Publications

2020

• Focussing protons from a Kilojoule Laser for intense Beam Heating using proximal target Structures
  
  • Mcguffey C.
  • Kim J.
  • Wei M.S.
  • Nilson P. M.
  • Chen S. N
  • Fuchs J.
  • Fitzsimmons P.
  • Foord M. E
  • Mariscal D.
  • Mclean H. S
  • Patel P. K.
  • Stephens R. B
  • Beg F. N
  Scientific Reports, Nature Publishing Group, 2020, 10, pp.9415. Proton beams driven by chirped pulse amplified lasers have multi-picosecond duration and can isochorically and volumetrically heat material samples, potentially providing an approach for creating samples of warm dense matter with conditions not present on Earth. Envisioned on a larger scale, they could heat fusion fuel to achieve ignition. We have shown in an experiment that a kilojoule-class, multi-picosecond short pulse laser is particularly effective for heating materials. The proton beam can be focussed via target design to achieve exceptionally high flux, important for the applications mentioned. The laser irradiated spherically curved diamond-like-carbon targets with intensity 4 × 1018 W/cm2, producing proton beams with 3 MeV slope temperature. A Cu witness foil was positioned behind the curved target, and the gap between was either empty or spanned with a structure. With a structured target, the total emission of Cu Kα fluorescence was increased 18 fold and the emission profile was consistent with a tightly focussed beam. Transverse proton radiography probed the target with ps order temporal and 10 μm spatial resolution, revealing the fast-acting focussing electric field. Complementary particle-in-cell simulations show how the structures funnel protons to the tight focus. The beam of protons and neutralizing electrons induce the bright Kα emission observed and heat the Cu to 100 eV. (10.1038/s41598-020-65554-4)
  DOI : 10.1038/s41598-020-65554-4
• Laboratory Observation of Radiative Shock Deceleration and Application to SN 1987A
  
  • M Koenig
  • Mabey Paul
  The Astrophysical Journal, American Astronomical Society, 2020, 888 (1). The first laboratory evidence of a radiative shock (RS) decelerating during its free expansion phase in an optically thick medium is presented. A shock is generated in a multilayer solid target under the irradiation of a high-power laser at the GEKKO XII laser facility. The rear surface of the target is connected to a gas cell filled with Xe. Upon breakout, an RS, characterized by low Boltzmann number Bo MUCH LESS-THAN 1 and Mihalas number R 10, is generated. Experimental results reveal that radiative losses through the radiative precursor cause the shock to lose energy and decelerate. A model is developed that describes the shock propagation as a function of time. The model is in agreement with both numerical simulations and experimental results. These results have tremendous consequences for astrophysical systems, such as SN 1987A, where radiative deceleration may play a role in the formation of the observed hotspots in the circumstellar ring. (10.3847/1538-4357/ab5956)
  DOI : 10.3847/1538-4357/ab5956
• Transport of high-energy charged particles through spatially-intermittent turbulent magnetic fields
  
  • Chen L.E.
  • Bott A.F.A.
  • Tzeferacos P.
  • Rigby A.
  • Bell A.
  • Bingham R.
  • Graziani C.
  • Katz J.
  • Koenig M.
  • Li C.K.
  • Petrasso R.
  • Park H.-S.
  • Ross J.S.
  • Ryu 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, 2020, 892, pp.114. Identifying the sources of the highest energy cosmic rays requires understanding how they are deflected by the stochastic, spatially intermittent intergalactic magnetic field. Here we report measurements of energetic charged-particle propagation through a laser-produced magnetized plasma with these properties. We characterize the diffusive transport of the particles experimentally. The results show that the transport is diffusive and that, for the regime of interest for the highest-energy cosmic rays, the diffusion coefficient is unaffected by the spatial intermittency of the magnetic field. (10.3847/1538-4357/ab7a19)
  DOI : 10.3847/1538-4357/ab7a19
• Velocity and mass density of the ejecta produced from sinusoidal grooves in laser shock-loaded tin
  
  • Prudhomme G.
  • de Resseguier T.
  • Roland Caroline
  • Sollier A.
  • Lescoute E.
  • Loison Didier
  • Brambrink E.
  Journal of Applied Physics, American Institute of Physics, 2020, 128 (15), pp.155903. When a shock wave of several tens of GPa breaks out at a free surface, a material is ejected ahead of this surface. The amount and velocity of such ejecta depend on the breakout pressure, state of the released material (solid, liquid, or mixed), whether the shockwave is supported or unsupported, and the initial geometrical perturbation (or roughness) of the free surface. If surface defects consist of small grooves, pits, or scratches, material ejection occurs in the form of jets breaking up into tiny particles (so-called microjetting), with jet tip velocities up to several times higher than the free surface velocity. The laser-based experiments presented in this paper focus on microjetting in shock-melted tin with periodic surface perturbations. Several complementary diagnostics are combined to measure the velocity and mass of ejecta during the early stages of the jetting process. One relevant advancement is the use of ps-laser x-ray radiography to probe the density of the ejecta in distinct jets a few tens of μ m-wide. The effects of the depth and wavelength of the initial perturbation are investigated in both linear and near-linear growth regimes. The results are compared with predictions derived from the Richtmyer-Meshkov Instability theory. © 2020 Author(s). (10.1063/5.0022940)
  DOI : 10.1063/5.0022940
• Improvement in the temporal contrast in the tens of ps range of the multi-PW Apollon laser front-end
  
  • Ranc Lucas
  • Le Blanc Catherine
  • Lebas Nathalie
  • Martin Luc
  • Zou Ji-Ping
  • Mathieu François
  • Radier Christophe
  • Ricaud Sandrine
  • Druon Frédéric
  • Papadopoulos Dimitris
  Optics Letters, Optical Society of America - OSA Publishing, 2020, 45 (16), pp.4599. (10.1364/OL.401272)
  DOI : 10.1364/OL.401272
• Experimental characterization of the interaction zone between counterpropagating Taylor Sedov blast waves
  
  • Albertazzi B
  • Mabey P
  • Michel Th
  • Rigon G
  • Marquès J.-R
  • Pikuz S
  • Ryazantsev S
  • Falize E
  • Van L
  • Som Box
  • Meinecke J
  • Ozaki N
  • Ciardi A
  • Gregori G
  • Koenig M
  Physics of Plasmas, American Institute of Physics, 2020. This paper was selected as Featured This paper was selected as Scilight ARTICLES YOU MAY BE INTERESTED IN Three-dimensional signatures of self-similarity in a high-energy-density plasma shear-driven mixing layer (10.1063/1.5137795)
  DOI : 10.1063/1.5137795
• Orbital Angular Momentum beams generation from 61 channels Coherent Beam Combining femtosecond Digital Laser
  
  • Veinhard Matthieu
  • Bellanger Severine
  • Daniault Louis
  • Fsaifes Ihsan
  • Bourderionnet Jerome
  • Larat Christian
  • Lallier Eric
  • Brignon Arnaud
  • Chanteloup Jean-Christophe
  Optics Letters, Optical Society of America - OSA Publishing, 2020. We report on the use of a 61 beamlets Coherent Beam Combination femtosecond fiber amplifiers as a digital laser source to generate high power Orbital Angular Momentum beams. Such approach opens the path for higher order non-symmetrical user-defined far field distributions. (10.1364/OL.405975)
  DOI : 10.1364/OL.405975
• In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures
  
  • Morard Guillaume
  • Hernandez Jean-Alexis
  • Guarguaglini Marco
  • Bolis Riccardo
  • Benuzzi-Mounaix Alessandra
  • Vinci Tommaso
  • Fiquet Guillaume
  • Baron Marzena A
  • Shim Sang Heon
  • Ko Byeongkwan
  • Gleason Arianna
  • Mao Wendy L
  • Alonso-Mori Roberto
  • Lee Hae Ja
  • Nagler Bob
  • Galtier Eric
  • Sokaras Dimosthenis
  • Glenzer Siegfried H
  • Andrault Denis
  • Garbarino Gaston
  • Mezouar Mohamed
  • Schuster Anja K
  • Ravasio Alessandra
  Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2020, 117 (22), pp.11981-11986. Properties of liquid silicates under high pressure and high temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core-mantle boundary. Here, we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6000 K along the MgSiO3 glass Hugoniot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth's core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely-used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures. (10.1073/pnas.1920470117)
  DOI : 10.1073/pnas.1920470117
• Time-resolved fast turbulent dynamo in a laser plasma
  
  • Bott A. F. A.
  • Tzeferacos P.
  • Chen L.
  • Palmer C. A. J.
  • Rigby A.
  • Bell A.
  • Bingham R.
  • Birkel A.
  • Graziani C.
  • Froula D. H.
  • Katz J.
  • Koenig M.
  • Kunz M. W.
  • Li C. K.
  • Meinecke J.
  • Miniati F.
  • Petrasso R.
  • Park H. -S.
  • Remington B. A.
  • Reville B.
  • Ross J. S.
  • Ryu D.
  • Ryutov D.
  • Séguin F.
  • White T. G.
  • Schekochihin A. A.
  • Lamb D. Q.
  • Gregori G.
  , 2020. Understanding magnetic-field generation and amplification in turbulent plasma is essential to account for observations of magnetic fields in the universe. A theoretical framework attributing the origin and sustainment of these fields to the so-called fluctuation dynamo was recently validated by experiments on laser facilities in low-magnetic-Prandtl-number plasmas ($\mathrm{Pm} < 1$). However, the same framework proposes that the fluctuation dynamo should operate differently when $\mathrm{Pm} \gtrsim 1$, the regime relevant to many astrophysical environments such as the intracluster medium of galaxy clusters. This paper reports a new experiment that creates a laboratory $\mathrm{Pm} \gtrsim 1$ plasma dynamo for the first time. We provide a time-resolved characterization of the plasma's evolution, measuring temperatures, densities, flow velocities and magnetic fields, which allows us to explore various stages of the fluctuation dynamo's operation. The magnetic energy in structures with characteristic scales close to the driving scale of the stochastic motions is found to increase by almost three orders of magnitude from its initial value and saturate dynamically. It is shown that the growth of these fields occurs exponentially at a rate that is much greater than the turnover rate of the driving-scale stochastic motions. Our results point to the possibility that plasma turbulence produced by strong shear can generate fields more efficiently at the driving scale than anticipated by idealized MHD simulations of the nonhelical fluctuation dynamo; this finding could help explain the large-scale fields inferred from observations of astrophysical systems.
• Calculating the temperature of strongly radiative shocks
  
  • Mabey Paul
  • Michel Thibault
  • Albertazzi Bruno
  • Falize Émeric
  • Charpentier Nicolas
  • Koenig Michel
  Physics of Plasmas, American Institute of Physics, 2020. A new method of calculating the temperature of strongly radiative shocks (Mihalas number of order unity or lower) is proposed. By including ionization, radiative energy and radiative flux terms in the Rankine-Hugoniot jump conditions across the shock front, a new, self-consistent method of calculating the temperature of radiative shocks is developed. The method is compared to those used to calculate temperature in previous works using similar methods, including those which partially included radiative and/or ionization effects. The method is also compared to experimental data, taken from the literature, as well as SESAME equation of state tables and radiative hydrodynamics simulations. The results show the importance of including all radiative terms for the case of strongly radiative shocks. This result has important implications for the design and interpretation of future laboratory experiments where ever faster radiative shocks may be generated. Previously unseen phenomena could be accessible when the radiative energy plays a significant role in the system. (10.1063/5.0008301)
  DOI : 10.1063/5.0008301
• Physics of chromatic focusing, post-acceleration and bunching of laser-driven proton beams in helical coil targets
  
  • Bardon M
  • Moreau J
  • Romagnani L
  • Rousseaux C
  • Ferri M
  • Lefévre F
  • Lantuéjoul I
  • Etchessahar B
  • Bazzoli S
  • Farcage D
  • Maskrot H
  • Serres F
  • Chevrot M
  • Loyez E
  • Veuillot E
  • Cayzac W
  • Vauzour B
  • Boutoux G
  • Sary G
  • Compant La Fontaine A
  • Gremillet L
  • Poyé A
  • d'Humiéres E
  • Tikhonchuk V
  Plasma Physics and Controlled Fusion, IOP Publishing, 2020, 62 (12), pp.125019. To increase the fluence and maximum energy of laser-driven proton beams in view of potential applications such as isochoric heating of dense material or isotope production, it has been proposed to attach a helical coil normally to the rear side of the irradiated target. By driving the target discharge current pulse through the coil, this scheme allows a fraction of the proton beam to be selected in energy and to be focused and further accelerated. The previously published results are extended to higher laser pulse energies and longer coils. This leads to an increased number of guided protons and the generation of several proton bunches. Large scale particle-in-cell simulations with realistic boundary conditions reproduce well the experimental results. A detailed analysis of the numerical simulations and an analytical model demonstrate that the current propagation along a helical wire differs from the one of a linear or folded wire. In a helical wire, the current pulse is subject to velocity dispersion, which results in progressive modification of its spatial profile, and so in proton bunch trapping and focusing. (10.1088/1361-6587/abbe35)
  DOI : 10.1088/1361-6587/abbe35
• On the growth of the thermally modified non-resonant streaming instability
  
  • Marret A.
  • Ciardi A.
  • Smets R.
  • Fuchs J.
  Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2020, 500 (2), pp.2302-2315. The cosmic rays non-resonant streaming instability is believed to be the source of substantial magnetic field amplification. In this work, we investigate the effects of the ambient plasma temperature on the instability and derive analytical expressions of its growth rate in the hot, demagnetized regime of interaction. To study its non-linear evolution, we perform hybrid-PIC simulations for a wide range of temperatures. We find that in the cold limit, about two-thirds of the cosmic rays drift kinetic energy is converted into magnetic energy. Increasing the temperature of the ambient plasma can substantially reduce the growth rate and the magnitude of the saturated magnetic field. (10.1093/mnras/staa3465)
  DOI : 10.1093/mnras/staa3465