Modification of optical properties of Be mirrors under bombardment by deuterium ions

Abstract Effects of D ion bombardment on Be mirror reflectance, R(λ), in λ=220–650 nm were studied as modelling the impact of charge exchange atoms in a fusion reactor. Without any mass change of mirror, a sharp drop of R(λ) was observed for different kinds of beryllium at high ion energies (600–1350 eV) after ion fluence ∼1018 ions/cm2. It is hypothesized that under deuterium ions the BeO surface film was transformed into the Be(OD)2 film accompanying by changing the film optical properties. Effects of ion energy and ion fluence variation on R(λ) of Be mirror are discussed.