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Descripción
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| One of the challenges in the design of the future nuclear power plant is to develop materials capable to resist in the hostile environment of a fusion reactor. Because of its low sputtering yield, low-activation with a high melting point, high thermal conductivity, and low thermal expansion, tungsten is one of the most attractive materials proposed for first wall applications in the nuclear fusion reactors [1-3]. Even when W is assumed to be the best candidate as plasma facing material (PFM), some limitations have been identified that have to be defeated in order to fulfil specifications i. e one of the important point of concern is the light species behaviour (mainly H, D, T and He). Nowadays some strategies to overcome these limitations are being investigated [4]. In this work we focus on the study of the capabilities of nanoW as PFM. Firstly, we report about DC magnetron sputtering deposition procedure, presenting the dependence of sample microstructure on deposition parameters. Microestructural characterization studies, carried out by XRD, TEM and SEM, evidence that nanostructured samples are polycrystalline, preferentially oriented along the (110) direction and are composed of columns with a diameter in between 50 and 200 nm. Then, the thermal properties (conductivity and stability) are studied. These results illustrate that the column diameter does not significantly increases in the temperature range up to 400ºC. For temperatures higher than 800ºC the adhesion between W and the steel substrate has identified to be a major problem. Finally, the light species behavior is characterized as a function of sample microstructure and implantation conditions. Moreover, the role of the synergetic effects, taking place when the samples are simultaneously exposed to different particle irradiation, in the light species behaviour is addressed. For this purpose resonant nuclear reaction (RNRA) experiments were carried out by using the H(15N,He)12C nuclear reaction in nanoestrcutred (nW) and polycrystalline (pW) samples implanted with (i) H at an energy of 170 keV, (ii) sequentially implanted with C at an energy of 665 KeV and H at 170 KeV and (iii) simultaneously implanted with C and H at the above described energies. Implantations were carried out at a fluence of 5x1016 at/cm2and at two different temperatures RT and 400ºC. RNRA data evidence that the highest H retention is observed for the C and H co-implanted samples, being the lower one measured for those samples implanted only with H. In general, the H retention is higher for nW than for pW samples. Moreover, increasing the irradiation temperature up to 400ºC drives the H to completely out diffusion in nW as well as, in nW samples. The role of microstructure and radiation-induced damage on light species behaviour will be discussed. References [1] C. H. Wu et al. J. Nucl. Mater. 220-222 (1995) 860 [2] G. Federic et al. J. Nucl. Mater. 266-269 (11999) 14 [3] M. Kaufmann et al. Fusion Engineering and Design 82 (2007) 521-527 [4] Alvarez J., Rivera A., Gonzalez-Arrabal R., Garoz D., Del Rio E., Perlado J.M. Accepted in Fus. Sci. and Technol. | |
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Internacional
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Si |
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Nombre congreso
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2012 MRS Fall Meeting & Exhibit |
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Tipo de participación
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960 |
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Lugar del congreso
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Boston (USA) |
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Revisores
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Si |
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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26/11/2012 |
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Fecha fin congreso
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30/11/2012 |
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