Imaging subsurface damage of grinded fused silica optics by confocal fluorescence microscopy

International audienceWe report an experimental investigation of fluorescence confocal microscopy as a tool to measure subsurface damage on grinded fused silica optics. Confocal fluorescence microscopy was performed with an excitation at the wavelength of 405 nm on fixed abrasive diamond grinded fused silica samples. We detail the measured fluorescence spectrums and compare them to those of oil based coolants and grinding slurries. We evidence that oil based coolant used in diamond grinding induces a fluorescence that marks the subsurface damages and eases its observation. Such residual traces might also be involved in the laser damage process

Subsurface damage measurement of ground fused silica parts by HF etching techniques

International audienceDetection and measurement of subsurface damage of ground optical surfaces are of major concern in the assessment of high damage thresholds fused silica optics for high power laser applications. We herein detail a new principle of SSD measurement based on the utilization of HF acid etching. We also review and compare different subsurface damage (SSD) characterization techniques applied to ground and fine ground fused silica samples. We demonstrate good concordance between the different measurements

Quantitative phase field model for dislocation sink strength calculations

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Identification of a major soluble protein in mitochondria from nonphotosynthetic tissues as NAD-dependent formate dehydrogenase

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Repression of formate dehydrogenase in Solanum tuberosum increases steady-state levels of formate and accelerates the accumulation of proline in response to osmotic stress

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A new scenario for ‹c› vacancy loop formation in zirconium based on atomic-scale modeling

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Atomic modelling of carbon atom diffusion in monoclinic zirconia volume, subsurface and surface

International audienceCarbon atom diffusion in monoclinic zirconia from bulk to the ( 1¯ 11) surface is studied by Density Functional Theory and atomic Kinetic Monte Carlo (KMC) calculations. The aim is to characterize the behaviour of 14 C in one type of nuclear waste in its deep disposal site during a geological timescale at 50 °C. In bulk, diffusion coefficient expression Dbulk=1.6 ×10−3(cm2s)×e(−1.19 eVkBT) shows a very slow diffusion of 10 −22  cm 2 /s at 50 °C. The carbon atom at the subsurface frontier in the bulk side prefers to diffuse towards the surface rather than staying in the bulk or moving laterally. Diffusion from subsurface to surface is accessible at 50 °C with a minimum migration energy calculated at 0.20 eV. On the surface, diffusion is more probable than in the bulk with a diffusion coefficient expression Dsurf=1.1×10−3(cm2s)×e(−0.76 eVkBT) equals to 10 −15  cm 2 /s at 50 °C. Atomic KMC simulation shows one dimensional diffusion along an identified path on the surface