Publications

2018

• From quantum to classical modeling of radiation reaction: a focus on the radiation spectrum
  
  • Niel F
  • Riconda C.
  • Amiranoff François
  • Lobet M.
  • Derouillat J.
  • Perez F.
  • Vinci T.
  • Grech M.
  Plasma Physics and Controlled Fusion, IOP Publishing, 2018, 60 (9), pp.094002. Soon available multi petawatt ultra-high-intensity (UHI) lasers will allow us to probe high-amplitude electromagnetic fields interacting with either ultrarelativistic electron beams or hot plasmas in the so-called moderately quantum regime. The correct modelling of the back-reaction of high-energy photon emission on the radiating electron dynamics, a.k.a. radiation reaction, in this regime is a key point for UHI physics. This will lead to both validation of theoretical predictions on the photon spectrum emitted during the laser-particle interaction and to the generation of high energy photon sources. In this paper we analyse in detail such emission using recently developed models to account for radiation reaction. We show how the predictions on the spectrum can be linked to a reduced description of the electron distribution function in terms of the first energy moments. The temporal evolution of the spectrum is discussed, as well as the parameters for which quantum effects induce hardening of the spectrum. (10.1088/1361-6587/aace22)
  DOI : 10.1088/1361-6587/aace22
• Mini-Review of Intra-Stark X-ray Spectroscopy of Relativistic Laser–Plasma Interactions
  
  • Dalimier Elisabeth
  • Pikuz Tatiana
  • Angelo Paulo
  Atoms, MDPI, 2018, 6 (3), pp.45. (10.3390/atoms6030045)
  DOI : 10.3390/atoms6030045
• SEPAGE: a proton-ion-electron spectrometer for LMJ-PETAL
  
  • Lantuéjoul Isabelle
  • Vauzour Benjamin
  • Duval Alain
  • Rossé Bertrand
  • Reverdin Charles
  • Marchet Bruno
  • Lecherbourg Ludovic
  • Rousseaux Christophe
  • Toussaint Jean-Christian
  • Chancé Antoine
  • Dubreuil Didier
  • Gastineau Bernard
  • Guillard Jean-Christophe
  • Harrault Francis
  • Leboeuf Didier
  • Loiseau Denis
  • Lotode Ange
  • Pes Chhon
  • Granet Francois
  • Boutoux Guillaume
  • Caillaud Tony
  • Prunet Pierre
  • Ceccotti Tiberio
  • Fuchs Julien
  • Batani Dimitri
  • Ducret Jean-Eric
  • Hulin Sébastien
  • Raffestin Didier
  • Sérani Laurent
  • Leboeuf Xavier
  • Jakubowska Katarzyna
  • Rabhi Nesrine
  , 2018, 10763. The SEPAGE spectrometer (Spectromètre Electrons Protons A Grandes Energies) was realized within the PETAL+ project funded by the French ANR (French National Agency for Research). This plasma diagnostic, installed on the LMJ-PETAL laser facility, is dedicated to the measurement of charged particle energy spectra generated by experiments using PETAL (PETawatt Aquitaine Laser). SEPAGE is inserted inside the 10-meter diameter LMJ experimental chamber with a SID (Diagnostic Insertion System) in order to be close enough to the target. It is composed of two Thomson Parabola measuring ion spectra and more particularly proton spectra ranging from 0.1 to 20 MeV and from 8 to 200 MeV for the low and high energy channels respectively. The electron spectrum is also measured with an energy range between 0.1 and 150 MeV. The front part of the diagnostic carries a film stack that can be placed as close as 100 mm from the target center chamber. This stack allows a spatial and spectral characterization of the entire proton beam. It can also be used to realize proton radiographies. (10.1117/12.2504146)
  DOI : 10.1117/12.2504146
• Picosecond x-ray radiography of microjets expanding from laser shock-loaded grooves
  
  • de Resseguier T.
  • Prudhomme G.
  • Roland C.
  • Brambrink E.
  • Loison Didier
  • Jodar B.
  • Lescoute E.
  • Sollier A.
  Journal of Applied Physics, American Institute of Physics, 2018, 124 (6), pp.065106. Material ejection upon the breakout of a shock wave at a rough surface is a key safety issue for various applications, including pyrotechnics and inertial confinement fusion. For a few years, we have used laser driven compression to investigate microjetting from calibrated grooves in the free surface of shock-loaded specimens. Fast transverse optical shadowgraphy, time-resolved measurements of planar surface and jet tip velocities, and post-shock analysis of some recovered material have provided data over ranges of small spatial and temporal scales, short loading pulses (ns-order), and extremely high strain rates. In the new experiment reported here, picosecond laser irradiation of a thin copper wire generates an ultrashort x-ray burst which is used to radiograph the microjets expanding from plane wedged-shape grooves in tin and copper samples shock-loaded by a longer, nanosecond laser pulse. Such ultrafast radiography provides estimates of the density gradients along the jets and of the total ejected mass at different times after shock breakout. Furthermore, it reveals regions of low density inside the samples deep beneath the grooves, associated with subsurface damage due to tension induced by the interaction of rarefaction waves. Thus, combining this x-ray probe with our former experimental techniques provides a more complete insight into the physics of microjetting at very high loading rates and the ballistic properties of the resulting ejecta. © 2018 Author(s). (10.1063/1.5040304)
  DOI : 10.1063/1.5040304
• EuPRAXIA – a compact, cost-efficient particle and radiation source
  
  • Weikum M.K.
  • Akhter T.
  • Alesini P.D.
  • Alexandrova A.S.
  • Anania M.P.
  • Andreev N.E.
  • Andriyash I.
  • Aschikhin A.
  • Assmann R.W.
  • Audet T.
  • Bacci A.
  • Barna I.F.
  • Beaton A.
  • Beck A.
  • Beluze A.
  • Bernhard A.
  • Bielawski S.
  • Bisesto F.G.
  • Brandi F.
  • Bringer O.
  • Brinkmann R.
  • Bründermann E.
  • Büscher M.
  • Bussmann M.
  • Bussolino G.C.
  • Chance A.
  • Chanteloup J.C.
  • Chen M.
  • Chiadroni E.
  • Cianchi A.
  • Clarke J.
  • Cole J.
  • Couprie M.E.
  • Croia M.
  • Cros B.
  • Crump P.
  • Dattoli G.
  • Delerue N.
  • Delferriere O.
  • Delinikolas P.
  • de Nicola S.
  • Dias J.
  • Dorda U.
  • Fedele R.
  • Pousa A. Ferran
  • Ferrario M.
  • Filippi F.
  • Fils J.
  • Fiore G.
  • Fonseca R.A.
  • Galimberti M.
  • Gallo A.
  • Garzella D.
  • Gastinel P.
  • Giove D.
  • Giribono A.
  • Gizzi L.A.
  • Grüner F.J.
  • Habib A.F.
  • Heinemann T.
  • Hidding B.
  • Holzer B.J.
  • Hooker S.M.
  • Hosokai T.
  • Hübner M.
  • Irman A.
  • Jafarinia F.
  • Jaroszynski D.A.
  • Jaster-Merz S.
  • Joshi C.
  • Kaluza M.C.
  • Kando M.
  • Karger O.S.
  • Karsch S.
  • Khazanov E.
  • Khikhlukha D.
  • Knetsch A.
  • Kocon D.
  • Koester P.
  • Kononenko O.
  • Korn G.
  • Kostyukov I.
  • Kruchinin K.
  • Labate L.
  • Lechner C.
  • Leemans W.P.
  • Lehrach A.
  • Li F.Y.
  • Li X.
  • Libov V.
  • Lifschitz Agustin
  • Litvinenko V.
  • Lu W.
  • Lundh O.
  • Maier A.R.
  • Malka Victor
  • Manahan G.G.
  • Mangles S.P.D.
  • Marchetti B.
  • Marocchino A.
  • de la Ossa A. Martinez
  • Martins J.L.
  • Mason P.
  • Massimo F.
  • Mathieu F.
  • Maynard G.
  • Mazzotta Z.
  • Mehrling T.J.
  • Molodozhentsev A.Y.
  • Mostacci A.
  • Müller A.S.
  • Murphy C.D.
  • Najmudin Z.
  • Nghiem P.A.P.
  • Nguyen F.
  • Niknejadi P.
  • Osterhoff J.
  • Papadopoulos D.
  • Patrizi B.
  • Petrillo V.
  • Pocsai M.A.
  • Poder K.
  • Pompili R.
  • Pribyl L.
  • Pugacheva D.
  • Romeo S.
  • Rajeev P.P.
  • Rossetti Conti M.
  • Rossi A.R.
  • Rossmanith R.
  • Roussel E.
  • Sahai A.A.
  • Sarri G.
  • Schaper L.
  • Scherkl P.
  • Schramm U.
  • Schroeder C.B.
  • Schwindling J.
  • Scifo J.
  • Serafini L.
  • Sheng Z.M.
  • Silva L.O.
  • Silva T.
  • Simon C.
  • Sinha U.
  • Specka A.
  • Streeter M.J.V.
  • Svystun E.N.
  • Symes D.
  • Szwaj C.
  • Tauscher G.
  • Terzani D.
  • Thompson N.
  • Toci G.
  • Tomassini P.
  • Torres R.
  • Ullmann D.
  • Vaccarezza C.
  • Vannini M.
  • Vieira J.M.
  • Villa F.
  • Wahlström C.-G.
  • Walczak R.
  • Walker P.A.
  • Wang K.
  • Welsch C.P.
  • Wolfenden J.
  • Xia G.
  • Yabashi M.
  • Yu L.
  • Zhu J.
  • Zigler A.
  , 2019, 2160, pp.040012. Plasma accelerators present one of the most suitable candidates for the development of more compact particle acceleration technologies, yet they still lag behind radiofrequency (RF)-based devices when it comes to beam quality, control, stability and power efficiency. The Horizon 2020-funded project EuPRAXIA (“European Plasma Research Accelerator with eXcellence In Applications”) aims to overcome the first three of these hurdles by developing a conceptual design for a first international user facility based on plasma acceleration. In this paper we report on the main features, simulation studies and potential applications of this future research infrastructure. (10.1063/1.5127692)
  DOI : 10.1063/1.5127692
• Modelling magnetized accretion columns of young stars in the laboratory
  
  • Revet Guilhem
  , 2018. The work that is presented here has been performed in the frame of laboratory astrophysics, which consists in studying in the laboratory physical processes occurring in astrophysical objects. The main advantages in doing so are that the processes can be studied in a controlled way and that their full dynamics can be investigated. Here, we have been taking advantage of high-intensity laser facilities to perform our studies.In this manuscript, will be treated issues that include the interaction of a plasma expanding into vacuum with an ambient magnetic field. The presence of a magnetic field in a variety of astrophysical phenomena makes the inclusion of this component in the laboratory of great interest. We have used for our study a split Helmholtz coil, specifically designed in order to work in a laser environment, that allows for reaching a magnetic field strength up to 30 T.The astrophysical objects on which this study is focused are Young Stellar Objects (YSOs). Several steps of the star formation process are here investigated: (i) the generation of very long range, bright jets, (ii) the accretion dynamic involving, in the standard representation, matter falling down on the star in the shape of magnetically confined columns, and (iii) more exotic accretion channels, as the equatorial accretion that implies propagation of plasma perpendicularly to magnetic field lines.More precisely, in a first chapter, the jet formation dynamic will be discussed. A first part is dedicated to the jet formation mechanism in a poloidal magnetic field (aligned with respect to the main plasma expansion axis). A second part is dealing with the distortion of such jet formation via the interaction of the same expanding plasma with a misaligned magnetic field (i.e. presenting an angle with respect to the plasma expansion axis). Finally, a third part details the propagation of the plasma within a perpendicular magnetic field. This last part allows us to investigate exotic channels of matter accretion onto the stars, consisting of equatorial accretion from the disk to the star, through orthogonal magnetic field lines. The second chapter addresses the topic of the standard accretion dynamic via magnetically confined columns of matter, falling down onto the stellar surface. Using the same experimental setup as in the first chapter, the formed jet (in the case of the perfectly aligned magnetic field) is used to mimic the accretion column, and is launched onto a secondary target that acts as the stellar surface. The shock dynamic at the obstacle location is carefully studied and links with astrophysical accretion observations are built. A plasma cocoon, shaped around the impact region via the interaction with the magnetic field, is found to be similar to the one found in astrophysical simulations. This cocoon is an important element as a potential X-ray absorptive medium in order to explain observed discrepancies, between observed UV/Optical and X-ray emissions emitted from accreting stars. (10.70675/41593387zbd09z46b1zb43cze24ff913e0e6)
  DOI : 10.70675/41593387zbd09z46b1zb43cze24ff913e0e6
• Coupling between plasticity and phase transition in shock- and ramp-compressed single-crystal iron
  
  • Amadou N.
  • de Resseguier T.
  • Dragon A.
  • Brambrink E.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2018, 98 (2). Molecular dynamics simulations have been used to investigate the coupling process between plasticity and structural phase transformation in single-crystal iron under both shock and ramp compressions. In both cases, iron was found to yield via twinning. Then, the onset of the bcc-hcp phase transformation was shown to be tightly dependent on the plasticity history through a hardening-like effect, which in some conditions may inhibit the nucleation of the hcp phase. (10.1103/PhysRevB.98.024104)
  DOI : 10.1103/PhysRevB.98.024104
• Development of new diagnostics based on LiF detector for pump-probe experiments
  
  • Pikuz T.
  • Faenov A.
  • Ozaki N.
  • Matsuoka T.
  • Albertazzi Bruno
  • Hartley N.J.
  • Miyanishi K.
  • Katagiri K.
  • Matsuyama S.
  • Yamauchi K.
  • Habara H.
  • Inubushi Y.
  • Togashi T.
  • Yumoto H.
  • Ohashi H.
  • Tange Y.
  • Yabuuchi T.
  • Yabashi M.
  • Grum-Grzhimailo A.
  • Casner A.
  • Skobelev I.
  • Makarov S.
  • Pikuz S.
  • Rigon G.
  • Koenig M.
  • Tanaka K.A.
  • Ishikawa T.
  • Kodama R.
  Matter and Radiation at Extremes, AIP Publishing, 2018, 3 (4), pp.197 - 206. (10.1016/j.mre.2018.01.006)
  DOI : 10.1016/j.mre.2018.01.006
• Transition from nonlocal electron transport to radiative regime in an expanding blast wave
  
  • Marocchino A.
  • Ravasio A.
  • Levy A.
  • Lancia L.
  • Fukuda Y.
  • Jinno S.
  • Atzeni S.
  • Doria D.
  • Prigent C.
  • Lamour E.
  • Vernhet D.
  • Borghesi M.
  • Romagnani L.
  Applied Physics Letters, American Institute of Physics, 2018, 112 (26), pp.264104. We have investigated the formation, evolution, and late-time propagation of a laser-generated cylindrical blast wave (BW). The whole blast wave evolution over timescales of several nanoseconds was reconstructed experimentally (via temporally resolved interferometric measurements) and via hydrodynamic simulations that included modeling of nonlocal electron transport and radiation diffusion. Comparison between the experimental results and the simulations indicates that the early expansion phase is characterised by nonlocal electron heat transport causing energy spread on times shorter than the typical timescales for hydrodynamic expansion. Nonlocal electron transport ionizes the gas ahead of the plasma front and gives rise to a smooth radial density gradient. At later times, once the shock is launched and the BW is formed, radiation results in reduced shock velocity compared to the adiabatic case. These investigations provide a suitable and effective platform to benchmark the inclusion of kinetic and radiative effects in fluid modeling of the plasma dynamics over timescales that may be inaccessible to fully kinetic simulations. (10.1063/1.5022698)
  DOI : 10.1063/1.5022698
• Investigation of the spatio-temporal effects in the Apollon 10 PW laser
  
  • Zou J.P.
  • Ranc L.
  • Leblanc Catherine
  • Druon Frédéric
  • Papadopoulos Dimitrios
  , 2018.
• Coherent beam combining of seven femtosecond chirped-pulse fiber amplifiers using an interferometric phase measurement technique
  
  • Heilmann Anke
  • Le Dortz Jérémy
  • Bellanger Séverine
  • Daniault Louis
  • Fsaifes Ihsan
  • Antier Marie
  • Bourderionnet Jérôme
  • Larat Christian
  • Lallier Eric
  • Brignon Arnaud
  • Durand Eric
  • Simon-Boisson Christophe
  • Chanteloup Jean-Christophe
  , 2018, pp.SM2N.8. We report on the coherent combination of seven fiber amplifiers in the femtosec-ond regime using an interferometric phase measurement technique. A combination efficiencyof 54 % and a compressed pulse length of 225 fs were achieved. (10.1364/CLEO_SI.2018.SM2N.8)
  DOI : 10.1364/CLEO_SI.2018.SM2N.8
• High Energy Emission from Shocks Due to Jets and Accretion in Young Stars with Disks: Combining Observations, Numerical Models, and Laboratory Experiments
  
  • Bonito R.
  • Argiroffi Costanza
  • Orlando Salvatore
  • Miceli Marco
  • Fuchs Julien
  • Ciardi Andrea
  , 2019, 55, pp.49. (10.1007/978-3-030-14128-8_7)
  DOI : 10.1007/978-3-030-14128-8_7
• Setup for meV-resolution inelastic X-ray scattering measurements and X-ray diffraction at the Matter in Extreme Conditions endstation at the Linac Coherent Light Source
  
  • Mcbride E.E.
  • White T.G.
  • Descamps A.
  • Fletcher L.B.
  • Appel K.
  • Condamine F.
  • Curry C.B.
  • Dallari F.
  • Funk S.
  • Galtier E.
  • Gauthier M.
  • Goede S.
  • Kim J.B.
  • Lee H.J.
  • Ofori-Okai B.K.
  • Oliver M.
  • Rigby A.
  • Schoenwaelder C.
  • Sun P.
  • Tschentscher Th.
  • Witte B.B. L.
  • Zastrau U.
  • Gregori G.
  • Nagler B.
  • Hastings J.
  • Glenzer S.H.
  • Monaco G.
  , 2018, 89 (10), pp.10F104. We describe a setup for performing inelastic X-ray scattering and X-ray diffraction measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce silicon (533) monochromator was used in conjunction with three silicon (533) diced crystal analyzers to provide an energy resolution of ∼50 meV over a range of ∼500 meV in single shot measurements. In addition to the instrument resolution function, we demonstrate the measurement of longitudinal acoustic phonon modes in polycrystalline diamond. Furthermore, this setup may be combined with the high intensity laser drivers available at MEC to create warm dense matter and subsequently measure ion acoustic modes. (10.1063/1.5039329)
  DOI : 10.1063/1.5039329
• From quantum to classical modeling of radiation reaction: A focus on stochasticity effects
  
  • Niel F.
  • Riconda C.
  • Amiranoff François
  • Duclous R.
  • Grech M.
  Physical Review E, American Physical Society (APS), 2018, 97 (4). (10.1103/PhysRevE.97.043209)
  DOI : 10.1103/PhysRevE.97.043209
• Extensive study of electron acceleration by relativistic surface plasmons
  
  • Cantono A.
  • Sgattoni A.
  • Fedeli L.
  • Garzella D.
  • Réau F.
  • Riconda C.
  • Macchi A.
  • Ceccotti T.
  Physics of Plasmas, American Institute of Physics, 2018, 25 (3), pp.031907. The excitation of surface plasmons with ultra-intense (I ∼ 5 × 1019 W/cm2), high contrast (∼1012) laser pulses on periodically modulated solid targets has been recently demonstrated to produce collimated bunches of energetic electrons along the target surface [Fedeli et al., Phys. Rev. Lett. 116, 015001 (2016)]. Here, we report an extensive experimental and numerical study aimed to a complete characterization of the acceleration mechanism, demonstrating its robustness and promising characteristics for an electron source. By comparing different grating structures, we identify the relevant parameters to optimize the acceleration and obtain bunches of ∼650 pC of charge at several MeV of energy with blazed gratings. (10.1063/1.5017706)
  DOI : 10.1063/1.5017706
• Tracking the ultrafast XUV optical properties of x-ray free-electron-laser heated matter with high-order harmonics
  
  • Williams Gareth O.
  • Künzel S.
  • Daboussi S.
  • Iwan B.
  • Gonzalez A.
  • Boutu W.
  • Hilbert V.
  • Zastrau U.
  • Lee H.
  • Nagler B.
  • Granados E.
  • Galtier E.
  • Heimann P.
  • Barbrel B.
  • Dovillaire G.
  • Lee R.
  • Dunn J.
  • Recoules V.
  • Blancard C.
  • Renaudin P.
  • de La Varga A.
  • Velarde P.
  • Audebert P.
  • Merdji H.
  • Zeitoun Ph.
  • Fajardo M.
  Physical Review A : Atomic, molecular, and optical physics [1990-2015], American Physical Society, 2018, 97 (2). We present measurements of photon absorption by free electrons as a solid is transformed to plasma. A femtosecond x-ray free-electron laser is used to heat a solid, which separates the electron and ion heating time scales. The changes in absorption are measured with an independent probe pulse created through high-order-harmonic generation. We find an increase in electron temperature to have a relatively small impact on absorption, contrary to several predictions, whereas ion heating increases absorption. We compare the data to current theoretical and numerical approaches and find that a smoother electronic structure yields a better fit to the data, suggestive of a temperature-dependent electronic structure in warm dense matter. (10.1103/PhysRevA.97.023414)
  DOI : 10.1103/PhysRevA.97.023414
• Towards coherent combination of 61 fiber amplifiers
  
  • Chanteloup Jean-Christophe
  • Heilmann Anke
  • Le Dortz Jérémy
  • Bellanger Séverine
  • Daniault Louis
  • Fsaifes Ihsan
  • Antier Marie
  • Bourderionnet Jérôme
  • Larat Christian
  • Lallier Eric
  • Brignon Arnaud
  • Simon-Boisson Christophe
  • Chantelpoup Jean-Christophe
  • Durand Eric
  , 2018, pp.10. The XCAN project aims at the coherent combination of 61 ber ampliers in the femtosecond regime. An important intermediate step towards this goal is the implementation of a seven ber test setup, which allows to address key scientic and technical challenges which might occur in the scaled version of 61 bers. This work includes the design and characterization of a support unit able to hold 61 bers with the high precision required for an ecient coherent combination in tiled aperture conguration. This conguration, in combination with an interferometric phase measurement and active phase control, is particularly well suited for the coherent combination of a very large number of beams. Our rst preliminary results with seven bers include a combination eciency of 30% and a residual phase error between two bers as low as /40 rms. Experiments conducted with three bers in order to evaluate technical improvements revealed an increase of eciency to 54 %. The combined beam was temporally compressed to 225 fs, which is Fourier transform limited with respect to the measured spectrum. (10.1117/12.2287862)
  DOI : 10.1117/12.2287862
• Self focusing in a spatially modulated electrostatic field particle accelerator
  
  • Russman F.
  • Marini S.
  • Peter E.
  • Oliveira G.I. De
  • Rizzato F.B.
  Phys.Plasmas, 2018, 25 (2), pp.023110. In the present analysis, we study the action of a three-dimensional (3D) modulated electrostatic wave over a charged particle. Meanwhile, the particle's velocity is smaller than the phase-velocity of the carrier, and the particle could be reflected by the potential or could pass through the potential with no significant change in the longitudinal velocity—and its dynamics could be described by a ponderomotive approximation. Otherwise, the particle is trapped by the potential and it is accelerated towards the speed of light, independently of the initial particle's phase—in this case, the ponderomotive approximation is no longer valid. During the acceleration process, numerical simulations show the particle is focused, simultaneously. These results suggest the accelerator proposed here is promising. (10.1063/1.5020724)
  DOI : 10.1063/1.5020724
• Experimental evidence for the enhanced and reduced stopping regimes for protons propagating through hot plasmas
  
  • Chen S. N
  • Atzeni S.
  • Gangolf T.
  • Gauthier M.
  • Higginson D. P
  • Hua R.
  • Kim J.
  • Mangia F.
  • Mcguffey C.
  • Marquès J-R
  • Riquier R.
  • Pépin H.
  • Shepherd R.
  • Willi O.
  • Beg F. N
  • Deutsch C.
  • Fuchs J.
  Scientific Reports, Nature Publishing Group, 2018, 8, pp.14586. Our understanding of the dynamics of ion collisional energy loss in a plasma is still not complete, in part due to the difficulty and lack of high-quality experimental measurements. These measurements are crucial to benchmark existing models. Here, we show that such a measurement is possible using high-flux proton beams accelerated by high intensity short pulse lasers, where there is a high number of particles in a picosecond pulse, which is ideal for measurements in quickly expanding plasmas. By reducing the energy bandwidth of the protons using a passive selector, we have made proton stopping measurements in partially ionized Argon and fully ionized Hydrogen plasmas with electron temperatures of hundreds of eV and densities in the range 1020–1021 cm−3. In the first case, we have observed, consistently with previous reports, enhanced stopping of protons when compared to stopping power in non-ionized gas. In the second case, we have observed for the first time the regime of reduced stopping, which is theoretically predicted in such hot and fully ionized plasma. The versatility of these tunable short-pulse laser based ion sources, where the ion type and energy can be changed at will, could open up the possibility for a variety of ion stopping power measurements in plasmas so long as they are well characterized in terms of temperature and density. In turn, these measurements will allow tests of the validity of existing theoretical models. (10.1038/s41598-018-32726-2)
  DOI : 10.1038/s41598-018-32726-2
• Self-compression in a multipass cell
  
  • Jargot Gaëtan
  • Daher Nour
  • Lavenu Loic
  • Delen Xavier
  • Forget Nicolas
  • Hanna Marc
  • Georges Patrick
  Optics Letters, Optical Society of America - OSA Publishing, 2018, 43 (22), pp.5643. We demonstrate self-compression of short-wavelength infrared pulses in a multipass cell (MPC) containing a plate of silica. Nonlinear propagation in the cell in the anomalous dispersion regime results in the generation of 14 μJ 22 fs pulses at 125 kHz repetition rate and 1550 nm wavelength. Periodic focusing inside the cell allows us to circumvent catastrophic self-focusing, despite an output peak power of 440 MW well beyond the critical power in silica of 10 MW. This technique allows straightforward energy scaling of self-compression setups and control over the spatial manifestation of Kerr nonlinearity. More generally, MPCs can be used to perform, at higher energy levels, temporal manipulations of pulses that have been previously demonstrated in waveguides. (10.1364/OL.43.005643)
  DOI : 10.1364/OL.43.005643
• Multidisciplinary constraints on the abundance of diamond and eclogite in the cratonic lithosphere
  
  • Garber Joshua M.
  • Maurya Satish
  • Hernandez Jean-Alexis
  • Duncan Megan S.
  • Zeng Li
  • Zhang Hongluo L.
  • Faul Ulrich
  • Mccammon Catherine
  • Montagner Jean-Paul
  • Moresi Louis
  • Romanowicz Barbara A.
  • Rudnick Roberta L.
  • Stixrude Lars
  Geochemistry, Geophysics, Geosystems, AGU and the Geochemical Society, 2018, 19, pp.2062-2086. Some seismic models derived from tomographic studies indicate elevated shear-wave velocities (≥4.7 km/s) around 120-150 km depth in cratonic lithospheric mantle. These velocities are higher than those of cratonic peridotites, even assuming a cold cratonic geotherm (i.e., 35 mW/m<SUP>2</SUP> surface heat flux) and accounting for compositional heterogeneity in cratonic peridotite xenoliths and the effects of anelasticity. We reviewed various geophysical and petrologic constraints on the nature of cratonic roots (seismic velocities, lithology/mineralogy, electrical conductivity, and gravity) and explored a range of permissible rock and mineral assemblages that can explain the high seismic velocities. These constraints suggest that diamond and eclogite are the most likely high-V<SUB>s</SUB> candidates to explain the observed velocities, but matching the high shear-wave velocities requires either a large proportion of eclogite (>50 vol.%) or the presence of up to 3 vol.% diamond, with the exact values depending on peridotite and eclogite compositions and the geotherm. Both of these estimates are higher than predicted by observations made on natural samples from kimberlites. However, a combination of ≤20 vol.% eclogite and ~2 vol.% diamond may account for high shear-wave velocities, in proportions consistent with multiple geophysical observables, data from natural samples, and within mass balance constraints for global carbon. Our results further show that cratonic thermal structure need not be significantly cooler than determined from xenolith thermobarometry. <P />could not parse page for 10.1029/2018GC007496 (10.1029/2018GC007534)
  DOI : 10.1029/2018GC007534
• Stochastic transport of high-energy particles through a turbulent plasma
  
  • Chen L.
  • Bott A.
  • Tzeferacos P.
  • Rigby A.
  • Bell A.
  • Bingham R.
  • Graziani C.
  • Katz J.
  • Li C.
  • Koenig M.
  • Petrasso R
  • Park H.-S
  • Ross J S
  • Ryu D
  • Ryutov D
  • White T G
  • Reville B
  • Matthews J
  • Meinecke J
  • Miniati F
  • Zweibel E G
  • Sarkar S
  • Schekochihin A A
  • Lamb D Q
  • Froula D H
  • Gregori G
  The Astrophysical Journal, American Astronomical Society, 2018. The interplay between charged particles and turbulent magnetic fields is crucial to understanding how cosmic rays propagate through space. A key parameter which controls this interplay is the ratio of the particle gyroradius to the correlation length of the magnetic turbulence. For the vast majority of cosmic rays detected at the Earth, this parameter is small, and the particles are well confined by the Galactic magnetic field. But for cosmic rays more energetic than about 30 EeV, this parameter is large. These highest energy particles are not confined to the Milky Way and are presumed to be extragalactic in origin. Identifying their sources requires understanding how they are deflected by the intergalactic magnetic field, which appears to be weak, turbulent with an unknown correlation length, and possibly spatially intermittent. This is particularly relevant given the recent detection by the Pierre Auger Observatory of a significant dipole anisotropy in the arrival directions of cosmic rays of energy above 8 EeV. Here we report measurements of energetic-particle propagation through a random magnetic field in a laser-produced plasma. We characterize the diffusive transport of these particles and recover experimentally pitch-angle scattering measurements and extrapolate to find their mean free path and the associated diffusion coefficient, which show scaling-relations consistent with theoretical studies. This experiment validates these theoretical tools for analyzing the propagation of ultra-high energy cosmic rays through the intergalactic medium.
• Laboratory radiative accretion shocks on GEKKO XII laser facility for POLAR project
  
  • van Box Som L.
  • Falize E.
  • Koenig M.
  • Sakawa Y.
  • Albertazzi B.
  • Barroso P.
  • Bonnet-Bidaud J.-M.
  • Busschaert C.
  • Ciardi A.
  • Hara Y.
  • Katsuki N.
  • Kumar R.
  • Lefevre F.
  • Michaut C.
  • Michel Th.
  • Miura T.
  • Morita T.
  • Mouchet M.
  • Rigon G.
  • Sano T.
  • Shiiba S.
  • Shimogawara H.
  • Tomiya S.
  High Power Laser Science and Engineering, Cambridge University Press, 2018, 6, pp.e35. A new target design is presented to model high-energy radiative accretion shocks in polars. In this paper, we present the experimental results obtained on the GEKKO XII laser facility for the POLAR project. The experimental results are compared with 2D FCI2 simulations to characterize the dynamics and the structure of plasma flow before and after the collision. The good agreement between simulations and experimental data confirm the formation of a reverse shock where cooling losses start modifying the post-shock region. With the multi-material structure of the target, a hydrodynamic collimation is exhibited and a radiative structure coupled with the reverse shock is highlighted in both experimental data and simulations. The flexibility on the laser energy produced on GEKKO XII, allowed us to produce high-velocity flows and study new and interesting radiation hydrodynamic regimes between those obtained on the LULI2000 and Orion laser facilities. (10.1017/hpl.2018.32)
  DOI : 10.1017/hpl.2018.32
• Extreme Ultraviolet Beam Enhancement by Relativistic Surface Plasmons
  
  • Cantono G.
  • Fedeli L.
  • Sgattoni A.
  • Denoeud A.
  • Chopineau L.
  • Réau F.
  • Ceccotti T.
  • Macchi A.
  Physical Review Letters, American Physical Society, 2018, 120 (26), pp.264803. The emission of high-order harmonics in the extreme ultraviolet range from the interaction of a short, intense laser pulse with a grating target is investigated experimentally. When resonantly exciting a surface plasmon, both the intensity and the highest order observed for the harmonic emission along the grating surface increase with respect to a flat target. Harmonics are obtained when a suitable density gradient is preformed at the target surface, demonstrating the possibility to manipulate the grating profile on a nanometric scale without preventing the surface plasmon excitation. In support of this, the harmonic emission is spatiotemporally correlated to the acceleration of multi-MeV electron bunches along the grating surface. Particle-in-cell simulations reproduce the experimental results and give insight on the mechanism of high harmonic generation in the presence of surface plasmons. (10.1103/PhysRevLett.120.264803)
  DOI : 10.1103/PhysRevLett.120.264803
• Perpendicular relativistic shocks in magnetized pair plasma
  
  • Plotnikov Illya
  • Grassi Anna
  • Grech Mickael
  Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2018, 477 (4), pp.5238-5260. Perpendicular relativistic (γ_0= 10) shocks in magnetized pair plasmas are investigated using two-dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the transition from Weibel-mediated to magnetic-reflection-shaped shocks. This transition is found to occur for upstream flow magnetizations 10^−3 < σ < 10^−2 at which a strong perpendicular net current is observed in the precursor, driving the so-called current-filamentation instability. The global structure of the shock and shock formation time are discussed. The magnetohydrodynamics shock jump conditions are found in good agreement with the numerical results, except for 10^−4 < σ < 10^−2 where a deviation up to 10 per cent is observed. The particle precursor length converges towards the Larmor radius of particles injected in the upstream magnetic field at intermediate magnetizations. For σ > 10^−2, it leaves place to a purely electromagnetic precursor following from the strong emission of electromagnetic waves at the shock front. Particle acceleration is found to be efficient in weakly magnetized perpendicular shocks in agreement with previous works, and is fully suppressed for σ > 10^−2. Diffusive shock acceleration is observed only in weakly magnetized shocks, while a dominant contribution of shock drift acceleration is evidenced at intermediate magnetizations. The spatial diffusion coefficients are extracted from the simulations allowing for a deeper insight into the self-consistent particle kinematics and scale with the square of the particle energy in weakly magnetized shocks. These results have implications for particle acceleration in the internal shocks of active galactic nucleus jets and in the termination shocks of pulsar wind nebulae. (10.1093/mnras/sty979)
  DOI : 10.1093/mnras/sty979