核融合炉材料のヘリウム損傷 7.非金属材料におけるヘリウム照射損傷について

Helium irradiation effects on non-metallic materials from an atomic to a macroscopic scale are reviewed from the viewpoint of fundamental lattice defects. Following a rough description of radiation damage phenomena in covalent and ionic materials, general but characteristic property changes associated with helium ion irradiation are introduced, taking the localized character of valence electrons incorporated in the atomic bonding into account. Further, simple kinetic equations are derived to discuss the damaging processes of the near-surface region under ion irradiation. Finally, a new method to precisely estimate the mechanical properties of ion-irradiated materials and future direction of this field are presented.