Publications

2020

• Equation of state and electrical conductivity of warm dense ammonia at the conditions of large icy planets' interiors.
  
  • Hernandez J. A.
  • Ravasio A.
  • Bethkenhagen M.
  • Benuzzi-Mounaix A.
  • Datchi F.
  • French M.
  • Guarguaglini M.
  • Lefèvre Franck
  • Ninet S.
  • Redmer R.
  • Vinci T.
  , 2020, pp.abstract #MR024-07. Super-Earths, mini-Neptunes and Neptune-sized (exo-)planets have mantles potentially composed of large amounts of H, He, C, N and O. Modelling of their structure and dynamics requires knowledge of the equations of state and transport properties of the relevant mixtures up to several Mbar and thousands of Kelvin. At these conditions, highly hydrogenated molecular compounds (e.g H2O, NH3, CH4, hydrocarbons) present complex phase diagrams with multiple solid phases, superionic regimes, dissociations, metal-insulator transitions. In the last two decades, much effort has been dedicated to H2O. The recent discovery of superionic water ices in laser-shock experiments [Millot et al., Nature 569, 2019] illustrates this success, validating a two-decade-old prediction [Cavazzoni et al., Science 283, 1999]. In this study, we focus on NH3, another end-member showing strong hydrogen disordering in the solid phase, and whose behavior in the warm dense regime remains unexplored. We investigate the equation of state, the optical properties and the electrical conductivity of warm dense ammonia by combining both laser-driven shock experiments coupled to static compression devices (pre-shock pressures ranging between 14 bar and 3.1 GPa) and state-of-the-art first-principles atomistic simulations. Temperature measurements along the Hugoniot of liquid NH3 (initial state at 14 bar and 295 K)shows a subtle slope change at 7000 K and 90 GPa, which coincides with the gradual transition from a liquid dominated by molecules to a plasma state in our new ab initio simulations. Measurements in shocked solid ammonia III provide strong constraints on the melting curve of ammonia around 100 GPa. Our reflectivity data furnish the first experimental evidence of electronic conduction in high pressure ammonia and are in excellent agreement with the reflectivity computed from atomistic simulations. Corresponding conductivity values are found up to one order of magnitude higher than in water in the 100 GPa regime, with possible implications on the generation of magnetic dynamos in large icy planets' interiors.
• Inefficient magnetic-field amplification in supersonic laser-plasma turbulence
  
  • Bott A. F. A.
  • Chen L.
  • Boutoux G.
  • Caillaud T.
  • Koenig M
  • Khiar B.
  • Lantuéjoul I.
  • Le-Deroff L.
  • Reville B.
  • Rosch R.
  • Ryu D.
  • Spindloe C.
  • Vauzour B.
  • Villette B.
  • Schekochihin A. A.
  • Lamb D. Q.
  • Tzeferacos P.
  • Gregori G.
  • Casner A.
  , 2020. We report a laser-plasma experiment that was carried out at the LMJ-PETAL facility and realized the first magnetized, turbulent, supersonic plasma with a large magnetic Reynolds number ($\mathrm{Rm} \approx 45$) in the laboratory. Initial seed magnetic fields were amplified, but only moderately so, and did not become dynamically significant. A notable absence of magnetic energy at scales smaller than the outer scale of the turbulent cascade was also observed. Our results support the notion that moderately supersonic, low-magnetic-Prandtl-number plasma turbulence is inefficient at amplifying magnetic fields.
• Effect of plasma hydrodynamics on laser-produced bremsstrahlung MeV photon dose
  
  • Courtois C.
  • Compant La Fontaine A.
  • Bonnet T.
  • Gobet F.
  • Hannachi F.
  • Marquès Jean-Raphaël
  • Tarisien M.
  • Versteegen M.
  • Vinci T.
  Physics of Plasmas, American Institute of Physics, 2020, 27 (11), pp.113108. (10.1063/5.0019816)
  DOI : 10.1063/5.0019816
• Dielectronic recombination in non-LTE plasmas
  
  • Rosmej F.
  • Astapenko V.
  • Lisitsa V.
  • Vainshtein L.
  Matter and Radiation at Extremes, AIP Publishing, 2020, 5 (6), pp.064201. Novel phenomena and methods related to dielectronic capture and dielectronic recombination are studied for non-local thermodynamic equilibrium (LTE) plasmas and for applications to non-LTE ionization balance. It is demonstrated that multichannel autoionization and radiative decay strongly suppress higher-order contributions to the total dielectronic recombination rates, which are overestimated by standard approaches by orders of magnitude. Excited-state coupling of dielectronic capture is shown to be much more important than ground-state contributions, and electron collisional excitation is also identified as a mechanism driving effective dielectronic recombination. A theoretical description of the effect of angular-momentum-changing collisions on dielectronic recombination is developed from an atomic kinetic point of view and is visualized with a simple analytical model. The perturbation of the autoionizing states due to electric fields is discussed with respect to ionization potential depression and perturbation of symmetry properties of autoionization matrix elements. The first steps in the development of statistical methods are presented and are realized in the framework of a local plasma frequency approach. Finally, the impact of collisional–radiative processes and atomic population kinetics on dielectronic recombination is critically discussed, and simple analytical formulas are presented. (10.1063/5.0014158)
  DOI : 10.1063/5.0014158
• TOF diagnosis of laser accelerated, high-energy protons
  
  • Scuderi V.
  • Milluzzo G.
  • Doria D.
  • Alejo A.
  • Amico A.G.
  • Booth N.
  • Cuttone G.
  • Green J.S.
  • Kar S.
  • Korn G.
  • Larosa G.
  • Leanza R.
  • Martin P.
  • Mckenna P.
  • Padda H.
  • Petringa G.
  • Pipek J.
  • Romagnani L.
  • Romano F.
  • Russo A.
  • Schillaci F.
  • Cirrone G.A.P.
  • Margarone D.
  • Borghesi M.
  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Elsevier, 2020, 978, pp.164364. (10.1016/j.nima.2020.164364)
  DOI : 10.1016/j.nima.2020.164364
• White-line evolution in shocked solid Ta evidenced by synchrotron x-ray absorption spectroscopy
  
  • Pépin C.
  • Torchio R.
  • Occelli F.
  • Lescoute E.
  • Mathon O.
  • Recoules V.
  • Bouchet J.
  • Videau L.
  • A. Benuzzi-Mounaix
  • Vinci T.
  • Briggs R.
  • Pascarelli S.
  • Gaal R.
  • Loubeyre P.
  • Sollier A.
  Physical Review B, American Physical Society, 2020, 102 (14). Time-resolved x-ray absorption experiments have been performed on shocked tantalum. Using a single 100 ps synchrotron x-ray pulse, nanosecond-lived equilibrium states of shocked solid Ta have been measured by L3-edge absorption spectroscopy. The energy shift and intensity change of the white line were measured up to 130 GPa and 2000 K. The experimental results are discussed in light of density functional theory calculations and FEFF simulations. The absence of occurrence of the hcp-ω phase is suggested from the analysis of the shape of the white line. (10.1103/PhysRevB.102.144102)
  DOI : 10.1103/PhysRevB.102.144102
• Laboratory evidence for an asymmetric accretion structure upon slanted matter impact in young stars
  
  • Burdonov K.
  • Revet G.
  • Bonito R.
  • Argiroffi C.
  • Béard Jérome
  • Bolanõs S.
  • Cerchez M.
  • Chen S. N.
  • Ciardi A.
  • Espinosa G.
  • Filippov E.
  • Pikuz S.
  • Rodriguez R.
  • Šmíd M.
  • Starodubtsev M.
  • Willi O.
  • Orlando S.
  • Fuchs J.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2020, 642, pp.A38. Aims. Investigating the process of matter accretion onto forming stars through scaled experiments in the laboratory is important in order to better understand star and planetary system formation and evolution. Such experiments can indeed complement observations by providing access to the processes with spatial and temporal resolution. A previous investigation revealed the existence of a two-component stream: a hot shell surrounding a cooler inner stream. The shell was formed by matter laterally ejected upon impact and refocused by the local magnetic field. That laboratory investigation was limited to normal incidence impacts. However, in young stellar objects, the complex structure of magnetic fields causes variability of the incident angles of the accretion columns. This led us to undertake an investigation, using laboratory plasmas, of the consequence of having a slanted accretion impacting a young star.Methods. Here, we used high power laser interactions and strong magnetic field generation in the laboratory, complemented by numerical simulations, to study the asymmetry induced upon accretion structures when columns of matter impact the surface of young stars with an oblique angle.Results. Compared to the scenario where matter accretes perpendicularly to the star surface, we observe a strongly asymmetric plasma structure, strong lateral ejecta of matter, poor confinement of the accreted material, and reduced heating compared to the normal incidence case. Thus, slanted accretion is a configuration that seems to be capable of inducing perturbations of the chromosphere and hence possibly influencing the level of activity of the corona. (10.1051/0004-6361/202038189)
  DOI : 10.1051/0004-6361/202038189
• Analytical approach to level delocalization and line shifts in finite temperature dense plasmas
  
  • Li X.
  • Rosmej F.B.
  Physics Letters A, Elsevier, 2020, 384, pp.126478. (10.1016/j.physleta.2020.126478)
  DOI : 10.1016/j.physleta.2020.126478
• Direct observation of shock-induced disordering of enstatite below the melting temperature
  
  • Hernandez J.-A
  • Morard G.
  • Guarguaglini M.
  • Alonso‐mori R.
  • Benuzzi‐mounaix A.
  • Bolis R.
  • Fiquet G.
  • Galtier E.
  • Gleason A. E
  • Glenzer S.
  • Guyot F.
  • Ko B.
  • Lee H. J
  • Mao W. L
  • Nagler B.
  • Ozaki N.
  • Schuster A. K
  • Shim S. H
  • Vinci T.
  • Ravasio A.
  Geophysical Research Letters, American Geophysical Union, 2020, 47 (15). We report in situ structural measurements of shock-compressed single crystal orthoenstatite up to 337±55 GPa on the Hugoniot, obtained by coupling ultrafast X-ray diffraction (XRD) to laser-driven shock-compression. Shock compression induces a disordering of the crystalline structure evidenced by the appearance of a diffuse XRD signal at nanosecond time scales at 80±13 GPa on the Hugoniot, well below the equilibrium melting pressure (> 170 GPa). The formation of bridgmanite and post-perovskite have been indirectly reported in microsecond-scale plate-impact experiments. Therefore, we interpret the high-pressure disordered state we observed at nanosecond-scale as an intermediate structure from which bridgmanite and post-perovskite crystallize at longer timescales. This evidence of a disordered structure of MgSiO3 on the Hugoniot indicates that the degree of polymerization of silicates is a key parameter to constrain the actual thermodynamics of shocks in natural environments. (10.1029/2020GL088887)
  DOI : 10.1029/2020GL088887
• Comparison of multi-pass and regenerative strategies for energetic high-gain amplifiers based on Yb:CaF2
  
  • Druon Frédéric
  • Genevrier Kévin
  • Georges Patrick
  • Papadopoulos Dimitris N
  Optics Letters, Optical Society of America - OSA Publishing, 2020, 45 (16), pp.4408-4411. Yb-doped materials, due to their high saturation fluence and consequently their low gain, represent a challenging choice for high-energy amplifiers. In this Letter, we study two original amplifier designs adapted to a large number of passes capable of operating in the 100 mJ energy range at repetition rates up to 100 Hz using Yb:CaF 2 crystals as active media. Amplification geometries based on double-head active-mirror configurations are presented. We confront two alternative strategies suitable for amplification of large beams: regenerative and geometrical multi-pass amplifiers. This Letter consists of finding the pivot point, allowing us to discriminate the specific interest of each strategy. We present compensation methods of the thermal lens adapted to each amplifier configuration with and without cavity, and we demonstrate that despite similar laser heads and pumping conditions, the thermal lens impacts differently the optimal performance for multi-pass or regenerative strategy. We perform amplification up to 66 mJ pulses at 10 Hz with the regenerative amplifier and 52 mJ at 100 Hz with the multi-pass amplifier. (10.1364/ol.398612)
  DOI : 10.1364/ol.398612
• Preliminary results from the LMJ-PETAL experiment on hot electrons characterization in the context of Shock Ignition
  
  • Baton S.
  • Colaitis A.
  • Rousseaux C.
  • Boutoux G.
  • Brygoo S.
  • Jacquet L
  • Koenig M.
  • Batani D.
  • Casner A.
  • Le Bel E.
  • Raffestin D.
  • Tikhonchuk V.
  • Trela J.
  • Reverdin C.
  • Le-Deroff L
  • Theobald W.
  • Cristoforetti G
  • Gizzi L. A.
  • Koester P
  • Labate L.
  • Shigemori K
  High Energy Density Physics, Elsevier, 2020, 36, pp.100796. In the Shock Ignition scheme, the spike pulse intensity is well above the threshold of parametric instabilities, which produce a considerable amount of hot electrons that could be beneficial or detrimental to the ignition. To study their impact, an experiment has been carried out on the LMJ-PETAL facility with a goal to generate a strong shock inside a plastic layer under plasma conditions relevant to full-scale shock ignition targets. To evaluate the effect of hot electrons on the shock characteristics, laser temporal smoothing was either switched on or off, which in turns varies the quantity of hot electrons being generated. In this paper, we present preliminary results obtained during the experiment dedicated to the hot electron characterization. We present also calculations for the second part of the experiment, scheduled in 2020 and focused on the shock characterization. (10.1016/j.hedp.2020.100796)
  DOI : 10.1016/j.hedp.2020.100796
• Coherent beam combining of 61 femtosecond fiber amplifiers
  
  • Fsaifes Ihsan
  • Daniault Louis
  • Bellanger Severine
  • Veinhard Matthieu
  • Bourderionnet Jerome
  • Larat Christian
  • Lallier Eric
  • Durand Eric
  • Brignon Arnaud
  • Chanteloup Jean-Christophe
  Optics Express, Optical Society of America - OSA Publishing, 2020, 28 (14), pp.20152. We report on the coherent beam combining of 61 femtosecond fiber chirped-pulse amplifiers in a tiled-aperture configuration along with an interferometric phase measurement technique. Relying on coherent beam recombination in the far field, this technique appears suitable for the combination of a large number of fiber amplifiers. The 61 output beams are stacked in a hexagonal arrangement and collimated through a high fill factor hexagonal micro-lens array. The residual phase error between two fibers is as low as λ/90 RMS, while a combining efficiency of ∼50% is achieved. (10.1364/oe.394031)
  DOI : 10.1364/oe.394031
• Instabilités hydrodynamiques : Application à l'astrophysique de laboratoire et diagnostics X à haute résolution
  
  • Rigon Gabriel
  , 2020. Le développement des lasers de puissance au cours du 20ème siècle a permis d’atteindre le régime que l'on appelle des hautes densités d’énergie (HDE), où la matière est portée dans des conditions extrêmes. Cela a permis l’essor d’une nouvelle discipline: l’astrophysique de laboratoire. Celle-ci vise à reproduire en laboratoire des conditions comparables à celles observées en astrophysique au sein de planètes, d’étoiles, ou lors de phénomènes cataclysmiques par exemple.Cette thèse porte sur l’étude expérimentale et numérique d’instabilités hydrodynamiques pouvant être trouvées dans de telles situations. Ces instabilités influencent l’évolution d’objets astrophysiques et en gênent l’observation. Ici nous nous intéresserons plus particulièrement aux instabilités de Rayleigh-Taylor (IRT) et de Richtmyer-Meshkov (IRM). La première apparaît dès lors qu’un fluide dense repose sur un fluide moins dense. La seconde peut être considérée comme un cas particulier de la première où la force responsable de l’instabilité est due à une onde de choc. Ces deux instabilités se retrouvent en astrophysique dans les restes de supernovæ, qui sont constitués de la matière éjectée lors de la mort (explosion) d’une étoile massive. Nous pouvons aussi les trouver en fusion par confinement inertiel, où elles sont en partie responsable des difficultés à atteindre l’ignition.Dans cette thèse nous présentons les résultats d’expériences réalisées sur les installations LULI2000 à Palaiseau (France), GEKKO XII à Osaka (Japon) et SACLA (Japon) visant l’étude de ces instabilités. Ces travaux expérimentaux nous ont permis d’observer directement et de reconstituer l’évolution de l’IRT de sa phase linéaire, aux temps courts, à sa phase turbulente, aux temps longs. Nous avons ainsi effectué une étude paramétrique de l’IRT où nous faisions varier les paramètres classiques l’influençant : longueur d’onde de perturbation, rapport des densités au travers de l’interface (nombre d’Atwood). Cela constitue donc une étude expérimentale complète de l’IRT et présente un caractère inédit quant à l’observation de la turbulence avec une résolution sans précédent dans le domaine de la HDE.Cette étude expérimentale est complétée d’une étude numérique réalisée à l’aide de FLASH, un code de magnéto-hydrodynamique développé par l’université de Chicago. Les simulations effectuées lors de cette thèse ont permis à la fois de préparer l’ensemble de l’étude expérimentale, et d’interpréter et de comprendre les résultats.En parallèle de ces études d’instabilités, un diagnostic de radiographie à rayons X à haute résolution spatiale a été développé. Il utilise un cristal de LiF comme détecteur. Une étude des caractéristiques de ce diagnostic a été effectuée (réponse spectrale, variation de résolution…) sur le synchrotron SOLEIL. Cela nous a alors permis d'utiliser le LiF comme détecteur principal lors de nos expériences sur SACLA où une résolution spatiale sub-micronique et temporelle de l’ordre de 10 fs ont été obtenues. (10.70675/53cfd6ddz40edz43b5z8348zac5893fc5b9c)
  DOI : 10.70675/53cfd6ddz40edz43b5z8348zac5893fc5b9c
• Simulation of XFEL induced fluorescence spectra of hollow ions and studies of dense plasma effects
  
  • Deschaud B.
  • Peyrusse O.
  • Rosmej F.
  Physics of Plasmas, American Institute of Physics, 2020, 27 (6), pp.063303. (10.1063/5.0011193)
  DOI : 10.1063/5.0011193
• Laboratory Study of Bilateral Supernova Remnants and Continuous MHD Shocks
  
  • Mabey P.
  • Albertazzi B.
  • Rigon G.
  • Marquès J.-R.
  • Palmer C. A. J.
  • Topp-Mugglestone J.
  • Perez-Martin P.
  • Kroll F.
  • Brack F.-E.
  • Cowan T. E
  • Schramm U.
  • Falk K.
  • Gregori G.
  • Falize E.
  • Koenig M.
  The Astrophysical Journal, American Astronomical Society, 2020, 896 (2), pp.167. Many supernova remnants (SNRs), such as G296.5 + 10.0, exhibit an axisymmetric or barrel shape. Such morphologies have previously been linked to the direction of the Galactic magnetic field (GMF) although this remains uncertain. These SNRs generate magnetohydrodynamic (MHD) shocks in the interstellar medium (ISM), modifying its physical and chemical properties. The ability to study these shocks through observations is difficult due to the small spatial scales involved. In order to answer these questions, we perform a scaled laboratory experiment in which a laser-generated blast wave expands under the influence of a uniform magnetic field. The blast wave exhibits a spheroidal shape, whose major axis is aligned with the magnetic field, in addition to a more continuous shock front. The implications of our results are discussed in the context of astrophysical systems. (10.3847/1538-4357/ab92a4)
  DOI : 10.3847/1538-4357/ab92a4
• Growth of concomitant laser-driven collisionless and resistive electron filamentation instabilities over large spatiotemporal scales
  
  • Ruyer C.
  • Bolaños S.
  • Albertazzi B.
  • Chen S.
  • Antici P.
  • Böker J.
  • Dervieux V.
  • Lancia L.
  • Nakatsutsumi M.
  • Romagnani L.
  • Shepherd R.
  • Swantusch M.
  • Borghesi M.
  • Willi O.
  • Pépin H.
  • Starodubtsev M.
  • Grech M.
  • Riconda C.
  • Gremillet L.
  • Fuchs J.
  Nature Physics, Nature Publishing Group [2005-....], 2020. Collective processes in plasmas often induce micro-instabilities that play an important role in many space or laboratory plasma environments. Particularly notable is the Weibel-type current filamentation instability, which is believed to drive the creation of collisionless shocks in weakly magnetized astrophysical plasmas. Here, this instability class is studied through interactions of ultraintense and short laser pulses with solid foils, leading to localized generation of MeV electrons. Proton radiographic measurements of both low-and high-resistivity targets show two distinct, superimposed electromagnetic field patterns arising from the interpenetration of the MeV electrons and the background plasma. Particle-in-cell simulations and theoretical estimates suggest that the collisionless Weibel instability building up in the dilute expanding plasmas formed at the target surfaces causes the observed azimuthally symmetric electromagnetic filaments. For a sufficiently high resistivity of the target foil, an additional resistive instability is triggered in the bulk target, giving rise to radially elongated filaments. The data reveal the growth of both filamentation instabilities over large temporal (tens of picoseconds) and spatial (hundreds of microns) scales. (10.1038/s41567-020-0913-x)
  DOI : 10.1038/s41567-020-0913-x
• Physics and Phenomenology of Weakly Magnetized, Relativistic Astrophysical Shock Waves
  
  • Vanthieghem Arno
  • Lemoine Martin
  • Plotnikov Illya
  • Grassi Anna
  • Grech Mickael
  • Gremillet Laurent
  • Pelletier Guy
  Galaxies, MDPI, 2020, 8 (2), pp.33. Weakly magnetized, relativistic collisionless shock waves are not only the natural offsprings of relativistic jets in high-energy astrophysical sources, they are also associated with some of the most outstanding displays of energy dissipation through particle acceleration and radiation. Perhaps their most peculiar and exciting feature is that the magnetized turbulence that sustains the acceleration process, and (possibly) the secondary radiation itself, is self-excited by the accelerated particles themselves, so that the phenomenology of these shock waves hinges strongly on the microphysics of the shock. In this review, we draw a status report of this microphysics, benchmarking analytical arguments with particle-in-cell simulations, and extract consequences of direct interest to the phenomenology, regarding in particular the so-called microphysical parameters used in phenomenological studies. (10.3390/galaxies8020033)
  DOI : 10.3390/galaxies8020033
• All-fiber counter-propagation pumped amplifier tailored for Coherent Beam Combining technique
  
  • Chanteloup Jean-Christophe
  • Fsaifes Ihsan
  • Daniault Louis
  • Bellanger Séverine
  • Veinhard Matthieu
  • Schulz Daniel
  • Tafoya Jason
  • Sipes Donald
  , 2020. we report on the qualification of an all-fiber counter propagating pumped amplifier by using a narrow-linewidth single-frequency nanosecond fiber laser. The proposed amplifier design is tailored to be used for coherent beam combining of fiber amplifiers in tiled-aperture configuration.
• Programmable Orbital Angular Momentum beam generated from a 61 channels Coherent Beam Combining femtosecond laser
  
  • Chanteloup Jean-Christophe
  • Veinhard Matthieu
  • Bellanger Séverine
  • Daniault Louis
  • Fsaifes Ihsan
  , 2020. A 61 beamlets Coherent Beam Combination femtosecond laser is used as a programmable phase source to generate high power Orbital Angular Momentum beams and open the path for higher order non-symmetrical user-defined far field distributions. (10.1364/CLEO_SI.2020.STh4P.3)
  DOI : 10.1364/CLEO_SI.2020.STh4P.3
• All-fiber counter-propagation pumped amplifier tailored for Coherent Beam Combining technique
  
  • Chanteloup Jean-Christophe
  • Fsaifes Ihsan
  • Daniault Louis
  • Bellanger Séverine
  • Veinhard Matthieu
  • Schulz Daniel
  • Tafoya Jason
  • Sipes Donald
  , 2020, pp.JW2E.11. (10.1364/CLEO_AT.2020.JW2E.11)
  DOI : 10.1364/CLEO_AT.2020.JW2E.11
• Characteristics of ion beams generated in the interaction of ultra-short laser pulses with ultra-thin foils
  
  • Mcilvenny A
  • Ahmed H Ben
  • Scullion C
  • Doria D
  • Romagnani L
  • Martin P
  • Naughton K
  • Sgattoni A
  • Symes D
  • Macchi A
  • Mckenna P
  • Zepf M
  • Kar S
  • Borghesi M
  Plasma Physics and Controlled Fusion, IOP Publishing, 2020, 62 (5), pp.054001. (10.1088/1361-6587/ab7d26)
  DOI : 10.1088/1361-6587/ab7d26
• Modelling energy deposition in TR image plate detectors for various ion types
  
  • Lelasseux V.
  • Fuchs J.
  Journal of Instrumentation, IOP Publishing, 2020, 15 (04), pp.P04002-P04002. Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR imaging plate M. Nishiuchi et al-This content was downloaded from IP address 92.184.117.159 on 12/11/2020 at 15:45 (10.1088/1748-0221/15/04/P04002)
  DOI : 10.1088/1748-0221/15/04/P04002
• Laser-Plasma Interaction Experiment for Solar Burst Studies
  
  • Marquès J.-R.
  • Briand C.
  • Amiranoff F.
  • Depierreux S.
  • Grech M.
  • Lancia L.
  • Pérez F.
  • Sgattoni A.
  • Vinci T.
  • Riconda C.
  Physical Review Letters, American Physical Society, 2020, 124 (13), pp.135001. A new experimental platform based on laser-plasma interaction is proposed to explore the fundamental processes of wave coupling at the origin of interplanetary radio emissions. It is applied to the study of electromagnetic (EM) emission at twice the plasma frequency (2 ωp) observed during solar bursts and thought to result from the coalescence of two Langmuir waves (LWs). In the interplanetary medium, the first LW is excited by electron beams, while the second is generated by electrostatic decay of Langmuir waves. In the present experiment, instead of an electron beam, an energetic laser propagating through a plasma excites the primary LW, with characteristics close to those at near-Earth orbit. The EM radiation at 2 ωp is observed at different angles. Its intensity, spectral evolution, and polarization confirm the LW-coalescence scenario. (10.1103/PhysRevLett.124.135001)
  DOI : 10.1103/PhysRevLett.124.135001
• Laboratory blast wave experiments provide insights on interactions between supernova remnants
  
  • Bandari Anashe
  Scilight, 2020, 2020 (7), pp.071105. (10.1063/10.0000790)
  DOI : 10.1063/10.0000790
• Coherent beam combining of 60 femtosecond fiber amplifiers
  
  • Fsaifes Ihsan
  • Daniault Louis
  • Bellanger Séverine
  • Veinhard Matthieu
  • Bourderionnet Jérôme
  • Larat Christian
  • Lallier Eric
  • Durand Eric
  • Brignon Arnaud
  • Chanteloup Jean-Christophe
  , 2020. We report on the first coherent beam combining of 60 fiber chirped-pulse amplifiers in a tiled-aperture configuration along with an interferometric phase measurement technique. Relying on coherent beams recombination in the far field, this technique appears well suited for the combination of a large number of fiber amplifiers. The 60 output beams are stacked in a hexagonal arrangement and collimated through a high fill factor hexagonal microlens array. The measured residual errors within the fiber array yields standard deviations of 4.2 μm for the fiber pitch and 3.1 mrad for the beam-to-beam pointing, allowing a combining efficiency of 50 %. The phasing of 60 fiber amplifiers demonstrates both pulse synchronization and phase stabilization with a residual phase error as low as lambda/100 RMS. (10.1117/12.2545229)
  DOI : 10.1117/12.2545229