A. Sollier - Academia.edu (original) (raw)

Papers by A. Sollier

Scientific reports, Jun 1, 2016

Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in sci... more Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in scientific research. There exists very little experimental data probing WDM states at the atomic level to test current models and those performed up to now are limited in quality. Here, we report a proof-of-principle experiment that makes microscopic investigations of materials under dynamic compression easily accessible to users and with data quality close to that achievable at ambient. Using a single 100 ps synchrotron x-ray pulse, we have measured, by K-edge absorption spectroscopy, ns-lived equilibrium states of WDM Fe. Structural and electronic changes in Fe are clearly observed for the first time at such extreme conditions. The amplitude of the EXAFS oscillations persists up to 500 GPa and 17000 K, suggesting an enduring local order. Moreover, a discrepancy exists with respect to theoretical calculations in the value of the energy shift of the absorption onset and so this comparison s...

International Congress on Applications of Lasers & Electro-Optics, 2014

Laser shot processing consists in irradiating a material covered by a transparent layer such wate... more Laser shot processing consists in irradiating a material covered by a transparent layer such water with a laser in the range of few GWcm2. A plasma is generated at the interface between water and material producing strong shock wave (GPa) which can be used to improve metallic surface (Laser Shock Processing (LSP)) or to test interface adhesion (Laser Adhesion Test (LASAT)) . Many studies deals with effect of the process inside material or plasma simulations. However, there is a lack of datas on laser interaction to validate models. Experiments are limited to pressure plasma determination because it is difficult to diagnose this specific configuration. Many issues remain about these dense and cold plasmas. For example, models make the assumption that the laser is completely absorbed whereas this has not been checked. We propose in this paper an original experiment of absorption measurement in water confinement regime. It is based on a measurement of reflectivity also giving the temporal profiles of the brightness of plasma and laser intensity absorbed. The laser has a duration of 10 ns, a wavelength of 532 ns in intensity range 0.1-10 GW/cm2. This configuration is representative of actual LSP application. Results show that the absorption increases when irradiance increases from 5% (cold material) to 95% only. There is also an influence of water breakdown on the absorption levels and its temporal profile. Plasma confinement threshold was also measured (0.06 GW/cm2).Laser shot processing consists in irradiating a material covered by a transparent layer such water with a laser in the range of few GWcm2. A plasma is generated at the interface between water and material producing strong shock wave (GPa) which can be used to improve metallic surface (Laser Shock Processing (LSP)) or to test interface adhesion (Laser Adhesion Test (LASAT)) . Many studies deals with effect of the process inside material or plasma simulations. However, there is a lack of datas on laser interaction to validate models. Experiments are limited to pressure plasma determination because it is difficult to diagnose this specific configuration. Many issues remain about these dense and cold plasmas. For example, models make the assumption that the laser is completely absorbed whereas this has not been checked. We propose in this paper an original experiment of absorption measurement in water confinement regime. It is based on a measurement of reflectivity also giving the temporal profiles of the bri...

International Congress on Applications of Lasers & Electro-Optics, 1998

The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investig... more The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investigated for the first, second and third harmonics of Nd:Glass laser (1,064, 0,532, 0,355 μn) with 0.6, 10 and 25 ns laser pulse durations. Pressure measurements have been mainly performed using a Velocimetry Interferometer System for Any Reflector (VTSAR). It appears that, depending on laser parameters, above a given laser intensity threshold, the peak pressure is saturated and the pressure duration is reduced due to laser-induced breakdown plasma in the confining water. The observation of the interaction zone (confined plasma and confining water) with a fast intensified camera shows that this parasitic breakdown occurs exclusively at the surface of water and limits the efficiency of the process. The time-resolved transitivity of this plasma has been measured with a continuous Argon laser beam for a 1.064 μm/25 ns incident laser irradiation. Above 10 GW/cm2, the peak power density transmitted through the breakdown plasma saturates and the laser pulse transmitted is reduced in agreement with pressure measurements. The relative influence of main physical mechanisms occurring during the generation of the laser breakdown at the surface of water have been discussed. According to the wavelength effect which tends to authorize higher pressure with longer wavelengths, the influence of multiphotoionic processes seem to dominate the effect of avalanche ionization. The protective coatings and laser spot size influences have been also investigated regarding the stress levels induced in the targets. About 30 % stresses increase in the material is shown to occur with adapted coating. On the contrary, the laser spot size has no specific effects on the pressure induced in WCR. Residual Stresses (RS) field have been determined for different laser conditions.The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investigated for the first, second and third harmonics of Nd:Glass laser (1,064, 0,532, 0,355 μn) with 0.6, 10 and 25 ns laser pulse durations. Pressure measurements have been mainly performed using a Velocimetry Interferometer System for Any Reflector (VTSAR). It appears that, depending on laser parameters, above a given laser intensity threshold, the peak pressure is saturated and the pressure duration is reduced due to laser-induced breakdown plasma in the confining water. The observation of the interaction zone (confined plasma and confining water) with a fast intensified camera shows that this parasitic breakdown occurs exclusively at the surface of water and limits the efficiency of the process. The time-resolved transitivity of this plasma has been measured with a continuous Argon laser beam for a 1.064 μm/25 ns incident laser irradiation. Above 10 GW/cm2, the peak power density transmitted through the breakdow...

The Review of scientific instruments, 2018

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great ... more Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 μm and a spacing of 500 μm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 μg/cm2 thick carbon foil as an energy-loss target and a...

The Review of scientific instruments, 2021

An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been develop... more An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-ray source. In comparison to a transmission geometry setup, this configuration allows us to probe only a small portion of the compressed sample, as well as to shield the detectors against the x-rays generated by the laser-plasma interaction on the front side of the target. Thus, this new platform facilitates probing of spatially and temporarily uniform thermodynamic conditions and enables us to study samples of a large range of atomic numbers, thicknesses, and compression dynamics. As a proof-of-concept, we report direct structural measurements of the bcc-hcp transition both in shock and ramp-compressed polycrystalline iron with diffraction signals recorded between 2θ ∼ 30° and ∼150°. In parallel, the pressure and temperature history of probed sampl...

Journal of Applied Physics, 2020

When a shock wave of several tens of GPa breaks out at a free surface, material is ejected ahead ... more When a shock wave of several tens of GPa breaks out at a free surface, material is ejected ahead of this surface. The amount and velocity of such ejecta depend on the breakout pressure, state of the released material (solid, liquid, or mixed), whether the shockwave is supported or unsupported and the initial geometrical perturbation (or roughness) of the free surface. If surface defects consist of small grooves, pits or scratches, material ejection occurs in the form of jets breaking up into tiny particles (so-called microjetting), with jet tip velocities up to several times higher than the free surface velocity. The laser-based experiments presented in this paper focus on microjetting in shock-melted tin with periodic surface perturbations. Several complementary diagnostics are combined to measure the velocity and mass of ejecta during the early stages of the jetting process. One relevant advancement is the use of ps-laser X-ray radiography to probe the density of the ejecta in distinct jets a few tens of µm-wide. The effects of the depth and wavelength of the initial perturbation are investigated in both linear and near-linear growth regimes. The results are compared with predictions derived from the Richtmyer-Meshkov Instability (RMI) theory.

Journal of Dynamic Behavior of Materials, 2016

When a material is submitted to a dynamic compression, a shock wave propagates through the bulk a... more When a material is submitted to a dynamic compression, a shock wave propagates through the bulk and potentially interacts with a free surface. If this surface has geometrical defects such as grooves, some material ejection can occur. The energy of the high velocity ejecta is an area of concern for many applications, such as industrial safety, pyrotechnics or inertial confinement fusion. We have studied this phenomenon of microjetting from calibrated grooves in laser shock-loaded Cu samples, combining complementary experimental, numerical and analytical approaches, in order to investigate the formation and the fragmentation of the jets over ranges of small spatial (*lm) and temporal (*ns) scales and extremely high strain rates (*10 7 s-1). Various grooves were used with different depths and aperture halfangles (20°, 30°, 45°). The velocities measured by fast shadowgraphy and heterodyne velocimetry were compared to numerical predictions using the finite element or the smoothed particles hydrodynamics formulations with the Radioss code. Size distribution of the ejecta was inferred from rough measurements of the debris sizes and compared to analytical predictions from a probability law.

High Pressure Research, 2016

ABSTRACT We present in this paper recent advances in the high pressure domain provided by the int... more ABSTRACT We present in this paper recent advances in the high pressure domain provided by the introduction of time-resolved energy-dispersive XAS (EDXAS) techniques at synchrotrons. We highlight technical aspects and describe two modes of acquisition: the ‘movie’ mode, where the time resolution is given by the detector acquisition speed and the ‘pump-and-probe’ mode, where the time resolution is given by the delay between the pump and the probe. These two modes define a frontier in the time resolution, respectively above and below the ∼10 μs regime. In the former, examples of applications are chemical stability and reactions at high pressure and high temperature or probing the warm dense matter regime using rapid current ramps. In the latter, an example is given on studies of dynamically compressed matter, by coupling single-bunch EDXAS at high-brilliance synchrotron to a nanosecond high-power laser.

Journal of Applied Physics, 2022

Photonic Doppler velocimetry and digital high-speed shadowgraphy have been used to characterize t... more Photonic Doppler velocimetry and digital high-speed shadowgraphy have been used to characterize the chemical reaction zone parameters of pressed trinitrotoluene (TNT) samples with an initial density of 1.568 g cm À3. Comparison of the nanosecond time-resolved particle velocity histories of the free surfaces of detonating charges in air and light vacuum and of the interfaces between TNT detonation products and lithium fluoride or polymethyl methacrylate windows allow one to bracket the von Neumann spike pressure between 24.8 and 28.8 GPa. Our velocity waveforms confirm the two-step reaction pathway already observed in TNT, triaminotrinitrobenzene (TATB), and nitromethane, with a first fast energy release over 80 ns followed by a slower release over 250 additional ns. We consider the end of the first release zone as the locus of the Chapman-Jouguet (CJ) state, and the CJ pressure thus lies between 17.6 and 17.7 GPa. The energy release is not completed in this Jouguet plane but only after about %280 ns when the carbon cluster formation process ends. This corresponds to both the end of the slow release part of the interface velocity profiles and to the moment at which the free surface velocity profiles reach their maximum. Our shadowgraphy images confirm that carbon formation occurs very rapidly after the detonation breakout, in good agreement with previous time-resolved small-angle x-ray scattering measurements. The comparison with similar results previously obtained on TATB allows one to further highlight their similarities, which mainly result from their excess carbon production at late times.

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, 2020

We have completed a series of experiments to measure the shock initiation behavior in the TATB an... more We have completed a series of experiments to measure the shock initiation behavior in the TATB and HMX based explosive TX1. The growth of the reaction in the shocked explosive was monitored by eleven embedded particle velocity gauges located at different depths. In addition, three gauges elements called "shock trackers" have been used to monitor the progress of the shock front as a function of time and position as it moves through the explosive sample. Their analysis yielded the position and time where the wave attains detonation. Particle velocity wave profile data and run distance-to-detonation vs. input pressure (Pop-plot) data have been obtained on TX1 samples submitted to both single shock and double shock loadings at different pressures. Particle velocity wave profiles recorded in TX1 are similar to those recorded in various HMX compositions under similar loading conditions, which confirms that the reactivity of TX1 is driven by its HMX component. EXPERIMENTAL SETUP Our experiments were performed using the 60 mm bore powder gun of CEA Le Ripault. We used TX1 samples composed of 52 wt. % of TATB (50-60 µm grain size), 45 wt. % of HMX (0-100 µm grain size), and 3 wt. % of phenoxy binder. These samples had a mean density of 1.848 g/cm 3. They were prepared by machining TX1 into

Metals, 2021

This review proposes to summarize the development of laser shock applications in a confined regim... more This review proposes to summarize the development of laser shock applications in a confined regime, mainly laser shock peening, over the past 50 years since its discovery. We especially focus on the relative importance of the source term, which is directly linked to plasma pressure. Discussions are conducted regarding the experimental setups, experimental results, models and numerical simulations. Confined plasmas are described and their specific properties are compared with those of well-known plasmas. Some comprehensive keys are provided to help understand the behavior of these confined plasmas during their interaction with laser light to reach very high pressures that are fundamental for laser shock applications. Breakdown phenomena, which limit pressure generation, are also presented and discussed. A historical review was conducted on experimental data, such as pressure, temperature, and density. Available experimental setups used to characterize the plasma pressure are also dis...

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter

A high resolution picosecond laser imaging diagnostic has been developed for making high-resoluti... more A high resolution picosecond laser imaging diagnostic has been developed for making high-resolution spatial measurements of ejecta particles moving at high velocities (a few km/s). Preliminary results obtained with UV (355nm) lighting are presented for laser shock-driven tin ejecta experiments performed with different kind of surface defects. These results are compared with those obtained at LANL under high explosive loading using ultraviolet in-line Fraunhofer holography, and also with molecular dynamics (MD) simulations performed at lower space and time scales.

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter

Ejecta production upon the breakout of a shock wave at a rough surface has been the subject of ex... more Ejecta production upon the breakout of a shock wave at a rough surface has been the subject of extensive research work for about six decades. For a few years, we have investigated how laser-driven shocks could provide original, complementary data on this issue, over specific ranges of very high loading pressures, very short pulse durations (ns-order), small dimensions (tens of µm) and extremely high strain rates. Here, selected results are presented in two metals (Cu and Sn), with either single triangular grooves of controlled depths and sharp angles or periodic, quasi-sinusoidal perturbations of different amplitudes. Experimental data combine measurements of jet velocities, using both optical shadowgraphy and Photonic Doppler Velocimetry, with ultra-fast laser based X-ray radiography to estimate mass ejection. Results are briefly compared with the predictions of analytical models and data obtained by other teams from explosive-based experiments, at lower pressure and over much larger temporal and spatial scales. Thus, both interest and limitations of laser shocks for this particular field of shock physics are illustrated and discussed.

Journal of Applied Physics

Journal of Applied Physics

The interaction of a shock wave with a rough free surface may lead to the ejection of high veloci... more The interaction of a shock wave with a rough free surface may lead to the ejection of high velocity (~ km/s) particles of small size (~ µm). This process is a safety issue for various applications such as pyrotechnics or inertial confinement fusion. To complement data obtained by other groups under explosive loading or plate impacts, we use laser driven shock loading to study microjetting from V-shaped grooves of various angles in copper and tin samples, with a combination of complementary experimental techniques. To simulate such experiments, we have chosen to use the Smoothed Particles Hydrodynamics formulation, well-suited for the very high strains involved in jet expansion and subsequent fragmentation. In this paper, we report some advances in this modelling effort, then we compare computed predictions with new experimental results including fragments size distributions inferred from post-test microtomography after soft recovery in a low density gel. Special focus is made on the dependence of the ejecta ballistic properties (velocity and mass distributions) on numerical parameters such as the initial inter-particular distance, the smoothing length and a random geometrical noise introduced to simulate inner irregularities of the material. Shock Compression of Condensed Matter -2017 AIP Conf. Proc. 1979, 080012-1-080012-5; https://doi.

Journal of Synchrotron Radiation

Time-resolved X-ray diffraction measurements have been carried out on dynamically compressed Sn u... more Time-resolved X-ray diffraction measurements have been carried out on dynamically compressed Sn up to a maximum pressure of ∼13 GPa at the European Synchrotron Radiation Facility. The phase transition from β-Sn to body-centered tetragonal (b.c.t.) Sn has been observed using synchrotron X-ray diffraction for the first time undergoing shock compression and release. Following maximum compression, the sample releases to lower pressures for several nanoseconds until the reverse transition occurs. The data are in good agreement with previous shock boundaries that indicate that the β-Sn phase is stable ∼2 GPa higher than the static boundary upon compression and the b.c.t.-Sn phase is stable ∼1 GPa lower upon release. The transition to the high-pressure phase reveals a loss of texture in the X-ray diffraction data from the `quasi' single-crystal β-Sn structure to a more powder-like Debye–Scherrer ring.

Debris ejection upon shock breakout at a rough surface is a key issue for many applications, incl... more Debris ejection upon shock breakout at a rough surface is a key issue for many applications, including pyrotechnics and inertial confinement fusion. For a few years, we have used laser driven shocks to investigate microjetting in metallic samples with calibrated grooves in their free surface. Fast transverse optical shadowgraphy, time-resolved measurements of both planar surface and jet tip velocities, and post-shock analysis of recovered material have provided data over ranges of small spatial and temporal scales, short loading pulses (ns-order) and extremely high strain rates. The new experiment presented here involves two laser beams in a pump-probe configuration.

Soda-lime glass behavior under laser shock DIDIER LOISON, JEAN AR-NAUD SOLLIER, cea/dam, LAURENT ... more Soda-lime glass behavior under laser shock DIDIER LOISON, JEAN AR-NAUD SOLLIER, cea/dam, LAURENT BERTHE, PIMM UMR CNRS 8006, MICHEL BOUSTIE, Institut Pprime UPR 3346 -Understanding and modeling the glass behavior is an issue for certain aeronautical, military and civil applications. For example, parts of satellites and shuttles are made of glass. During their lifetime, they are subjected to high velocity impacts, which in the end may damage them. To determine the behavior of these structures during and after impact we used instrumented laser driven shock loading performed on high power intensity Laser facilities: Transverse shadowgraphs of the front wave propagating inside the transparent material were taken at different times. They provide information regarding the position of the shock wave front and of the first damage. PDV or VISAR measurements provide time-resolved free surface velocity to determine mater velocity when shock wave breakout and spall strength for the most powerful laser shots. Under High pressure conditions glass permanently densify, traces of such a plastic deformation are looked for on the path of the shock wave. Those experimental data are necessary to characterize the material behavior under such conditions and to model the mechanical behavior of glass structures. In this presentation we will present experimental results obtained for soda-lime silica glass samples loaded by laser induced shock.

Scientific reports, Jun 1, 2016

Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in sci... more Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in scientific research. There exists very little experimental data probing WDM states at the atomic level to test current models and those performed up to now are limited in quality. Here, we report a proof-of-principle experiment that makes microscopic investigations of materials under dynamic compression easily accessible to users and with data quality close to that achievable at ambient. Using a single 100 ps synchrotron x-ray pulse, we have measured, by K-edge absorption spectroscopy, ns-lived equilibrium states of WDM Fe. Structural and electronic changes in Fe are clearly observed for the first time at such extreme conditions. The amplitude of the EXAFS oscillations persists up to 500 GPa and 17000 K, suggesting an enduring local order. Moreover, a discrepancy exists with respect to theoretical calculations in the value of the energy shift of the absorption onset and so this comparison s...

International Congress on Applications of Lasers & Electro-Optics, 2014

Laser shot processing consists in irradiating a material covered by a transparent layer such wate... more Laser shot processing consists in irradiating a material covered by a transparent layer such water with a laser in the range of few GWcm2. A plasma is generated at the interface between water and material producing strong shock wave (GPa) which can be used to improve metallic surface (Laser Shock Processing (LSP)) or to test interface adhesion (Laser Adhesion Test (LASAT)) . Many studies deals with effect of the process inside material or plasma simulations. However, there is a lack of datas on laser interaction to validate models. Experiments are limited to pressure plasma determination because it is difficult to diagnose this specific configuration. Many issues remain about these dense and cold plasmas. For example, models make the assumption that the laser is completely absorbed whereas this has not been checked. We propose in this paper an original experiment of absorption measurement in water confinement regime. It is based on a measurement of reflectivity also giving the temporal profiles of the brightness of plasma and laser intensity absorbed. The laser has a duration of 10 ns, a wavelength of 532 ns in intensity range 0.1-10 GW/cm2. This configuration is representative of actual LSP application. Results show that the absorption increases when irradiance increases from 5% (cold material) to 95% only. There is also an influence of water breakdown on the absorption levels and its temporal profile. Plasma confinement threshold was also measured (0.06 GW/cm2).Laser shot processing consists in irradiating a material covered by a transparent layer such water with a laser in the range of few GWcm2. A plasma is generated at the interface between water and material producing strong shock wave (GPa) which can be used to improve metallic surface (Laser Shock Processing (LSP)) or to test interface adhesion (Laser Adhesion Test (LASAT)) . Many studies deals with effect of the process inside material or plasma simulations. However, there is a lack of datas on laser interaction to validate models. Experiments are limited to pressure plasma determination because it is difficult to diagnose this specific configuration. Many issues remain about these dense and cold plasmas. For example, models make the assumption that the laser is completely absorbed whereas this has not been checked. We propose in this paper an original experiment of absorption measurement in water confinement regime. It is based on a measurement of reflectivity also giving the temporal profiles of the bri...

International Congress on Applications of Lasers & Electro-Optics, 1998

The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investig... more The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investigated for the first, second and third harmonics of Nd:Glass laser (1,064, 0,532, 0,355 μn) with 0.6, 10 and 25 ns laser pulse durations. Pressure measurements have been mainly performed using a Velocimetry Interferometer System for Any Reflector (VTSAR). It appears that, depending on laser parameters, above a given laser intensity threshold, the peak pressure is saturated and the pressure duration is reduced due to laser-induced breakdown plasma in the confining water. The observation of the interaction zone (confined plasma and confining water) with a fast intensified camera shows that this parasitic breakdown occurs exclusively at the surface of water and limits the efficiency of the process. The time-resolved transitivity of this plasma has been measured with a continuous Argon laser beam for a 1.064 μm/25 ns incident laser irradiation. Above 10 GW/cm2, the peak power density transmitted through the breakdown plasma saturates and the laser pulse transmitted is reduced in agreement with pressure measurements. The relative influence of main physical mechanisms occurring during the generation of the laser breakdown at the surface of water have been discussed. According to the wavelength effect which tends to authorize higher pressure with longer wavelengths, the influence of multiphotoionic processes seem to dominate the effect of avalanche ionization. The protective coatings and laser spot size influences have been also investigated regarding the stress levels induced in the targets. About 30 % stresses increase in the material is shown to occur with adapted coating. On the contrary, the laser spot size has no specific effects on the pressure induced in WCR. Residual Stresses (RS) field have been determined for different laser conditions.The generation of shock waves by laser-plasma in Water Confinement Regime (WCR) has been investigated for the first, second and third harmonics of Nd:Glass laser (1,064, 0,532, 0,355 μn) with 0.6, 10 and 25 ns laser pulse durations. Pressure measurements have been mainly performed using a Velocimetry Interferometer System for Any Reflector (VTSAR). It appears that, depending on laser parameters, above a given laser intensity threshold, the peak pressure is saturated and the pressure duration is reduced due to laser-induced breakdown plasma in the confining water. The observation of the interaction zone (confined plasma and confining water) with a fast intensified camera shows that this parasitic breakdown occurs exclusively at the surface of water and limits the efficiency of the process. The time-resolved transitivity of this plasma has been measured with a continuous Argon laser beam for a 1.064 μm/25 ns incident laser irradiation. Above 10 GW/cm2, the peak power density transmitted through the breakdow...

The Review of scientific instruments, 2018

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great ... more Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 μm and a spacing of 500 μm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 μg/cm2 thick carbon foil as an energy-loss target and a...

The Review of scientific instruments, 2021

An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been develop... more An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-ray source. In comparison to a transmission geometry setup, this configuration allows us to probe only a small portion of the compressed sample, as well as to shield the detectors against the x-rays generated by the laser-plasma interaction on the front side of the target. Thus, this new platform facilitates probing of spatially and temporarily uniform thermodynamic conditions and enables us to study samples of a large range of atomic numbers, thicknesses, and compression dynamics. As a proof-of-concept, we report direct structural measurements of the bcc-hcp transition both in shock and ramp-compressed polycrystalline iron with diffraction signals recorded between 2θ ∼ 30° and ∼150°. In parallel, the pressure and temperature history of probed sampl...

Journal of Applied Physics, 2020

When a shock wave of several tens of GPa breaks out at a free surface, material is ejected ahead ... more When a shock wave of several tens of GPa breaks out at a free surface, material is ejected ahead of this surface. The amount and velocity of such ejecta depend on the breakout pressure, state of the released material (solid, liquid, or mixed), whether the shockwave is supported or unsupported and the initial geometrical perturbation (or roughness) of the free surface. If surface defects consist of small grooves, pits or scratches, material ejection occurs in the form of jets breaking up into tiny particles (so-called microjetting), with jet tip velocities up to several times higher than the free surface velocity. The laser-based experiments presented in this paper focus on microjetting in shock-melted tin with periodic surface perturbations. Several complementary diagnostics are combined to measure the velocity and mass of ejecta during the early stages of the jetting process. One relevant advancement is the use of ps-laser X-ray radiography to probe the density of the ejecta in distinct jets a few tens of µm-wide. The effects of the depth and wavelength of the initial perturbation are investigated in both linear and near-linear growth regimes. The results are compared with predictions derived from the Richtmyer-Meshkov Instability (RMI) theory.

Journal of Dynamic Behavior of Materials, 2016

When a material is submitted to a dynamic compression, a shock wave propagates through the bulk a... more When a material is submitted to a dynamic compression, a shock wave propagates through the bulk and potentially interacts with a free surface. If this surface has geometrical defects such as grooves, some material ejection can occur. The energy of the high velocity ejecta is an area of concern for many applications, such as industrial safety, pyrotechnics or inertial confinement fusion. We have studied this phenomenon of microjetting from calibrated grooves in laser shock-loaded Cu samples, combining complementary experimental, numerical and analytical approaches, in order to investigate the formation and the fragmentation of the jets over ranges of small spatial (*lm) and temporal (*ns) scales and extremely high strain rates (*10 7 s-1). Various grooves were used with different depths and aperture halfangles (20°, 30°, 45°). The velocities measured by fast shadowgraphy and heterodyne velocimetry were compared to numerical predictions using the finite element or the smoothed particles hydrodynamics formulations with the Radioss code. Size distribution of the ejecta was inferred from rough measurements of the debris sizes and compared to analytical predictions from a probability law.

High Pressure Research, 2016

ABSTRACT We present in this paper recent advances in the high pressure domain provided by the int... more ABSTRACT We present in this paper recent advances in the high pressure domain provided by the introduction of time-resolved energy-dispersive XAS (EDXAS) techniques at synchrotrons. We highlight technical aspects and describe two modes of acquisition: the ‘movie’ mode, where the time resolution is given by the detector acquisition speed and the ‘pump-and-probe’ mode, where the time resolution is given by the delay between the pump and the probe. These two modes define a frontier in the time resolution, respectively above and below the ∼10 μs regime. In the former, examples of applications are chemical stability and reactions at high pressure and high temperature or probing the warm dense matter regime using rapid current ramps. In the latter, an example is given on studies of dynamically compressed matter, by coupling single-bunch EDXAS at high-brilliance synchrotron to a nanosecond high-power laser.

Journal of Applied Physics, 2022

Photonic Doppler velocimetry and digital high-speed shadowgraphy have been used to characterize t... more Photonic Doppler velocimetry and digital high-speed shadowgraphy have been used to characterize the chemical reaction zone parameters of pressed trinitrotoluene (TNT) samples with an initial density of 1.568 g cm À3. Comparison of the nanosecond time-resolved particle velocity histories of the free surfaces of detonating charges in air and light vacuum and of the interfaces between TNT detonation products and lithium fluoride or polymethyl methacrylate windows allow one to bracket the von Neumann spike pressure between 24.8 and 28.8 GPa. Our velocity waveforms confirm the two-step reaction pathway already observed in TNT, triaminotrinitrobenzene (TATB), and nitromethane, with a first fast energy release over 80 ns followed by a slower release over 250 additional ns. We consider the end of the first release zone as the locus of the Chapman-Jouguet (CJ) state, and the CJ pressure thus lies between 17.6 and 17.7 GPa. The energy release is not completed in this Jouguet plane but only after about %280 ns when the carbon cluster formation process ends. This corresponds to both the end of the slow release part of the interface velocity profiles and to the moment at which the free surface velocity profiles reach their maximum. Our shadowgraphy images confirm that carbon formation occurs very rapidly after the detonation breakout, in good agreement with previous time-resolved small-angle x-ray scattering measurements. The comparison with similar results previously obtained on TATB allows one to further highlight their similarities, which mainly result from their excess carbon production at late times.

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, 2020

We have completed a series of experiments to measure the shock initiation behavior in the TATB an... more We have completed a series of experiments to measure the shock initiation behavior in the TATB and HMX based explosive TX1. The growth of the reaction in the shocked explosive was monitored by eleven embedded particle velocity gauges located at different depths. In addition, three gauges elements called "shock trackers" have been used to monitor the progress of the shock front as a function of time and position as it moves through the explosive sample. Their analysis yielded the position and time where the wave attains detonation. Particle velocity wave profile data and run distance-to-detonation vs. input pressure (Pop-plot) data have been obtained on TX1 samples submitted to both single shock and double shock loadings at different pressures. Particle velocity wave profiles recorded in TX1 are similar to those recorded in various HMX compositions under similar loading conditions, which confirms that the reactivity of TX1 is driven by its HMX component. EXPERIMENTAL SETUP Our experiments were performed using the 60 mm bore powder gun of CEA Le Ripault. We used TX1 samples composed of 52 wt. % of TATB (50-60 µm grain size), 45 wt. % of HMX (0-100 µm grain size), and 3 wt. % of phenoxy binder. These samples had a mean density of 1.848 g/cm 3. They were prepared by machining TX1 into

Metals, 2021

This review proposes to summarize the development of laser shock applications in a confined regim... more This review proposes to summarize the development of laser shock applications in a confined regime, mainly laser shock peening, over the past 50 years since its discovery. We especially focus on the relative importance of the source term, which is directly linked to plasma pressure. Discussions are conducted regarding the experimental setups, experimental results, models and numerical simulations. Confined plasmas are described and their specific properties are compared with those of well-known plasmas. Some comprehensive keys are provided to help understand the behavior of these confined plasmas during their interaction with laser light to reach very high pressures that are fundamental for laser shock applications. Breakdown phenomena, which limit pressure generation, are also presented and discussed. A historical review was conducted on experimental data, such as pressure, temperature, and density. Available experimental setups used to characterize the plasma pressure are also dis...

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter

A high resolution picosecond laser imaging diagnostic has been developed for making high-resoluti... more A high resolution picosecond laser imaging diagnostic has been developed for making high-resolution spatial measurements of ejecta particles moving at high velocities (a few km/s). Preliminary results obtained with UV (355nm) lighting are presented for laser shock-driven tin ejecta experiments performed with different kind of surface defects. These results are compared with those obtained at LANL under high explosive loading using ultraviolet in-line Fraunhofer holography, and also with molecular dynamics (MD) simulations performed at lower space and time scales.

SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter

Ejecta production upon the breakout of a shock wave at a rough surface has been the subject of ex... more Ejecta production upon the breakout of a shock wave at a rough surface has been the subject of extensive research work for about six decades. For a few years, we have investigated how laser-driven shocks could provide original, complementary data on this issue, over specific ranges of very high loading pressures, very short pulse durations (ns-order), small dimensions (tens of µm) and extremely high strain rates. Here, selected results are presented in two metals (Cu and Sn), with either single triangular grooves of controlled depths and sharp angles or periodic, quasi-sinusoidal perturbations of different amplitudes. Experimental data combine measurements of jet velocities, using both optical shadowgraphy and Photonic Doppler Velocimetry, with ultra-fast laser based X-ray radiography to estimate mass ejection. Results are briefly compared with the predictions of analytical models and data obtained by other teams from explosive-based experiments, at lower pressure and over much larger temporal and spatial scales. Thus, both interest and limitations of laser shocks for this particular field of shock physics are illustrated and discussed.

Journal of Applied Physics

Journal of Applied Physics

The interaction of a shock wave with a rough free surface may lead to the ejection of high veloci... more The interaction of a shock wave with a rough free surface may lead to the ejection of high velocity (~ km/s) particles of small size (~ µm). This process is a safety issue for various applications such as pyrotechnics or inertial confinement fusion. To complement data obtained by other groups under explosive loading or plate impacts, we use laser driven shock loading to study microjetting from V-shaped grooves of various angles in copper and tin samples, with a combination of complementary experimental techniques. To simulate such experiments, we have chosen to use the Smoothed Particles Hydrodynamics formulation, well-suited for the very high strains involved in jet expansion and subsequent fragmentation. In this paper, we report some advances in this modelling effort, then we compare computed predictions with new experimental results including fragments size distributions inferred from post-test microtomography after soft recovery in a low density gel. Special focus is made on the dependence of the ejecta ballistic properties (velocity and mass distributions) on numerical parameters such as the initial inter-particular distance, the smoothing length and a random geometrical noise introduced to simulate inner irregularities of the material. Shock Compression of Condensed Matter -2017 AIP Conf. Proc. 1979, 080012-1-080012-5; https://doi.

Journal of Synchrotron Radiation

Time-resolved X-ray diffraction measurements have been carried out on dynamically compressed Sn u... more Time-resolved X-ray diffraction measurements have been carried out on dynamically compressed Sn up to a maximum pressure of ∼13 GPa at the European Synchrotron Radiation Facility. The phase transition from β-Sn to body-centered tetragonal (b.c.t.) Sn has been observed using synchrotron X-ray diffraction for the first time undergoing shock compression and release. Following maximum compression, the sample releases to lower pressures for several nanoseconds until the reverse transition occurs. The data are in good agreement with previous shock boundaries that indicate that the β-Sn phase is stable ∼2 GPa higher than the static boundary upon compression and the b.c.t.-Sn phase is stable ∼1 GPa lower upon release. The transition to the high-pressure phase reveals a loss of texture in the X-ray diffraction data from the `quasi' single-crystal β-Sn structure to a more powder-like Debye–Scherrer ring.

Debris ejection upon shock breakout at a rough surface is a key issue for many applications, incl... more Debris ejection upon shock breakout at a rough surface is a key issue for many applications, including pyrotechnics and inertial confinement fusion. For a few years, we have used laser driven shocks to investigate microjetting in metallic samples with calibrated grooves in their free surface. Fast transverse optical shadowgraphy, time-resolved measurements of both planar surface and jet tip velocities, and post-shock analysis of recovered material have provided data over ranges of small spatial and temporal scales, short loading pulses (ns-order) and extremely high strain rates. The new experiment presented here involves two laser beams in a pump-probe configuration.

Soda-lime glass behavior under laser shock DIDIER LOISON, JEAN AR-NAUD SOLLIER, cea/dam, LAURENT ... more Soda-lime glass behavior under laser shock DIDIER LOISON, JEAN AR-NAUD SOLLIER, cea/dam, LAURENT BERTHE, PIMM UMR CNRS 8006, MICHEL BOUSTIE, Institut Pprime UPR 3346 -Understanding and modeling the glass behavior is an issue for certain aeronautical, military and civil applications. For example, parts of satellites and shuttles are made of glass. During their lifetime, they are subjected to high velocity impacts, which in the end may damage them. To determine the behavior of these structures during and after impact we used instrumented laser driven shock loading performed on high power intensity Laser facilities: Transverse shadowgraphs of the front wave propagating inside the transparent material were taken at different times. They provide information regarding the position of the shock wave front and of the first damage. PDV or VISAR measurements provide time-resolved free surface velocity to determine mater velocity when shock wave breakout and spall strength for the most powerful laser shots. Under High pressure conditions glass permanently densify, traces of such a plastic deformation are looked for on the path of the shock wave. Those experimental data are necessary to characterize the material behavior under such conditions and to model the mechanical behavior of glass structures. In this presentation we will present experimental results obtained for soda-lime silica glass samples loaded by laser induced shock.