Effect of sputtering on the samples of ITER-grade tungsten preliminarily irradiated by tungsten ions: Optical investigations

The simultaneous effect of sputtering and neutron irradiation on the optical properties of tungsten mirrors has been considered, which was simulated by bombardment by 20-MeV W +6 ions. The action of charge-exchange atoms was imitated using Ar + ions with an energy of 600 eV. The dependence of the structure of the surface and optical properties of tungsten on the fluence of Ar ions has been studied using optical microscopy, interferometry, reflectometry, and ellipsometry. It has been shown that irradiation with neutrons should introduce a significant additional contribution to the processes at the tungsten surface that occur under the effect of charge-exchange atoms. An analysis of experimental data obtained by using reflectometry and ellipsometry made it possible to suggest a realistic model of the process of surface modification for samples of ITER-grade tungsten (that were preliminarily irradiated by tungsten ions) using prolonged sputtering by Ar + ions.