Publications

2011

• Electron bunch diagnostics for laser-plasma accelerators, from THz to X-rays
  
  • Plateau Guillaume
  , 2011. This thesis presents a series of single-shot non-intrusive diagnostics of key attributes of electron bunches produced by a laser-plasma accelerator (LPA). Three injection mechanisms of the LPA are characterized: channeled and self-guided self-injection, plasma down-ramp injection, and two-beam colliding pulse injection. New diagnostic techniques are successfully demonstrated: up to 8 times higher sensitivity wavefront sensor-based plasma density measurements, strong spatiotemporal coupling of the focused THz pulse is demonstrated using the temporal electric-field cross-correlation (TEX) of a long chirped probe with a short probe and confirms the two-component structure of the bunch observed by electron spectrometry, and normalized transverse emittances as low as 0.1 mm mrad are demonstrated for 0.5 GeV-class beams produced in a capillary-guided LPA by characterizing the betatron radiation emitted by the electrons inside the plasma using a new single-shot X-ray spectroscopy technique.
• Matériaux lasers dopés à l'ion ytterbium : Performances lasers en pompage par diodes lasers et étude des propriétés thermo-optiques à des températures cryogéniques
  
  • Cardinali Vanessa
  , 2011. Dans les lasers, les gradients de température dans les milieux à gain provoquent des déformations de l'onde laser qui s'y propage. Le but de ma thèse est de mesurer les propriétés thermo-optiques (conductivité thermique, coefficient thermo-optique dn/dT, coefficient de dilatation) de nouveaux matériaux lasers permettant d'atteindre des énergies élevées à de hautes cadences de tir. Ces matériaux sont des céramiques sesquioxydes de scandium Sc2O3, de lutétium Lu2O3 et d'yttrium Y2O3 dopées ytterbium. Les mesures se font à basse température (température de l'azote liquide, 77 K) car les propriétés thermiques sont améliorées lorsque la température du matériau diminue. Ces matériaux ont également été testés en configuration d'oscillateur laser relaxé, montrant ainsi tout l'intérêt de travailler à basse température. Les mesures de ces propriétés représentent un enjeu majeur pour le développement des lasers de forte puissance, d'autant plus que les données de la littérature concernant ces matériaux, dans ces domaines de température, sont quasiment inexistantes. D'autres matériaux comme des cristaux et des céramiques de YAG, des cristaux de fluorure de calcium CaF2 dopés ytterbium, et des verres phosphates dopés néodyme ont également été testés.
• Augmentation de l'énergie des faisceaux de proton accélérés par laser ultra-intense et étude des caractéristiques des faisceaux accélérés par laser ultra-court
  
  • Buffechoux Sébastien
  , 2011. De rapides avancées technologiques ont autorisé depuis le début des années 1980 un développement important des lasers de puissance et ont ouvert la voie aux régimes d’interaction laser-matière relativiste. L’accès aux intensités lumineuses supérieures à 1.1018 W.cm-2 a ainsi donné la possibilité à la communauté scientifique d’explorer une nouvelle physique riche d’applications. Bien que le principal moteur ait historiquement été constitué par les recherche sur la fusion par confinement inertiel, l’astrophysique de laboratoire, la génération de rayonnement (harmoniques, bétatron, X) ou la génération de particules énergétiques (électrons, ions) élargissent de plus en plus ce domaine d’étude.En effet, les très bonnes qualités des sources lumineuses et des sources d’ions créées par laser laissent fortement envisager qu’elles viendront un jour remplacer les sources conventionnelles comme les synchrotrons ou les accélérateurs qui sont des machines très coûteuses.Dans le cadre de cette thèse, une attention toute particulière a été portée à l’accélération d’ions qui a déjà montré son fort potentiel en termes de qualité des faisceaux accélérés. Malheureusement, ses applications sont encore limitées (radiographie, chauffage isochorique) à cause de paramètres limitants comme la divergence du faisceau, le spectre large ou l’énergie maximale atteinte par ces faisceaux. Au cours de ce travail de thèse, l’accent a plus particulièrement été mis sur l’augmentation de l’énergie maximale des faisceaux de protons dans le cadre des régimes à ultra haute intensité (supérieur à 1.1019W.cm-2). Cette recherche s’est orientée suivant deux axes principaux (impulsions longue et courtes), qui ont donné lieu à de nombreux échanges et au renforcement de la collaboration entre les laboratoires du LULI à l’École Polytechnique (France) et l’INRS-EMT (Canada).Dans le cadre des recherches menées au sein du LULI, des techniques innovantes ont pu être explorées afin de poursuivre la compréhension des mécanismes et d’améliorer les qualités de l’accélération d’ions à partir d’impulsion “longues” (entre 300 fs et 1,5 ps). Nous avons montré que l’utilisation de cibles ayant des dimensions transverses réduites permettait le confinement géométrique des électrons dans la zone d’impact du laser et augmentait ainsi significativement le taux de conversion de l’énergie laser vers les protons et l’énergie maximale atteinte par le faisceau. Par ailleurs, l’utilisation originale d’une optique plasma refocalisante a démontré son efficacité quant à réduire fortement la surface de focalisation du laser, conduisant à augmenter son intensité et donc l’énergie de coupure des faisceaux d’ions accélérés. Enfin, l’utilisation de deux impulsions laser a mis en évidence qu’une interaction entre les électrons accélérés par chaque impulsion était possible et qu’elle permet de modifier l’énergie et la typologie des faisceaux de protons.Les expériences réalisées au sein de l’INRS-EMT visaient quant à elle à améliorer la compréhension des régimes d’accélération femtoseconde, où peu d’études à ultrahaute intensité existaient au début de cette thèse, et à valider ou non la pertinence de ces régimes. Les nombreuses expériences menées ont clairement établi l’importance du contraste laser et la nécessité que ce derniers soit important pour que l’accélération de protons soit efficace dans ces régimes ultracourts. L’analyse systématique des faisceaux accélérés en face avant et en face arrière d’une cible mince montre que le processus d’accélération manifeste une certaine symétrie et prouve, qu’à énergie laser constante,l’accélération d’ions par laser n’est pas la plus efficace pour la plus courte durée d’impulsion. (10.70675/1023fbb3z052bz4591zbaf7zc2d859a89e93)
  DOI : 10.70675/1023fbb3z052bz4591zbaf7zc2d859a89e93
• High-harmonic generation from plasma mirrors at kilohertz repetition rate
  
  • Borot Antonin
  • Malvache Arnaud
  • Chen Xiaowei
  • Douillet Denis
  • Iaquianiello Grégory
  • Lefrou Thierry
  • Audebert Patrick
  • Geindre Jean-Paul
  • Mourou Gérard
  • Quéré Fabien
  • Lopez-Martens Rodrigo
  Optics Letters, Optical Society of America - OSA Publishing, 2011, 36 (8), pp.1461. We report the first demonstration of high-harmonic generation from plasma mirrors at a 1 kHz repetition rate. Harmonics up to nineteenth order are generated at peak intensities close to 10$^{18}$ W=cm$^2$ by focusing 1 mJ, 25 fs laser pulses down to 1:7 μm FWHM spot size without any prior wavefront correction onto a moving target. We minimize target surface motion with respect to the laser focus using online interferometry to ensure reproducible interaction conditions for every shot and record data at 1 kHz with unprecedented statistics. This allows us to unambiguously identify coherent wake emission as the main generation mechanism
• Proton radiography of laser-driven imploding target in cylindrical geometry
  
  • Volpe L.
  • Batani D.
  • Vauzour B.
  • Nicolai Ph
  • Santos J. J.
  • Regan C.
  • Morace A.
  • Dorchies F.
  • Fourment C.
  • Hulin S.
  • Perez F.
  • Baton S.
  • Lancaster K.
  • Galimberti M.
  • Heathcote R.
  • Tolley M.
  • Spindloe Ch
  • Koester P.
  • Labate L.
  • Gizzi L. A.
  • Benedetti C.
  • Sgattoni A.
  • Richetta M.
  • Pasley J.
  • Beg F.
  • Chawla S.
  • Higginson D. P.
  • Macphee A. G.
  Physics of Plasmas, American Institute of Physics, 2011, 18 (1). An experiment was done at the Rutherford Appleton Laboratory (Vulcan laser petawatt laser) to study fast electron propagation in cylindrically compressed targets, a subject of interest for fast ignition. This was performed in the framework of the experimental road map of HiPER (the European high power laser energy research facility project). In the experiment, protons accelerated by a picosecond-laser pulse were used to radiograph a 220 mu m diameter cylinder (20 mu m wall, filled with low density foam), imploded with similar to 200 J of green laser light in four symmetrically incident beams of pulse length 1 ns. Point projection proton backlighting was used to get the compression history and the stagnation time. Results are also compared to those from hard x-ray radiography. Detailed comparison with two-dimensional numerical hydrosimulations has been done using a Monte Carlo code adapted to describe multiple scattering and plasma effects. Finally we develop a simple analytical model to estimate the performance of proton radiography for given implosion conditions. (10.1063/1.3530596)
  DOI : 10.1063/1.3530596
• Efficient laser-overdense plasma coupling via surface plasma waves and steady magnetic field generation
  
  • Bigongiari A
  • Raynaud M
  • Riconda C
  • Héron Anne
  • Macchi A
  Physics of Plasmas, American Institute of Physics, 2011. The efficiency of laser overdense plasma coupling via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed over a wide range of laser pulse intensity from 10 15 to 10 20 W cm À2 lm 2 with electron density ranging from 25 to 100n c to describe the laser interaction with a grating target where a surface plasma wave excitation condition is fulfilled. The numerical studies confirm an efficient coupling with an enhancement of the laser absorption up to 75%. The simulations also show the presence of a localized, quasi-static magnetic field at the plasma surface. Two interaction regimes are identified for low (Ik 2 < 10 17 W cm À2 lm 2) and high (Ik 2 > 10 17 W cm À2 lm 2) laser pulse intensities. At " relativistic " laser intensity, steady magnetic fields as high as $580 MG lm/k 0 at 7 Â 10 19 W cm À2 lm 2 are obtained in the simulations. (10.1063/1.3646520)
  DOI : 10.1063/1.3646520
• Magnetically Guided Fast Electrons in Cylindrically Compressed Matter
  
  • Perez F.
  • Debayle A.
  • Honrubia J.
  • Koenig M.
  • Batani D.
  • Baton S. D.
  • Beg F. N.
  • Benedetti C.
  • Brambrink E.
  • Chawla S.
  • Dorchies F.
  • Fourment C.
  • Galimberti M.
  • Gizzi L. A.
  • Gremillet L.
  • Heathcote R.
  • Higginson D. P.
  • Hulin S.
  • Jafer R.
  • Koester P.
  • Labate L.
  • Lancaster K. L.
  • Mackinnon A. J.
  • Macphee A. G.
  • Nazarov W.
  • Nicolai P.
  • Pasley J.
  • Ramis R.
  • Richetta M.
  • Santos J. J.
  • Sgattoni A.
  • Spindloe C.
  • Vauzour B.
  • Vinci T.
  • Volpe L.
  Physical Review Letters, American Physical Society, 2011, 107 (6), pp.065004. Fast electrons produced by a 10 ps, 160 J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. K(alpha)-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter. (10.1103/PhysRevLett.107.065004)
  DOI : 10.1103/PhysRevLett.107.065004
• The HiPER project for inertial confinement fusion and some experimental results on advanced ignition schemes
  
  • Batani D.
  • Koenig M.
  • Baton S.
  • Perez F.
  • Gizzi L. A.
  • Koester P.
  • Labate L.
  • Honrubia J.
  • Antonelli L.
  • Morace A.
  • Volpe L.
  • Santos J.
  • Schurtz G.
  • Hulin S.
  • Ribeyre X.
  • Fourment C.
  • Nicolai P.
  • Vauzour B.
  • Gremillet L.
  • Nazarov W.
  • Pasley J.
  • Richetta M.
  • Lancaster K.
  • Spindloe Ch
  • Tolley M.
  • Neely D.
  • Kozlova M.
  • Nejdl J.
  • Rus B.
  • Wolowski J.
  • Badziak J.
  • Dorchies F.
  Plasma Physics and Controlled Fusion, IOP Publishing, 2011, 53 (12). This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to ‘advanced ignition schemes’, i.e. the fast ignition and the shock ignition approaches to inertial fusion. Such schemes are aimed at achieving a higher gain, as compared with the classical approach which is used in NIF, as required for future reactors, and make fusion possible with smaller facilities. In particular, a series of experiments related to fast ignition were performed at the RAL (UK) and LULI (France) Laboratories and studied the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser–plasma coupling in the 1016 W cm−2 intensity regime of interest for shock ignition. (10.1088/0741-3335/53/12/124041)
  DOI : 10.1088/0741-3335/53/12/124041
• Steady magnetic-field generation via surface-plasma-wave excitation
  
  • Bigongiari A
  • Raynaud M
  • Riconda C
  Physical Review E, American Physical Society (APS), 2011, 84 (1), pp.015402(R). The possibility of inducing a magnetic field via surface plasma-wave excitation is investigated with a simple nonrelativistic hydrodynamic model. A static magnetic field is predicted at the plasma surface, scaling with the square of the surface-wave field amplitude, and the influence of the electron plasma density is studied. In the case of resonant surface-wave excitation by laser this result can be applied to low intensities such that the electron quiver velocity in the field of the surface wave is less than its thermal velocity. (10.1103/PhysRevE.84.015402)
  DOI : 10.1103/PhysRevE.84.015402
• Highly radiative shock experiments driven by GEKKO XII
  
  • Dizière A.
  • Michaut Claire
  • Koenig M.
  • Gregory C. D.
  • Ravasio Alessandra
  • Sakawa Youichi
  • Kuramitsu Y.
  • Morita T.
  • Ide T.
  • Tanji H.
  • Takabe H.
  • Barroso Patrice
  • Boudenne J.-M.
  Astrophysics and Space Science, Springer Verlag, 2011, 336, pp.213-218. In this paper, recent results obtained on highly radiative shocks generated in a xenon filled gas cell using the GEKKO XII laser facility are presented. Data show extremely high shock velocity (>=150 km/s) never achieved before in gas. Preliminary analyses based on theoretical dimensionless numbers and numerical simulations suggest that these radiative shocks reach a new radiative regime where the radiative pressure plays a role in the dynamics and structure of the shock. A major effect observed is a strong anisotropic emission in the downstream gas. This unexpected feature is discussed and compared to available 2D radiation hydrodynamic simulations. (10.1007/s10509-011-0653-6)
  DOI : 10.1007/s10509-011-0653-6
• Can proton radiography be used to image imploding target in ICF experiments ?
  
  • Volpe L.
  • Batani D.
  • Vauzour B.
  • Nicolai Ph
  • Santos J. J.
  • Dorchies F.
  • Fourment C.
  • Hulin S.
  • Regan C.
  • Perez F.
  • Baton S.
  • Koenig M.
  • Lancaster K.
  • Galimberti M.
  • Heathcote R.
  • Tolley M.
  • Spindloe Ch
  • Koester P.
  • Labate L.
  • Gizzi L. A.
  • Benedetti C.
  • Sgattoni A.
  • Richetta M.
  , 2011, 8080. no abstract
• Comparison of Fe and Ni opacity calculations for a better understanding of pulsating stellar envelopes
  
  • Gilles D.
  • Turck-Chieze Sylvaine
  • Loisel G.
  • Piau Laurent
  • Ducret J.-E.
  • Poirier M.
  • Blenski T.
  • Thais Frédéric
  • Blancard Christophe
  • Cossé Philippe
  • Faussurier Gérald
  • Gilleron F.
  • Pain J. C.
  • Porcherot Q.
  • Guzik Joyce A.
  • Kilcrease D. P.
  • Magee N. H.
  • Harris J.
  • Busquet Michel
  • Delahaye Franck
  • Zeippen Claude J.
  • Bastiani-Ceccotti S.
  High Energy Density Physics, Elsevier, 2011, 7, pp.312-319. Opacity is an important ingredient of the evolution of stars. The calculation of opacity coefficients is complicated by the fact that the plasma contains partially ionized heavy ions that contribute to opacity dominated by H and He. Up to now, the astrophysical community has greatly benefited from the work of the contributions of Los Alamos [1], Livermore [2] and the Opacity Project (OP) [3]. However unexplained differences of up to 50% in the radiative forces and Rosseland mean values for Fe have been noticed for conditions corresponding to stellar envelopes. Such uncertainty has a real impact on the understanding of pulsating stellar envelopes, on the excitation of modes, and on the identification of the mode frequencies. Temperature and density conditions equivalent to those found in stars can now be produced in laboratory experiments for various atomic species. Recently the photo-absorption spectra of nickel and iron plasmas have been measured during the LULI 2010 campaign, for temperatures between 15 and 40 eV and densities of &tilde;3 mg/cm<SUP>3</SUP>. A large theoretical collaboration, the "OPAC", has been formed to prepare these experiments. We present here the set of opacity calculations performed by eight different groups for conditions relevant to the LULI 2010 experiment and to astrophysical stellar envelope conditions. (10.1016/j.hedp.2011.06.001)
  DOI : 10.1016/j.hedp.2011.06.001
• Invariance concepts and scalability of two-temperature astrophysical radiating fluids
  
  • Falize Emeric
  • Dizière A.
  • Loupias B.
  Astrophysics and Space Science, Springer Verlag, 2011, 336, pp.201-205. In this work, we present a classification of laboratory astrophysics experiments. We introduce different invariance concepts in order to build scaling laws and to determine the astrophysical relevant of laboratory experiments. Finally we present an analysis of the two-temperature radiating fluid scalability. (10.1007/s10509-011-0677-y)
  DOI : 10.1007/s10509-011-0677-y
• Radiative properties of stellar plasmas and open challenges
  
  • Turck-Chieze Sylvaine
  • Loisel G.
  • Gilles D.
  • Piau Laurent
  • Blancard Christophe
  • Blenski T.
  • Busquet Michel
  • Caillaud T.
  • Cossé Philippe
  • Delahaye Franck
  • Faussurier Gérald
  • Fariaut J.
  • Gilleron F.
  • Guzik Joyce A.
  • Harris J.
  • Kilcrease D. P.
  • Magee N. H.
  • Pain J. C.
  • Porcherot Q.
  • Poirier M.
  • Soullier G.
  • Zeippen Claude J.
  • Bastiani-Ceccotti S.
  • Reverdin C.
  • Silvert V.
  • Thais Frédéric
  • Villette B.
  Astrophysics and Space Science, Springer Verlag, 2011, 336, pp.103-109. The lifetime of solar-like stars, the envelope structure of more massive stars, and stellar acoustic frequencies largely depend on the radiative properties of the stellar plasma. Up to now, these complex quantities have been estimated only theoretically. The development of the powerful tools of helio- and astero- seismology has made it possible to gain insights on the interiors of stars. Consequently, increased emphasis is now placed on knowledge of the monochromatic opacity coefficients. Here we review how these radiative properties play a role, and where they are most important. We then concentrate specifically on the envelopes of beta Cephei variable stars. We discuss the dispersion of eight different theoretical estimates of the monochromatic opacity spectrum and the challenges we need to face to check these calculations experimentally. (10.1007/s10509-010-0583-8)
  DOI : 10.1007/s10509-010-0583-8
• Proton radiography of cylindrical laser-driven implosions
  
  • Volpe L.
  • Jafer R.
  • Vauzour B.
  • Nicolai Ph
  • Santos J. J.
  • Dorchies F.
  • Fourment C.
  • Hulin S.
  • Regan C.
  • Perez F.
  • Baton S.
  • Lancaster K.
  • Galimberti M.
  • Heathcote R.
  • Tolley M.
  • Spindloe Ch
  • Nazarov W.
  • Koester P.
  • Labate L.
  • Gizzi L. A.
  • Benedetti C.
  • Sgattoni A.
  • Richetta M.
  • Pasley J.
  • Beg F. N.
  • Chawla S.
  • Higginson D. P.
  • Mackinnon A.
  • Macphee A. G.
  • Batani D.
  Plasma Physics and Controlled Fusion, IOP Publishing, 2011, 53 (3). no abstract (10.1088/0741-3335/53/3/032003)
  DOI : 10.1088/0741-3335/53/3/032003
• The scalability of the accretion column in magnetic cataclysmic variables: the POLAR project
  
  • Falize Emeric
  • Loupias B.
  • Ravasio Alessandra
  • Gregory C. D.
  • Dizière A.
  • Koenig M.
  • Michaut Claire
  • Cavet Cécile
  • Barroso Patrice
  • Leidinger J.-P.
  • Ribeyre X.
  • Breil J.
  • Takabe H.
  • Sakawa Youichi
  • Kuramitsu Y.
  • Morita T.
  • Woolsey N. C.
  • Nazarov W.
  • Pikuz S. A.
  Astrophysics and Space Science, Springer Verlag, 2011, 336, pp.81-85. In this paper, theoretical and experimental laboratory astrophysics results are presented from the POLAR project, the main focus of which is to design and diagnose an exact scaled accretion column using powerful lasers. These measurements allow the testing of the astrophysical models of accretion processes present in magnetic cataclysmic variables. (10.1007/s10509-011-0655-4)
  DOI : 10.1007/s10509-011-0655-4
• Laser-driven cylindrical compression of targets for fast electron transport study in warm and dense plasmas
  
  • Vauzour B.
  • Perez F.
  • Volpe L.
  • Lancaster K.
  • Nicolai Ph
  • Batani D.
  • Baton S. D.
  • Beg F. N.
  • Benedetti C.
  • Brambrink E.
  • Chawla S.
  • Dorchies F.
  • Fourment C.
  • Galimberti M.
  • Gizzi L. A.
  • Heathcote R.
  • Higginson D. P.
  • Hulin S.
  • Jafer R.
  • Koester P.
  • Labate L.
  • Mackinnon A. J.
  • Macphee A. G.
  • Nazarov W.
  • Pasley J.
  • Regan C.
  • Ribeyre X.
  • Richetta M.
  • Schurtz G.
  • Sgattoni A.
  • Santos J. J.
  Physics of Plasmas, American Institute of Physics, 2011, 18 (4). Fast ignition requires a precise knowledge of fast electron propagation in a dense hydrogen plasma. In this context, a dedicated HiPER (High Power laser Energy Research) experiment was performed on the VULCAN laser facility where the propagation of relativistic electron beams through cylindrically compressed plastic targets was studied. In this paper, we characterize the plasma parameters such as temperature and density during the compression of cylindrical polyimide shells filled with CH foams at three different initial densities. X-ray and proton radiography were used to measure the cylinder radius at different stages of the compression. By comparing both diagnostics results with 2D hydrodynamic simulations, we could infer densities from 2 to 11 g/cm(3) and temperatures from 30 to 120 eV at maximum compression at the center of targets. According to the initial foam density, kinetic, coupled (sometimes degenerated) plasmas were obtained. The temporal and spatial evolution of the resulting areal densities and electrical conductivities allow for testing electron transport in a wide range of configurations. (10.1063/1.3578346)
  DOI : 10.1063/1.3578346
• Unraveling the solid-liquid-vapor phase transition dynamics at the atomic level with ultrafast X-ray absorption near-edge spectroscopy
  
  • Dorchies F.
  • Levy A.
  • Goyon C.
  • Combis P.
  • Descamps D.
  • Fourment C.
  • Harmand M.
  • Hulin S.
  • Leguay P. M.
  • Petit S.
  • Peyrusse O.
  • Santos J. J.
  Physical Review Letters, American Physical Society, 2011, 107 (24), pp.245006. X-ray absorption near-edge spectroscopy (XANES) is a powerful probe of electronic and atomic structures in various media, ranging from molecules to condensed matter. We show how ultrafast time resolution opens new possibilities to investigate highly nonequilibrium states of matter including phase transitions. Based on a tabletop laser-plasma ultrafast x-ray source, we have performed a time-resolved (∼3 ps) XANES experiment that reveals the evolution of an aluminum foil at the atomic level, when undergoing ultrafast laser heating and ablation. X-ray absorption spectra highlight an ultrafast transition from the crystalline solid to the disordered liquid followed by a progressive transition of the delocalized valence electronic structure (metal) down to localized atomic orbitals (nonmetal—vapor), as the average distance between atoms increases. (10.1103/PhysRevLett.107.245006)
  DOI : 10.1103/PhysRevLett.107.245006
• Electronic Structure Investigation of Highly Compressed Aluminum with K Edge Absorption Spectroscopy
  
  • Benuzzi-Mounaix A.
  • Dorchies F.
  • Recoules V.
  • Festa F.
  • Peyrusse O.
  • Lévy Arthur
  • Ravasio A.
  • Hall T.
  • Koenig M.
  • Amadou N.
  • Brambrink E.
  • Mazevet S.
  Physical Review Letters, American Physical Society, 2011, 107, pp.165006. The electronic structure evolution of highly compressed aluminum has been investigated using timeresolved $K$ edge x-ray absorption spectroscopy. A long laser pulse (500 ps, I$_L$ $\approx$ 8 X 10$^{13}$ W/cm$^2$) wasused to create a uniform shock. A second ps pulse (I$_L$ $\approx$ 10$^{17}$ W/cm$^2$) generated an ultrashort broadbandx-ray source near the Al $K$ edge. The main target was designed to probe aluminum at reshocked conditionsup to now unexplored (3 times the solid density and temperatures around 8 eV). The hydrodynamicalconditions were obtained using rear side visible diagnostics. Data were compared to ${ab}$ ${initio}$ and denseplasma calculations, indicating potential improvements in either description. This comparison shows thatx-ray-absorption near-edge structure measurements provide a unique capability to probe matter at theseextreme conditions and severally constrains theoretical approaches currently used. (10.1103/PhysRevLett.107.165006)
  DOI : 10.1103/PhysRevLett.107.165006
• Experimental study of fast electron propagation in compressed matter
  
  • Chawla S.
  • Coury M.
  • Dorchies F.
  • Fourment C.
  • Galimberti M.
  • Gizzi L. A.
  • Heathcote R.
  • Higginson D. P.
  • Honrubia J. J.
  • Hulin S.
  • Jafer R.
  • Jarrot L. C.
  • Lobate L.
  • Lancaster K.
  • Koster P.
  • Mackinnon A. J.
  • Mckenna P.
  • Mcphee A. G.
  • Nazarov W.
  • Pasley J.
  • Ramis R.
  • Rhee Y.
  • Regan C.
  • Ribeyre X.
  • Richetta M.
  • Serres F.
  • Schlenvoigt H. P.
  • Schurtz G.
  • Sgattoni A.
  • Spindloe C.
  • Vaisseau X.
  • Volpe L.
  • Yahia V.
  • Vauzour B.
  • Santos J. J.
  • Batani D.
  • Baton S. D.
  • Koenig M.
  • Nicolai Ph
  • Perez F.
  • Beg F. N.
  • Benedetti C.
  • Benocci R.
  • Brambrink E.
  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Elsevier, 2011, 653 (1), pp.176-180. no abstract (10.1016/j.nima.2010.12.062)
  DOI : 10.1016/j.nima.2010.12.062