A Novel Power Supply for Generating a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP®)

A high voltage transformer connected to an atmospheric plasma generator is driven as a current-fed push-pull parallel resonant system, switched by a resonant lamp controller integrated circuit from Texas Instruments (UC3872) in such a manner as to be automatically maintained at resonance. The frequency range of interest is the audio range, which creates a particularly uniform glow discharge in atmospheric pressure air. Frequency control is achieved by a specially constructed high voltage variable capacitor connected parallel to the secondary, in conjunction with a variable parallel primary inductance. Voltage control is achieved by variation of the input DC current amplitude

New chalcogenide glasses in the GeSe2-Ga2Se3-In2Se3 and GeSe2-Ga2Se3-PbSe domains

International audienceTwo new chalcogenide glassy domains were explored by substituting Ga for In or Pb in compositions from the GeSe2-Ga2Se3 tie line in the Ge-Ga-Se ternary diagram. The thermal, optical and mechanical properties of these glasses were determined and the effect of the substitutions on these properties was assessed. It is shown that addition of lead tends to destabilize the glasses while the addition of indium tends to stabilize them. Both elements induce a systematic increase in the onset of transmission values and in the densities when substituted to gallium. The glasses synthesized represent good potential candidates for the production of glass-ceramics with photovoltaic or nonlinear properties

Enhanced luminescence in Er3+-doped chalcogenide glass-ceramics based on selenium

International audienceRare earth doped glass-ceramics transparent in the infrared region up to 16 µm have been prepared and studied. The enhancement of the emission of Er3+ ions at 1.54 µm with increasing crystallinity was demonstrated in a selenium-based glass-ceramic having a composition of 80GeSe2-20Ga2Se3+1000 ppm Er. The optical transmission, microstructure and luminescence properties of a base glass and glass-ceramics were investigated. Luminescence intensities up to 7 times greater were obtained in glass-ceramics in comparison to the base glass. These materials are promising candidates for the production of new laser sources in the mid-infrared region

Synthesis of Germanium-Gallium-Tellurium (Ge-Ga-Te) Ceramics by Ball-Milling and Sintering

International audienceIn this paper, we present the preparation of a bulk material with a composition of 80GeTe2-20Ga2Te3 by combining mechanosynthesis and sintering. This composition cannot be prepared by conventional melt/quenching technique. The progressive evolution of the powder during ball milling is followed by XRD and DSC analysis. The final powder obtained is highly crystalline but a glass transition temperature is observed, indicating the presence of some amorphous phase remaining, allowing for its efficient sintering. By hot pressing, a dense bulk material with a fine microstructure and a high electrical conductivity is obtained. The synthesis method described represents a simple and cost effective way to produce tellurium-based materials of desired dimension with potential applications for optical storage or thermoelectric devices

Self-similarity in a General Aggregation-Fragmentation Problem ; Application to Fitness Analysis

We consider the linear growth and fragmentation equation with general coefficients. Under suitable conditions, the first eigenvalue represents the asymptotic growth rate of solutions, also called \emph{fitness} or \emph{Malthus coefficient} in population dynamics ; it is of crucial importance to understand the long-time behaviour of the population. We investigate the dependency of the dominant eigenvalue and the corresponding eigenvector on the transport and fragmentation coefficients. We show how it behaves asymptotically as transport dominates fragmentation or \emph{vice versa}. For this purpose we perform suitable blow-up analysis of the eigenvalue problem in the limit of small/large growth coefficient (resp. fragmentation coefficient). We exhibit possible non-monotonic dependency on the parameters, conversely to what would have been conjectured on the basis of some simple cases