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Proceedings Paper

Laser erosion diagnostics of plasma facing materials with displacement sensors and their application to safeguard monitors to protect nuclear fusion chambers
Author(s): Koichi Kasuya; Shinji Motokoshi; Seiji Taniguchi; Mitsuo Nakai; Kazutoshi Tokunaga; Waldemar Mroz; Boguslaw Budner; Barbara Korczyc
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Paper Abstract

Tungsten and SiC are candidates for the structural materials of the nuclear fusion reactor walls, while CVD poly-crystal diamond is candidate for the window material under the hazardous fusion stresses. We measured the surface endurance strength of such materials with commercial displacement sensors and our recent evaluation method. The pulsed high thermal input was put into the material surfaces by UV lasers, and the surface erosions were diagnosed. With the increase of the total number of the laser shots per position, the crater depth increased gradually. The 3D and 2D pictures of the craters were gathered and compared under various experimental conditions. For example, the maximum crater depths were plotted as a function of shot accumulated numbers, from which we evaluated the threshold thermal input for the surface erosions to be induced. The simple comparison-result showed that tungsten was stronger roughly two times than SiC. Then we proposed how to monitor the surface conditions of combined samples with such diamonds coated with thin tungsten layers, when we use such samples as parts of divertor inner walls, fusion chamber first walls, and various diagnostic windows. We investigated how we might be able to measure the inner surface erosions with the same kinds of displacement sensors. We found out the measurable maximum thickness of such diamond which is useful to monitor the erosion. Additionally we showed a new scheme of fusion reactor systems with injectors for anisotropic pellets and heating lasers under the probable use of W and/or SiC.

Paper Details

Date Published: 3 February 2015
PDF: 6 pages
Proc. SPIE 9255, XX International Symposium on High-Power Laser Systems and Applications 2014, 925548 (3 February 2015); doi: 10.1117/12.2065233
Show Author Affiliations
Koichi Kasuya, Institute of Applied Flow (Japan)
Institute of Laser Technology (Japan)
Shinji Motokoshi, Institute of Laser Technology (Japan)
Seiji Taniguchi, Institute of Laser Technology (Japan)
Mitsuo Nakai, Osaka Univ. (Japan)
Kazutoshi Tokunaga, Kyushu Univ. (Japan)
Waldemar Mroz, Military Univ. of Technology (Poland)
Boguslaw Budner, Military Univ. of Technology (Poland)
Barbara Korczyc, Military Univ. of Technology (Poland)

Published in SPIE Proceedings Vol. 9255:
XX International Symposium on High-Power Laser Systems and Applications 2014
Chun Tang; Shu Chen; Xiaolin Tang, Editor(s)

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