Time filter

Source Type

Frascati, Italy

Goncharova O.,National Academy of Sciences of Belarus | Goncharova O.,Frascati Research Center | Montereali R.M.,Frascati Research Center | Baldacchini G.,Frascati Research Center
Journal of Physics: Conference Series | Year: 2010

To discover well the properties of nanothin crystalline layers and nanometer-sized crystals, we investigated the relatively thick multilayer structures composed of high quantity of nanothin layers with nanocrystals. Alternate nanolayers of 150-10 nm thicknesses with LiF, CaF 2 and CdS nanocrystals have been deposited onto irradiation-resistive substrates by thermal evaporation of pure crystals. Some multilayers were γ-irradiated in air at room temperature with dose of 83 kGy. X-ray diffraction and microscopy studies reveal that the multilayers consist of nanocrystals with cubic phase and defined size. Thin-film structures were oriented along the (111) plane. Absorption spectra of non-irradiated LiF nanocrystals of 100 nm size suggest evidence of metal colloids presence. We find that photoluminescence spectra of γ-irradiated nanostructures with metal colloids and various LiF contents show the enhancement of F 3 +-colour centres excitation in the region of metal colloids absorption and the increase is observed of the emission intensities ratio of F 3 + and F 2 centers with respect to initial crystals γ-coloured in identical conditions. Emission intensities of both centers under excitation at 458 nm correlate with LiF content. These effects, which are related to high-quality nanostructures, but at the same time depend strongly on the defect content, especially as far as their 1-2 ps nonlinearities are concerned, could depend on nanocrystal purity and metal excess collection in their boundaries regions. Our results provide an original contribution to the understanding of the influence of the nanolayer-by-nanolayer deposition, γ-irradiation on these specific structures, and of the metal aggregates on the properties of nanocrystals and nanolayers. © 2010 IOP Publishing Ltd. Source

Marignetti F.,University of Cassino and Southern Lazio | Cavaliere V.,Consorzio Ricerche Innovative per Il Sud Ansaldo | Giunchi G.,Edison S.p.a | Messina G.,Frascati Research Center | And 2 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2013

Magnesium diboride is a promising superconducting material with interesting electrical and mechanical properties. Reactive liquid magnesium infiltration is an effective technology to produce cheap and reliable bulk components potentially suitable for application in electric machinery. This study deals with the magnetic flux-trapping capabilities of bulk samples manufactured through this technique. The aim of this work is to evaluate the samples as magnets for synchronous machines. In this paper, a number of trapped flux measurements on different magnesium diboride samples are reported. The experimental results are discussed on the basis of the numerical model of the superconducting material. © 2002-2011 IEEE. Source

Camprini P.C.,Brasimone Research Center | Bernardi D.,Brasimone Research Center | Pillon M.,Frascati Research Center | Angelone M.,Frascati Research Center | And 4 more authors.
Fusion Engineering and Design | Year: 2015

In the framework of fusion materials research, a neutron source has been considered a key installation to support EU plan toward DEMO reactor design. IFMIF facility being the present proposal, a pragmatic approach to EU fusion roadmap timeline considers complementary solutions mandatory, within a shared strategy. New Sorgentina Fusion Source (NSFS) has been recently proposed in order to populate an engineering database through materials irradiation tests. Proven technology of D-T neutron generators is implemented together with ion source and accelerator devices currently used in neutral injection systems at experimental tokamaks. Deuterium and tritium enriched hydride is on-line reloaded by impinging D-T beams via ion implantation onto a high-speed rotating target - D-T retention is allowed through temperature control. Hydride metal layer is re-deposited increasing plant availability factor. Target design is proposed to cope with thermal transients and mechanical loads. Solutions to thermal fatigue concerns are presented. Irradiation capability is then enhanced attaining relevant materials exposure. Main facility characteristics are provided as well as thermal and mechanical issues. © 2015 Elsevier B.V. Source

Discover hidden collaborations