On the problem of material for the in-vessel mirrors of plasma diagnostics in a fusion reactor

In the paper the problem on the choice of materials for the in-vessel mirrors for plasma diagnostics in the reactor-grade fusion device is discussed. The radiation environment in locations of mirrors is analyzed having for an object to find the correct criteria for the candidate materials. Two groups of mirrors are considered: 1st mirrors that directly view the plasma and 2nd mirrors located behind the radiation shield. The results of experiments simulating the impact of different kinds of radiation on optical properties are compared for mirrors fabricated of polycrystalline and monocrystalline metals, film mirrors on metallic and dielectric substrates.