Non-linear Synthesis of Complex Laser Waveforms at Remote Distances

Strong deformation of ultrashort laser pulse shapes is unavoidable when delivering high intensities at remote distances due to non-linear effects taking place while propagating. Relying on the reversibility of laser filamentation, we propose to explicitly design laser pulse shapes so that propagation serves as a non-linear field synthesizer at a remote target location. Such an approach allows, for instance, coherent control of molecules at a remote distance, in the context of standoff detection of pathogens or explosives.Comment: 17 pages, 6 figure

Effect of spray cooling on heat transfer in a two-phase helium flow

International audienceIn this paper, we describe an experimental study of the phenomenon of spray cooling in the case of liquid helium, either normal or superfluid, and its relationship to the heat transfer between an atomized diphasic flow contained in a long pipe, and the pipe walls. This situation is discussed in the context of the cooling of the superconducting magnets of the Large Hadron Collider (LHC). Experiments were conducted in a test loop reproducing the LHC cooling system, in which the vapor velocity and temperature could be varied in a large range. Shear induced atomization results in the generation of a droplet mist which was characterized by optical means. The thin liquid film deposited on the walls by the mist was measured using interdigitated capacitors. The cooling power of the mist was measured using thermal probes, and correlated to the local mist density. Analysis of the results shows that superfluidity has only a limited influence on both the film thickness and the mist cooling power. Using a simple model, we show that the phenomenon of spray cooling accounts for the measured non linearity of the global heat transfer. Finally, we discuss the relevance of our results for cooling the final focus magnets (inner triplets) in an upgraded version of the LHC

Algebraic Renormalization of N=1N=1 Supersymmetric Gauge Theories with Supersymmetry Breaking Masses

We provide N=1 Super Yang-Mills theory in the Wess-Zumino gauge with mass terms for the supersymmetric partners of the gauge fields and of the matter fields, together with a supersymmetric mass term for the fermionic matter fields. All mass terms are chosen in such a way to induce soft supersymmetry breakings at most, while preserving gauge invariance to all orders of perturbation theory. The breakings are controlled through an extended Slavnov-Taylor identity. The renormalization analysis, both in the ultraviolet and in the infrared region, is performed.Comment: 24 pages, plain LaTeX, no figure

Urban aerosols survey LIDAR and numerical model

In this paper, we present a new methodology for urban aerosol survey, coupling Lidar measurements and numerical models. The aim of this study is build a continuous survey of aerosol impact on the local and regional scale

Maximizing energy deposition by shaping few-cycle laser pulses

We experimentally investigate the impact of pulse shape on the dynamics of laser-generated plasma in rare gases. Fast-rising triangular pulses with a slower decay lead to early ionization of the gas and depose energy more efficiently than their temporally reversed counterparts. As a result, in both argon and krypton, the induced shockwave as well as the plasma luminescence are stronger. This is due to an earlier availability of free electrons to undergo inverse Bremsstrahlung on the pulse trailing edge. Our results illustrate the ability of adequately tailored pulse shapes to optimize the energy deposition in gas plasmas

Umweltpolitische Ziele der EU: deutsch-französische Beiträge zur Zielerreichung : Tagungsband des ersten deutsch-französischen Workshops Energiewirtschaft und Nachhaltigkeit in Karlsruhe am 29.-30. Januar 2009 = Concepts franco-allemands pour atteindre les objectifs environnementaux de l\u27UE : Actes du premier workshop franco-allemand Economie de l\u27Energie et Développement Durable à Karlsruhe les 29 et 30 janvier 2009

Dieses Buch ist ein Sammelband von deutschen und französischen Artikeln zu den Themen Nachhaltigkeit, Energieeffizienz, Klimawandel, Strommarkt und erneuerbare Energien, insbesondere Biomasse, die im Rahmen des ersten deutsch-französischen Workshops Energiewirtschaft und Nachhaltigkeit präsentiert wurden. Sie leisten jeweils einen Beitrag zur übergeordneten Themenstellung des Workshops: "Umweltpolitische Ziele der Europäischen Union: deutsch-französische Beiträge zur Zielerreichung"

Note on Constrained Cohomology

The cohomology of the BRS operator corresponding to a group of rigid symmetries is studied in a space of local field functionals subjected to a condition of gauge invariance. We propose a procedure based on a filtration operator counting the degree in the infinitesimal parameters of the rigid symmetry transformations. An application to Witten's topological Yang-Mills theory is given.Comment: appendix and refs adde