Determination of the color temperature in laser-produced shocks

Experimental results on the determination of the color temperature in shock waves produced with lasers are presented. The method is based on imaging the target rear side in two different spectral windows and on using phased zone plates to produce high-quality shocks. The shock velocity is also measured, allowing, with the use of the equation of state, the real shock temperature to be deduced and compared with the measured color temperature

Cristal trapézoïdal en spectroscopie X d'implosion par laser

Elastically bent, trapezoidal crystals for Bragg diffraction of X-rays allow designing broadband spectrometers with flat field, normal incidence and high resolution. This is applied to study microballoon implosions driven by six laser beams.En courbant élastiquement un cristal trapézoïdal pour la diffraction de Bragg des rayons X, on réalise un spectrographe à champ plan, large bande et haute résolution, sous incidence normale. Grâce à lui, on étudie des implosions de microballons par un laser à six faisceaux

Experimental design approach for the solid-phase extraction of residual aluminium coagulants in treated waters

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High-pressure shock generation in optically smoothed laser plasmas

We show the possibility of obtaining reproducible and quantitative measurements on shock wave dynamics with optically smoothed laser beams. We have used RPPs and Phased Zone Flares as beam smoothing techniques. These lasts allow the production of high quality nat shock waves

Hydrodynamic Efficiency Measurements from Directly Driven Implosion Experiments at λ = 0.26 μm

International audienceThe coupling and implosion efficiencies, defined respectively as the ratios of the thermal energy in the fuel and the kinetic energy in the shell to the absorbed laser energy, have been estimated in a series of experiments using λ = 0.26 μm laser illumination of D-T–filled glass microballoons

Experimental test of the relative coherence of equation of states of different materials compressed by laser shock-waves

We show some preliminary results on a new method developed to test the relative coherence of equation of slate table of strongly compressed materials. The method is based on the generation of very high quality shock waves and the use of two steps - two materials targets

Multivariate optimization of fecal bioindicator inactivation by coupling UV-A and UV-C LEDs

International audienceThe development of new technologies for water recycling is a priority for arid and semi-arid countries such as those of the Mediterranean basin. The aim of this study was to test the efficiency of UV-A and UV-C light emitting diodes (UV-LEDs) on bacteria inactivation. We used Escherichia coli and Enterococcus faecalis, bioin-dicators of fecal pollution typically found in urban wastewaters. An experimental design was performed to discriminate weight of factors influencing bacteria inactivation yields and reactivation phenomena. Four parameters were tested on simple bacterial cultures: pH, bacterial density, exposure time and wavelength. It appears that the exposure time and wavelength used have a significant effect on the response. The 280/ 365 nm or 280/405 nm coupled wavelengths, have the most important bactericidal effect, and we also note the absence of bacterial reactivation after 60 s of exposure to UV

Caractérisation et réactivité au chlore des particules relarguées par les baigneurs en piscine

International audienceDisinfecting swimming pool water is essential for preventing waterborne diseases. An unforeseen consequence of treating water with disinfectants is the formation of disinfection byproducts (DPBs) that can cause harmful effects to health through the interactions between the added disinfectant and organic matter in the water. The present work focuses on the chlorine reactivity with particles released by bathers. Such particles are collected in the filter backwash water of swimming pools and this study intends to distinguish DPBs generated from dissolved chemicals from those formed by particulate matter. Therefore, filtered and unfiltered backwash waters were collected from several swimming pools, analyzed physicochemically and chemically, and then chlorinated as is (79 mgL-1) and as diluted suspensions (36.2 and 11.9 mgL-1) at varying concentrations of chlorine (1.2 mg and 24 mgCl2L-1). Utilizing a DPD colorimetric technique and GC-ECD, respectively, the kinetics of chlorine consumption and DPBs production have been investigated. Up to 25.7 µgL-1 of chloroform was produced within 96 h at 1.2 mgCl2L-1 , followed by haloacetic acids (HAAs) and haloacetonitriles (HANs). Within 96 h, the concentration of trichloroacetic acid reached a maximum of 231.8 µgL-1 at a chlorine concentration of 231.8 µgL-1. The formations of 0.13 µmol THMs, 0.31 µmol HAAs, and 0.04 µmol HANs per mg of dissolved organic carbon (DOC) were finally determined by correlating the organic content of particles with the nature of the DBPs generated. Comparing the quantities of DBPs generated in filtered and unfiltered samples helps us conclude that ~50% of DBPs formed during the chlorination of swimming pool water are derived from particles brought by bathers