Reflective metallic coatings for first mirrors on ITER

• Published in: Fusion engineering and design Vol. 86; no. 9; pp. 2593 - 2596
• Main Authors: Eren, Baran, Marot, Laurent, Litnovsky, Andrey, Matveeva, Maria, Steiner, Roland, Emberger, Valentin, Wisse, Marco, Mathys, Daniel, Covarel, Gregory, Meyer, Ernst
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2011; Elsevier
• Subjects: Applied sciences; Boundaries; Controled nuclear fusion plants; Crystallites; Deposition; Energy; Energy. Thermal use of fuels; Engineering Sciences; Evaporation; Exact sciences and technology; First mirror; Installations for energy generation and conversion: thermal and electrical energy; ITER; Magnetron sputtering; Molybdenum; Other; Reflectivity; Rhodium; Surface roughness; First mirror; ITER; Magnetron sputtering; Evaporation; Rhodium; Molybdenum; Tokamak; Impurity; Roughness; Nuclear fusion reactor; Optical properties; Protective coatings; Deposition; Reflectance
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2010.12.038

Metallic mirrors are foreseen to play a crucial role for all optical diagnostics in ITER. Therefore, the development of reliable techniques for the production of mirrors which are able to maintain their optical properties in the harsh ITER environment is highly important. By applying magnetron sputtering and evaporation techniques, rhodium and molybdenum films have been prepared for tokamak tests. The films were characterised in terms of chemical composition, surface roughness, crystallite structure, reflectivity and adhesion. No impurities were detected on the surface after deposition. The effects of deposition parameters and substrate temperature on the resulting crystallite structure, surface roughness and hence on the reflectivity, were investigated. The films are found to exhibit nanometric crystallites with a dense columnar structure. Open boundaries between the crystallite columns, which are sometimes present after evaporation, are found to reduce the reflectivity as compared to rhodium or molybdenum references.