Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a...Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a promising tool,since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas.We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer.A polystyrene(CH)foil was irradiated by a laser of 133 J,1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser(153 J,11 ps).The ablation front interferograms were processed in combination with a set of reference images obtained ex situ using phase-stepping.We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above 1022 cm−3.These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.展开更多
Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the po...Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the polymeric membranes. Based on Hansen solubility parameters theory, the mixture of DMC and DMSO was selected among a dozen of solvents for the preparation of PVDF membranes by thermally induced phase separation. The addition of two protic ionic liquids(PILs), bis(2-ethyl hexyl) ammonium hydrogen phosphate [EHNH_2][H_2PO_4], and imidazolium hexanoate [Im][Hex] to PVDF membranes at concentrations(10% < wP IL< 50%) has been investigated by SEM, FTIR, DSC, TGA, EIS, and DMA. The inclusion of ionic liquids into the polymer matrix influences structural parameters(degree of crystallinity and electroactive phases), thermal stability, proton conductivity and mechanical properties of the membranes. The membranes become transparent regardless type of ionic liquid employed. A small amount of ionic liquids increases the degree of crystallinity and facilitates the production of polar β and γ crystals. The proton conductivity mechanism(Grotthuss) is dependent on the ionic liquid structure(due to its selforganization in water) and the content in the PVDF membrane, as well as the membrane water uptake.Different behavior has been observed for the two ionic liquids, which stresses the challenge on selecting an appropriate cation and anion combination. The obtained composite membranes exhibited excellent mechanical performance and reduced elastic modulus, with respect to the pure polymer matrix. These results indicate that PVDF/IL composite membranes have a high potential for PEMFC applications.展开更多
A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by couplin...A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by coupling a collective atomic spin model with an ML-IAP.Together they represent a potential energy surface from which the mechanical forces on the atoms and the precession dynamics of the atomic spins are computed.Both the atomic spin model and the ML-IAP are parametrized on data from first-principles calculations.We demonstrate the efficacy of our data-driven framework across magneto-structural phase transitions by generating a magneto-elastic ML-IAP forα-iron.The combined potential energy surface yields excellent agreement with firstprinciples magneto-elastic calculations and quantitative predictions of diverse materials properties including bulk modulus,magnetization,and specific heat across the ferromagnetic–paramagnetic phase transition.展开更多
Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor ph...Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor phase is of major importance concerning the control and characterization of the process. The liquid droplet size distribution has a high influence on the kinetic properties of the as-sprayed nanometer particles before impacting on a target substrate. An overview of existing models is provided dealing with the penetration of the liquid phase into the thermal flame and the resulting fragmentation and vaporization of this phase before impact. The physical characteristics of the flow as well as existing Lagrangian and Eulerian modeling strategies are briefly discussed while paying attention to the physical parameters characterized and measured by numerical simulation. The potential of the various models and also their limits are intended to be highlighted. Future coupled Eulerian-Lagrangian modeling strategies are also proposed for a global and more exhaustive representation of the injection, fragmentation and dispersion part of the two-phase gas-liquid flow before particle impact on the substrate.展开更多
The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser ine...The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production.Europe has a unique opportunity to empower research in this field internationally,and the scientific community is eager to engage in this journey.We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor.The proposed roadmap is based on four complementary axes:(ⅰ)the physics of laser-plasma interaction and burning plasmas;(ⅱ)high-energy high repetition rate laser technology;(ⅲ)fusion reactor technology and materials;and(ⅳ)reinforcement of the laser fusion community by international education and training programmes.We foresee collaboration with universities,research centres and industry and establishing joint activities with the private sector involved in laser fusion.This project aims to stimulate a broad range of high-profile industrial developments in laser,plasma and radiation technologies along with the expected high-level socio-economic impact.展开更多
We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pu...We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths.Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.展开更多
The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star forma...The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star formation rate within a galaxy.This process leads to fragmentation of the cloud and to its subsequent compression and can,eventually,initiate the gravitational collapse of a stable molecular cloud.It is,however,difficult to study such systems in detail using conventional techniques(numerical simulations and astronomical observations),since complex interactions of flows occur.In this paper,we experimentally investigate the compression of a foam ball by Taylor–Sedov blast waves,as an analog of supernova remnants interacting with a molecular cloud.The formation of a compression wave is observed in the foam ball,indicating the importance of such experiments for understanding how star formation is triggered by external agents.展开更多
A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experi...A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2 D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirms the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target,a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility of the laser energy produced on GEKKO XII allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities.展开更多
The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I ...The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I - 2 × 10^14 W. cm-2） of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15-20 4- 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.展开更多
This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on th...This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on the Orion laser facility(Hopps et al., Appl. Opt. 52, 3597–3601(2013)) at Atomic Weapons Establishment(AWE). This experiment, part of the POLAR project(Falize et al., Astrophys. Space Sci. 336, 81–85(2011); Busschaert et al., New J. Phys. 15, 035020(2013)),studied conditions relevant to the radiation-hydrodynamic processes occurring in a remarkable class of astrophysical star systems known as magnetic cataclysmic variables. A large number of complex fabrication technologies and research and development activities were required to field a total of 80 high-specification targets. Target design and fabrication procedures are described and initial alignment and characterization data are discussed.展开更多
基金supported by the National Nuclear Security Administration (DENA0003882)funding from the Conseil Règional Aquitaine (INTALAX)+1 种基金the Agence Nationale de la Recherche (ANR-10-IDEX-03-02, ANR-15CE30-0011)supported by Research Grant No. PID2019-108764RB-I00 from the Spanish Ministry of Science and Innovation
文摘Diagnosing the evolution of laser-generated high energy density(HED)systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions.Talbot–Lau interferometry constitutes a promising tool,since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas.We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer.A polystyrene(CH)foil was irradiated by a laser of 133 J,1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser(153 J,11 ps).The ablation front interferograms were processed in combination with a set of reference images obtained ex situ using phase-stepping.We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above 1022 cm−3.These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.
基金“La region Centre Val de Loire” for financial support to the researchers involved in this study under “Lavoisier II” regional program。
文摘Poly(vinylidene fluoride), PVDF, membranes have attracted considerable attention as polymer electrolytes for fuel cells. This study explores the effect of solvent on the spherulite size and the crystallinity of the polymeric membranes. Based on Hansen solubility parameters theory, the mixture of DMC and DMSO was selected among a dozen of solvents for the preparation of PVDF membranes by thermally induced phase separation. The addition of two protic ionic liquids(PILs), bis(2-ethyl hexyl) ammonium hydrogen phosphate [EHNH_2][H_2PO_4], and imidazolium hexanoate [Im][Hex] to PVDF membranes at concentrations(10% < wP IL< 50%) has been investigated by SEM, FTIR, DSC, TGA, EIS, and DMA. The inclusion of ionic liquids into the polymer matrix influences structural parameters(degree of crystallinity and electroactive phases), thermal stability, proton conductivity and mechanical properties of the membranes. The membranes become transparent regardless type of ionic liquid employed. A small amount of ionic liquids increases the degree of crystallinity and facilitates the production of polar β and γ crystals. The proton conductivity mechanism(Grotthuss) is dependent on the ionic liquid structure(due to its selforganization in water) and the content in the PVDF membrane, as well as the membrane water uptake.Different behavior has been observed for the two ionic liquids, which stresses the challenge on selecting an appropriate cation and anion combination. The obtained composite membranes exhibited excellent mechanical performance and reduced elastic modulus, with respect to the pure polymer matrix. These results indicate that PVDF/IL composite membranes have a high potential for PEMFC applications.
基金All authors thank Mark Wilson for his detailed review and edits.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology&Engineering Solutions of Sandia,LLC,a wholly owned subsidiary of Honeywell International Inc.,for the U.S.Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.This paper describes objective technical results and analysis.Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S.Department of Energy or the United States Government.A.C.acknowledges funding from the Center for Advanced Systems Understanding(CASUS)which is financed by the German Federal Ministry of Education and Research(BMBF)and by the Saxon State Ministry for Science,Art,and Tourism(SMWK)with tax funds on the basis of the budget approved by the Saxon State Parliament.
文摘A data-driven framework is presented for building magneto-elastic machine-learning interatomic potentials(ML-IAPs)for largescale spin-lattice dynamics simulations.The magneto-elastic ML-IAPs are constructed by coupling a collective atomic spin model with an ML-IAP.Together they represent a potential energy surface from which the mechanical forces on the atoms and the precession dynamics of the atomic spins are computed.Both the atomic spin model and the ML-IAP are parametrized on data from first-principles calculations.We demonstrate the efficacy of our data-driven framework across magneto-structural phase transitions by generating a magneto-elastic ML-IAP forα-iron.The combined potential energy surface yields excellent agreement with firstprinciples magneto-elastic calculations and quantitative predictions of diverse materials properties including bulk modulus,magnetization,and specific heat across the ferromagnetic–paramagnetic phase transition.
文摘Suspension Plasma Spraying is a complex process in which several physical mechanisms play a part. So the modeling and understanding of the interaction between a high-velocity and thermal flow and a liquid precursor phase is of major importance concerning the control and characterization of the process. The liquid droplet size distribution has a high influence on the kinetic properties of the as-sprayed nanometer particles before impacting on a target substrate. An overview of existing models is provided dealing with the penetration of the liquid phase into the thermal flame and the resulting fragmentation and vaporization of this phase before impact. The physical characteristics of the flow as well as existing Lagrangian and Eulerian modeling strategies are briefly discussed while paying attention to the physical parameters characterized and measured by numerical simulation. The potential of the various models and also their limits are intended to be highlighted. Future coupled Eulerian-Lagrangian modeling strategies are also proposed for a global and more exhaustive representation of the injection, fragmentation and dispersion part of the two-phase gas-liquid flow before particle impact on the substrate.
文摘The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research.This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production.Europe has a unique opportunity to empower research in this field internationally,and the scientific community is eager to engage in this journey.We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor.The proposed roadmap is based on four complementary axes:(ⅰ)the physics of laser-plasma interaction and burning plasmas;(ⅱ)high-energy high repetition rate laser technology;(ⅲ)fusion reactor technology and materials;and(ⅳ)reinforcement of the laser fusion community by international education and training programmes.We foresee collaboration with universities,research centres and industry and establishing joint activities with the private sector involved in laser fusion.This project aims to stimulate a broad range of high-profile industrial developments in laser,plasma and radiation technologies along with the expected high-level socio-economic impact.
基金the support of RFBR grant 14-29-06099Competitiveness Programme of NRNU MEPhI
文摘We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths.Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.
基金the support of Investissements d’Avenir of LabEx PALM(Grant No.ANR-10-LABX-0039-PALM)the Ministry of Science and Higher Education of the Russian Federation(Agreement with Joint Institute for High Temperatures RAS No.075-15-2020-785)G.G.acknowledges support from the UK EPSRC(Grant Nos.EP/M022331/1 and EP/N014472/1)。
文摘The interaction between a molecular cloud and an external agent(e.g.,a supernova remnant,plasma jet,radiation,or another cloud)is a common phenomenon throughout the Universe and can significantly change the star formation rate within a galaxy.This process leads to fragmentation of the cloud and to its subsequent compression and can,eventually,initiate the gravitational collapse of a stable molecular cloud.It is,however,difficult to study such systems in detail using conventional techniques(numerical simulations and astronomical observations),since complex interactions of flows occur.In this paper,we experimentally investigate the compression of a foam ball by Taylor–Sedov blast waves,as an analog of supernova remnants interacting with a molecular cloud.The formation of a compression wave is observed in the foam ball,indicating the importance of such experiments for understanding how star formation is triggered by external agents.
基金supported by the‘Programme National de Physique Stellaire’(PNPS)of CNRS/INSU,Francesupported by ANR Blanc grant No.12-BS09-025-01 SILAMPALABEX Plas@Par grant No.11-IDEX-0004-02 from theFrench agency ANR
文摘A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2 D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirms the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target,a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility of the laser energy produced on GEKKO XII allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities.
基金funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 654148 LaserlabEuropesupported by RAS Presidium Program for Basic Research #11+1 种基金by Competitiveness Program of NRNU MEPhIsupported by the NNSA-DS and SC-OFES Joint Program in High Energy Density Laboratory Plasmas, grant No. DENA0002956
文摘The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation （I - 2 × 10^14 W. cm-2） of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15-20 4- 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.
文摘This article describes the fabrication of a suite of laser targets by the Target Fabrication group in the Central Laser Facility(CLF), STFC Rutherford Appleton Laboratory for the first academic-access experiment on the Orion laser facility(Hopps et al., Appl. Opt. 52, 3597–3601(2013)) at Atomic Weapons Establishment(AWE). This experiment, part of the POLAR project(Falize et al., Astrophys. Space Sci. 336, 81–85(2011); Busschaert et al., New J. Phys. 15, 035020(2013)),studied conditions relevant to the radiation-hydrodynamic processes occurring in a remarkable class of astrophysical star systems known as magnetic cataclysmic variables. A large number of complex fabrication technologies and research and development activities were required to field a total of 80 high-specification targets. Target design and fabrication procedures are described and initial alignment and characterization data are discussed.
