Superconductivity in TTF[Ni(dmit)2]2 films

We report on the observation of a superconducting transition in a fiber-like film of the TTF[Ni(dmit)2]2 phase electrodeposited on silicon substrates. Superconductivity is evidenced by a broad drop of the resistance below 0.8K under the application of a hydrostatic pressure of 7.7 kbar. Zero resistance is not reached due to the contribution of inter-fiber resistance. Superconductivity is confirmed by the application of a magnetic field perpendicular to the plane of the film. The critical field determined on the film is in agreement with that obtained in bulk single crystals

EXPERIMENTAL STUDIES OF SOLUBILITY OF ELEMENTAL SULPHUR IN SUPERCRITICAL CARBON DIOXIDE BETWEEN 10 AND 40 MPA

International audienc

Caractérisation de la fraction volumique et de la température des suies d'une flamme de diffusion établie en micropesanteur

The soot has a dominant radiative role in microgravity diffusion flames. In fact, the radiative losses are particularly important in the trailing edge of the flame, where the combustion products, especially the soot, concentrate due to lack of convection. A new optical technique in microgravity is proposed that combines modulated absorption and emission measurements at two wavelengths simultaneously: 470 nm and 530 nm. A bicolor matrix of LEDs (blue and green) allows the emission of a series of little beams that cross the flame and form a detailed cartography of extinction along the flame. In this way, the conditions in the trailing edge of the diffusion flame, where quenching occurs, can be characterized in soot volume fraction and temperature

Evaluation of the Extinction Factor in a Laminar Flame Established over a PMMA Plate in Microgravity

A methodology for estimating the extinction factor at wavelength of 530 nm in diffusion flames is presented. All experiments have been in microgravity and have as their objective the production of quantitative data that can serve to evaluate the soot volume fraction. A better understanding of soot formation and radiative heat transfer is of extreme importance to many practical combustion related processes such as spacecraft fire safety. The experimental methodology implements non-axisymmetric configurations that provide a laminar diffusion flame at atmospheric pressure. PMMA is used as fuel and the oxidizer flows parallel to its surface. Optical measurements are performed at the 4.74 s ZARM drop tower

Soot Volume Fraction Measurements in a Three-Dimensional Laminar Diffusion Flame established in Microgravity

A methodology for the estimation of the soot volume fraction in a three-dimensional laminar diffusion flame is presented. All experiments are conducted in microgravity and have as objective producing quantitative data that can serve to estimate radiative heat transfer in flames representative of fires in spacecraft. The competitive nature of formation and oxidation of soot and its direct coupling with the streamlines (source of oxygen) require for these measurements to be conducted within the exact configuration. Thus three-dimensional measurements are needed. Ethylene is injected through a square porous burner and the oxidizer flows parallel to its surface. The methodology uses CH* chemiluminescence measurements to correct for three-dimensional effects affecting light attenuation measurements. Corrected local soot concentrations are thus obtained. All experiments are conducted during parabolic flights and the parameters varied are fuel and oxidizer flow rates

Interactions between Soot and CH* in a Laminar Boundary Layer Type Diffusion Flame in Microgravity

A three-dimensional laminar non-buoyant diffusion flame was studied with the objective of improving the understanding of the soot production. The flame originated from a porous ethylene burner discharging into a laminar boundary layer. Soot volume fractions were measured using Laser-Induced Incandescence (LII) and the spontaneous emission from CH* was determined using chemiluminescence. The main parameter varied was the oxidizer flow. CH* measurements allowed to identify the reaction zone, while LII measurements permitted the tracking of soot. It was observed that soot volume fractions are inversely proportional to the global residence time. This is in contradiction to previous studies on axi-symmetric non-buoyant diffusion flames. The combined measurements allowed to establish that the apparently contradictory behaviour can be explained by an analysis of the influence of the flow field on the ratio of soot production to oxidation