Radiation effects in optical coatings for ITER diagnostics



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Pereira González, Augusto and Medrano Casanova, Mercedes and León Gutiérrez, E. and Pastor Santos, Carmen and Mota García, Fernando and Vila Vázquez, Rafael Alberto and Rodríguez, C. and Carrasco García, Ricardo and Lapayese, F and Rodríguez Fernández, Carmen and Lapayese Puebla, Fernando and Peña Gómez, Ángel, de la and Soleto Palomo, Alfonso and Rincón Rincón, Esther and Cabrera Pérez, Santiago and Queral Mas, Vicente and Fernández Navarro, Alejandro and López Heredero, Raquel and Torquemada Vico, María del Carmen and Rodrigo, T and Gómez, L and Belenguer Dávila, Tomás and Vermeeren, Ludo and Leysen, Willem and Piqueras, Juanjo and Le Guern, Frederic and Alén Cordero, Cristina (2023) Radiation effects in optical coatings for ITER diagnostics. Fusion Engineering and Design, 188 . 7 p.. ISSN 0920-3796

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Official URL: https://doi.org/10.1016/j.fusengdes.2023.113438


The aim is to provide an assessment of radiation damage in coated films on refractive substrates that could be used as relevant information to protect the field lenses in optical diagnostics for ITER. Radiation-resistant optical materials with transparent properties should transfer light from plasma to detectors through the interspace until the port cell area where they are located (more than 10 m from the vacuum window). These optical coatings and substrates should have resilience enough to withstand neutron and gamma irradiation without significant degradation of their transmittance. Coated sapphire (Al2O3 windows), YAG with Broad Band Anti-Reflective (BBAR) and substrates of BaF2/CaF2 protected with anti-humidity coating (Parylene-C) were extensively tested. After testing, transmission mea- surements and analysis of optical surfaces yield significant discoveries. All substrates showed good refractive performance under gamma radiation. On the contrary, Parylene-C did not resist temperatures above 100 degrees Celsius as expected, according to manufacturing specifications. In addition, it was observed that with an energy dose of 332 kGy of gamma rays and a significantly lower temperature of 50 degrees Celsius, the Parylene-C protection is also damaged. Coated sapphire had the best overall performance with respect to the neutron irradiation tests. Nevertheless, the decrease in transmission observed in the YAG and BaF2 coated samples is not significant for the expected cumulative neutron dose that these samples will receive at their location within the diagnostic. This information was considered for the selection of the best candidates as refractive lenses and optical coatings for the Preliminary Design Review (PDR) of ex-vessel components that will integrate the Wide-Angle Viewing System (WAVS) for ITER Equatorial Port 12.

Item Type:Article
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Received 19 October 2022, Revised 11 December 2022, Accepted 27 December 2022, Available online 13 January 2023, Version of Record 13 January 2023

Uncontrolled Keywords:Radiation-resistant; Field lens; Optical coating; Parylene-C; Sapphire; YAG; BaF2
Subjects:Sciences > Physics > Materials
Medical sciences > Optics > Optical materials
Medical sciences > Optics > Geometrical and instumental optics
ID Code:76769
Deposited On:21 Feb 2023 19:05
Last Modified:22 Feb 2023 11:58

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