1. Ammonia formation and W coatings interaction with deuterium/nitrogen plasmas in the linear device GyM
- Author
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Espedito Vassallo, Matteo Passoni, R. Caniello, L. Laguardia, D. Minelli, Francesco Ghezzi, G. Gittini, A. Cremona, Gustavo Granucci, V. Mellera, F. Pallotta, D. Ricci, David Dellasega, and F. Dell'Era
- Subjects
Nuclear and High Energy Physics ,Chemistry ,Diffusion ,Divertor ,TUNGSTEN FILMS ,Analytical chemistry ,chemistry.chemical_element ,Plasma ,Nitrogen ,Ion ,Materials Science (all) ,Nuclear Energy and Engineering ,Ammonia ,chemistry.chemical_compound ,Deuterium ,X-ray photoelectron spectroscopy ,General Materials Science - Abstract
In this work results of the first D 2 /N 2 experiments in GyM, a linear device able to produce plasmas of interest for the ITER divertor ( n e 5 ⋅ 10 10 cm −3 , Te 5 eV, ion flux 3–5 ⋅ 10 20 m −2 s −1 ) are presented. Plasmas simulating a N-seeding scenario have been performed to evaluate ammonia formation and its effect on exposed W coatings. The presence of ND emission lines in the plasma can be correlated with the formation of ammonia, further directly detected and quantified by chromatography analysis of the exhaust. Four different W specimens were exposed in GyM to a plasma fluence of 8.78 ⋅ 10 23 m −2 . XPS analysis evidenced the formation of W x N y layers with nitrogen concentration in the range of 1–10% depending on the initial morphology and structure of the W samples. In all analyzed cases, nitrogen was bound and retained within the first 6 nm below the surface and no further diffusion of N into the bulk was observed.
- Published
- 2015
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