Design, construction, and beam tests of a rotatable collimator prototype for high-intensity and high-energy hadron accelerators

A rotatable-jaw collimator design was conceived as a solution to recover from catastrophic beam impacts which would damage a collimator at the Large Hadron Collider (LHC) or its High-Luminosity upgrade (HL-LHC). One such rotatable collimator prototype was designed and built at SLAC and delivered to CERN for tests with LHC-type circulating beams in the Super Proton Synchrotron (SPS). This was followed by destructive tests at the dedicated High Radiation to Materials (HiRadMat) facility to validate the design and rotation functionality. An overview of the collimator design, together with results from tests without and with beam are presented

Développement des moyens pour améliorer la maîtrise des irrigations de surface : conduite des arrosages en systèmes gravitaires modernisés : rapport de synthèse de la campagne 1986 - texte - annexes

[Notes_IRSTEA]graph., sch., tabl., ann.A partir d'observations réalisées sur 16 parcelles en 1986, on analyse les économies de main d'oeuvre possibles avec les matériels d'irrigation de surface et les problèmes rencontrés en matière de conduite des arrosages à la raie. Il en ressort que le mode traditionnel exige au minimum deux fois plus de travail et une main d'oeuvre plus qualifiée que les systèmes modernisés, alors que cette dernière se fait de plus en plus rare. La conduite des arrosages à la raie en systèmes modernisés est meilleure qu'en mode traditionnel principalement parce qu'elle assure une distribution latérale homogène lorsqu'un minimum de précautions sont prises. Mais le degré de performance allient en ce qui concerne l'adéquation de la dose apportée aux besoins et l'uniformité de la répartition longitudinale dépend des conditions particulères à chaque parcelle. On propose une hiérarchisation de ces conditions permettant de faire un pronostic sur les performances de la conduite. Les hypothèses émises ont été validées par un diagnostic réalisé à partir des observations de la campagne d'arrosage. Les problèmes les plus délicats à résoudre proviennent de la difficulté à définir la perméabilité du sol dans le temps etl'espace

Acquisition de références techniques et économiques sur les matériels d'irrigation de surface

The ARTEMIS test and demonstration operation (gathering of technical and economical references on ground irrigation systems) started in 1987-88 in the South-East of France in several farms that agreed to evaluate the interest of a modernization of traditional gravity irrigation. The article presents the study conclusions, and stresses the economic aspects at the plot level as well as the positive effects that can be expected on the collective organization of watering. / L'opération d'expérimentation et de démonstration ARTEMIS (acquisition de références technico-économiques sur les matériels d'irrigation de surface) a été engagé en 1987-88 dans le Sud-Est de la France auprés de plusieurs exploitations volontaires pour évaluer l'intérêt d'une modernisation de l'irrigation gravitaire traditionnelle. L'article résume les conclusions de l'étude en insistant sur les aspects économiques au niveau de la parcelle et les effets positifs attendus sur l'organisation collective des arrosages

Surface charges of oxides and wettability: Application to TiO2-SiO2 composite films

International audienceThe super-hydrophilicity which can exist at the interface between oxides and aqueous solutions is able to sustain industrial and domestic applications. Several experimental results obtained on TiO2-SiO2 composite thin films via a sol-gel route have confirmed a natural and persistent super hydrophilicity under standard atmosphere. This property can be easily photo-regenerated after a long aging period in ambient atmosphere using a short UV illumination. The electrochemical double layer which classically exists between oxide surfaces and aqueous solution is unfavorable to high wettability properties of ideal flat surfaces. The present study indicates how the surface rugosity and the disjoining pressure caused by surface charges are able to explain the stability of a prewetting film. This film can withstand to vaporization in a weakly under saturated atmosphere, having a protective action despite a carbon contamination brought by standard atmosphere. (C) 2013 The Authors. Published by Elsevier B. V. All rights reserved

Wetting properties of gas diffusion layers: Application of the Cassie-Baxter and Wenzel equations.

International audienceIn this paper, the wetting behaviours of as received and aged commercial 10% PTFE loaded gas diffusion layer were studied using the Wilhelmy plate method with liquid water temperature ranging from 5 to 60 degrees C. Comparison were made with an untreated sample and a PTFE smooth plate. These experimental results, supported by chemical and morphological surface characterizations, were discussed in the frame of the Wenzel and Cassie-Baxter regimes. For each wetting regime, surface fraction of solid, PTFE and carbon fibres and/or roughness coefficient were estimated by solving a system of Cassie-Baxter and/or Wenzel equations. The transition to one wetting regime to the other is also commented. Finally, the effects of ageing and of water temperature were studied. Ageing was found to alter the wetting behaviour of the GDL through its chemical degradation. An erosion and the crazing of the PTFE coating and an oxidation of the carbon fibres were pointed out. The decrease of the water surface tension linked to an increase of its temperature is also shown to lead to a better wetting and to an increase of the solid surface fraction value. This effect is reinforced by GDL ageing. (C) 2012 Elsevier B.V. All rights reserved

ARTEMIS - Acquisition de références technico-économiques sur les matériels d'irrigation de surface : guide technique des matériels d'irrigation de surface, vol.I

This guide, the goal of which is to help development agents faced with practical problems when applying recent gravity irrigation techniques, is the result of several observations performed in the South-East of France during the ARTEMIS (Gathering of technical and economical reference on surface irrigation) system study. It describes modern systems and details equipment sizing and installation, flow adjustment, and watering practical monitoring. Economic data which help choose equipment and analyze its yield, can also be found. / Destiné aux agents de développement confrontés aux problèmes pratiques de l'application des techniques récentes d'irrigation gravitaire, ce guide est la concrétisation de nombreuses observations réalisées dans le Sud-Est de la France au cours de l'étude ARTEMIS (acquisition de références technico-économiques sur les matériels d'irrigation de surface). Il décrit les matériels modernes et détaille le dimensionnement des équipements et leur installation, le réglage des débits et la conduite pratique des arrosages. On y trouve également des données économiques permettant de choisir un équipement et d'analyser sa rentabilité

Morphology-wettability relations in artificially structured superhydrophilic TiO2-SiO2 composite films

International audienceNaturally superhydrophilic TiO2-SiO2 composite films were deposited through a sol-gel route and the morphology of these films was artificially modified by nanosphere lithography using polystyrene spheres. Morphology changes induced by this structuration were studied by optical, scanning electron, and atomic force microscopy. The water wettability of the so-obtained films over aging under ambient atmosphere was then studied with respect to the sol composition and morphological features. This study i/confirms the assumption of a natural superhydrophilicity of composite films intrinsically induced by TiO2-SiO2 granular interfaces and ii/shows that this property can be greatly improved by artificially induced morphology features. Such features are discussed on the basis of well-established surface thermodynamic models