In-situ imaging of tungsten surface modification under ITER-like transient heat loads. (August 2017)

• Record Type: Journal Article
• Authors: Vasilyev, A.A.; Arakcheev, A.S.; Bataev, I.A.; Bataev, V.A.; Burdakov, A.V.; Kandaurov, I.V.; Kasatov, A.A.; Kurkuchekov, V.V.; Mekler, K.I.; Popov, V.A.; Shoshin, A.A.; Skovorodin, D.I.; Trunev, Yu.A.; Vyacheslavov, L.N.
• Is Part Of: Nuclear materials and energy. Volume 12(2017)
• Page Start: 553
• Page End: 558
• Publication Date: 2017-08
• Subjects: Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2016.11.017
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: A wide-area long-pulse electron beam was used for transient heating of tungsten. Sample surface was imaged with fast CCD cameras during the beam pulse. NIR-imaging showed strong nonuniformity of the surface temperature. Cracks along the surface and partially detached pieces are related to hot areas. Laser reflection revealed intense melting near crack edges and crack intersections. Abstract: Experimental research on behavior of rolled tungsten plates under intense transient heat loads generated by a powerful (a total power of up to 7 MW) long-pulse (0.1–0.3 ms) electron beam with full irradiation area of 2 cm 2 was carried out. Imaging of the sample by the fast CCD cameras in the NIR range and with illumination by the 532 nm continuous-wave laser was applied for in-situ surface diagnostics during exposure. In these experiments tungsten plates were exposed to heat loads 0.5–1 MJ/m 2 with a heat flux factor (Fhf ) close to and above the melting threshold of tungsten at initial room temperature. Crack formation and crack propagation under the surface layer were observed during multiple exposures. Overheated areas with excessive temperature over surrounding surface of about 500 K were found on severely damaged samples more than 5 ms after beam ending. The application of laser illumination enables to detect areas of intense tungsten melting near crack edges and crack intersections.