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E. d’Humières,
J. Rassuchine,
S. Baton,
J. Fuchs,
P. Guillou,
M. Koenig, L. Gremillet,
C. Rousseaux,
R. Kodama,
M. Nakatsutsumi, [......],
A. Morace,
R. Redaelli,
F. Dorchies,
C. Fourment,
J. J. Santos,
J. Adams,
G. Korgan,
S. Malekos,
Y. Sentoku,
T. E. Cowan
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ABSTRACT: An improved Monte Carlo collisional scheme modeling both elastic and inelastic interactions has been implemented into the particle-in-cell code CALDER [E. Lefebvre et al., Nucl. Fusion 43, 629 (2003)]. Based on the technique proposed by Nanbu and Yonemura [J. Comput. Phys. 145, 639 (1998)] allowing to handle arbitrarily weighted macro-particles, this binary collision scheme uses a more compact and accurate relativistic formulation than the algorithm recently worked out by Sentoku and Kemp [J. Comput. Phys. 227, 6846 (2008)]. Our scheme is validated through several test cases, demonstrating, in particular, its capability of modeling the electrical resistivity and stopping power of a solid-density plasma over a broad parameter range. A relativistic collisional ionization scheme is developed within the same framework, and tested in several physical scenarios. Finally, our scheme is applied in a set of integrated particle-in-cell simulations of laser-driven fast electron transport.
Physics of Plasmas 08/2012; 19(8):083104. · 2.15 Impact Factor
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S. D. Baton,
M. Koenig,
J. Fuchs, L. Gremillet,
C. Rousseaux,
D. Batani,
A. Morace,
M. Nakatsutsumi,
R. Kodama,
T. Norimatsu,
A. Nishida,
F. Dorchies,
C. Fourment,
J. J. Santos,
J. Rassuchine,
T. Cowan
[show abstract]
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ABSTRACT: We present experimental and numerical results obtained at LULI (Laboratoire pour l’Utilisation des Lasers intenses) on propagation and energy deposition of laser-generated fast electrons into conical targets. The experimental measurements
were performed by means of several diagnostics in order to assess the predicted benefit of conical targets over standard planar
ones. Various configurations have been tried, regarding the laser parameters with the aim of optimizing the laser-to-target
coupling. Our best results have been obtained when the laser was frequency-doubled at 0.53 μm, corresponding to interaction
conditions without laser pedestal due to the ASE (Amplified Spontaneous Emission). Our data pinpoint the detrimental influence of the pre-plasma generated by the laser pedestal at 1.057 μm, whose confinement
is enhanced in conical geometry as evidenced by shadowgraphic measurements which is also confirmed by 2D Cu-Ka transverse images obtained from Cu cones. The consequence is the filling of the cone, preventing the laser beam from efficiently
reaching the cone tip. These experimental results are compared to 2D PIC simulations modeling of the laser-cone interaction.
The European Physical Journal Special Topics 04/2012; 175(1):77-82. · 1.56 Impact Factor
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E. d’Humières,
J. Rassuchine,
S. Baton,
J. Fuchs,
P. Guillou,
M. Koenig, L. Gremillet,
C. Rousseaux,
R. Kodama,
M. Nakatsutsumi, [......],
A. Morace,
R. Redaelli,
F. Dorchies,
C. Fourment,
J. J. Santos,
J. Adams,
G. Korgan,
S. Malekos,
Y. Sentoku,
T. E. Cowan
[show abstract]
[hide abstract]
ABSTRACT: Obtaining keV ion temperatures at solid density, i.e. “warm dense matter”, in the laboratory would be of great interest to
measure opacity and equations of state of matter under extremes conditions. Here we report a new means to effectively confine
the energetic electrons and localize the energy deposition to a small, more uniformly heated, volume at the tip of nanofabricated
micro-cone targets. This is achieved with very high contrast laser irradiation, which interacts with the cone wall to generate
strong (~10 MG) localized resistive magnetic fields within the target bulk. Temperatures of up to ~200 eV are observed, with
an input laser energy of 10 J. This new means has been investigated both experimentally and with Particle-In-Cell simulations.
The European Physical Journal Special Topics 04/2012; 175(1):89-95. · 1.56 Impact Factor
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P. Antici,
J. Fuchs,
M. Borghesi,
T. Grismayer,
S. Atzeni,
C. A. Cecchetti, L. Gremillet,
A. Mancic,
P. Mora,
A. C. Pipahl,
A. Schiavi,
T. Toncian,
O. Willi,
P. Audebert
[show abstract]
[hide abstract]
ABSTRACT: We have used time and space resolved interferometry to measure the dynamics of a plasma expanding off the surface of a solid
target. This allows accessing 1) the time- and space-resolved dynamics of the fast electrons (laser-accelerated from solids
and expanding into vacuum from the rear target surface), and of the energy partition into bulk (cold) electrons and 2) the
expansion velocity of an isochorically heated target, from which information about the heating process can be retrieved.
The European Physical Journal Special Topics 04/2012; 175(1):139-142. · 1.56 Impact Factor
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ABSTRACT: In this paper, we derive coupled envelope equations modeling the growth of
stimulated Raman scattering (SRS) in a multi-dimensional geometry, and
accounting for nonlinear kinetic effects. In particular, our envelope equations
allow for the nonlinear reduction of the Landau damping rate, whose decrease
with the plasma wave amplitude depends on the rate of side-loss. Account is
also made of the variations in the extent of the plasma wave packet entailed by
the collisionless dissipation due to trapping. The dephasing between the
electron plasma wave (EPW) and the laser drive, as well as the self-focussing
of the plasma wave, both induced by the EPW nonlinear frequency shift, are also
included in our envelope equations. These equations are solved in a
multi-dimensional geometry using our code dubbed BRAMA, whose predictions
regarding the evolution of Raman reflectivity as a function of the laser
intensity are compared against previously published PIC results, thus
illustrating the ability of BRAMA simulations to provide the correct laser
threshold intensity for SRS, as well as the right order of magnitude of Raman
reflectivity above threshold.
12/2011;
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D Batani,
M Koenig,
S Baton,
F Perez,
L A Gizzi,
P Koester,
L Labate,
J Honrubia,
L Antonelli,
A Morace, [......],
K Lancaster,
Ch Spindloe,
M Tolley,
D Neely,
M Kozlová,
J Nejdl,
B Rus,
J Wolowski,
J Badziak,
F Dorchies
[show abstract]
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ABSTRACT: This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to 'advanced ignition schemes', i.e. the fast ignition and the shock ignition approaches to inertial fusion. Such schemes are aimed at achieving a higher gain, as compared with the classical approach which is used in NIF, as required for future reactors, and make fusion possible with smaller facilities.In particular, a series of experiments related to fast ignition were performed at the RAL (UK) and LULI (France) Laboratories and studied the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser–plasma coupling in the 1016 W cm−2 intensity regime of interest for shock ignition.
Plasma Physics and Controlled Fusion 11/2011; 53(12):124041. · 2.42 Impact Factor
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F Pérez,
A Debayle,
J Honrubia,
M Koenig,
D Batani,
S D Baton,
F N Beg,
C Benedetti,
E Brambrink,
S Chawla, [......],
P Nicolai,
J Pasley,
R Ramis,
M Richetta,
J J Santos,
A Sgattoni,
C Spindloe,
B Vauzour,
T Vinci,
L Volpe
[show abstract]
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ABSTRACT: Fast electrons produced by a 10 ps, 160 J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. K(α)-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter.
Physical Review Letters 08/2011; 107(6):065004. · 7.37 Impact Factor
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[show abstract]
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ABSTRACT: A novel numerical modeling of field ionization in PIC (Particle In Cell) codes is presented. Based on the quasistatic approximation of the ADK (Ammosov Delone Krainov) theory and implemented through a Monte Carlo scheme, this model allows for multiple ionization processes. Two-dimensional PIC simulations are performed to analyze the cut-off energies of the laser-accelerated carbon ions measured on the UHI 10 Saclay facility. The influence of the target and the hydrocarbon pollutant composition on laser-accelerated carbon ion energies is demonstrated.
Physics of Plasmas 03/2011; 18(3):033107-033107-7. · 2.15 Impact Factor
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D Batani,
M Koenig,
S Baton,
F Perez,
L A Gizzi,
P Koester,
L Labate,
J Honrubia,
A Debayle,
J Santos, [......],
P Norreys,
M Kozlova,
J Nejdl,
B Rus,
L Antonelli,
A Morace,
L Volpe,
J Davies,
J Wolowski,
J Badziak
DIODE-PUMPED HIGH ENERGY AND HIGH POWER LASERS ELI: ULTRARELATIVISTIC LASER-MATTER INTERACTIONS AND PETAWATT PHOTONICS AND HIPER: THE EUROPEAN PATHWAY TO LASER ENERGY; 01/2011
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D Batani,
M Koenig,
S Baton,
F Perez,
L A Gizzi,
P Koester,
L Labate,
J Honrubia,
L Antonelli,
A Morace, [......],
K Lancaster,
Ch Spindloe,
M Tolley,
D Neely,
M Kozlová,
J Nejdl,
B Rus,
J Wolowski,
J Badziak,
F Dorchies
Plasma Physics and Controlled Fusion 01/2011; · 2.42 Impact Factor
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[show abstract]
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ABSTRACT: The interest in relativistic beam-plasma instabilities has been greatly rejuvenated over the past two decades by novel concepts in laboratory and space plasmas. Recent advances in this long-standing field are here reviewed from both theoretical and numerical points of view. The primary focus is on the two-dimensional spectrum of unstable electromagnetic waves growing within relativistic, unmagnetized, and uniform electron beam-plasma systems. Although the goal is to provide a unified picture of all instability classes at play, emphasis is put on the potentially dominant waves propagating obliquely to the beam direction, which have received little attention over the years. First, the basic derivation of the general dielectric function of a kinetic relativistic plasma is recalled. Next, an overview of two-dimensional unstable spectra associated with various beam-plasma distribution functions is given. Both cold-fluid and kinetic linear theory results are reported, the latter being based on waterbag and Maxwell–Jüttner model distributions. The main properties of the competing modes (developing parallel, transverse, and oblique to the beam) are given, and their respective region of dominance in the system parameter space is explained. Later sections address particle-in-cell numerical simulations and the nonlinear evolution of multidimensional beam-plasma systems. The elementary structures generated by the various instability classes are first discussed in the case of reduced-geometry systems. Validation of linear theory is then illustrated in detail for large-scale systems, as is the multistaged character of the nonlinear phase. Finally, a collection of closely related beam-plasma problems involving additional physical effects is presented, and worthwhile directions of future research are outlined.
Physics of Plasmas 12/2010; 17(12):120501-120501-36. · 2.15 Impact Factor
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ABSTRACT: A technique developed to measure in time and space the dynamics of the electron populations resulting from the irradiation of thin solids by ultraintense lasers is presented. It is a phase reflectometry technique that uses an optical probe beam reflecting off the target rear surface. The phase of the probe beam is sensitive to both laser-produced fast electrons of low-density streaming into vacuum and warm solid density electrons that are heated by the fast electrons. A time and space resolved interferometer allows to recover the phase of the probe beam sampling the target. The entire diagnostic is computationally modeled by calculating the probe beam phase when propagating through plasma density profiles originating from numerical calculations of plasma expansion. Matching the modeling to the experimental measurements allows retrieving the initial electron density and temperature of both populations locally at the target surface with very high temporal and spatial resolution (~4 ps, 6 μm). Limitations and approximations of the diagnostic are discussed and analyzed.
The Review of scientific instruments 11/2010; 81(11):113302. · 1.52 Impact Factor
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J J Santos,
D Batani,
P McKenna,
S D Baton,
F Dorchies,
A Dubrouil,
C Fourment,
S Hulin,
E d'Humières,
P H Nicolaï, L Gremillet,
A Debayle,
J J Honrubia,
P Carpeggiani,
M Veltcheva,
M N Quinn,
E Brambrink,
V Tikhonchuk
[show abstract]
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ABSTRACT: We present results from an experimental characterization of fast electron transport in high density plasmas created by 1D shock wave compression. The Kα fluorescence from a Cu layer embedded in Al or CH foil targets is measured. We use long laser pulses (LP) with 180 J, 1.5 ns, 0.53μm to compress the foils by shock wave propagation to 2-3 times their solid density and heat them to ~ 4eV (close to the Fermi temperature). A counter-propagating high-intensity short laser pulse (SP), with 40 J, 1 ps, 57×1019 Wcm−2, generates intense currents of fast electrons which propagate through the deep regions of the target just before shock breakthrough. The results are compared to the uncompressed, solid density case (without the LP beam). The complete set of measurements is compared to numerical results, including a 2D hydrodynamic description of the compression and pre-pulse effects, 2D PIC simulations of the SP beam interaction and both hybrid and PIC simulations of the electron transport in the target depth and sheaths. In the case of the non-compressed targets we need to take fast electron refluxing into account to reproduce the experimental results. By exploring the domain of warm temperatures, we identify a regime for the incident fast electron current density, 1010 < jh < 1012 Acm−2, for which the collective mechanisms of electron transport differs appreciably between solid density and compressed matter.
Journal of Physics Conference Series 09/2010; 244(2):022060.
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ABSTRACT: We have analyzed the transport of hot electrons generated in the interaction between a short-pulse, ultra-high intensity laser beam (pulse duration τ<ps, intensity Iλ > 1018 W.cm 2.um2) and a solid or dense target through the use of proton emission imaging. We used targets of different material (Cu, Al, Au) with a regularly modulated rear target surface in order to compare the electron transport in different conditions. As result, we see that the electron transport depends on the target material and on the interaction conditions.
Journal of Physics Conference Series 09/2010; 244(2):022016.
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A Ravasio,
L Romagnani,
S Le Pape,
A Benuzzi-Mounaix,
C Cecchetti,
D Batani,
T Boehly,
M Borghesi,
R Dezulian, L Gremillet, [......],
A MacKinnon,
N Ozaki,
H S Park,
P Patel,
A Schiavi,
T Vinci,
R Clarke,
M Notley,
S Bandyopadhyay,
M Koenig
[show abstract]
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ABSTRACT: In this paper we report on the radiography of a shock-compressed target using laser produced proton beams. A low-density carbon foam target was shock compressed by long pulse high-energy laser beams. The shock front was transversally probed with a proton beam produced in the interaction of a high intensity laser beam with a gold foil. We show that from radiography data, the density profile in the shocked target can be deduced using Monte Carlo simulations. By changing the delay between long and short pulse beams, we could probe different plasma conditions and structures, demonstrating that the details of the steep density gradient can be resolved. This technique is validated as a diagnostic for the investigation of warm dense plasmas, allowing an in situ characterization of high-density contrasted plasmas.
Physical Review E 07/2010; 82(1 Pt 2):016407. · 2.26 Impact Factor
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ABSTRACT: Implicit particle-in-cell codes offer advantages over their explicit counterparts in that they suffer weaker stability constraints on the need to resolve the higher frequency modes of the system. This feature may prove particularly valuable for modeling the interaction of high-intensity laser pulses with overcritical plasmas, in the case where the electrostatic modes in the denser regions are of negligible influence on the physical processes under study. To this goal, we have developed the new two-dimensional electromagnetic code ELIXIRS (standing for ELectromagnetic Implicit X-dimensional Iterative Relativistic Solver) based on the relativistic extension of the so-called Direct Implicit Method [D. Hewett, A.B. Langdon, Electromagnetic direct implicit plasma simulation, J. Comput. Phys. 72 (1987) 121–155]. Dissipation-free propagation of light waves into vacuum is achieved by an adjustable-damping electromagnetic solver. In the highdensity case where the Debye length is not resolved, satisfactory energy conservation is ensured by the use of high-order weight factors. In this paper, we first derive the electromagnetic direct implicit method as a simplified Newton scheme. Its linear properties are then investigated through numerically solving the dispersion relations obtained for both light and plasma waves, accounting for finite space and time steps. Finally, our code is successfully benchmarked against explicit particle-in-cell simulations for two kinds of physical problems: plasma expansion into vacuum and relativistic laser–plasma interaction. In both cases, we will demonstrate the robustness of the implicit solver for crude discretizations, as well as the gains in efficiency which can be realized over standard explicit simulations.
Journal of Computational Physics 06/2010; 229(12):4781-4812. · 2.31 Impact Factor
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[show abstract]
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ABSTRACT: The collisional dynamics of a relativistic electron jet in a magnetized plasma are investigated within the framework of kinetic theory. The relativistic Fokker–Planck equation describing slowing down, pitch angle scattering, and cyclotron rotation is derived and solved. Based on the solution of this Fokker–Planck equation, an analytical formula for the root mean square spot size transverse to the magnetic field is derived and this result predicts a reduction in radial transport. Some comparisons with particle-in-cell simulation are made and confirm striking agreement between the theory and the simulation. For fast electron with 1 MeV typical kinetic energy interacting with a solid density hydrogen plasma, the energy deposition density in the transverse direction increases by a factor 2 for magnetic field of the order of 1 T. Along the magnetic field, the energy deposition profile is unaltered compared with the field-free case.
Physics of Plasmas 03/2010; 17(3):033106-033106-9. · 2.15 Impact Factor
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[show abstract]
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ABSTRACT: Following a recent Letter by Bret et al. Phys. Rev. Lett. 100 205008 (2008), we present a detailed report of the entire unstable k spectrum of a relativistic collisionless beam-plasma system within a fully kinetic framework. In contrast to a number of previously published studies, our linear analysis makes use of smooth momentum distribution functions of the Maxwell-Jüttner form. The three competing classes of instabilities, namely, two-stream, filamentation, and oblique modes, are dealt with in a unified manner, no approximation being made regarding the beam-plasma densities, temperatures, and drift energies. We investigate the hierarchy between the competing modes, paying particular attention to the relatively poorly known quasielectrostatic oblique modes in the regime where they govern the system. The properties of the fastest growing oblique modes are examined in terms of the system parameters and compared to those of the dominant two-stream and filamentation modes.
Phys. Rev. E. 03/2010; 81(3).
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[show abstract]
[hide abstract]
ABSTRACT: Following a recent Letter by Bret [Phys. Rev. Lett. 100, 205008 (2008)], we present a detailed report of the entire unstable k spectrum of a relativistic collisionless beam-plasma system within a fully kinetic framework. In contrast to a number of previously published studies, our linear analysis makes use of smooth momentum distribution functions of the Maxwell-Jüttner form. The three competing classes of instabilities, namely, two-stream, filamentation, and oblique modes, are dealt with in a unified manner, no approximation being made regarding the beam-plasma densities, temperatures, and drift energies. We investigate the hierarchy between the competing modes, paying particular attention to the relatively poorly known quasielectrostatic oblique modes in the regime where they govern the system. The properties of the fastest growing oblique modes are examined in terms of the system parameters and compared to those of the dominant two-stream and filamentation modes.
Physical Review E 03/2010; 81(3 Pt 2):036402. · 2.26 Impact Factor
