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Regensburg 2022 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 25: Poster

KFM 25.23: Poster

Thursday, September 8, 2022, 15:00–18:00, P2

Quantifying the Defect Density in Tungsten Single-Crystals by Positron Annihilation Doppler-Broadening Spectroscopy — •Vassily Vadimovitch Burwitz1, Annemarie Kärcher2,3, Lucian Mathes1, Thomas Schwarz-Selinger3, and Christoph Hugenschmidt11Heinz Maier-Leibnitz Zentrum, TU München — 2TU München — 3Max-Planck-Institut für Plasmaphysik, Garching bei München

In future nuclear fusion reactors tungsten will be used as inner wall cladding. Understanding the formation and behaviour of radiation induced defects in tungsten is therefore important for their safe oper- ation. To foster this understanding we use tungsten single-crystals as a model system. The tungsten samples used in this study were cut by spark erosion from the same single-crystal rod with orientation (111), polished mechanically and electro-chemically. One set of samples was irradiated by a 4.5 MeV electron beam to different fluences, in order to produce Frenkel pairs as the predominant defect type. Another set was quenched from various temperatures close to the melting point in order to freeze in single vacancies at well-defined concentrations. Positron annihilation Doppler-broadening spectroscopy (DBS) measurements were conducted in order to trace defect evolution throughout the sample preparation process. These depth resolved DBS measurements were performed using a slow positron beam setup fed by a tungsten moderated Na-22 source. The positrons were implantated with a maximum energy of 40 keV.

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