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MM: Fachverband Metall- und Materialphysik
MM 18: Poster Session I
MM 18.6: Poster
Montag, 16. März 2020, 18:15–20:00, P4
Analysis of Crystal Defects in Tungsten by Positron Annihilation Lifetime and Doppler-Broadening Spectroscopy — •Vassily Vadimovitch Burwitz1, Thomas Schwarz-Selinger2, and Christoph Hugenschmidt1 — 1Physik Department E21 and FRM II, TU München — 2Max-Planck-Institut für Plasmaphysik, Garching bei München
The quantitative analysis of radiation defects in tungsten is important for the safe operation of future nuclear fusion reactions.
Positron annihilation measurements were conducted in order to trace defect evolution through the treatment steps. All tungsten samples studied were cut by spark erosion from the same single-crystal rod with orientation (111), polished mechanically and electro-chemically before annealing at 2300 K under vacuum. One set of samples was irradiated by an MeV electron beam to different fluences, in order to produce Frenkel pairs as the predominant defect type. The other set was quenched from various temperatures close to the melting point in order to freeze in single vacancies at well-defined concentrations. This procedure provides a benchmark for single vacancies, thereby it is possible to determine if other defect types are present too. Positron annihilation lifetime (PALS) and Doppler-broadening spectroscopy (DBS) was performed simultaneously using a Na-22 source with two samples in sandwich geometry. First results are presented showing how different defect types in tungsten can be characterized by a combined analysis of DBS and PALS data.