Bidirectional reflectance distribution function of recrystallized tungsten mono-block exposed to cyclic heat loading. (October 2022)

• Record Type: Journal Article
• Authors: Natsume, Hiroki; Nojiri, Kunpei; Kajita, Shin; Fukuda, Makoto; Ushiki, Tomohiko; Tanaka, Hirohiko; Sugie, Tatsuo; Kitazawa, Sin-iti; Kikuchi, Takanori; Yokozuka, Tomohiro; Ohno, Noriyasu; Ezato, Koichiro; Hatae, Takaki
• Is Part Of: Nuclear materials and energy. Volume 33(2022)
• Publication Date: 2022-10
• Subjects: BRDF -- Goniophotometer -- Reflection modeling -- Tungsten monoblock -- Spectroscopic diagnostics -- Recrystallization; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2022.101243
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: BRDF of tungsten mono-blocks exposed to cyclic heat was measured. Overall values of BRDF decreased with increase in cyclic heat loading. Comparison between a modeled and measured BRDF was performed. Additional diffused reflection model is necessary to a specular model to fit the measured BRDFs. Abstract: The bidirectional reflectance distribution function (BRDF) of recrystallized tungsten mono-blocks exposed to cyclic heat loading for ITER divertor outer vertical target was measured using a goniophotometer at a wavelength of 473 nm. Laser microscope observations revealed that the surface roughness of the mono-block increased by an order of magnitude after cyclic heat loads of approximately 20 MWm −2 . Furthermore, the overall values of BRDF decreased with an increase in cyclic heat loading. A comparison between the modeled and measured BRDFs showed that an additional Lambertian component is necessary to a specular function (microfacet model or Gaussian function) to fit the measured BRDFs when the surface of the mono-blocks becomes rough.