München 2019 – scientific programme
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P: Fachverband Plasmaphysik
P 18: Postersitzung
P 18.123: Poster
Thursday, March 21, 2019, 16:30–18:30, Foyer Audimax
Exposure of diagnostic duct system with mirrors in EAST tokamak: first results — •Tiziana von Witzleben1,2, Andrey Litnovsky1, Jiao Peng1,3, Yury Krasikov1, and Christian Linsmeier1 — 1Forschungszentrum Jülich, Institut für Energie- und Klimaforschung, 52425 Jülich, Germany — 2RWTH Aachen University, Department of Particle Physics, 52064 Aachen, Germany — 3University of Science and Technology of China, 230026 Hefei, China
The first mirrors of future tokamaks, such as ITER, are receiving plasma radiation and guiding it to the tokamaks experimental detecting systems. They are used in all optical diagnostics in ITER and deliver important information on the physical processes and machine operations. To evaluate how the reflectivity of the mirrors changes in the tokamak and how it could be preserved, a diagnostic duct system was placed inside of the EAST tokamak from the 12.06.17 until the 23.07.17. It consists of three different pairs of tubes, that have single crystal Mo mirrors placed at their ends: two long tubes with a length of 10 cm, two medium tubes with a length of 7 cm and two short tubes, that measure 5 mm. One of the tubes of each pair is equipped with protective fins. The mirrors’ total, diffuse and specular reflectivity have been characterized before and after the exposure. The results show very strong degradation of the specular reflectivity for mirrors in the short tubes, of up to 65 % at a wavelength of 1290 nm. In the case of the medium tubes a maximal loss of reflectivity of 18 % at 252 nm can be measured. Similarly, mirrors in the long tubes show a loss of up to 18 % at a wavelength of 250 nm.