Large-scale collecting mirrors for ITER optical diagnostic

Abstract

The challenges of large-scale mirror design for in-vessel collection system of ITER Divertor Thomson Scattering (DTS) are under consideration. These are the mirrors located out-of-line vision of fusion plasma (so called “second mirrors” i.e. not First Mirrors) with high-reflective Ag-based coating. The paper outlines: approaches providing optical surface shape and angular position stability; Ag coating applicability in nuclear irradiation, ITER in-vessel application and its resistance to Steam Ingress. Although, this assessment and the proposed solutions are considered in terms of ITER DTS compatibility, they may also appear to be of some use in other ITER diagnostics and in diagnostics of other fusion devices.

Materials to Be Used in Future Magnetic Confinement Fusion Reactors: A Review

“…The fluence expected for FMs is ∼ n/m 2 over the entire lifetime of ITER with temperatures that range from 50–300 °C, depending on the location. Stainless steel grade 316LN-IG (a modification of grade 316LN with a reduced concentration of activation-susceptible elements (mainly Co, Nb and Ta) [ 112 ] ) is the main structural material [ 107 , 112 , 113 ].…”