Publications

2016

• Modeling of radiative and quantum electrodynamics effects in PIC simulations of ultra-relativistic laser-plasma interaction
  
  • Lobet Mathieu
  • d'Humieres Emmanuel
  • Grech Michael
  • Ruyer Charles
  • Davoine Xavier
  • Gremillet Laurent
  Journal of Physics: Conference Series, IOP Science, 2016, 688. (10.1088/1742-6596/688/1/012058)
  DOI : 10.1088/1742-6596/688/1/012058
• Coherent combination of ultrafast fiber amplifiers
  
  • Hanna Marc
  • Guichard Florent
  • Zaouter Yoann
  • Papadopoulos Dimitrios
  • Druon Frédéric
  • Georges Patrick
  Journal of Physics B: Atomic and Molecular Physics, Institute of Physics (IOP), 2016, 49 (6), pp.062004. We review recent progress in coherent combining of femtosecond pulses amplified in optical fibers as a way to scale the peak and average power of ultrafast sources. Different methods of achieving coherent pulse addition in space (beam combining) and time (divided pulse amplification) domains are described. These architectures can be widely classified into active methods, where the relative phases between pulses are subject to a servomechanism, and passive methods, where phase matching is inherent to the geometry. Other experiments that combine pulses with different spectral contents, pulses that have been nonlinearly broadened or successive pulses from a mode-locked laser oscillator, are then presented. All these techniques allow access to unprecedented parameter range for fiber ultrafast sources. (10.1088/0953-4075/49/6/062004)
  DOI : 10.1088/0953-4075/49/6/062004
• Signatures of the Self-Similar Regime of Strongly Coupled Stimulated Brillouin Scattering for Efficient Short Laser Pulse Amplification
  
  • Lancia L.
  • Giribono A.
  • Vassura L.
  • Chiaramello M.
  • Riconda C.
  • Weber Sébastien J.
  • Castan A.
  • Chatelain A.
  • Frank A.
  • Gangolf T.
  • Quinn M. n.
  • Fuchs J.
  • Marquès Jean-Raphaël
  Physical Review Letters, American Physical Society, 2016, 116 (7). (10.1103/PhysRevLett.116.075001)
  DOI : 10.1103/PhysRevLett.116.075001
• Propagation laser en plasma sous-dense et modélisation de déflectométrie protonique
  
  • Castan Anaïs
  , 2016. Dans le cadre de la Fusion par Confinement Inertiel, la maîtrise de la propagation des faisceaux laser intenses, qui se propagent dans le plasma sous-dense d'une cavité d'ignition, reste un enjeu majeur. En effet, durant leur propagation, les faisceaux vont modifier les paramètres du plasma, ces paramètres contrôlant eux-mêmes la propagation. Cette rétroaction entre le plasma et le laser est potentiellement instable et produit de l'autofocalisation, de la filamentation, etc. Ces mécanismes peuvent alors dégrader fortement la propagation et in fine l'uniformité du dépôt d'énergie recherché.Dans cette étude, expérimentale et numérique, nous nous intéressons à la propagation d'un filament laser (tache focale d'une dizaine de micromètres, impulsion de 1,5 ns et d'intensité variant de 1014 W.cm-2 à 1016 W.cm-2) dans un milieu très sous dense (quelques pour-cents de la densité électronique critique). Deux expériences ont été réalisées sur l'installation de puissance LULI2000 et ont permis à la fois d'observer la transmission laser et de caractériser les gradients de température. Ces gradients sont produits par le transport électronique et influencent la réponse du plasma au laser. Afin de modéliser le rôle des gradients de température dans les instabilités d'auto-focalisation et de filamentation, nous avons associé un code d'hydrodynamique-radiative (FCI2) à un code détaillé de propagation (Héra). Pour compléter les observables précédentes, nous avons aussi mis en œuvre un diagnostic de déflectométrie protonique. Ce diagnostic permet de mesurer les champs électriques présents dans le plasma, ces champs étant issus du chauffage et de l'interaction laser. Un nouvel outil, associant le code de propagation laser et un code Monte-Carlo de transport de protons, a donc été mis en place pour modéliser les déflexions des protons. Cet outil ouvre en plus de nouvelles perspectives pour discuter de l'influence des effets 3D dans l'exploitation de ce diagnostic. Les résultats obtenus confirment l'intérêt à sonder les champs électriques au cœur même du plasma pendant la propagation laser. (10.70675/ca7b5b75z9281z414aza111z8478a54f2292)
  DOI : 10.70675/ca7b5b75z9281z414aza111z8478a54f2292
• Magnetic field in laser plasmas : non-local electron transport and reconnection
  
  • Riquier Raphaël
  , 2016. In the framework of the inertial confinement fusion, a pellet filled with the deuterium-tritium fuel is imploded, either through laser irradiation (direct drive, laser – low atomic number target interaction) or by the black body radiation from a cavity converting the laser radiation (indirect drive, laser – high atomic number target interaction).In both cases, a correct modeling of the electron transport is of first importance in order to have predictive hydro-radiative simulations. Nonetheless, it has been shown early on that the hypothesis of the linear transport are not valid in the framework of a solid target irradiated by a high power laser (I~1014 W/cm²). This is due in part to very steep temperature gradients (kinetic effects, so-called « non-local ») and because of a magnetic field self-generated through the thermo-electric effect. Finally, the heat flux and the magnetic field are strongly coupled through two mecanisms: the advection of the field with the heat flux (Nernst effect) and the rotation and inhibition of the heat flux by the plasma's magnetization (Righi-Leduc effect).In this manuscript, we will first present the various electron transport models, particularly the non-local with magnetic field model included in the hydro-radiative code FCI2. Following, in order to validate this model, we will compare it first against a kinetic code, and then with an experiment during which the magnetic field has been probed through proton radiography. Once the model validated, we will use FCI2 simulations to explain the source and transport of the field, as well as its effect on the interaction.Finally, the reconnection of the magnetic field, during the irradiation of a solid target by two laser beams, will be studied. (10.70675/dfacab51z5872z4b37z8b95z31280d2a36a8)
  DOI : 10.70675/dfacab51z5872z4b37z8b95z31280d2a36a8
• Nanostructuring an erbium local environment inside sol–gel silica glasses: toward efficient erbium optical fiber lasers
  
  • Savelii Inna
  • El Hamzaoui Hicham
  • Bigot Laurent
  • Bouwmans Géraud
  • Fsaifes Ihsan
  • Capoen Bruno
  • Bouazaoui Mohamed
  Laser Physics Letters, IOP Publishing, 2016, 13 (2), pp.025108. To extend the use of erbium- (Er-)/aluminum- (Al-) codoped optical fibers in hostile environments, the reduction of the Al amount has been identified as a serious way to harden them against harsh radiation. In this work, sol–gel monolithic Er3+-doped and Er3+/Al3+-codoped silica glasses were prepared from nanoporous silica xerogels soaked in a solution containing an Er salt together or not with an Al salt. After sintering, these glasses were used as the core material of microstructured optical fibers made by the stack-and-draw method. The influence of Al incorporation on the optical properties of Er3+-doped silica glasses and fibers is investigated. This approach enabled the preparation of silica glasses containing dispersed Er3+ ions with low Al content. The obtained fibers have been tested in an all-fibered cavity laser architecture. The Er3+/Al3+-codoped fiber laser presents a maximum efficiency of 27% at 1530 nm. We show that without Al doping, the laser exhibits lower performances that depend on Er content inside the doped fiber core. The effect of Er pair-induced quenching also has been investigated through nonsaturable absorption experiments, which clearly indicate that the fraction of Er ion pairs is significantly reduced in the Al-codoped fiber. (10.1088/1612-2011/13/2/025108)
  DOI : 10.1088/1612-2011/13/2/025108
• Preface: EPS 2015
  
  • Bingham Robert
  • Jacquemot Sylvie
  Plasma Physics and Controlled Fusion, IOP Publishing, 2016, 58 (1), pp.010101. (10.1088/0741-3335/58/1/010101)
  DOI : 10.1088/0741-3335/58/1/010101
• Low temperature diode pumped active mirror Yb^3+:YAG disk laser amplifier studies
  
  • Marrazzo Samuel
  • Gonçalvès-Novo Thierry
  • Millet François
  • Chanteloup Jean-Christophe
  Optics Express, Optical Society of America - OSA Publishing, 2016, 24 (12), pp.12651. An experimental study of a static helium gas gap heat switch concept for laser amplification is presented. High single pass gains with large co-sintered ceramic Yb:YAG disks are recorded in the 80-200K temperature range on a diode pumped active mirror amplifier. (10.1364/OE.24.012651)
  DOI : 10.1364/OE.24.012651
• Buffered high charge spectrally-peaked proton beams in the relativistic-transparency regime
  
  • Dover N.P.
  • Palmer C.A.J.
  • Streeter M. J.V.
  • Ahmed H.
  • Albertazzi Bruno
  • Borghesi M.
  • Carroll D.C.
  • Fuchs J.
  • Heathcote R.
  • Hilz P.
  • Kakolee K.F.
  • Kar S.
  • Kodama R
  • Kon A.
  • Maclellan D.A.
  • Mckenna P.
  • Nagel S.R.
  • Neely D
  • Notley M.M.
  • Nakatsutsumi M
  • Prasad R.
  • Scott G.
  • Tampo M.
  • Zepf M.
  • Schreiber J.
  • Najmudin Z
  New Journal of Physics, Institute of Physics: Open Access Journals, 2016, 18, pp.013038. Spectrally-peaked proton beams of high charge (Ep ≈ 8 MeV, ΔE ≈ 4 MeV, N ≈ 50 nC) have been observed from the interaction of an intense laser ( >10^19 W cm−2) with ultrathin CH foils, as measured by spectrally-resolved full beam profiles. These beams are reproducibly generated for foil thicknesses 5–100 nm, and exhibit narrowing divergence with decreasing target thickness down to ≈8° for 5 nm. Simulations demonstrate that the narrow energy spread feature is a result of buffered acceleration of protons. The radiation pressure at the front of the target results in asymmetric sheath fields which permeate throughout the target, causing preferential forward acceleration. Due to their higher charge-to-mass ratio, the protons outrun a carbon plasma driven in the relativistic transparency regime. (10.1088/1367-2630/18/1/013038)
  DOI : 10.1088/1367-2630/18/1/013038
• Laser-initiated primary and secondary nuclear reactions in Boron-Nitride
  
  • Labaune Christine
  • Baccou C.
  • Yahia V.
  • Neuville C.
  • Rafelski J.
  Scientific Reports, Nature Publishing Group, 2016, 6, pp.21202. Nuclear reactions initiated by laser-accelerated particle beams are a promising new approach to many applications, from medical radioisotopes to aneutronic energy production. We present results demonstrating the occurrence of secondary nuclear reactions, initiated by the primary nuclear reaction products, using multicomponent targets composed of either natural boron (B) or natural boron nitride (BN). The primary proton-boron reaction (p + 11B → 3 α + 8.7 MeV), is one of the most attractive aneutronic fusion reaction. We report radioactive decay signatures in targets irradiated at the Elfie laser facility by laser-accelerated particle beams which we interpret as due to secondary reactions induced by alpha (α) particles produced in the primary reactions. Use of a second nanosecond laser beam, adequately synchronized with the short laser pulse to produce a plasma target, further enhanced the reaction rates. High rates and chains of reactions are essential for most applications. (10.1038/srep21202)
  DOI : 10.1038/srep21202
• Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam
  
  • Chen S.N.
  • Iwawaki T
  • Morita K
  • Antici P
  • Baton S. D.
  • Filippi F
  • Habara H
  • Nakatsutsumi M
  • Nicolaï P
  • Nazarov W
  • Rousseaux C
  • Starodubstev M
  • Tanaka K.A.
  • Fuchs J.
  Scientific Reports, Nature Publishing Group, 2016, 6, pp.21495. The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5–10 eV and densities around 10 21 cm −3 are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations. (10.1038/srep21495)
  DOI : 10.1038/srep21495
• High-pressure structural changes in liquid silica
  
  • Denoeud A.
  • Mazevet S.
  • Guyot F.
  • Dorchies F.
  • Gaudin J.
  • Ravasio A.
  • Brambrink E.
  • Benuzzi-Mounaix A.
  Physical Review E, American Physical Society (APS), 2016, 94 (3), pp.031201(R). The structural properties of liquid silica at high pressure and moderate temperature conditions, also referred to as the warm dense matter regime, were investigated using time-resolved K-edge x-ray absorption spectroscopy and ab initio calculations. We used a nanosecond laser beam to compress uniformly a solid SiO2 target and a picosecond laser beam to generate a broadband x-ray source. We obtained x-ray absorption spectra at the Si K edge over a large pressure-temperature domain to probe the liquid phase up to 3.6 times the normal solid density. Using ab initio simulations, we are able to interpret the changes in the x-ray absorption near-edge structure with increasing densities as an increase in the coordination number of silicon by oxygen atoms from 4 to 9. This indicates that, up to significant temperatures, the liquid structure becomes akin to what is found in the solid SiO2 phases. (10.1103/PhysRevE.94.031201)
  DOI : 10.1103/PhysRevE.94.031201
• X-ray emission spectroscopy of well-characterised non-LTE plasmas
  
  • Bourgaux A. C.
  • Bastiani-Ceccotti S.
  • Audebert P.
  • Marques J. R.
  • Vassura L.
  • Vinci T.
  • Dorchies F.
  • Leguay P. M.
  • Chung H. K.
  • Bowen C.
  • Dervieux V.
  • Renaudin P.
  • Silvert V.
  • Jacquemot S.
  , 2016, 688. no abstract