Publications

2012

• Conception et réalisation d'un prototype d'imageur X durs à sélection spectrale pour le Laser MégaJoule
  
  • Dennetiere David
  , 2012. Dans le cadre du projet Laser MégaJoule (LMJ), des chaînes de mesure, appelées diagnostics, sont nécessaires à la qualification de l'atteinte de l'ignition. Parmi ces diagnostics, des imageurs X devront observer le développement d'instabilités hydrodynamiques à la surface du microballon. L'imagerie de ces instabilités sera faite dans le domaine X par radiographie ou en utilisant l'émission propre de la cible. Aucun imageur X conçu aujourd'hui pour le LMJ ne permet de réaliser une telle image. L'imageur X développé dans cette thèse devra donc réaliser une image à haute résolution et à haute énergie tout en respectant les contraintes de fonctionnement lié à une installation telle que le LMJ. Nous avons tout d'abord étudié et amélioré un diagnostic existant : EHRXI. Nous avons optimisé la bande d'énergie X utile à l'imagerie par ce diagnostic en l'étendant jusqu'à 12 keV. Nous avons obtenu des résolutions inférieures à 5 μm dans un champ de 1 mm de diamètre. Ce diagnostic a été déployé avec succès sur les installations laser ELFIE 100 TW et OMEGA. Avec le retour d'expérience obtenu avec EHRXI nous avons conçu un prototype de diagnostic pour le LMJ : Merssix. Ce microscope aura une résolution inférieure à 5 μm dans un champ de 500 μm de diamètre pour des énergies s'étendant jusqu'à 22 keV. Merssix a été pensé et adapté aux conditions expérimentales du LMJ. Sa conception met notamment en jeu une sélection spectrale pour permettre une utilisation en radiographie en présence d'un environnement X complexe.
• High peak-power stretcher-free femtosecond fiber amplifier using passive spatio-temporal coherent combining
  
  • Daniault Louis
  • Hanna Marc
  • Papadopoulos Dimitris N.
  • Zaouter Yoann
  • Mottay Eric
  • Druon Frédéric
  • Georges Patrick
  Optics Express, Optical Society of America - OSA Publishing, 2012, 20 (19), pp.26705. We report on the passive coherent combining of up to 8 temporally and spatially separated ultrashort pulses amplified in a stretcher-free ytterbium-doped fiber system. An initial femtosecond pulse is split into 4 temporal replicas using divided-pulse amplification, and subsequently divided in two counter-propagating beams in a Sagnac interferometer containing a fiber amplifier. The spatio-temporal distribution of the peak-power inside the amplifier allows the generation of record 3.1 µJ and 50 fs pulses at 1 MHz of repetition rate with 52 MW of peak-power from a stretcher-free fiber amplifier and without additional nonlinear post-compression stages. (10.1364/OE.20.021627)
  DOI : 10.1364/OE.20.021627
• High Intensity Laser-Plasma Grating Interaction: surface wave excitation and particle acceleration
  
  • Alessandra Bigongiari
  , 2012. Surface waves in solids were first observed by Wood in 1902 as an anomaly in the diffraction of a continuous light source from a metal grating: the diffracted spectrum presented dark lines corresponding to certain wavelengths, which were later explained (Fano, 1941) in terms of the excitation of a surface wave sustained by the grating. Similarly to the metal grating case, a surface plasma wave (SPW) can be resonantly excited by a laser pulse at the surface of a laser-produced over-dense plasma, if the correct matching conditions are provided. SPWs propagate along the plasma-vacuum interface and are characterized by a localized, high frequency, resonant electric field. In the present work we describe numerically the dynamics of the plasma and the field distribution associated to SPW excitation, using two-dimensional particle-in-cell (PIC) simulations, where the plasma surface is initially pre-formed so that the SPW excitation conditions are fulfilled. We examine the surface wave excitation for a large range of laser intensities (Iλ2 =10^15-10^20 μm^2/Wcm^2) in order to study the transition from the non-relativistic to the relativistic regime. The simulations in which the wave is resonantly excited are compared to cases in which the resonant conditions are not provided and the coupling of the laser with the target is analyzed. We have considered the following aspects of the laser-plasma interaction, for different laser and target parameters: i) the laser absorption and the electric field at the surface ii) the generation of a quasi-static magnetic field iii) the electron heating and iiii) the ion acceleration. The possibility to excite a surface plasma wave on a structured target for a large range of laser energies has been demonstrated. In the cases where the surface wave is excited the electric field component normal to the target is amplified at the surface by a factor ranging from 3.2 to 7.2 with respect to the laser field. The absorption is also increased,for example it raises from 27% when the SPW is not excited up to 73% for Iλ^2=10^9 μm^2/Wcm^2. We have defined the optimal conditions for efficient coupling which increase laser absorption, that correspond to the relativistic laser intensities (Iλ^2>10^19 μm^2/Wcm^2). In this regime the main absorption mechanism is vacuum heating, associated to particles oscillating in the field perpendicular to the target, which is enhanced by the stronger, localized field of the SPW. The generation of a quasi-static magnetic field has been studied analytically and compared to the result of PIC simulations. The different field structure in presence of a SPW and for a flat target suggests that the enhanced field strength has caused partial confinement of particles at the target surface when SPW is present. The effects of the surface wave are more pronounced in thin laminar targets where electrons recirculate into the target interacting several times with the wave. Efficient electron heating increases the energy of the ions which are accelerated at both the irradiated and not irradiated target surface by the hot electrons space charge field. For the thinnest target (3.5 μm) the ion cut-off energy is about 14 Mev, approximately twice the value obtained when the SPW is not excited.
• High energy and broadband Yb:CaF2 multipass amplifier
  
  • Ricaud Sandrine
  • Papadopoulos Dimitris N.
  • Daniault Louis
  • Friebel Florence
  • Pellegrina Alain
  • Hanna Marc
  • Camy Patrice
  • Doualan Jean-Louis
  • Moncorgé Richard
  • Georges Patrick
  • Druon Frédéric
  , 2012.
• High-energy density laboratory astrophysics studies of accretion shocks in magnetic cataclysmic variables
  
  • Falize E.
  • Ravasio A.
  • Loupias B.
  • Diziere A.
  • Gregory C.D.
  • Michaut C.
  • Busschaert C.
  • Cavet C.
  • Koenig M.
  High Energy Density Physics, Elsevier, 2012, 8 (1), pp.1-4. (10.1016/j.hedp.2011.10.001)
  DOI : 10.1016/j.hedp.2011.10.001
• Yb-doped-based High Energy and Broadband Multipass Amplifiers at 100 Hz
  
  • Papadopoulos Dimitris N.
  • Ricaud Sandrine
  • Pellegrina Alain
  • Ramirez Patricia
  • Hanna Marc
  • Georges Patrick
  • Druon Frédéric
  , 2012.
• Astrophysique de laboratoire avec les lasers de haute énergie et de haute puissance : des chocs radiatifs aux jets d'étoiles jeunes
  
  • Dizière Alexandra
  , 2012. L'astrophysique de laboratoire est un domaine de la Physique des Hautes Densités d'Énergie en plein essor. Elle vise à recréer en laboratoire des processus physiques difficilement accessibles avec les diagnostics astronomiques. Nous aborderons, dans cette thèse, trois sujets majeurs: 1) les jets issus d'étoiles jeunes caractérisés par une collimation importante et se terminant par un choc d'étrave; 2) les chocs radiatifs pour lesquels le rayonnement propre du choc joue une rôle prépondérant dans sa structure et 3) les chocs d'accrétion dans le cas des variables cataclysmiques magnétiques dont l'important facteur de refroidissement permet d'atteindre la stationnarité. De la conception à la réalisation expérimentale, nous nous attacherons à reproduire en laboratoire chacun de ces processus en respectant les lois d'échelle liant les deux situations (expérimentale et astrophysique) précédemment établies. L'implémentation d'un grand nombre de diagnostics visibles et X nous permettra enfin de les caractériser complètement et de calculer les nombres sans dimension assurant la pertinence astrophysique.
• Gradient Doped Yb3+:YAG Crystals For Laser Applications
  
  • Arzakantsyan Mikayel
  • Délen Xavier
  • Balembois François
  • Georges Patrick
  • Ananyan Narine
  • Gevorgyan Vladimir
  • Chanteloup Jean-Christophe
  , 2012.
• Generation of scaled protogalactic seed magnetic fields in laser-produced shock waves
  
  • Gregori G.
  • Ravasio A.
  • D. Murphy C.
  • Schaar K.
  • Baird A.
  • R. Bell A.
  • Benuzzi-Mounaix A.
  • Bingham R.
  • Constantin C.
  • P. Drake R.
  • Edwards M.
  • T. Everson E.
  • D. Gregory C.
  • Kuramitsu Y.
  • Lau W.
  • Mithen J.
  • Niemann C.
  • Park H.-S.
  • A. Remington B.
  • Reville B.
  • P. L. Robinson A.
  • D. Ryutov D.
  • Sakawa Y.
  • Yang S.
  • C. Woolsey N.
  • Koenig M.
  • Miniati F.
  Nature, Nature Publishing Group, 2012, 481 (7382), pp.480-483. The standard model for the origin of galactic magnetic fields is through the amplification of seed fields via dynamo or turbulent processes to the level consistent with present observations1, 2, 3. Although other mechanisms may also operate4, 5, currents from misaligned pressure and temperature gradients (the Biermann battery process) inevitably accompany the formation of galaxies in the absence of a primordial field. Driven by geometrical asymmetries in shocks6 associated with the collapse of protogalactic structures, the Biermann battery is believed to generate tiny seed fields to a level of about 10−21 gauss (refs 7, 8). With the advent of high-power laser systems in the past two decades, a new area of research has opened in which, using simple scaling relations9, 10, astrophysical environments can effectively be reproduced in the laboratory11, 12. Here we report the results of an experiment that produced seed magnetic fields by the Biermann battery effect. We show that these results can be scaled to the intergalactic medium, where turbulence, acting on timescales of around 700 million years, can amplify the seed fields13, 14 sufficiently to affect galaxy evolution (10.1038/nature10747)
  DOI : 10.1038/nature10747
• Attosecond control of collective electron motion in plasmas
  
  • Borot Antonin
  • Malvache Arnaud
  • Chen Xiaowei
  • Jullien Aurélie
  • Geindre Jean-Paul
  • Audebert Patrick
  • Mourou Gérard
  • Quéré Fabien
  • Lopez-Martens Rodrigo B.
  Nature Physics, Nature Publishing Group [2005-....], 2012, 8, pp.416 - 421. Today, light fields of controlled and measured waveform can be used to guide electron motion in atoms and molecules with attosecond precision. Here, we demonstrate attosecond control of collective electron motion in plasmas driven by extreme intensity ($\approx$10$^{18}$ W cm$^{−2}$) light fields. Controlled few-cycle near-infrared waves are tightly focused at the interface between vacuum and a solid-density plasma, where they launch and guide subcycle motion of electrons from the plasma with characteristic energies in the multi-kiloelectronvolt range--two orders of magnitude more than has been achieved so far in atoms and molecules. The basic spectroscopy of the coherent extreme ultraviolet radiation emerging from the light-plasma interaction allows us to probe this collective motion of charge with sub-200 as resolution. This is an important step towards attosecond control of charge dynamics in laser-driven plasma experiments. (10.1038/nphys2269)
  DOI : 10.1038/nphys2269
• Focusing Dynamics of High-Energy Density, Laser-Driven Ion Beams
  
  • Chen S. N
  • d'Humières E
  • Lefebvre E.
  • Romagnani L.
  • Toncian T.
  • Antici P.
  • Audebert P.
  • Brambrink E.
  • Cecchetti C. A
  • Kudyakov T.
  • Pipahl A.
  • Sentoku Y.
  • Borghesi M.
  • Willi O.
  • Fuchs J.
  Physical Review Letters, American Physical Society, 2012, 108 (5), pp.055001. The dynamics of the focusing of laser-driven ion beams produced from concave solid targets was studied. Most of the ion beam energy is observed to converge at the center of the cylindrical targets with a spot diameter of 30 μm, which can be very beneficial for applications requiring high beam energy densities. Also, unbalanced laser irradiation does not compromise the focusability of the beam. However, significant filamentation occurs during the focusing, potentially limiting the localization of the energy deposition region by these beams at focus. These effects could impact the applicability of such high-energy density beams for applications, e.g., in proton-driven fast ignition. (10.1103/PhysRevLett.108.055001)
  DOI : 10.1103/PhysRevLett.108.055001
• Pump requirements for betatron-generated femtosecond X-ray laser at saturation from inner-shell transitions
  
  • Ribière Maxime
  • Sebban Stéphane
  • Jacquemot Sylvie
  • Chéron Bruno
  • Ta Phuoc Kim
  • Gautier Julien
  • Grunenwald Julien
  • Ribeiro Paul
  • Kozlova Michaela
  • Zeitoun Philippe
  • Rousse Antoine
  Applied Physics B - Laser and Optics, Springer Verlag, 2012, 106 (4), pp.809-816. We study pump requirements to produce femtosecond X-ray laser pulses at saturation from inner-shell transitions in the amplified spontaneous emission regime. Since laser-based betatron radiation is considered as the pumping source, we first study the impact of the driving laser power on its intensity. Then we investigate the amplification behavior of the K-a transition of nitrogen at 3.2 nm (395 eV) from radiative transfer calculations coupled with kinetics modeling of the ion population densities. We show that the saturation regime may be experimentally achieved by using PW-class laser-accelerated electron bunches. Finally, we show that this X-ray laser scheme can be extended to heavier atoms and we calculate pump requirements to reach saturation at 1.5 nm (849 eV) from the K-a transition of neon. © Springer-Verlag 2012. (10.1007/s00340-012-4912-1)
  DOI : 10.1007/s00340-012-4912-1
• X-ray diagnosis of the pressure Induced Mott Nonmetal-Metal Transition
  
  • Levy A.
  • Dorchies F.
  • Benuzzi-Mounaix A.
  • Ravasio A.
  • Festa F.
  • Recoules V.
  • Peyrusse O.
  • Amadou N.
  • Brambrink E.
  • Hall T.
  • Koenig M.
  • Mazevet S.
  Physical Review Letters, American Physical Society, 2012, 108 (5), pp.055002. The evolution of the K-edge x-ray absorption near-edge spectroscopy (XANES) spectrum is investigated for an aluminum plasma expanding from the solid density down to 0:5 g=cm3, with temperatures lying from 5 down to 2 eV. The dense plasma is generated by nanosecond laser-induced shock compression. These conditions correspond to the density-temperature region where a metal-nonmetal transition occurs as the density decreases. This transition is directly observed in XANES spectra measurements through the progressive formation of a preedge structure for densities around 1:6 g=cm3. Ab initio calculations based on density functional theory and a jellium model have been efficiently tested through direct comparison with the experimental measurements and show that this preedge corresponds to the relocalization of the 3p atomic orbital as the system evolves from a dense plasma toward a partially ionized atomic fluid. (10.1103/PhysRevLett.108.055002)
  DOI : 10.1103/PhysRevLett.108.055002
• Relativistic High-Current Electron-Beam Stopping-Power Characterization in Solids and Plasmas: Collisional Versus Resistive Effects
  
  • Vauzour B.
  • Santos J. J.
  • Debayle A.
  • Hulin S.
  • Schlenvoigt H. P.
  • Vaisseau X.
  • Batani D.
  • Baton S. D.
  • Honrubia J. J.
  • Nicolai Ph
  • Beg F. N.
  • Benocci R.
  • Chawla S.
  • Coury M.
  • Dorchies F.
  • Fourment C.
  • d'Humieres E.
  • Jarrot L. C.
  • Mckenna P.
  • Rhee Y. J.
  • Tikhonchuk V. T.
  • Volpe L.
  • Yahia V.
  Physical Review Letters, American Physical Society, 2012, 109 (25). We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K-alpha yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of approximate to 8 x 10(10) A/cm(2) they reach 1.5 keV/mu m and 0.8 keV/mu m, respectively. For higher current densities up to 10(12) A/cm(2), numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV/mu m for electron current densities of 10(14) A/cm(2), representative of the full-scale conditions in the fast ignition of inertially confined fusion targets. (10.1103/PhysRevLett.109.255002)
  DOI : 10.1103/PhysRevLett.109.255002
• Laser-driven quasi-isentropic compression experiments and numerical studies of the iron alpha-epsilon transition in the context of planetology
  
  • Amadou N.
  • Brambrink E.
  • Benuzzi-Mounaix A.
  • Vinci T.
  • de Resseguier T.
  • Mazevet S.
  • Morard Guillaume
  • Guyot F.
  • Ozaki N.
  • Miyanishi K.
  • Koenig M.
  AIP Conference Proceedings, American Institute of Physics, 2012, 1426, pp.1525. The iron alpha-epsilon transition is one of the most studied solid-solid phase transition. However, for quasi-isentropic compression, the dynamic and the influences of this transition on the high-pressure states of iron are still unknown. We present experimental results and numerical simulations to study these effects. Experiments performed at LULI2000 and the Janus laser facility (LNLL), using two different ramp shapes and different compression rates allowed to study the dynamic of the alpha-epsilon transition. We have observed the transition at particle velocity ranging from 0.25 km/s to 0.52 km/s depending on the compression rate. Depending on the ramp, either a shock formation was observed (high compression rate) at the transition or a flat plateau whose duration is function of compression rate. Increasing the compression rate leads to a smaller plateau duration. These results are important for reproducing Earth and Super-earth core conditions (2-15Mbar, 5- 15000K) on laboratory where the quasi-isentropic compression is the most promising experimental scheme. (10.1063/1.3686573)
  DOI : 10.1063/1.3686573
• Measuring hot electron distributions in intense laser interaction with dense matter
  
  • Antici P.
  • Albertazzi Bruno
  • Audebert P.
  • Buffechoux S.
  • Hannachi F.
  • d'Humi'Eres E.
  • Gobet F.
  • Grismayer T.
  • Mancic A.
  • Nakatsutsumi M.
  • Plaisir C.
  • Romagnani L.
  • Tarisien M.
  • Pépin H.
  • Sentoku Y.
  • Fuchs J.
  New Journal of Physics, Institute of Physics: Open Access Journals, 2012, 14, pp.063023. Retrieving the characteristics of hot electrons produced in the interaction between solid targets and ultra-intense (I > 1018 W cm−2) laser pulses is essential for achieving progress in our understanding of the interaction physics, which is key for optimizing numerous downstream applications. Until now, various methods have been used, direct or indirect, but no correlation and no assessment of their respective merits were performed. Here we compare results retrieved from four different diagnostics, direct or indirect, as well as local or non-local, i.e. spectrometry of electrons, spectrometry of the protons accelerated by the electrons and optical probing of these beams expanding into vacuum from the targets. We show that measurements obtained locally at the target rear surface are consistent with those far away from the target and that one can use the diagnostics of the co-moving proton beams to retrieve information about electrons. (10.1088/1367-2630/14/6/063023)
  DOI : 10.1088/1367-2630/14/6/063023
• Bulk laser-induced damage threshold of titanium-doped sapphire crystals
  
  • Bussiere Benoît
  • Uteza Olivier
  • Sanner Nicolas
  • Sentis Marc
  • Riboulet G.
  • Vigroux L.
  • Commandre Mireille
  • Wagner Frank R.
  • Natoli Jean-Yves
  • Chambaret J.P.
  Applied optics, Optical Society of America, 2012, 51, pp.7826-7833.