditions, providing a foundation for radiation-hardened optical component design in aerospace applications.