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132 results on '"Barradas, N.P."'

20. Overview of the JET ITER-like wall divertor

Author

Widdowson, A., Alves, E., Baron-Wiechec, A., Barradas, N.P., Catarino, N., Coad, J.P., Corregidor, V., Garcia-Carrasco, A., Heinola, K., Koivuranta, S., Krat, S., Lahtinen, A., Likonen, J., Mayer, M., Petersson, P., Rubel, M., and Van Boxel, S.

Published
2017
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39. Ion beam analysis of fusion plasma-facing materials and components: facilities and research challenges

Author

Mayer, M, Möller, S, Rubel, M, Widdowson, A, Charisopoulos, S, Ahlgren, T, Alves, E, Apostolopoulos, G, Barradas, N.P., Donnelly, S, Fazinić, S, Heinola, K, Kakuee, O, Khodja, H, Kimura, A, Lagoyannis, A, Li, M, Markelj, S, Mudrinić, Mihajlo, Petersson, P, Portnykh, I, Primetzhofer, D, Reichart, P, Ridikas, D, Silva, T, Gonzalez de Vicente, S.M., Wang, Y.Q., Mayer, M, Möller, S, Rubel, M, Widdowson, A, Charisopoulos, S, Ahlgren, T, Alves, E, Apostolopoulos, G, Barradas, N.P., Donnelly, S, Fazinić, S, Heinola, K, Kakuee, O, Khodja, H, Kimura, A, Lagoyannis, A, Li, M, Markelj, S, Mudrinić, Mihajlo, Petersson, P, Portnykh, I, Primetzhofer, D, Reichart, P, Ridikas, D, Silva, T, Gonzalez de Vicente, S.M., and Wang, Y.Q.

Abstract

Following the IAEA Technical Meeting on 'Advanced Methodologies for the Analysis of Materials in Energy Applications Using Ion Beam Accelerators', this paper reviews the current status of ion beam analysis (IBA) techniques and some aspects of ion-induced radiation damage in materials for the field of materials relevant to fusion. Available facilities, apparatus development, future research options and challenges are presented and discussed. The analysis of beryllium and radioactivity-containing samples from future experiments in JET or ITER represents not only an analytical but also a technical challenge. A comprehensive list of the facilities, their current status, and analytical capabilities comes alongside detailed descriptions of the labs. A discussion of future issues of sample handling and the current status of facilities at JET complete the technical section. To prepare the international IBA community for these challenges, the IAEA technical meeting concludes the necessity for determining new nuclear reaction cross-sections and improving the inter-laboratory comparability by defining international standards and testing these via a round-robin test.

Published
2020

41. IBA for materials analysis in fusion research

Author

Mayer, M., Möller, S., Rubel, M., Widdowson, A., Charisopoulos, S., Ahlgren, T., Alves, E., Apostolopoulos, G., Barradas, N.P., Donnelly, S., Fazinić, Stjepko, Heinola, K., Kakuee, O., Khodja, H., Kimura, A., Lagoyannis, A., Li, M., Markelj, S., Mudrinic, M., Petersson, P., Portnykh, I., Primetzhofer, D., Reichart, P., Ridikas, D., Silva, T., Gonzalez de Vicente, S.M., Wang, Y.Q., Garrido, F., Moncoffre, N., Pacheco, C., and Vickridge, I.

Subjects
IBA, materials analysis, fusion research
Abstract

The interaction between the confined hot plasma in a controlled fusion device and the surrounding vessel walls is a major challenge on the road to a successful use of fusion energy. First wall materials undergo serious modification by physical and chemical processes arising from plasma–wall interactions. This includes material erosion, transport of eroded material in the plasma and re-deposition leading to the formation of mixed-material layers, and accumulation of hydrogen isotopes including tritium in the wall materials by implantation, diffusion and co-deposition. The understanding of these processes is crucial for the economy and safety of reactor operation. Ion Beam Analysis (IBA) techniques play a particularly prominent role in the analysis of first wall materials due to their sensitivity for individual isotopes in the low-Z range up to 10 (especially for D, T, Be and tracer isotopes such as 13C or 15N), high sensitivity, absolute quantification without the need for reference samples, applicability to rough or multi-phase samples, and the possibility to use several methods in a single run. The analysis of first wall materials is challenging not only for the analytical but also for the technical capabilities due to the broad range of isotopes and elements, the need of analysis of rough samples with technical surfaces, handling of large and heavy sample with sizes up to more than 30 cm and weights of several kg, and handling of hazardous and radioactive materials such as beryllium and tritium. The IAEA Technical Meeting on “Advanced Methodologies for the Analysis of Materials in Energy Applications Using Ion Beam Accelerators” [1] took place in October 2018 and reviewed the current status of ion beam analysis techniques for the field of materials relevant to fusion. Available facilities, apparatus developments and future research options, challenges and analytical needs were presented and discussed. The high level of international cooperation in fusion research yields advantages by providing a variety of analysis setups optimized for different tasks, but also results in problems of inter-comparability and standardization. To prepare the international ion beam analysis community for these challenges, the IAEA technical meeting concludes the necessity to provide facilities for handling of hazardous materials (tritium, activated samples, beryllium) for existing experiments and ITER ; to determine and possibly evaluate cross-sections and stopping powers for elements and isotopes with relevance for fusion ; to standardize measurement and evaluation procedures ; and to perform an international round-robin test with fusion relevant samples for determining the accuracy and comparability of different laboratories.

Published
2019

42. Ion beam analysis of fusion plasma-facing materials and components: facilities and research challenges

Author

Mayer, M., primary, Möller, S., additional, Rubel, M., additional, Widdowson, A., additional, Charisopoulos, S., additional, Ahlgren, T., additional, Alves, E., additional, Apostolopoulos, G., additional, Barradas, N.P., additional, Donnelly, S., additional, Fazinić, S., additional, Heinola, K., additional, Kakuee, O., additional, Khodja, H., additional, Kimura, A., additional, Lagoyannis, A., additional, Li, M., additional, Markelj, S., additional, Mudrinic, M., additional, Petersson, P., additional, Portnykh, I., additional, Primetzhofer, D., additional, Reichart, P., additional, Ridikas, D., additional, Silva, T., additional, Gonzalez de Vicente, S.M., additional, and Wang, Y.Q., additional

Published
2019
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44. Overview of the JET ITER-like wall divertor

Author

Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Widdowson, A., Alves, E., Baron-Wiechec, A., Barradas, N.P., Catarino, N., Jet Contributors, García Muñoz, Manuel, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Widdowson, A., Alves, E., Baron-Wiechec, A., Barradas, N.P., Catarino, N., Jet Contributors, and García Muñoz, Manuel

Abstract

The work presented draws on new analysis of components removed following the second JET ITER-like wall campaign 2013–14 concentrating on the upper inner divertor, inner and outer divertor corners, life- time issues relating to tungsten coatings on JET carbon fibre composite divertor tiles and dust/particulate generation. The results show that the upper inner divertor remains the region of highest deposition in the JET-ILW. Variations in plasma configurations between the first and second campaign have altered ma- terial migration to the corners of the inner and outer divertor. Net deposition is shown to be beneficial in the sense that it reduces W coating erosion, covers small areas of exposed carbon surfaces and even encapsulates particles.

Published
2017

45. Assessment of erosion, deposition and fuel retention in the JET-ILW divertor from ion beam analysis data

Author

Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, Catarino, N., Barradas, N.P., Corregidor, V., Widdowson, A., Baron-Wiechec, A., Jet Contributors, García Muñoz, Manuel, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, Catarino, N., Barradas, N.P., Corregidor, V., Widdowson, A., Baron-Wiechec, A., Jet Contributors, and García Muñoz, Manuel

Abstract

Post-mortem analyses of individual components provide relevant information on plasma-surface interac- tions like tungsten erosion, beryllium deposition and plasma fuel retention with divertor tiles via implan- tation or co-deposition. Ion Beam techniques are ideal tools for such purposes and have been extensively used for post-mortem analyses of selected tiles from JET following each campaign. In this contribution results from tiles removed from the JET ITER-Like Wall (JET-ILW) divertor follow- ing the 2013–2014 campaign are presented. The results summarize erosion, deposition and fuel retention along the poloidal cross section of the divertor surface and provide data for comparison with the first JET-ILW campaign, showing a similar pattern of material migration with the exception of Tile 6 where the strike point time on the tile was ∼4 times longer in 2013–2014 than in 2011–2012, which is likely to account for more material migration to this region. The W deposition on top of the Mo marker coating of Tile 4 shows that the enrichment takes place at the strike point location.

Published
2017

46. Composition measurement of epitaxial ScxGa1-xN films

Author

Tsui, H.C.L., Goff, L.E., Barradas, N.P., Alves, E., Pereira, S., Palgrave, R.G., Davies, R.J., Beere, H.E., Farrer, I., Ritchie, D.A., and Moram, M.A.

Abstract

Four different methods for measuring the compositions of epitaxial ScxGa1-xN films were assessed and compared to determine which was the most reliable and accurate. The compositions of epitaxial ScxGa1-xN films with 0 ≤ x ≤ 0.26 were measured directly using Rutherford backscattering (RBS) and x-ray photoelectron spectroscopy (XPS), and indirectly using c lattice parameter measurements from x-ray diffraction and c/a ratio measurements from electron diffraction patterns. RBS measurements were taken as a standard reference. XPS was found to underestimate the Sc content, whereas c lattice parameter and c/a ratio were not reliable for composition determination due to the unknown degree of strain relaxation in the film. However, the Sc flux used during growth was found to relate linearly with x and could be used to estimate the Sc content.

Published
2016

49. Overview of fuel inventory in JET with the ITER-like wall

Author

Widdowson, A., primary, Coad, J.P., additional, Alves, E., additional, Baron-Wiechec, A., additional, Barradas, N.P., additional, Brezinsek, S., additional, Catarino, N., additional, Corregidor, V., additional, Heinola, K., additional, Koivuranta, S., additional, Krat, S., additional, Lahtinen, A., additional, Likonen, J., additional, Matthews, G.F., additional, Mayer, M., additional, Petersson, P., additional, and Rubel, M., additional

Published
2017
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