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P: Plasmaphysik

P 15: Diagnostik 2; Niedertemperaturplasmen / Plasmatechnologie 5; Plasma-Wand Wechselwirkung 1

P 15.40: Poster

Dienstag, 28. März 2006, 17:00–19:00, Flure

A remote ellipsometer for TEXTOR — •Timo Dittmar¹, Achim von Keudell¹, and Arkadi Kreter² — ¹Ruhr Universität Bochum — ²Forschungszentrum Jülich

Deposition and erosion of plasma faced surfaces inside fusion reactors are a key issue for the estimation of the life time of the first wall in present and future fusion devices. In-situ measurements of erosion rates or changes in composition and texture of the deposited layer are currently not possible. Ellipsometry seems to be a proper technique for this kind of measurements. It offers mono layer film thickness resolution and allows the precise and sensitive determination of the optical properties of thin films high sensitivity. Therefore it is feasible to study processes at the plasma-wall interface in real time and with high accuracy. Since the optical constants of a material are closely linked with its stoichiometry it is possible to correlate them with the composition. Nevertheless conventional ellipsometric instruments are not suitable in the Tokamak environment due to the Faraday-Effect in the retarding elements and problems with optical access in the divertor region. The limitations of conventional Ellipsometry can overcome with the constructing of an in-situ reverse ellipsometry probe head using a four diode stokesmeter. On this poster we present the first results during testing and calibration of an miniature ellipsometric probe head on an ICP reactor.