Imitation of effects of a fusion reactor environment on optical properties of metallic mirrors

Results of imitation experiments on effects of charge exchange atoms bombardment on optical properties of metallic mirrors (in the spectrum range of 200–800 nm) are presented. The long-term sputtering of mirror samples made of stainless steel, copper and hot pressed beryllium have been carried out with plasma ions (H +, D +, He +, or Ar +) of keV energy range. It was shown that in the case of a stainless steel mirror, the sputtering of a layer of ∼2 μm thick did not lead to significant change in reflectivity. As to a copper mirror, a noticeable change of reflectivity was observed after sputtering of ∼0.7 μm layer using He + ions. The highest rate of degradation, especially in the UV region, was found in the case of beryllium mirrors.