Publications associées à Femtosecond laser-shockwave induced densification in fused silica

Characterization of low-temperature plasmas generated by dielectric barrier discharges for bacterial inactivation

Low-temperature plasmas (LTPs) at atmospheric pressure hold great promise for disinfection and sterilization applications. When compared to traditional sterilization technologies like autoclaving, LTPs may offer several benefits, including reduced energy c ...

EPFL2024

Effect of femtosecond laser-induced high pressure on fused silica polymorphism

Arunkrishnan Radhakrishnan

High-pressure studies in silica are of great interest to earth and planetary sciences. Highpressure phases are rarely found in nature as a result of shock events like meteorite impacts or volcanic events in nature. Recreating these phases remains a challen ...

EPFL2022

Abnormal temperature dependent elastic properties of fused silica irradiated by ultrafast lasers

Yves Bellouard, Pieter Vlugter

Materials with thermal-invariant elastic properties are of interest for resonant device frequency and dimensional stability of precision devices. Here, we demonstrate that the temperature coefficient of elasticity (TCE) of amorphous silica can be locally r ...

2022

Transport barrier in 5D gyrokinetic flux-driven simulations

Two ways for producing a transport barrier through strong shear of the E x B poloidal flow have been investigated using GYSELA gyrokinetic simulations in a flux-driven regime. The first one uses an external poloidal momentum (i.e. vorticity) source that lo ...

IOP Publishing Ltd2022

Ultrafast laser interaction with transparent multi-layer SiO2/Si3N4 films

Yves Bellouard, Ruben Ricca, Victor Carle Adrien Boureau

We investigate the use of ultrafast lasers exposure to induce localized crystallization and elemental redistribution in amorphous dielectric multi-layers, composed of alternating Si3N4 and SiO2 layers of sub-micrometer thickness. Specifically, we report on ...

2021

The concept of the mobilized domain: how it can explain and predict the forces exerted by a cohesive granular avalanche on an obstacle

Christophe Ancey, Betty Sovilla, Johan Alexandre Philippe Gaume, Michael Lukas Kyburz

The calculation of the impact pressure on obstacles in granular flows is a fundamental issue of practical relevance, e.g. for snow avalanches impacting obstacles. Previous research shows that the load on the obstacle builds up, due to the formation of forc ...

2022

Shining Diamond: from Micro- and Nano-Engineering to Quantum Photonics

Sichen Mi

The discovery of room-temperature single photon emission from color centers in diamond has in recent years boosted research interest in this renowned material in photonics and quantum community and beyond. Following understanding some basic principles of h ...

EPFL2021

Composition and Pressure Effects on Partitioning of Ferrous Iron in Iron-Rich Lower Mantle Heterogeneities

Marco Cantoni, Philippe Gillet, Farhang Nabiei, Susannah McGregor Dorfman, James Badro, Charles-Edouard Boukaré

Both seismic observations of dense low shear velocity regions and models of magma ocean crystallization and mantle dynamics support enrichment of iron in Earth’s lowermost mantle. Physical properties of iron-rich lower mantle heterogeneities in the modern ...

2021

Physical Mechanism and Flow Control of Tip Vortex Cavitation

Ali Amini

Occurrence of cavitation in hydraulic machines is a challenging issue because it is often accompanied with loss of efficiency, noise emissions, vibrations, and erosion damages. Tip vortices, in particular, are an ideal site for the development of cavitatio ...

EPFL2020

Ultrafast carbothermal reduction of silica to silicon using a CO2 laser beam

Jaeki Jeong

We report the extraction of silicon via a carbothermal reduction process using a CO2 laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown after laser beam irradiation for a few tens of seconds, and clear peak ...

NATURE RESEARCH2020

A New Reference for the Thermal Equation of State of Iron

James Badro

The high-pressure, high-temperature behavior of iron was investigated to 140 GPa and 3500 K with in situ synchrotron X-ray diffraction. Iron samples were compressed in diamond-anvil cells and heated up with the double-sided laser-heating system installed a ...

MDPI2020

Investigation of femtosecond laser-tuned thermomechanical properties of fused silica

Pieter Vlugter

The thermomechanical properties of materials are among the most important properties for designing precision instruments, in particular for devices seeking high-dimensional stability, invariant temperature-elastic properties or low thermoelastic losses. De ...

EPFL2020

Elastic properties of self-organized nanogratings produced by femtosecond laser exposure of fused silica

Yves Bellouard, Pieter Vlugter

Under certain exposure conditions, a femtosecond laser beam focused in the bulk of fused silica leads to the formation of self-organized structures consisting of a series of “nanolayers,” parallel to one another. Remarkably, this laser-induced nanoscale an ...

2020

Nanosecond pulsed laser-processing of CVD diamond

Patrik Willi Hoffmann, Marco Cantoni, Sébastien Equis

This work considers the resulting material structural effects of laser-processing chemical vapor deposited (CVD) diamond. The utilized 532 nm wavelength laser had a pulse duration of 40 ns together with a spot diameter of ca. 40 mu m. The effect of cutting ...

ELSEVIER SCI LTD2020

Decoupling the role of inertia, friction and cohesion in dense granular avalanche pressure build‐up on obstacles

Christophe Ancey, Johan Alexandre Philippe Gaume, Michael Lukas Kyburz

Understanding the physical processes involved in snow avalanche‐obstacle interaction is essential to be able to estimate the pressure exerted on structures. Although avalanche impact pressure has been measured in field experiments for decades, the underlyi ...

2020

Mechanical and hydraulic transport properties of transverse-isotropic Gneiss deformed under deep reservoir stress and pressure conditions

Marie Estelle Solange Violay, Mateo Alejandro Acosta

In central Europe, many geo-energy reservoirs have revealed to be hosted in transverse isotropic crystalline rock, where the rock's mechanical and hydraulic transport properties are poorly constrained. Here, we performed triaxial experiments on Cresciano G ...

2020

Impact of oxygen content in powders on the morphology of the laser molten tracks in preparation for additive manufacturing of silicon

Patrik Willi Hoffmann, Lucas Güniat, Marc Leparoux

Powder additive pulsed Nd:YAG laser (wavelength 1064 nm), with the aim of preparing AM of such material. The influence of oxygen content in the initial silicon powders on the continuous tracks morphology was investigated. It was found that the initial oxyg ...

ELSEVIER2020

Crack front waves: A 3D dynamic response to a local perturbation of tensile and shear cracks

Jean-François Molinari, Fabian Barras, Damien Spielmann, Fatima-Ezzahra Fekak

Crack front waves are long-lived perturbations propagating along the crack front. They are triggered by heterogeneities on the crack plane, as for instance tough asperities, which disturb the crack front shape. Crack front waves are thought to leave a trac ...

PERGAMON-ELSEVIER SCIENCE LTD2020

On the physical mechanism of tip vortex cavitation hysteresis

Mohamed Farhat, Martino Reclari, Matthieu Dreyer, Ali Amini

Inception and desinence thresholds of tip vortex cavitation (TVC), generated by an elliptical NACA 16-020 hydrofoil, are measured at different flow conditions for various gas contents. It is observed that TVC often disappears at cavitation indices signific ...

SPRINGER2019

Procedure for predicting part load resonance in Francis turbine hydropower units based on swirl number and local cavitation coefficient similitude

François Avellan, Christophe Nicolet, Christian Landry, Sébastien Alligné, Arthur Tristan Favrel, Loïc Andolfatto

Francis turbines operating at part load conditions develop a cavitation precessing vortex known as a vortex rope in the draft tube cone below the runner outlet. At part load conditions, this vortex precession acts as an excitation source inducing pressure ...

ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD2019