High-Dose Neutron Irradiation Performance of Dielectric Mirrors
| Autor: | N.A.P. Kiran Kumar, Lance Lewis Snead, Keith J. Leonard, Gerald Earle Jellison Jr |
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| Rok vydání: | 2015 |
| Předmět: |
Nuclear and High Energy Physics
Materials science Energy-dispersive X-ray spectroscopy 02 engineering and technology Dielectric engineering.material 01 natural sciences Optics Coating 0103 physical sciences General Materials Science Neutron Irradiation Composite material Civil and Structural Engineering 010302 applied physics business.industry Mechanical Engineering 021001 nanoscience & nanotechnology Nuclear Energy and Engineering Transmission electron microscopy engineering Sapphire 0210 nano-technology business High Flux Isotope Reactor |
| Zdroj: | Fusion Science and Technology. 67:771-783 |
| ISSN: | 1943-7641 1536-1055 |
| DOI: | 10.13182/fst14-875 |
| Popis: | The study presents the high-dose behavior of dielectric mirrors specifically engineered for radiation-tolerance: alternating layers of Al2O3/SiO2 and HfO2/SiO2 were grown on sapphire substrates and exposed to neutron doses of 1 and 4 dpa at 458 10K in the High Flux Isotope Reactor (HFIR). In comparison to previously reported results, these higher doses of 1 and 4 dpa results in a drastic drop in optical reflectance, caused by a failure of the multilayer coating. HfO2/SiO2 mirrors failed completely when exposed to 1 dpa, whereas the reflectance of Al2O3/SiO2 mirrors reduced to 44%, eventually failing at 4 dpa. Transmission electron microscopy (TEM) observation of the Al2O3/SiO2 specimens showed SiO2 layer defects which increases size with irradiation dose. The typical size of each defect was 8 nm in 1 dpa and 42 nm in 4 dpa specimens. Buckling type delamination of the interface between the substrate and first layer was typically observed in both 1 and 4 dpa HfO2/SiO2 specimens. Composition changes across the layers were measured in high resolution scanning-TEM mode using energy dispersive spectroscopy. A significant interdiffusion between the film layers was observed in Al2O3/SiO2 mirror, though less evident in HfO2/SiO2 system. Lastly, the ultimate goal of this work ismore » the provide insight into the radiation-induced failure mechanisms of these mirrors.« less |
| Databáze: | OpenAIRE |
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