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Abstract
Plasma fluence at the divertor of a future magnetic confinement fusion device can accumulate up to ~1028-1029 m-2 per year. Yet hydrogen isotope retention under such high-fluence plasma exposure has been rarely reported. To investigate deuterium (D) retention in tungsten (W) exposed to such high-fluence plasma, a series of high-flux D plasma exposures were preformed using recrystallized W samples at ~500 K in Magnum-PSI. The highest fluence achieved was ~1×1029 m-2. Surface morphology observations indicate an initial increase in the number of blisters at the sample surface with increasing fluence, followed by saturation at ~1×1029 m-2. Multiple bursts of blisters with open cracks or edges were observed under the two highest fluences of ~1×1028 m-2 and ~1×1029 m-2. 3He nuclear reaction analysis (NRA) shows a maximum D concentration up to 0.012 at.fr., distributed within the first 4 μm from the sample surface under the highest fluence. D retention, as measured by NRA and thermal desorption spectroscopy, tends to saturate with increasing fluence. Simulations of D2 thermal desorption, performed using the TMAP rate equation code, show a maximum D trapping depth of ~10 µm, consistent with the defect depth profile revealed by transmission electron microscopy. D retention saturation observed in this work is attributed to the sample surface morphology modifications and the saturation of plasma-induced defects. This investigation provides a valuable reference for understanding the evolution of total hydrogen isotope retention in W under high-fluence plasma exposure in future fusion devices.- Book : ()
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Variations in solar energy when it reaches the Earth impact the production of photovoltaic (PV) solar plants and, in turn, the dynamics of clean energy expansion. This incentivizes the objective of experimentally forecasting solar energy by parametric models, the results of which are then refined by machine learning methods (MLMs). To estimate solar energy, parametric models consider all atmospheric, climatic, geographic, and spatiotemporal factors that influence decreases in solar energy. In this study, data on ozone, evenly mixed gases, water vapor, aerosols, and solar radiation were gathered throughout the year in the mid-north area of Mozambique. The results show that the calculated solar energy was close to the theoretical solar energy under a clear sky. When paired with MLMs, the clear-sky index had a correlational order of 0.98, with most full-sun days having intermediate and clear-sky types. This suggests the potential of this area for PV use, with high correlation and regression coefficients in the range of 0.86 and 0.89 and a measurement error in the range of 0.25. We conclude that evenly mixed gases and the ozone layer have considerable influence on transmittance. However, the parametrically forecasted solar energy is close to the energy forecasted by the theoretical model. By adjusting the local characteristics, the model can be used in diverse contexts to increase PV plants’ electrical power output efficiency.- Book : 10(3)
- Pub. Date : 2025
- Page : pp.37-37
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No Brasil, todo Serviço de Medicina Nuclear precisa apresentar um memorial de blindagem aos órgãos reguladores antes da construção e do início de suas atividades. As dependências de instalações radiativas devem possuir blindagens suficientes para manter as doses recebidas pelo público e pelos Indivíduos Ocupacionalmente Expostos dentro dos níveis de referência estabelecidos pelas resoluções da Comissão Nacional de Energia Nuclear. A blindagem consiste na adoção de barreiras físicas adicionais às estruturas existentes, com intuito de atenuar a radiação ionizante proveniente das fontes existentes nas instalações, o que requer cálculos complexos devido às muitas variáveis envolvidas, uma vez que em medicina nuclear utilizam-se fontes não seladas de radiação ionizante e os próprios pacientes se tornam fontes radioativas. Poucos documentos até hoje foram publicados sobre o tema e, até o momento, não foi encontrada na literatura uma publicação que reúna de forma clara todas as informações e orientações necessárias para realização de cálculos de blindagem de instalações de medicina nuclear. O objetivo deste trabalho é apresentar um guia com bases metodológicas e uma linha de raciocínio lógica para realização de cálculos de blindagem em medicina nuclear no Brasil, reunindo as definições e considerações encontradas na literatura.- Book : 19()
- Pub. Date : 2025
- Page : pp.799-799
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Nuclear medium effects on B+ meson production are studied using the binary-collision scaled cross section ratio between events of different charged-particle multiplicities from proton-lead collisions. Data, collected by the CMS experiment in 2016 at a nucleon-nucleon center-of-mass energy of sNN=8.16 TeV, corresponding to an integrated luminosity of 175 nb−1, were used. The scaling factors in the ratio are determined using a novel approach based on the Z→μ−μ+ cross sections measured in the same events. The scaled ratio for B+ is consistent with unity for all event multiplicities, putting stringent constraints on nuclear modification for heavy flavor.
© 2025 CERN, for the CMS Collaboration
2025
CERN
- Book : 134(11)
- Pub. Date : 2025
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