The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
G Gregori - One of the best experts on this subject based on the ideXlab platform.
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laboratory measurements of resistivity in warm Dense Plasmas relevant to the microphysics of brown dwarfs
Nature Communications, 2015Co-Authors: N Booth, G Gregori, A P L Robinson, P Hakel, R J Clarke, R J Dance, D Doria, L A Gizzi, P KoesterAbstract:Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm Dense Plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm Dense plasma related to the viscosity of brown dwarfs.
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observations of strong ion ion correlations in Dense Plasmas
Physics of Plasmas, 2014Co-Authors: L B Fletcher, G Gregori, A Pak, D A Chapman, R W Falcone, C Fortmann, E Galtier, D O Gericke, J B Hastings, O L LandenAbstract:Using simultaneous spectrally, angularly, and temporally resolved x-ray scattering, we measure the pronounced ion-ion correlation peak in a strongly coupled plasma. Laser-driven shock-compressed aluminum at ∼3× solid density is probed with high-energy photons at 17.9 keV created by molybdenum He-α emission in a laser-driven plasma source. The measured elastic scattering feature shows a well-pronounced correlation peak at a wave vector of k=4A−1. The magnitude of this correlation peak cannot be described by standard plasma theories employing a linear screened Coulomb potential. Advanced models, including a strong short-range repulsion due to the inner structure of the aluminum ions are however in good agreement with the scattering data. These studies have demonstrated a new highly accurate diagnostic technique to directly measure the state of compression and the ion-ion correlations. We have since applied this new method in single-shot wave-number resolved S(k) measurements to characterize the physical pro...
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extent of validity of the hydrodynamic description of ions in Dense Plasmas
Physical Review E, 2011Co-Authors: J Mithen, Jerome Daligault, G GregoriAbstract:We show that the hydrodynamic description can be applied to modeling the ionic response in Dense Plasmas for a wide range of length scales that are experimentally accessible. Using numerical simulations for the Yukawa model, we find that the maximum wave number ${k}_{\mathrm{max}}$ at which the hydrodynamic description applies is independent of the coupling strength, given by ${k}_{\mathrm{max}}{\ensuremath{\lambda}}_{s}\ensuremath{\simeq}0.43$, where ${\ensuremath{\lambda}}_{s}$ is the ionic screening length. Our results show that the hydrodynamic description can be used for interpreting x-ray scattering data from fourth generation light sources and high power lasers. In addition, our investigation sheds new light on how the domain of validity of the hydrodynamic description depends on both the microscopic properties and the thermodynamic state of fluids in general.
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derivation of the static structure factor in strongly coupled non equilibrium Plasmas for x ray scattering studies
High Energy Density Physics, 2007Co-Authors: S H Glenzer, G Gregori, A Ravasio, A Holl, S J RoseAbstract:Abstract We present a fully analytical derivation of the static response function in strongly coupled and non-equilibrium Plasmas. The model we are proposing is based on a linear response formalism coupled to a charged hard sphere reference for the ions. The electrons, instead, are treated using a local field correction which satisfies the compressibility sum rule at finite temperatures. The model is applied to calculate an effective ion mass that accounts for the self-energy correction of the free particle energy. We will discuss the implication of this approach in the interpretation of experimental results in X-ray scattering measurements from Dense Plasmas.
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x ray probe development for collective scattering measurements in Dense Plasmas
Journal of Quantitative Spectroscopy & Radiative Transfer, 2006Co-Authors: G Gregori, M K Urry, O L Landen, A Pak, S H GlenzerAbstract:Abstract X-ray spectra and conversion efficiencies of the laser-produced chlorine Ly- α and K- α line radiation have been investigated to develop X-ray probes for the collective scattering regime. The Ly- α radiation was produced by either smoothed or un-smoothed laser beams with nanosecond-long laser pulses yielding high conversion efficiencies of up to 0.3% sufficient for X-ray scattering measurements. However, the time-integrated measurements show a significant dielectronic satellite emission on the red wing of the primary Ly- α line which must be avoided to resolve the plasmon feature in the scattering spectra. We find no red wing emission features for ultra-short pulse laser produced K- α radiation. The bandwidth of Δ E / E = 2 × 10 - 3 is suited for collective scattering, but the conversion efficiency falls short of the high values achieved for the Ly- α . These findings indicate that present laser-produced X-ray sources will restrict the choice of detectors and plasma conditions for collective X-ray scattering from Dense Plasmas.
S H Glenzer - One of the best experts on this subject based on the ideXlab platform.
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observations of non linear plasmon damping in Dense Plasmas
Physics of Plasmas, 2018Co-Authors: S H Glenzer, B B L Witte, P Sperling, Martin French, V Recoules, R RedmerAbstract:We present simulations using finite-temperature density-functional-theory molecular-dynamics to calculate dynamic dielectric properties in warm Dense aluminum. The comparison between exchange-correlation functionals in the Perdew, Burke, Ernzerhof approximation, Strongly Constrained and Appropriately Normed Semilocal Density Functional, and Heyd, Scuseria, Ernzerhof (HSE) approximation indicates evident differences in the electron transition energies, dc conductivity, and Lorenz number. The HSE calculations show excellent agreement with x-ray scattering data [Witte et al., Phys. Rev. Lett. 118, 225001 (2017)] as well as dc conductivity and absorption measurements. These findings demonstrate non-Drude behavior of the dynamic conductivity above the Cooper minimum that needs to be taken into account to determine optical properties in the warm Dense matter regime.
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frontiers of the physics of Dense Plasmas and planetary interiors experiments theory applications
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: Jonathan J. Fortney, Michel Koenig, B. Militzer, D Saumon, S H Glenzer, Diana ValenciaAbstract:Recent developments of dynamic x-ray characterization experiments of Dense matter are reviewed, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. Several applications of this work are examined. These include the structure of massive "Super Earth" terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as the benchmark for giant planets.
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derivation of the static structure factor in strongly coupled non equilibrium Plasmas for x ray scattering studies
High Energy Density Physics, 2007Co-Authors: S H Glenzer, G Gregori, A Ravasio, A Holl, S J RoseAbstract:Abstract We present a fully analytical derivation of the static response function in strongly coupled and non-equilibrium Plasmas. The model we are proposing is based on a linear response formalism coupled to a charged hard sphere reference for the ions. The electrons, instead, are treated using a local field correction which satisfies the compressibility sum rule at finite temperatures. The model is applied to calculate an effective ion mass that accounts for the self-energy correction of the free particle energy. We will discuss the implication of this approach in the interpretation of experimental results in X-ray scattering measurements from Dense Plasmas.
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x ray probe development for collective scattering measurements in Dense Plasmas
Journal of Quantitative Spectroscopy & Radiative Transfer, 2006Co-Authors: G Gregori, M K Urry, O L Landen, A Pak, S H GlenzerAbstract:Abstract X-ray spectra and conversion efficiencies of the laser-produced chlorine Ly- α and K- α line radiation have been investigated to develop X-ray probes for the collective scattering regime. The Ly- α radiation was produced by either smoothed or un-smoothed laser beams with nanosecond-long laser pulses yielding high conversion efficiencies of up to 0.3% sufficient for X-ray scattering measurements. However, the time-integrated measurements show a significant dielectronic satellite emission on the red wing of the primary Ly- α line which must be avoided to resolve the plasmon feature in the scattering spectra. We find no red wing emission features for ultra-short pulse laser produced K- α radiation. The bandwidth of Δ E / E = 2 × 10 - 3 is suited for collective scattering, but the conversion efficiency falls short of the high values achieved for the Ly- α . These findings indicate that present laser-produced X-ray sources will restrict the choice of detectors and plasma conditions for collective X-ray scattering from Dense Plasmas.
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electronic structure measurements of Dense Plasmas
Physics of Plasmas, 2004Co-Authors: G Gregori, F J Rogers, O L Landen, S H Glenzer, P Renaudin, S M Pollaine, C Blancard, G Faussurier, S Kuhlbrodt, R RedmerAbstract:This paper presents an improved analytical expression for the x-ray dynamic structure factor from a Dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z Plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. The theory is used to interpret x-ray scattering experiments from solid density carbon Plasmas and to extract accurate measurements of electron temperature, electron density, and charge state. The experimental results are applied to validate various equation-of-state models for carbon Plasmas.
Henri Vincenti - One of the best experts on this subject based on the ideXlab platform.
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identification of coupling mechanisms between ultraintense laser light and Dense Plasmas
Physical Review X, 2019Co-Authors: L Chopineau, Adrien Leblanc, G Blaclard, A Denoeud, Maxence Thevenet, Jeanluc Vay, G Bonnaud, Ph Martin, Henri VincentiAbstract:Experiments and simulations reveal distinct regimes of electron behavior in plasma generated by ultraintense laser light hitting a solid target, a key insight for interpreting future experiments that rely on extreme laser pulses.
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identification of coupling mechanisms between ultraintense laser light and Dense Plasmas
arXiv: Plasma Physics, 2018Co-Authors: L Chopineau, Adrien Leblanc, G Blaclard, A Denoeud, Maxence Thevenet, Jeanluc Vay, G Bonnaud, Ph Martin, Henri VincentiAbstract:The interaction of intense laser beams with Plasmas created on solid targets involves a rich non-linear physics. Because such Dense Plasmas are reflective for laser light, the coupling with the incident beam occurs within a thin layer at the interface between plasma and vacuum. One of the main paradigms used to understand this coupling, known as Brunel mechanism, is expected to be valid only for very steep plasma surfaces. Despite innumerable studies, its validity range remains uncertain, and the physics involved for smoother plasma-vacuum interfaces is unclear, especially for ultrahigh laser intensities. We report the first comprehensive experimental and numerical study of the laser-plasma coupling mechanisms as a function of the plasma interface steepness, in the relativistic interaction regime. Our results reveal a clear transition from the temporally-periodic Brunel mechanism to a chaotic dynamic associated to stochastic heating. By revealing the key signatures of these two distinct regimes on experimental observables, we provide an important landmark for the interpretation of future experiments.
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attosecond lighthouses how to use spatiotemporally coupled light fields to generate isolated attosecond pulses
Physical Review Letters, 2012Co-Authors: Henri Vincenti, Fabien QuéréAbstract:Under the effect of even simple optical components, the spatial properties of femtosecond laser beams can vary over the duration of the light pulse. We show how using such spatiotemporally coupled light fields in high harmonic generation experiments (e.g., in gases or Dense Plasmas) enables the production of attosecond lighthouses, i.e., sources emitting a collection of angularly well-separated light beams, each consisting of an isolated attosecond pulse. This general effect opens the way to a new generation of light sources, particularly suitable for attosecond pump-probe experiments, and provides a new tool for ultrafast metrology, for instance, giving direct access to fluctuations of the carrier-envelope relative phase of even the most intense ultrashort lasers.
O L Landen - One of the best experts on this subject based on the ideXlab platform.
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observations of strong ion ion correlations in Dense Plasmas
Physics of Plasmas, 2014Co-Authors: L B Fletcher, G Gregori, A Pak, D A Chapman, R W Falcone, C Fortmann, E Galtier, D O Gericke, J B Hastings, O L LandenAbstract:Using simultaneous spectrally, angularly, and temporally resolved x-ray scattering, we measure the pronounced ion-ion correlation peak in a strongly coupled plasma. Laser-driven shock-compressed aluminum at ∼3× solid density is probed with high-energy photons at 17.9 keV created by molybdenum He-α emission in a laser-driven plasma source. The measured elastic scattering feature shows a well-pronounced correlation peak at a wave vector of k=4A−1. The magnitude of this correlation peak cannot be described by standard plasma theories employing a linear screened Coulomb potential. Advanced models, including a strong short-range repulsion due to the inner structure of the aluminum ions are however in good agreement with the scattering data. These studies have demonstrated a new highly accurate diagnostic technique to directly measure the state of compression and the ion-ion correlations. We have since applied this new method in single-shot wave-number resolved S(k) measurements to characterize the physical pro...
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lorentz mapping of magnetic fields in hot Dense Plasmas
APS, 2009Co-Authors: R D Petrasso, F H Seguin, J R Rygg, J A Frenje, R Betti, James Knauer, D D Meyerhofer, P Amendt, D H Froula, O L LandenAbstract:Unique detection of electromagnetic fields and identification of field type and strength as a function of position were used to determine the nature of self-generated fields in a novel experiment with lasergenerated plasma bubbles on two sides of a plastic foil. Field-induced deflections of monoenergetic 15-MeV probe protons passing through the two bubbles, measured quantitatively with proton radiography, were combined with Lorentz mapping to provide separate measurements of magnetic and electric fields. The result was absolute identification and measurement of a toroidal magnetic field around each bubble and determination that any electric field component parallel to the foil was below measurement uncertainties.
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x ray probe development for collective scattering measurements in Dense Plasmas
Journal of Quantitative Spectroscopy & Radiative Transfer, 2006Co-Authors: G Gregori, M K Urry, O L Landen, A Pak, S H GlenzerAbstract:Abstract X-ray spectra and conversion efficiencies of the laser-produced chlorine Ly- α and K- α line radiation have been investigated to develop X-ray probes for the collective scattering regime. The Ly- α radiation was produced by either smoothed or un-smoothed laser beams with nanosecond-long laser pulses yielding high conversion efficiencies of up to 0.3% sufficient for X-ray scattering measurements. However, the time-integrated measurements show a significant dielectronic satellite emission on the red wing of the primary Ly- α line which must be avoided to resolve the plasmon feature in the scattering spectra. We find no red wing emission features for ultra-short pulse laser produced K- α radiation. The bandwidth of Δ E / E = 2 × 10 - 3 is suited for collective scattering, but the conversion efficiency falls short of the high values achieved for the Ly- α . These findings indicate that present laser-produced X-ray sources will restrict the choice of detectors and plasma conditions for collective X-ray scattering from Dense Plasmas.
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electronic structure measurements of Dense Plasmas
Physics of Plasmas, 2004Co-Authors: G Gregori, F J Rogers, O L Landen, S H Glenzer, P Renaudin, S M Pollaine, C Blancard, G Faussurier, S Kuhlbrodt, R RedmerAbstract:This paper presents an improved analytical expression for the x-ray dynamic structure factor from a Dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z Plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. The theory is used to interpret x-ray scattering experiments from solid density carbon Plasmas and to extract accurate measurements of electron temperature, electron density, and charge state. The experimental results are applied to validate various equation-of-state models for carbon Plasmas.
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demonstration of spectrally resolved x ray scattering in Dense Plasmas
Physical Review Letters, 2003Co-Authors: S H Glenzer, F J Rogers, G Gregori, R W Lee, S W Pollaine, O L LandenAbstract:We present the first spectrally resolved x-ray scattering measurements from solid-density Plasmas. The scattering spectra show the broadened Compton down-shifted feature allowing us to determine the electron temperature and density with high accuracy. In the low temperature limit, our data indicate that the ionization balance reflects the electrons in the conduction band consistent with calculations that include quantum mechanical corrections to the interaction potential.
Jerome Daligault - One of the best experts on this subject based on the ideXlab platform.
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crossover from classical to fermi liquid behavior in Dense Plasmas
Physical Review Letters, 2017Co-Authors: Jerome DaligaultAbstract:We explore the crossover from classical plasma to quantum Fermi liquid behavior of electrons in Dense Plasmas. To this end, we analyze the evolution with density and temperature of the momentum lifetime of a test electron introduced in a Dense electron gas. This allows us (1) to determine the boundaries of the crossover region in the temperature-density plane and to shed light on the evolution of scattering properties across it, (2) to quantify the role of the fermionic nature of electrons on electronic collisions across the crossover region, and (3) to explain how the concept of the Coulomb logarithm emerges at a high enough temperature but disappears at a low enough temperature.
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ionic transport coefficients of Dense Plasmas without molecular dynamics
Bulletin of the American Physical Society, 2016Co-Authors: Jerome Daligault, D Saumon, C E Starrett, Scott D Baalrud, Travis SjostromAbstract:We present a theoretical model that allows a fast and accurate evaluation of ionic transport properties of realistic Plasmas spanning from warm and Dense to hot and dilute conditions, including mixtures. This is achieved by combining a recent kinetic theory based on effective interaction potentials with a model for the equilibrium radial density distribution based on an average atom model and the integral equations theory of fluids. The model should find broad use in applications where nonideal plasma conditions are traversed, including inertial confinement fusion, compact astrophysical objects, solar and extrasolar planets, and numerous present-day high energy density laboratory experiments.
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fast and accurate quantum molecular dynamics of Dense Plasmas across temperature regimes
Physical Review Letters, 2014Co-Authors: Travis Sjostrom, Jerome DaligaultAbstract:We develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of Dense Plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lower temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.
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extent of validity of the hydrodynamic description of ions in Dense Plasmas
Physical Review E, 2011Co-Authors: J Mithen, Jerome Daligault, G GregoriAbstract:We show that the hydrodynamic description can be applied to modeling the ionic response in Dense Plasmas for a wide range of length scales that are experimentally accessible. Using numerical simulations for the Yukawa model, we find that the maximum wave number ${k}_{\mathrm{max}}$ at which the hydrodynamic description applies is independent of the coupling strength, given by ${k}_{\mathrm{max}}{\ensuremath{\lambda}}_{s}\ensuremath{\simeq}0.43$, where ${\ensuremath{\lambda}}_{s}$ is the ionic screening length. Our results show that the hydrodynamic description can be used for interpreting x-ray scattering data from fourth generation light sources and high power lasers. In addition, our investigation sheds new light on how the domain of validity of the hydrodynamic description depends on both the microscopic properties and the thermodynamic state of fluids in general.
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correlation effects on the temperature relaxation rates in Dense Plasmas
Physical Review E, 2009Co-Authors: Jerome Daligault, Guy DimonteAbstract:We present a model for the rate of temperature relaxation between electrons and ions in Plasmas. The model includes self-consistently the effects of particle screening, electron degeneracy, and correlations between electrons and ions. We successfully validate the model over a wide range of plasma coupling against molecular-dynamics simulations of classical Plasmas of like-charged electrons and ions. We present calculations of the relaxation rates in Dense hydrogen and show that, while electron-ion correlation effects are indispensable in classical, like-charged Plasmas at any density and temperature, quantum diffraction effects prevail over electron-ion correlation effects in Dense hydrogen Plasmas.