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Marion L.F.,CEA Saclay Nuclear Research Center | Monnet I.,CNRS Center for Research on Ions, Materials and Photonics
Journal of Nuclear Materials

The good radiation resistance of Ti3(Si1-xAl x)C2 (x = 0.05, 0.07, 0.1) has been recently demonstrated through 95 MeV Xe irradiations up to 2 × 1019 m-2 which did not induce amorphisation. In this work, the irradiation damage level of Ti3(Si0.95Al0.05)C2 was raised up to 4.5 × 1019 m-2: saturation of hardness above 1019 cm-2 suggests saturation of microstructure disorder. Same conclusions could be deduced from irradiation of (Ti0.95Zr 0.05)(Si0.9Al0.1)C2. © 2012 Elsevier B.V. All rights reserved. Source

Moncorge R.,CNRS Center for Research on Ions, Materials and Photonics
Optical Materials

The purpose of this presentation is to review the spectroscopic properties of the main laser materials based on transition metal ions which lead to noticeable laser performance at room temperature and, for very few cases, because of unique properties, when they are operated at cryogenic temperatures. The description also includes the materials which are currently being used as saturable absorbers for passive-Q-switching of a variety of other near- and mid-infrared solid state lasers. A substantial part of the article is devoted first to the description of the energy levels and of the absorption and emission transitions of the transition metal ions in various types of environments by using the well-known Tanabe-Sugano diagrams. It is shown in particular how these diagrams can be used along with other theoretical considerations to understand and describe the spectroscopic properties of ions sitting in crystal field environments of near-octahedral or near-tetrahedral symmetry. The second part is then dedicated to the description (positions and intensities) of the main absorption and emission features which characterize the different types of materials. © 2016. Source

Hasnaoui A.,University of Science and Technology Houari Boumediene | Ait-Ameur K.,CNRS Center for Research on Ions, Materials and Photonics
Applied Optics

This paper considers the transverse optical properties of an absorbing ring when it is lighted by a symmetrical Laguerre-Gauss beam TEMp0. It is demonstrated that the insertion of an opaque ring having adequate size inside a diaphragmed laser cavity is able to improve greatly (rate of about 100%) the discrimination between the TEM00 and the TEM10 modes, while keeping the diffraction losses unchanged or even decreased. © 2010 Optical Society of America. Source

Ait-Ameur K.,CNRS Center for Research on Ions, Materials and Photonics
Optics Communications

We consider the transverse characteristics of a Gaussian laser beam subject to a phase or amplitude clipping due to a pupil which is a π-plate or an opaque disc (stop). In particular, we consider the correlation between two features, the Strehl ratio and divergence angle, usually used for characterising the focusability of a diffracted beam. It is demonstrated that the Strehl ratio does not give systematically a global view, from a divergence point of view, on the transverse properties of a Gaussian beam suffering amplitude or phase diffraction. In addition, we consider the case of self-diffraction of a Gaussian beam upon a Gaussian phase aberration of same width, and it is found that the on-axis intensity describes correctly the whole diffracted beam cross-section, from a divergence point of view, only if the central phase shift is smaller than π. Another example showing that the focusability of a pure high-order Laguerre-Gauss TEM p0 beam, free from any clipping, cannot be correctly described by Strehl ratio is also considered. © 2011 Elsevier B.V. All rights reserved. Source

Fremont F.,CNRS Center for Research on Ions, Materials and Photonics
Journal of Physics B: Atomic, Molecular and Optical Physics

A classical model is used to study electron capture and single ionization (SI) following H+ + Ar collisions at projectile energies varying from 400 to 40 keV. In the present model, the Ar electrons are treated independently from each other, and only the 3s and 3p electrons are supposed to be captured by the projectile. In addition, a Coulombic potential with an effective charge Z eff = 6.75, derived from Slater rules, is used in the calculations to simulate the screening of the Ar nucleus due to the presence of the core and 2l electrons. Total cross sections for single electron capture and SI are calculated and compared with previous experiments and earlier calculations based on a semiclassical approach. The reasonable agreement we observed allows a preliminary study of double electron capture (DC). The total cross section for DC is found to be much larger than the experimental one. Possible reasons for this disagreement are discussed. © 2016 IOP Publishing Ltd. Source

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