Study on melting and solidification behaviors of tungsten loaded by high heat flux for divertor in tokamak fusion reactor

Study on melting and solidification behaviors of tungsten loaded by high heat flux for divertor in tokamak fusion reactor

Tungsten is a candidate as a surface material of divertor in Tokamak fusion reactor. A pulsed high heat flux emitted in plasma disruption and Type I Edge Localized Mode (ELM) is considered to melt the tungsten surface repeatedly. The repetitive phase change can transmute surface characteristics of d...

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Bibliographic Details
Published in:Fusion engineering and design Vol. 136; pp. 350 - 356
Main Authors: Hoashi, Eiji, Kuroyanagi, Shinpei, Okita, Takafumi, Maeji, Takeru, Ibano, Kenzo, Ueda, Yoshio
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 01-11-2018
Elsevier Science Ltd
Subjects:
Dimensional measurement
Disruption
Fusion reactors
Heat flux
Heat transfer
In-situ observation
Irradiation
Lasers
Measurement methods
Melting
Nuclear engineering
Nuclear safety
Phase change
Phase transitions
Photography
Radiation
Reactors
Solidification
Solids
Stereophotography
Stereoscopic photography
Surface properties
Thermal resistance
Tokamak devices
Tungsten
Tungsten divertor
Tungsten divertor
In-situ observation
Phase change
Stereoscopic photography
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Summary:Tungsten is a candidate as a surface material of divertor in Tokamak fusion reactor. A pulsed high heat flux emitted in plasma disruption and Type I Edge Localized Mode (ELM) is considered to melt the tungsten surface repeatedly. The repetitive phase change can transmute surface characteristics of divertor and then reduce the thermal resistance. For the safety design and the development acceleration of fusion demonstration reactor, investigation and understanding of surface melting and solidification procedure are important. In previous studies, experiments have been conducted by Ueda et al. and the surface after the laser irradiation had the geometry as a crater with a center cone. However, the formation mechanism of the crater was not fully understood. In this paper, two measurement methods are studied. One is an in-situ observation method of tungsten and molybdenum surface during the laser irradiation using high speed video camera, and another is a 3-dimensional measurement of tungsten surface shape after the laser irradiation experiments using a stereoscopic photography technique. In the former, it was confirmed that a molten pool had wavy surface pattern until solidification, and the applicability of the stereoscopic photography technique for the in-situ observation during the laser irradiation was indicated in the latter.
ISSN:0920-3796
1873-7196
DOI:10.1016/j.fusengdes.2018.02.028