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2017
"Interaction of Ultraintense Laser Vortices with Plasma Mirrors"
Denoeud A, Chopineau L, Leblanc A et Quéré F, Phys. Rev. Lett., January, 2017. Vol. 118(3), pp. 033902-. American Physical Society, (2017).
Abstract: Laser beams carrying orbital angular momentum (OAM) have found major applications in a variety of scientific fields, and their potential for ultrahigh-intensity laser-matter interactions has since recently been considered theoretically. We present an experiment where such beams interact with plasma mirrors up to laser intensities such that the motion of electrons in the laser field is relativistic. By measuring the spatial intensity and phase profiles of the high-order harmonics generated in the reflected beam, we obtain evidence for the helical wavefronts of the high-intensity laser at focus, and study the conservation of OAM in highly nonlinear optical processes at extreme laser intensities. The physical effects determining the field mode content of the twisted harmonic beams are elucidated.
BibTeX:
@article{denoeud2017,
  author = {Denoeud, A. and Chopineau, L. and Leblanc, A. and Quéré, F.},
  title = {Interaction of Ultraintense Laser Vortices with Plasma Mirrors},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2017},
  volume = {118},
  number = {3},
  pages = {033902--},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.118.033902},
  doi = {10.1103/PhysRevLett.118.033902}
}
"Plasma holograms for ultrahigh-intensity optics"
Leblanc A, Denoeud A, Chopineau L, Mennerat G, Martin P et Quere F, Nat Phys., January, 2017. Vol. advance online publication, pp. -. Nature Publishing Group. (2017).
Abstract: The manipulation of ultraintense laser beams gets increasingly challenging with growing laser peak power, as the breakdown of conventional optics imposes ever larger beam diameters. Using compact plasma-based optical elements to control or even generate such beams is a promising approach, since plasmas can sustain considerable light intensities. We introduce a new type of plasma optics, called plasma holograms, by initiating plasma expansion on a flat solid target with a holographic prepulse beam focus. A modulated plasma surface then grows out of the target after ionization, which can be used for several picoseconds to diffract and spatially shape ultraintense laser beams. On the basis of this concept, we demonstrate the generation of fork plasma gratings, which we use to induce optical vortices on a femtosecond laser beam as well as its high-order harmonics, at intensities exceeding 1019Wcm-2. These plasma holograms open up a whole new range of possibilities for the manipulation of ultraintense lasers and the generation of structured coherent short-wavelength sources.
BibTeX:
@article{leblanc2017,
  author = {Leblanc, A. and Denoeud, A. and Chopineau, L. and Mennerat, G. and Martin, Ph. and Quere, F.},
  title = {Plasma holograms for ultrahigh-intensity optics},
  journal = {Nat Phys},
  publisher = {Nature Publishing Group},
  year = {2017},
  volume = {advance online publication},
  pages = {--},
  url = {http://dx.doi.org/10.1038/nphys4007},
  doi = {10.1038/nphys4007}
}
"Dynamic wavefront rotation in the attosecond lighthouse"
Balogh E, Zhang C, Ruchon T, Hergott J-F, Quere F, Corkum P, Nam CH et Kim KT , Optica., In Optica. Vol. 4(1), pp. 48-53. OSA, (2017).
Abstract: Attosecond pulses propagating in different directions, generated in a rotating wavefront of a driving laser field, can provide a source of multiple isolated attosecond pulses. Clear spatial separation of the attosecond pulses is attained if the divergence of the individual attosecond pulse is smaller than their angular separation, which is limited by the bandwidth of the driving laser pulse. Here we demonstrate both experimentally and numerically that an additional wavefront rotation is imposed during the propagation of the driving laser pulse in a highly ionizing medium. This dynamic wavefront rotation enables the generation of the isolated attosecond pulse even in the case when the conditions derived from a linear diffraction theory do not permit the angular separation. The described nonlinear phenomenon has its roots in the half-cycle ionization events, and may open up new ways to study strong field processes in highly ionizing media.
BibTeX:
@article{Balogh2017,
  author = {Balogh, Emeric and Zhang, Chunmei and Ruchon, Thierry and Hergott, Jean-Francois and Quere, Fabien and Corkum, Paul and Nam, Chang Hee and Kim, Kyung Taec},
  title = {Dynamic wavefront rotation in the attosecond lighthouse},
  booktitle = {Optica},
  journal = {Optica},
  publisher = {OSA},
  year = {2017},
  volume = {4},
  number = {1},
  pages = {48--53},
  url = {http://www.osapublishing.org/optica/abstract.cfm?URI=optica-4-1-48},
  doi = {10.1364/OPTICA.4.000048}
}
2016
"High field plasmonics and laser-plasma acceleration in solid targets"
Sgattoni A, Fedeli L, Cantono G, Ceccotti T et Macchi A, Plasma Physics and Controlled Fusion. Vol. 58(1), pp. 014004-, (2016).
Abstract: The interaction of low intensity laser pulses with metal nano-structures is at the basis of plasmonics and the excitation of surface plasmon polaritons (SP) is one of its building blocks. Some of the configurations adopted in classical plasmonics can be explored considering high intensity lasers interacting with properly structured targets. SP excitation at intensities such that the electrons quiver at relativistic velocities, poses new questions and might open new frontiers for manipulation and amplification of high power laser pulses. Here we discuss two configurations which show evidence of the resonant coupling between relativistically intense laser pulses with the SPs on plasma targets with surface modulations. Evidences of SP excitation were observed in a recent experiment when a high contrast (1012), high intensity laser pulse ($I=5\centerdot {{10}^{19}}$ W cm−2) was focussed on a grating target (engraved surface at sub-micron scale); a strong emission of multi-MeV electron bunches accelerated by SPs was observed only in conditions for the resonant SP excitation. Theoretical and numerical analysis of the Light-Sail (LS) Radiation Pressure Acceleration (RPA) regime show how the plasmonic resonant coupling of the laser light with the target rippling, affects the growth of Rayleigh Taylor Instability (RTI) driven by the radiation pressure.
BibTeX:
@article{Sgattoni2016,
  author = {Sgattoni, A and Fedeli, L and Cantono, G and Ceccotti, T and Macchi, A},
  title = {High field plasmonics and laser-plasma acceleration in solid targets},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2016},
  volume = {58},
  number = {1},
  pages = {014004--},
  url = {http://stacks.iop.org/0741-3335/58/i=1/a=014004},
  doi = {10.1088/0741-3335/58/1/014004}
}
"Ion acceleration in the transparent regime and the critical influence of the plasma density scale length"
Loch RA, Ceccotti T, Quéré F, George H, Bonnaud G, Réau F, D'Oliveira P, Luttikhof MJH, Bijkerk F, Boller K-J, Blaclard G et Combis P, Physics of Plasmas., In Physics of Plasmas., September, 2016. Vol. 23(9), pp. 093117-. American Institute of Physics, (2016).
Abstract: The influence of a plasma density gradient on ions accelerated along the specular (back reflection) direction in the transparent Target Normal Sheath Acceleration regime is investigated. Enhanced acceleration of ions is experimentally observed in this regime using high-intensity and ultra-high contrast laser pulses and extremely thin foils of few nanometer thicknesses. The experimental trend for the maximum proton energy appeared quite different from the already published numerical results in this regime where an infinitely steep plasma gradient was assumed. We showed that for a realistic modelling, a finite density gradient has to be taken into account. By means of particle-in-cell (PIC) simulations, we studied for the first time the influence of the plasma density scale length on ion acceleration from these nanofoil targets. Through a qualitative agreement between our numerical particle-in-cell simulations and our experiments, the main conclusion with regard to the experimental requirements is that, in the transparent regime evidenced with nanofoils as compared to the opaque regime, the plasma expansion has to be taken into account and both the pulse contrast and the damage threshold of the material are essential parameters.
The influence of a plasma density gradient on ions accelerated along the specular (back reflection) direction in the transparent Target Normal Sheath Acceleration regime is investigated. Enhanced acceleration of ions is experimentally observed in this regime using high-intensity and ultra-high contrast laser pulses and extremely thin foils of few nanometer thicknesses. The experimental trend for the maximum proton energy appeared quite different from the already published numerical results in this regime where an infinitely steep plasma gradient was assumed. We showed that for a realistic modelling, a finite density gradient has to be taken into account. By means of particle-in-cell (PIC) simulations, we studied for the first time the influence of the plasma density scale length on ion acceleration from these nanofoil targets. Through a qualitative agreement between our numerical particle-in-cell simulations and our experiments, the main conclusion with regard to the experimental requirements is that, in the transparent regime evidenced with nanofoils as compared to the opaque regime, the plasma expansion has to be taken into account and both the pulse contrast and the damage threshold of the material are essential parameters.
BibTeX:
@article{Loch2016,
  author = {Loch, R. A. and Ceccotti, T. and Quéré, F. and George, H. and Bonnaud, G. and Réau, F. and D'Oliveira, P. and Luttikhof, M. J. H. and Bijkerk, F. and Boller, K.-J. and Blaclard, G. and Combis, P.},
  title = {Ion acceleration in the transparent regime and the critical influence of the plasma density scale length},
  booktitle = {Physics of Plasmas},
  journal = {Physics of Plasmas},
  publisher = {American Institute of Physics},
  year = {2016},
  volume = {23},
  number = {9},
  pages = {093117--},
  url = {http://dx.doi.org/10.1063/1.4962571},
  doi = {10.1063/1.4962571}
}
"Electron injector for compact staged high energy accelerator"
Audet T, Desforges F, Maitrallain A, Dobosz Dufrénoy S, Bougeard M, Maynard G, Lee P, Hansson M, Aurand B, Persson A, González IG, Monot P, Wahlström C-G, Lundh O et Cros B, ScienceDirect, in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment., In 2nd European Advanced Accelerator Concepts Workshop - EAAC 2015., September, 2016. Vol. 829, pp. 304-308 , (2016).
Abstract: An electron injector for multi-stage laser wakefield experiments is presented. It consists of a variable length gas cell of small longitudinal dimension (View the MathML source <= 10mm). The gas filling process in this cell was characterized both experimentally and with fluid simulation. Electron acceleration experiments were performed at two different laser facilities. Results show low divergence and low pointing fluctuation electron bunches suitable for transport to a second stage, and a peaked energy distribution suitable for injection into the second stage wakefield accelerator.
BibTeX:
@article{,
  author = {Audet, T.L. and Desforges, F.G. and Maitrallain, A. and Dufrénoy, S Dobosznoy, S. and Bougeard, M. and Maynard, G. and Lee, P. and Hansson, M. and Aurand, B. and Persson, A. and González, I. Gallardo and Monot, P. and Wahlström, C-G and Lundh, O. and Cros, B.},
  title = {Electron injector for compact staged high energy accelerator},
  booktitle = {2nd European Advanced Accelerator Concepts Workshop - EAAC 2015},
  journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  year = {2016},
  volume = {829},
  pages = {304--308},
  url = {http://www.sciencedirect.com/science/article/pii/S0168900216000516},
  doi = {10.1016/j.nima.2016.01.035}
}
"Space-time characterization of ultra-intense femtosecond laser beams"
Pariente G, Gallet V, Borot A, Gobert O et Quéré F, Nat Photon., August, 2016. Vol. 10(8), pp. 547-553. Nature Publishing Group, (2016).
Abstract: Femtosecond lasers can now deliver ultrahigh intensities at focus, making it possible to induce relativistic motion of charged particles with light and opening the way to new generations of compact particle accelerators and X-ray sources. With diameters of up to tens of centimetres, ultra-intense laser beams tend to suffer from spatiotemporal distortions, that is, a spatial dependence of their temporal properties that can dramatically reduce their peak intensities. At present, however, these intense electromagnetic fields are characterized and optimized in space and time separately. Here, we present the first complete spatiotemporal experimental reconstruction of the field E(t,r) for a 100 TW peak-power laser, and reveal the spatiotemporal distortions that can affect such beams. This new measurement capability opens the way to in-depth characterization and optimization of ultra-intense lasers and ultimately to the advanced control of relativistic motion of matter with femtosecond laser beams structured in space-time.
BibTeX:
@article{Pariente2016,
  author = {Pariente, G. and Gallet, V. and Borot, A. and Gobert, O. and Quéré, F.},
  title = {Space-time characterization of ultra-intense femtosecond laser beams},
  journal = {Nat Photon},
  publisher = {Nature Publishing Group},
  year = {2016},
  volume = {10},
  number = {8},
  pages = {547--553},
  url = {http://dx.doi.org/10.1038/nphoton.2016.140},
  doi = {10.1038/nphoton.2016.140}
}
"Attosecond lighthouses in gases: A theoretical and numerical study"
Auguste T, Gobert O, Ruchon T et Quere F, Phys. Rev. A., Mar, 2016. Vol. 93, pp. 033825. American Physical Society, (2016).
Abstract: We present an extensive theoretical and numerical study of the attosecond lighthouse effect in gases. We study how this scheme impacts the spatiotemporal structure of the driving laser field all along the generation medium, and show that this can modify the phase matching relation governing high-harmonic generation (HHG) in gases. We then present a set of numerical simulations performed to test the robustness of the effect against variations of HHG parameters, and to identify possible solutions for relaxing the constraint on the driving laser pulse duration. We thus demonstrate that the lighthouse effect can actually be achieved with laser pulses consisting of up to ~8 optical periods available from current lasers without postcompression, for instance by using an appropriate combination of 800- and 1600-nm wavelength fields.
BibTeX:
@article{PhysRevA.93.033825,
  author = {Auguste, T. and Gobert, O. and Ruchon, T. and Quere, F.},
  title = {Attosecond lighthouses in gases: A theoretical and numerical study},
  journal = {Phys. Rev. A},
  publisher = {American Physical Society},
  year = {2016},
  volume = {93},
  pages = {033825},
  url = {http://link.aps.org/doi/10.1103/PhysRevA.93.033825},
  doi = {10.1103/PhysRevA.93.033825}
}
"Vacuum laser acceleration of relativistic electrons using plasma mirror injectors"
Thevenet M, Leblanc A, Kahaly S, Vincenti H, Vernier A, Quere F et Faure J, Nat Phys., April, 2016. Vol. 12(4), pp. 355-360. Nature Publishing Group, (2016).
Abstract: Accelerating particles to relativistic energies over very short distances using lasers has been a long-standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration. With the advent of petawatt lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.
BibTeX:
@article{Thevenet2016,
  author = {Thevenet, M. and Leblanc, A. and Kahaly, S. and Vincenti, H. and Vernier, A. and Quere, F. and Faure, J.},
  title = {Vacuum laser acceleration of relativistic electrons using plasma mirror injectors},
  journal = {Nat Phys},
  publisher = {Nature Publishing Group},
  year = {2016},
  volume = {12},
  number = {4},
  pages = {355--360},
  url = {http://www.nature.com/nphys/journal/v12/n4/full/nphys3597.html},
  doi = {10.1038/nphys3597}
}
"Localization of ionization-induced trapping in a laser wakefield accelerator using a density down-ramp"
Hansson, M., Audet, T. L., Ekerfelt, H., Aurand, B., González, I. G., Desforges, F. G., Davoine, X., Maitrallain, A., Reymond, S., Monot, P., Persson, A., Dobosz Dufrénoy, S. D., Wahlström, C., Cros, B. & Lundh, O , Plasma Physics and Controlled Fusion. vol. 58(5) p. 055009 , (2016).
Abstract: We report on a study on controlled trapping of electrons, by field ionization of nitrogen ions, in laser wakefield accelerators in variable length gas cells. In addition to ionization-induced trapping in the density plateau inside the cells, which results in wide, but stable, electron energy spectra, a regime of ionization-induced trapping localized in the density down-ramp at the exit of the gas cells, is found. The resulting electron energy spectra are peaked, with 10% shot-to-shot fluctuations in peak energy. Ionization-induced trapping of electrons in the density down-ramp is a way to trap and accelerate a large number of electrons, thus improving the efficiency of the laser-driven wakefield acceleration.
BibTeX:
@ARTICLE{Hansson2016,
  author = {Hansson, M and Audet, T L and Ekerfelt, H and Aurand, B and González,
	I Gallardo and Desforges, F G and Davoine, X and Maitrallain, A and
	Reymond, S and Monot, P and Persson, A and Dufrénoy, S Dobosz and
	Wahlström, C-G and Cros, B and Lundh, O},
  title = {Localization of ionization-induced trapping in a laser wakefield
	accelerator using a density down-ramp},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2016},
  volume = {58},
  pages = {055009--},
  number = {5},
  abstract = {We report on a study on controlled trapping of electrons, by field
	ionization of nitrogen ions, in laser wakefield accelerators in variable
	length gas cells. In addition to ionization-induced trapping in the
	density plateau inside the cells, which results in wide, but stable,
	electron energy spectra, a regime of ionization-induced trapping
	localized in the density down-ramp at the exit of the gas cells,
	is found. The resulting electron energy spectra are peaked, with
	10% shot-to-shot fluctuations in peak energy. Ionization-induced
	trapping of electrons in the density down-ramp is a way to trap and
	accelerate a large number of electrons, thus improving the efficiency
	of the laser-driven wakefield acceleration.},
  issn = {0741-3335},
  owner = {jubera},
  timestamp = {2016.03.25},
  url = {http://stacks.iop.org/0741-3335/58/i=5/a=055009}
}
"Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell"
Audet TL, Hansson M, Lee P, Desforges FG, Maynard G, Dobosz Dufrénoy S, Lehe R, Vay J-L, Aurand B, Persson A, Gallardo González I, Maitrallain A, Monot P, Wahlström C-G, Lundh O et Cros B, , Physics of Plasmas. Vol. 23(2), pp. 023110, (2016).
Abstract: Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of . Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and acceleratedcharge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. The interest of this regime for optimizing the bunch charge in a selected energy window is discussed.
BibTeX:
@article{Audet2016,
  author = {Audet, T. L. and Hansson, M. and Lee, P. and Desforges, F. G. and Maynard, G. and Dobosz Dufrenoy, S. and Lehe, R. and Vay, J.-L. and Aurand, B. and Persson, A. and Gallardo González, I. and Maitrallain, A. and Monot, P. and Wahlström, C.-G. and Lundh, O. and Cros, B.},
  title = {Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell},
  journal = {Physics of Plasmas},
  year = {2016},
  volume = {23},
  number = {2},
  pages = {023110},
  url = {http://scitation.aip.org/content/aip/journal/pop/23/2/10.1063/1.4942033}
}
"Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction"
Fedeli L, Sgattoni A, Cantono G, Garzella D, Réau F, Prencipe I, Passoni M, Raynaud M, Květoň M, Proska J, Macchi A et Ceccotti T, Phys. Rev. Lett., Jan, 2016. Vol. 116, pp. 015001. American Physical Society - (2016).
Abstract: The generation of energetic electron bunches by the interaction of a short, ultraintense (I>1019 W/cm2) laser pulse with “grating” targets has been investigated in a regime of ultrahigh pulse-to-prepulse contrast (1012). For incidence angles close to the resonant condition for surface plasmon excitation, a strong electron emission was observed within a narrow cone along the target surface, with energy spectra peaking at 5-8 MeV and total charge of ~ 100 pC . Both the energy and the number of emitted electrons were strongly enhanced with respect to simple flat targets. The experimental data are closely reproduced by three-dimensional particle-in-cell simulations, which provide evidence for the generation of relativistic surface plasmons and for their role in driving the acceleration process. Besides the possible applications of the scheme as a compact, ultrashort source of MeV electrons, these results are a step forward in the development of high-field plasmonics.
BibTeX:
@article{PhysRevLett.116.015001,
  author = {Fedeli, L. and Sgattoni, A. and Cantono, G. and Garzella, D. and Reau, F. and Prencipe, I. and Passoni, M. and Raynaud, M. and Kveton, M. and Proska, J. and Macchi, A. and Ceccotti, T.},
  title = {Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2016},
  volume = {116},
  pages = {015001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.116.015001},
  doi = {10.1103/PhysRevLett.116.015001}
}
"Detailed analysis of the effects of stencil spatial variations with arbitrary high-order finite-difference Maxwell solver"
Vincenti H et Vay J-L, Computer Physics Communications., March, 2016. Vol. 200, pp. 147-167, (2016).
Abstract: Very high order or pseudo-spectral Maxwell solvers are the method of choice to reduce discretization effects (e.g. numerical dispersion) that are inherent to low order Finite-Difference Time-Domain (FDTD) schemes. However, due to their large stencils, these solvers are often subject to truncation errors in many electromagnetic simulations. These truncation errors come from non-physical modifications of Maxwell’s equations in space that may generate spurious signals affecting the overall accuracy of the simulation results. Such modifications for instance occur when Perfectly Matched Layers (PMLs) are used at simulation domain boundaries to simulate open media. Another example is the use of arbitrary order Maxwell solver with domain decomposition technique that may under some condition involve stencil truncations at subdomain boundaries, resulting in small spurious errors that do eventually build up. In each case, a careful evaluation of the characteristics and magnitude of the errors resulting from these approximations, and their impact at any frequency and angle, requires detailed analytical and numerical studies. To this end, we present a general analytical approach that enables the evaluation of numerical errors of fully three-dimensional arbitrary order finite-difference Maxwell solver, with arbitrary modification of the local stencil in the simulation domain. The analytical model is validated against simulations of domain decomposition technique and PMLs, when these are used with very high-order Maxwell solver, as well as in the infinite order limit of pseudo-spectral solvers. Results confirm that the new analytical approach enables exact predictions in each case. It also confirms that the domain decomposition technique can be used with very high-order Maxwell solvers and a reasonably low number of guard cells with negligible effects on the whole accuracy of the simulation.
BibTeX:
@article{,
  author = {Vincenti, H. and Vay, J.-L.},
  title = {Detailed analysis of the effects of stencil spatial variations with arbitrary high-order finite-difference Maxwell solver},
  journal = {Computer Physics Communications},
  year = {2016},
  volume = {200},
  pages = {147--167},
  url = {http://www.sciencedirect.com/science/article/pii/S0010465515004208}
}
"An efficient and portable SIMD algorithm for charge/current deposition in Particle-In-Cell codes"
Vincenti H., Lehe R, Sasanka R et Vay J-L. ArXiv e-prints., (2016).
Abstract: In current computer architectures, data movement (from die to network) is by far the most energy consuming part of an algorithm (10pJ/word on-die to 10,000pJ/word on the network). To increase memory locality at the hardware level and reduce energy consumption related to data movement, future exascale computers tend to use more and more cores on each compute nodes ("fat nodes") that will have a reduced clock speed to allow for efficient cooling. To compensate for frequency decrease, machine vendors are making use of long SIMD instruction registers that are able to process multiple data with one arithmetic operator in one clock cycle. SIMD register length is expected to double every four years. As a consequence, Particle-In-Cell (PIC) codes will have to achieve good vectorization to fully take advantage of these upcoming architectures. In this paper, we present a new algorithm that allows for efficient and portable SIMD vectorization of current/charge deposition routines that are, along with the field gathering routines, among the most time consuming parts of the PIC algorithm. Our new algorithm uses a particular data structure that takes into account memory alignement constraints and avoids gather/scatter instructions that can significantly affect vectorization performances on current CPUs. The new algorithm was successfully implemented in the 3D skeleton PIC code PICSAR and tested on Haswell Xeon processors (AVX2-256 bits wide data registers). Results show a factor of ×2 to ×2.5 speed-up in double precision for particle shape factor of order 1 to 3. The new algorithm can be applied as is on future KNL (Knights Landing) architectures that will include AVX-512 instruction sets with 512 bits register lengths (8 doubles/16 singles).
BibTeX:
@article{Vincenti2016Bis,
  author = {VVincenti, H., and Lehe, R. and Sasanka, R. and  Vay, J-L.},
  title = {An efficient and portable SIMD algorithm for charge/current deposition in Particle-In-Cell codes},
  journal = {ArXiv e-prints},
  year = {2016},
  url = {http://adsabs.harvard.edu/abs/2016arXiv160102056V}
}
"Ptychographic measurements of ultrahigh-intensity laser-plasma interactions"
Leblanc A, Monchoce S, Bourassin-Bouchet C, Kahaly S et Quere F, Nat Phys., December, 2015. Vol. advance online publication, pp. -. Nature Publishing Group. (2016)
Abstract: The extreme intensities now delivered by femtosecond lasers make it possible to drive and control relativistic motion of charged particles with light, opening a path to compact particle accelerators and coherent X-ray sources. Accurately characterizing the dynamics of ultrahigh-intensity laser-plasma interactions as well as the resulting light and particle emissions is an essential step towards such achievements. This remains a considerable challenge, as the relevant scales typically range from picoseconds to attoseconds in time, and from micrometres to nanometres in space. In these experiments, owing to the extreme prevalent physical conditions, measurements can be performed only at macroscopic distances from the targets, yielding only partial information at these microscopic scales. This letter presents a major advance by applying the concepts of ptychography to such measurements, and thus retrieving microscopic information hardly accessible until now. This paves the way to a general approach for the metrology of extreme laser-plasma interactions on very small spatial and temporal scales.
BibTeX:
@article{Leblanc2015,
  author = {Leblanc, A. and Monchoce, S. and Bourassin-Bouchet, C. and Kahaly, S. and Quere, F.},
  title = {Ptychographic measurements of ultrahigh-intensity laser-plasma interactions},
  journal = {Nat Phys},
  publisher = {Nature Publishing Group},
  year = {2015},
  volume = {advance online publication},
  pages = {--},
  url = {http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3596.html},
  doi = {10.1038/nphys3596}
}
2015
"Enhanced electron acceleration via ultra-intense laser interaction with structured targets"
Fedeli L, Sgattoni A, Cantono G, Prencipe I, Passoni M, Klimo O, Proska J, Macchi A et Ceccotti T, SPIE Vol. 9514, pp. 95140R-95140R-8, (2015).
Abstract: The generation of energetic electrons by the interaction of a short laser pulse with solid “grating” targets, having a periodic groove on the irradiated surface, has been investigated in a regime of ultrahigh contrast (1012) and relativistically strong intensity (> 1019W/cm2). A strong enhancement of both the energy and number of electrons emitted from the target, with respect to at targets, has been observed for incidence angles close to the resonant condition for surface wave excitation. In particular we identified bunches of electrons with energies exceeding 10 MeV which are emitted in a direction close to the target surface. The experimental results are well reproduced by a three-dimensional particle-in-cell simulation, which confirms the dominant role of the surface wave in accelerating the electrons. These results are a step forward the development of high field plasmonics for a number of applications. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
BibTeX:
@inproceedings{Fideli2015,
  author = {Fedeli, Luca and Sgattoni, Andrea and Cantono, Giada and Prencipe, I. and Passoni, M. and Klimo, O. and Proska, J. and Macchi, Andrea and Ceccotti, T.},
  title = {Enhanced electron acceleration via ultra-intense laser interaction with structured targets},
  year = {2015},
  volume = {9514},
  pages = {95140R--95140R-8},
  url = {http://dx.doi.org/10.1117/12.2178816},
  doi = {10.1117/12.2178816}
}
"Spatio-temporal light springs: extended encoding of orbital angular momentum in ultrashort pulses"
Pariente G and Quéré F, In Optics Letters. Vol. 40(9), pp. 2037-2040. OSA. (2015).
Abstract: We introduce a new class of spatio-temporally coupled ultrashort laser beams, which are obtained by superimposing Laguerre-Gauss beams whose azimuthal mode index is correlated to their frequency. These beams are characterized by helical structures for their phase and intensity profiles, which both encode the orbital angular momentum carried by the light. They can easily be engineered in the optical range, and are naturally produced at shorter wavelengths when attosecond pulses are generated by intense femtosecond Laguerre-Gauss laser beams. These spatio-temporal "light springs" will allow for the transfer of the orbital angular momentum to matter by stimulated Raman scattering.
BibTeX:
@article{Pariente2015,
  author = {Pariente, G. and Quéré, F.},
  title = {Spatio-temporal light springs: extended encoding of orbital angular momentum in ultrashort pulses},
  booktitle = {Optics Letters},
  journal = {Opt. Lett.},
  publisher = {OSA},
  year = {2015},
  volume = {40},
  number = {9},
  pages = {2037--2040},
  url = {http://ol.osa.org/abstract.cfm?URI=ol-40-9-2037},
  doi = {10.1364/OL.40.002037}
}
"Analysis of electron injection in Laser Wakefield Acceleration using betatron emission in capillary tubes"
Desforges FG, Paradkar BS, Hansson M, Audet TL, Ju J, Gallardo-González I, Aurand B, Lee P, Senje L, Persson A, Dobosz Dufrénoy S, Lundh O, Maynard G, Monot P, Vay JL, Wahlström C-G and Cros B, Proc. SPIE 9514, Laser Acceleration of Electrons, Protons, and Ions III; and Medical Applications of Laser-Generated Beams of Particles III, 95140Z (May 14, 2015).
Abstract: The dynamics of ionization-induced electron injection in the high density (~ 1:2 * 1019cm-3) regime of Laser Wakefield Acceleration (LWFA) was investigated by analyzing betatron X-ray emission inside dielectric capillary tubes. A comparative study of the electron and betatron X-ray properties was performed for both self-injection and ionization-induced injection. Direct experimental evidence of early onset of ionization-induced injection into the plasma wave was obtained by mapping the X-ray emission zone inside the plasma. Particle-In-Cell (PIC) simulations showed that the early onset of ionization-induced injection, due to its lower trapping threshold, suppresses self-injection of electrons. An increase of X-ray fluence by at least a factor of two was observed in the case of ionization-induced injection due to an increased trapped charge compared to self-injection mechanism.
BibTeX:
@inproceedings{Desforges2015,
  author = {Desforges, F. G. and Paradkar, B. S. and Hansson, M. and Audet, T. L. and Ju, J. and Gallardo-González , I. and Aurand, B. and Lee, P. and Senje, L. and Persson, A. and Dobosz Dufrénoy, S. and Lundh, O. and Maynard, G. and Monot, P. and Vay, J. L. and Wahlström , C.-G. and Cros, B.},
  title = {Analysis of  electron injection in Laser Wakefield Acceleration using betatron emission in capillary tubes},
  year = {2015},
  volume = {9514},
  pages = {95140Z--95140Z-11},
  url = {http://dx.doi.org/10.1117/12.2178654},
  doi = {10.1117/12.2178654}
}
2014
"Dual spectral-band interferometry for spatio-temporal characterization of high-power femtosecond lasers"
Gallet V, Kahaly S, Gobert O and Quéré F, In Optics Letters. Vol. 39(16), pp. 4687-4690. OSA. (2014).
Abstract: We present and demonstrate a technique called RED-SEA TADPOLE for the spatio-temporal characterization of high peak power femtosecond lasers. It retains the basic principle of an existing method, where a scanning monomode fiber is utilized in an interferometric scheme to measure the spectral amplitude and phase at all points across an ultrashort laser beam. We combine this approach with dual spectral-band interferometry, to correct for all phase errors occurring in this interferometer, thus allowing for the simultaneous measurement of the beam wavefront and pulse front in a collimated beam of large diameter. The generic phase correction procedure implemented here can also be extended to other fiber optic device applications sensitive to phase fluctuations.
BibTeX:
@article{Gallet2014,
  author = {Gallet, V. and Kahaly, S. and Gobert, O. and Quéré, F.},
  title = {Dual spectral-band interferometry for spatio-temporal characterization of high-power femtosecond lasers},
  booktitle = {Optics Letters},
  journal = {Opt. Lett.},
  publisher = {OSA},
  year = {2014},
  volume = {39},
  number = {16},
  pages = {4687--4690},
  url = {http://ol.osa.org/abstract.cfm?URI=ol-39-16-4687},
  doi = {10.1364/OL.39.004687}
}
Fuchs J, Gonoskov A, Nakatsutsumi M, Nazarov W, Quéré F, Sergeev A et Yan X (2014), "Plasma devices for focusing extreme light pulses", The European Physical Journal Special Topics. Vol. 223(6), pp. 1169-1173.
Abstract: Since the inception of the laser, there has been a constant push toward increasing the laser peak intensity, as this has lead to opening the exploration of new territories, and the production of compact sources of particles and radiation with unprecedented characteristics. However, increasing the peak laser intensity is usually performed by enhancing the produced laser properties, either by lowering its duration or increasing its energy, which involves a great level of complexity for the laser chain, or comes at great cost. Focusing tightly is another possibility to increase the laser intensity, but this comes at the risk of damaging the optics with target debris, as it requires their placement in close proximity to the interaction region. Plasma devices are an attractive, compact alternative to tightly focus extreme light pulses and further increase the final laser intensity.
BibTeX:
@article{Fuchs2014,
  author = {Fuchs, J. and Gonoskov, A.A. and Nakatsutsumi, M. and Nazarov, W. and Quéré, F. and Sergeev, A.M. and Yan, X.Q.},
  title = {Plasma devices for focusing extreme light pulses},
  journal = {The European Physical Journal Special Topics},
  year = {2014},
  volume = {223},
  number = {6},
  pages = {1169--1173},
  url = {http://dx.doi.org/10.1140/epjst/e2014-02169-y},
  doi = {10.1140/epjst/e2014-02169-y}
}
"Optically Controlled Solid-Density Transient Plasma Gratings"
Monchocé S, Kahaly S, Leblanc A, Videau L, Combis P., Réau F, Garzella D, D'Oliveira P, Martin P and Quéré F, Phys. Rev. Lett., Vol. 112(14), pp. 145008-. American Physical Society. April, (2014).
Abstract: A general approach for optically controlled spatial structuring of overdense plasmas generated at the surface of initially plain solid targets is presented. We demonstrate it experimentally by creating sinusoidal plasma gratings of adjustable spatial periodicity and depth, and study the interaction of these transient structures with an ultraintense laser pulse to establish their usability at relativistically high intensities. We then show how these gratings can be used as a "spatial ruler" to determine the source size of the high-order harmonic beams produced at the surface of an overdense plasma. These results open new directions both for the metrology of laser-plasma interactions and the emerging field of ultrahigh intensity plasmonics.
BibTeX:
@article{Monchocé2014,
  author = {Monchocé, S. and Kahaly, S. and Leblanc, A. and Videau, L. and Combis,P., and Réau, F. and Garzella, D. and D'Oliveira, P. and Martin, Ph. and Quéré, F.},
  title = {Optically Controlled Solid-Density Transient Plasma Gratings},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2014},
  volume = {112},
  number = {14},
  pages = {145008--},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.112.145008},
  doi = {10.1103/PhysRevLett.112.145008}
}
"Enhanced stability of laser wakefield acceleration using dielectric capillary tubes"
Hansson M, Senje L, Persson A, Lundh O, Wahlström C-G, Desforges FG, Ju J, Audet TL, Cros B, Dobosz Dufrénoy S et Monot P, Phys. Rev. ST Accel. Beams., Mar, 2014. Vol. 17, pp. 031303. American Physical Society, (2014).
Abstract: The stability of beams of laser wakefield accelerated electrons in dielectric capillary tubes is experimentally investigated. These beams are found to be more stable in charge and pointing than the corresponding beams of electrons accelerated in a gas jet. Electron beams with an average charge of 43 pC and a standard deviation of 14% are generated. The fluctuations in charge are partly correlated to fluctuations in laser pulse energy. The pointing scatter of the electron beams is measured to be as low as 0.8 mrad (rms). High laser beam pointing stability improved the stability of the electron beams.
BibTeX:
@article{PhysRevSTAB.17.031303,
  author = {Hansson, M. and Senje, L. and Persson, A. and Lundh, O. and Wahlström, C-G. and Desforges, F. G. and Ju, J. and Audet, T. L. and Cros, B. and Dobosz Dufrénoy, S. and Monot, P.},
  title = {Enhanced stability of laser wakefield acceleration using dielectric capillary tubes},
  journal = {Phys. Rev. ST Accel. Beams},
  publisher = {American Physical Society},
  year = {2014},
  volume = {17},
  pages = {031303},
  url = {http://link.aps.org/doi/10.1103/PhysRevSTAB.17.031303},
  doi = {10.1103/PhysRevSTAB.17.031303}
}
"Applications of ultrafast wavefront rotation in highly nonlinear optics"
Quéré F, Vincenti H, Borot A, Monchocé S., Hammond TJ, Kim KT, Wheeler JA, Zhang C, Ruchon T, Auguste T, Hergott JF, Villeneuve DM, Corkum PB and Lopez-Martens R, Journal of Physics B: Atomic, Molecular and Optical Physics. Vol. 47(12), pp. 124004-. (2014).
Abstract: This paper provides an overview of ultrafast wavefront rotation of femtosecond laser pulses and its various applications in highly nonlinear optics, focusing on processes that lead to the generation of high-order harmonics and attosecond pulses. In this context, wavefront rotation can be exploited in different ways, to obtain new light sources for time-resolved studies, called 'attosecond lighthouses', to perform time-resolved measurements of nonlinear optical processes, using 'photonic streaking', or to track changes in the carrier-envelope relative phase of femtosecond laser pulses. The basic principles are explained qualitatively from different points of view, the experimental evidence obtained so far is summarized, and the perspectives opened by these effects are discussed.
BibTeX:
@article{Quéré2014,
  author = {Quéré, F and Vincenti, H and Borot, A and Monchocé, S., and Hammond, T J and Kim, Kyung Taec and Wheeler, J A and Zhang, Chunmei and Ruchon, T and Auguste, T and Hergott, J F and Villeneuve, D M and Corkum, P B and Lopez-Martens, R},
  title = {Applications of ultrafast wavefront rotation in highly nonlinear optics},
  journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  year = {2014},
  volume = {47},
  number = {12},
  pages = {124004--},
  url = {http://stacks.iop.org/0953-4075/47/i=12/a=124004},
  doi = {10.1088/0953-4075/47/12/124004}
}
"Dynamics of ionization-induced electron injection in the high density regime of laser wakefield acceleration"
Desforges FG, Paradkar BS, Hansson M, Ju J, Senje L, Audet TL, Persson A, Dobosz-Dufrénoy S, Lundh O, Maynard G, Monot P, Vay J-L, Wahlström C-G and Cros B, Physics of Plasmas (1994-present). Vol. 21(12), pp. (2014).
Abstract: The dynamics of ionization-induced electron injection in high density (~1.2 * 1019 cm-3) regime of laser wakefield acceleration is investigated by analyzing the betatron X-ray emission. In such high density operation, the laser normalized vector potential exceeds the injection-thresholds of both ionization-injection and self-injection due to self-focusing. In this regime, direct experimental evidence of early on-set of ionization-induced injection into the plasma wave is given by mapping the X-ray emission zone inside the plasma. Particle-In-Cell simulations show that this early on-set of ionization-induced injection, due to its lower trapping threshold, suppresses the trapping of self-injected electrons. A comparative study of the electron and X-ray properties is performed for both self-injection and ionization-induced injection. An increase of X-ray fluence by at least a factor of two is observed in the case of ionization-induced injection due to increased trapped charge compared to self-injection mechanism.
BibTeX:
@article{:/content/aip/journal/pop/21/12/10.1063/1.4903845,
  author = {Desforges, F. G. and Paradkar, B. S. and Hansson, M. and Ju, J. and Senje, L. and Audet, T. L. and Persson, A. and Dobosz-Dufrénoy, S. and Lundh, O. and Maynard, G. and Monot, P. and Vay, J.-L. and Wahlström, C.-G. and Cros, B.},
  title = {Dynamics of ionization-induced electron injection in the high density regime of laser wakefield acceleration},
  journal = {Physics of Plasmas (1994-present)},
  year = {2014},
  volume = {21},
  number = {12},
  pages = {-},
  url = {http://scitation.aip.org/content/aip/journal/pop/21/12/10.1063/1.4903845},
  doi = {10.1063/1.4903845}
}
"Energetic ions at moderate laser intensities using foam-based multi-layered targets"
Passoni M, Zani A, Sgattoni A, Dellasega D, Macchi A, Prencipe I, Floquet V, Martin P, Liseykina TV and Ceccotti T, Plasma Physics and Controlled Fusion. Vol. 56(4), pp. 045001 - (2014).
Abstract: The experimental feasibility of the laser-driven ion acceleration concept with multi-layered, foam-based targets has been investigated. Targets with the required features have been produced and characterized, exploiting the potential of the pulsed laser deposition technique. In the intensity range 1016-1017 W cm-2, they allow us to obtain maximum proton energies 2-3 times higher compared to bare solid targets, able to reach and surpass the MeV range with both low and ultrahigh contrast pulses. The results of two-dimensional particle-in-cell simulations, supporting the interpretation of the experimental results, and directions to exploit the concept also at ultrahigh intensities, are presented.
BibTeX:
@article{Passoni2014,
  author = {Passoni, M and Zani, A and Sgattoni, A and Dellasega, D and Macchi, A and Prencipe, I and Floquet, V and Martin, P and Liseykina, T V and Ceccotti, T},
  title = {Energetic ions at moderate laser intensities using foam-based multi-layered targets},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2014},
  volume = {56},
  number = {4},
  pages = {045001},
  url = {http://stacks.iop.org/0741-3335/56/i=4/a=045001},
  doi = {10.1088/0741-3335/56/4/045001}
}
"Enhanced stability of laser wakefield acceleration using dielectric capillary tubes"
Hansson M, Senje L,Persson A, Lundh O, Wahlström C.G, Desforges F.G, Lu J, Audet TL, Cros B, Dobosz Dufrénoy S, Monot P, Phys. Rev. ST Accel. Beams - (2014).
Abstract: The stability of beams of laser wakefield accelerated electrons in dielectric capillary tubes is experimentally investigated. These beams are found to be more stable in charge and pointing than the corresponding beams of electrons accelerated in a gas jet. Electron beams with an average charge of 43 pC and a standard deviation of 14% are generated. The fluctuations in charge are partly correlated to fluctuations in laser pulse energy. The pointing scatter of the electron beams is measured to be as low as 0.8 mrad (rms). High laser beam pointing stability improved the stability of the electron beams.
BibTeX:
@article{Hansson2014,
  author = {Hansson, M. and Senje M.  Persson, A. and Lundh, O. and Wahlström, C.G.and Desforges, F.G. and Lu, J. and. Audet, T. L. and  Cros, B. and Dobosz Dufrénoy, S. and Monot},
  title = {Enhanced stability of laser wakefield acceleration using dielectric capillary tubes},
  journal = {PRST AB},
  year = {2014},
  url = {http://journals.aps.org/prstab/abstract/10.1103/PhysRevSTAB.17.031303},
  doi = {10.1103/PhysRevSTAB.17.031303}
}
"Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX"
Cros B, Paradkar B, Davoine X, Chancé A, Desforges F, Dobosz-Dufrénoy S, Delerue N, Ju J, Audet T, Maynard G, Lobet M, Gremillet L, Mora P, Schwindling J, Delferrière O, Bruni C, Rimbault C, Vinatier T, Di Piazza A, Grech M, Riconda C, Marquès J, Beck A, Specka A, Martin P, Monot P, Normand D, Mathieu F, Audebert P and Amiranoff F, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. La Biodola, Italie Vol. 740, pp. 27-33. Elsevier - (2014).
Abstract: Laser plasma acceleration of electrons has progressed along with advances in laser technology. It is thus expected that the development in the near-future of multi-PW-class laser and facilities will enable a vast range of scientific opportunities for laser plasma acceleration research. On one hand, high peak powers can be used to explore the extremely high intensity regime of laser wakefield acceleration, producing for example large amounts of electrons in the GeV range or generating high energy photons. On the other hand, the available laser energy can be used in the quasi-linear regime to create accelerating fields in large volumes of plasma and study controlled acceleration in a plasma stage of externally injected relativistic particles, either electrons or positrons. In the frame of the Centre Interdisciplinaire de la Lumière EXtrème (CILEX), the Apollon-10P laser will deliver two beams at the 1 PW and 10 PW levels, in ultra-short (View the MathML source) pulses, to a target area dedicated to electron acceleration studies, such as the exploration of the non-linear regimes predicted theoretically, or multi-stage laser plasma acceleration.
BibTeX:
@inproceedings{cros:in2p3-00903672,
  author = {Cros, B. and Paradkar, B.S. and Davoine, X. and Chancé, A. and Desforges, F.G. and Dobosz-Dufrénoy, S. and Delerue, N. and Ju, J. and Audet, T.L. and Maynard, G. and Lobet, M. and Gremillet, L. and Mora, P. and Schwindling, J. and Delferrière, O. and Bruni, C. and Rimbault, C. and Vinatier, T. and Di Piazza, A. and Grech, M. and Riconda, C. and Marquès, J.R. and Beck, A. and Specka, A. and Martin, Ph. and Monot, P. and Normand, D. and Mathieu, F. and Audebert, P. and Amiranoff, F.},
  editor = {Ralph Assmann, Massimo Ferrario, Jens Osterhoff, Arnd E. Specka },
  title = {Laser plasma acceleration of electrons with multi-PW laser beams in the frame of CILEX},
  booktitle = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  publisher = {Elsevier},
  year = {2014},
  volume = {740},
  pages = {27-33},
  note = {LAL/RT 13-48 },
  url = {http://hal.in2p3.fr/in2p3-00903672},
  doi = {10.1016/j.nima.2013.10.090}
}
"Reproducibility of electron beams from laser wakefield acceleration in capillary tubes"
Desforges F, Hansson M, Ju J, Senje L, Audet T, Dobosz-Dufrénoy S, Persson A, Lundh O, Wahlström C-G and Cros B, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment., In Proceedings of the first European Advanced Accelerator Concepts Workshop 2013., Vol. 740(0), pp. 54-59 - March, (2014).
Abstract: The stability of accelerated electron beams produced by self-injection of plasma electrons into the wakefield driven by a laser pulse guided inside capillary tubes is analyzed statistically in relation to laser and plasma parameters, and compared to results obtained in a gas jet. The analysis shows that reproducible electron beams are achieved with a charge of 66 pC ±11%, a FWHM beam divergence of 9 mrad ±14%, a maximum energy of 120 MeV ±10% and pointing fluctuations of 2.3 mrad using 10 mm long, 178μm diameter capillary tubes at an electron density of (10.0±1.5)*1018 cm-3. Active stabilization of the laser pointing was used and laser parameters were recorded on each shot. Although the shot-to-shot laser energy fluctuations can account for a fraction of the electrons fluctuations, gas density fluctuations are suspected to be a more important source of instability.
BibTeX:
@article{Desforges2014,
  author = {Desforges, F.G. and Hansson, M. and Ju, J. and Senje, L. and Audet, T.L. and Dobosz-Dufrénoy, S. and Persson, A. and Lundh, O. and Wahlström, C.-G. and Cros, B.},
  title = {Reproducibility of electron beams from laser wakefield acceleration in capillary tubes},
  booktitle = {Proceedings of the first European Advanced Accelerator Concepts Workshop 2013},
  journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  year = {2014},
  volume = {740},
  number = {0},
  pages = {54--59},
  url = {http://www.sciencedirect.com/science/article/pii/S0168900213014538}
}
"Ultrafast formation of hydrated electrons in water at high concentration: experimental evidence of the free electron"
Palianov P, Martin P, Quéré F and Pommeret S, Journal of Experimental and Theoretical Physics. Vol. Vol. 145 (3) - (2014).
Abstract: Using a time-resolved optical interferometric technique, we investigate the ultrafast primary events following the interaction of an ultrashort laser pulse with pure water in the TW/cm<sup>2</sup> regime. Because our method is sensitive to the quasi-instantaneous electron energy level position, we demonstrate that in contrast to the well-known low-intensity regime, where the free electrons are instantaneously captured by pre-existing traps, in this new regime of excitation, free electrons are clearly observed, exhibiting a substantial contribution in the near IR. The delayed localization is attributed to the saturation of pre-existing cavities in the liquid by the large number of the excited electron states created.
BibTeX:
@article{Palianov2014,
  author = {Palianov, P. and Martin, P.and Quéré, P. and Pommeret, S.},
  title = {ULTRAFAST FORMATION OF HYDRATED ELECTRONS IN WATER AT HIGH CONCENTRATION: EXPERIMENTAL EVIDENCE OF THE FREE ELECTRON},
  journal = {Journal of Experimental and Theoretical Physics},
  year = {2014},
  volume = {Vol. 145 (3)},
  url = {http://jetp.ac.ru/cgi-bin/e/index/r/145/3/p559?a=list}
}
"Investigation of amplitude spatio-temporal couplings at the focus of a 100 TW-25 fs laser"
Kahaly, Monchocé S, Gallet V, Gobert O, Réau F, Tcherbakoff O, D'Oliveira P. Martin P and Quéré F, Applied Physics Letters - (2014).
Abstract: We address the on target focal spot spatio-temporal features of an ultrashort, 100 TW class laser chain by using spectrally resolved imaging diagnostics. The observed spatio-spectral images, which we call rotating imaging spectrographs, are obtained single shot to reveal the essential information about the spatio-temporal couplings. We observe nontrivial effects in the focal plane due to compressor defects which significantly affect the maximum on target intensity. This diagnostic might become an essential tool for improving compressor alignment in many upcoming multi-petawatt short pulse laser facilities.
BibTeX:
@article{Kahaly2014,
  author = {Kahaly, and Monchocé, S. and Gallet, V. and Gobert, O. and Réau, F. and Tcherbakoff, O. and D'Oliveira, P. Martin, P. and Quéré, F},
  title = {Investigation of amplitude spatio-temporal couplings at the focus of a 100 TW-25 fs laser},
  journal = {Applied Physics Letters},
  year = {2014},
  url = {http://scitation.aip.org/content/aip/journal/apl/104/5/10.1063/1.4863828}
}
"Optical properties of relativistic plasma mirrors"
Vincenti H, Monchocé S., Kahaly S, Bonnaud G, Martin P and Quéré F, Nat Commun.,Vol. 5, pp. -. Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. - March, (2014).
Abstract: The advent of ultrahigh-power femtosecond lasers creates a need for an entirely new class of optical components based on plasmas. The most promising of these are known as plasma mirrors, formed when an intense femtosecond laser ionizes a solid surface. These mirrors specularly reflect the main part of a laser pulse and can be used as active optical elements to manipulate its temporal and spatial properties. Unfortunately, the considerable pressures exerted by the laser can deform the mirror surface, unfavourably affecting the reflected beam and complicating, or even preventing, the use of plasma mirrors at ultrahigh intensities. Here we derive a simple analytical model of the basic physics involved in laser-induced deformation of a plasma mirror. We validate this model numerically and experimentally, and use it to show how such deformation might be mitigated by appropriate control of the laser phase.
BibTeX:
@article{Vincenti2014,
  author = {Vincenti, H. and Monchocé, S., and Kahaly, S. and Bonnaud, G. and Martin, Ph. and Quéré,  F.},
  title = {Optical properties of relativistic plasma mirrors},
  journal = {Nat Commun},
  publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
  year = {2014},
  volume = {5},
  pages = {--},
  url = {http://dx.doi.org/10.1038/ncomms4403},
  doi = {10.1038/ncomms4403}
}
2013
"Evidence of Resonant Surface-Wave Excitation in the Relativistic Regime through Measurements of Proton Acceleration from Grating Targets"
Ceccotti T, Floquet V, Sgattoni A, Bigongiari A, Klimo O, Raynaud M, Riconda C, Heron A, Baffigi F, Labate L, Gizzi LA, Vassura L, Fuchs J, Passoni M, Kveton M, Novotny F, Possolt M, Prokupek J, Proska J, Psikal J, Stolcova L, Velyhan A, Bougeard M, D'Oliveira P, Tcherbakoff O, Reau F, Martin P and Macchi A, Phys. Rev. Lett., Vol. 111, pp. 185001. American Physical Society - Oct, (2013).
Abstract: The interaction of laser pulses with thin grating targets, having a periodic groove at the irradiated surface, has been experimentally investigated. Ultrahigh contrast (~ 1012) pulses allowed to demonstrate an enhanced laser-target coupling for the first time in the relativistic regime of ultra-high intensity > 1019 W/cm2. A maximum increase by a factor of 2.5 of the cut-off energy of protons produced by Target Normal Sheath Acceleration has been observed with respect to plane targets, around the incidence angle expected for resonant excitation of surface waves. A significant enhancement is also observed for small angles of incidence, out of resonance.
BibTeX:
@article{PhysRevLett.111.185001,
  author = {Ceccotti, T. and Floquet, V. and Sgattoni, A. and Bigongiari, A. and Klimo, O. and Raynaud, M. and Riconda, C. and Heron, A. and Baffigi, F. and Labate, L. and Gizzi, L. A. and Vassura, L. and Fuchs, J. and Passoni, M. and Kveton, M. and Novotny, F. and Possolt, M. and Prokupek, J. and Proška, J. and Pšikal, J. and Štolcová, L. and Velyhan, A. and Bougeard, M. and D'Oliveira, P. and Tcherbakoff, O. and Reau, F. and Martin, P. and Macchi, A.},
  title = {Evidence of Resonant Surface-Wave Excitation in the Relativistic Regime through Measurements of Proton Acceleration from Grating Targets},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2013},
  volume = {111},
  pages = {185001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.111.185001},
  doi = {10.1103/PhysRevLett.111.185001}
}
"Spectral characterization of laser-driven solid-based high harmonics in the coherent wake emission regime"
Van Tilborg J, Shaw BH, Sokollik T, Rykovanov S, Leemans WP, Monchocé S, Quéré F, Martin P and Malvache A, Optics Letters, Accepted - (2013).
Abstract: Laser-produced surface high harmonic generation (SHHG) is an attractive source of extreme ultra-violet radiation due to its coherent properties and high peak power. By operating at sub-relativistic laser intensities in the coherent wake emission regime, the harmonic spectrum was experimentally studied versus laser properties. At higher laser intensities (>1017 W/cm2) a higher spectral cut-off was observed, with accompanying blue-shifting and spectral broadening of the individual orders. A model based on an expanding critical-surface provides qualitative agreement to the observations.
BibTeX:
@article{Vantilborg2013,
  author = {Van Tilborg, J. and Shaw, B. H. and Sokollik,  T. and Rykovanov, S. and Leemans, W. P. and Monchocé, S. and Quéré, F. and Martin, Ph. and Malvache,  A.},
  title = {Spectral characterization of laser-driven solid-based high harmonics in the coherent wake emission regime},
  journal = {Optics Letters, Accepted (2013)},
  year = {2013},
  url = {http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww%2Eopticsinfobase%2Eorg%2FDirectPDFAccess%2F88B73657%2DBF18%2DD2BE%2DDA2D00F96AD4A837%5Fads192293%2Epdf%3Fda%3D1%26adsid%3D192293%26journal%3D3%26seq%3D0%26mobile%3Dno&org=}
}
"Photonic streaking of attosecond pulse trains"
Kim KT, Zhang C, Ruchon T, Hergott J-F, Auguste T, Villeneuve D.M., Corkum P.B. and Quere F, Nat Photon., Vol. 7(8), pp. 651-656. Nature Publishing Group - August, (2013).
Abstract: High harmonic radiation, produced when intense laser pulses interact with matter, is composed of a train of attosecond pulses. Individual pulses in this train carry information on ultrafast dynamics that vary from one half-optical-cycle to the next. Here, we demonstrate an all-optical photonic streaking measurement that provides direct experimental access to each attosecond pulse by mapping emission time onto propagation angle. This is achieved by inducing an ultrafast rotation of the instantaneous laser wavefront at the focus. We thus time-resolve attosecond pulse train generation, and hence the dynamics in the nonlinear medium itself. We apply photonic streaking to harmonic generation in gases and directly observe, for the first time, the influence of non-adiabatic electron dynamics and plasma formation on the generated attosecond pulse train. These experimental and numerical results also provide the first evidence of the generation of attosecond lighthouses in gases, which constitute ideal sources for attosecond pump-probe spectroscopy.
BibTeX:
@article{Kim2013,
  author = {Kim, Kyung Taec and Zhang, Chunmei and Ruchon, Thierry and Hergott, Jean-Francois and Auguste, Thierry and M., VilleneuveD. and B., CorkumP. and QuereF.},
  title = {Photonic streaking of attosecond pulse trains},
  journal = {Nat Photon},
  publisher = {Nature Publishing Group},
  year = {2013},
  volume = {7},
  number = {8},
  pages = {651--656},
  url = {http://dx.doi.org/10.1038/nphoton.2013.170},
  doi = {10.1038/nphoton.2013.170}
}
"Micro-sphere layered targets efficiency in laser driven proton acceleration"
Floquet V, Klimo O, Psikal J, Velyhan A, Limpouch J, Proska J, Novotny F, Stolcova L, Macchi A, Sgattoni A, Vassura L, Labate L, Baffigi F, Gizzi LA, Martin P and Ceccotti T, J. Appl. Phys., Vol. 114(8), pp. 083305-5. AIP - August, (2013).
Abstract: Proton acceleration from the interaction of high contrast, 25 fs laser pulses at >1019 W/cm2 intensity with plastic foils covered with a single layer of regularly packed micro-spheres has been investigated experimentally. The proton cut-off energy has been measured as a function of the micro-sphere size and laser incidence angle for different substrate thickness, and for both P and S polarization. The presence of micro-spheres with a size comparable to the laser wavelength allows to increase the proton cut-off energy for both polarizations at small angles of incidence (10°). For large angles of incidence, however, proton energy enhancement with respect to flat targets is absent. Analysis of electron trajectories in particle-in-cell simulations highlights the role of the surface geometry in the heating of electrons.
BibTeX:
@article{Floquet2013,
  author = {Floquet, V. and Klimo, O. and Psikal, J. and Velyhan, A. and Limpouch, J. and Proska, J. and Novotny, F. and Stolcova, L. and Macchi, A. and Sgattoni, A. and Vassura, L. and Labate, L. and Baffigi, F. and Gizzi, L. A. and Martin, Ph. and Ceccotti, T.},
  title = {Micro-sphere layered targets efficiency in laser driven proton acceleration},
  journal = {J. Appl. Phys.},
  publisher = {AIP},
  year = {2013},
  volume = {114},
  number = {8},
  pages = {083305--5},
  url = {http://dx.doi.org/10.1063/1.4819239},
  doi = {10.1063/1.4819239}
}
"Space- and time-resolved observation of extreme laser frequency upshifting during ultrafast-ionization"
Giulietti A, Andre A, Dobosz Dufrénoy S, Giulietti D, Hosokai T, Koester P, Kotaki H, Labate L, Levato T, Nuter R, Pathak NC, Monot P and Gizzi LA, Physics of Plasmas. Vol. 20(8), pp. 082307. AIP - (2013).
Abstract: A 65-fs, 800-nm, 2-TW laser pulse propagating through a nitrogen gas jet has been experimentally studied by 90° Thomson scattering. Time-integrated spectra of scattered light show unprecedented broadening towards the blue which exceeds 300 nm. Images of the scattering region provide for the first time a space- and time-resolved description of the process leading quite regularly to such a large upshift. The mean shifting rate was as high as δλ/δt≈Å/fs, never observed before. Interferometry shows that it occurs after partial laser defocusing. Numerical simulations prove that such an upshift is consistent with a laser-gas late interaction, when laser intensity has decreased well below relativistic values (a0 << 1) and ionization process involves most of the laser pulse. This kind of interaction makes spectral tuning of ultrashort intense laser pulses possible in a large spectral range.
BibTeX:
@article{giulietti:082307,
  author = {A. Giulietti and A. Andre and S. Dobosz Dufrénoy and D. Giulietti and T. Hosokai and P. Koester and H. Kotaki and L. Labate and T. Levato and R. Nuter and N. C. Pathak and P. Monot and L. A. Gizzi},
  title = {Space- and time-resolved observation of extreme laser frequency upshifting during ultrafast-ionization},
  journal = {Physics of Plasmas},
  publisher = {AIP},
  year = {2013},
  volume = {20},
  number = {8},
  pages = {082307},
  url = {http://link.aip.org/link/?PHP/20/082307/1},
  doi = {10.1063/1.4818602}
}
"Direct Observation of Density-Gradient Effects in Harmonic Generation from Plasma Mirrors"
Kahaly S, Monchocé S, Vincenti H, Dzelzainis T, Dromey B, Zepf M, Martin P and Quéré F , Phys. Rev. Lett., Vol. 110, pp. 175001. American Physical Society - Apr, (2013).
Abstract: High-order harmonics and attosecond pulses of light can be generated when ultraintense, ultrashort laser pulses reflect off a solid-density plasma with a sharp vacuum interface, i.e., a plasma mirror. We demonstrate experimentally the key influence of the steepness of the plasma-vacuum interface on the interaction, by measuring the spectral and spatial properties of harmonics generated on a plasma mirror whose initial density gradient scale length L is continuously varied. Time-resolved interferometry is used to separately measure this scale length.
BibTeX:
@article{PhysRevLett.110.175001,
  author = {Kahaly, S. and Monchocé, S. and Vincenti,H. and Dzelzainis, T. and Dromey, B.  and Zepf,  M. and Martin, Ph. and Quéré, F.},
  title = {Direct Observation of Density-Gradient Effects in Harmonic Generation from Plasma Mirrors},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2013},
  volume = {110},
  pages = {175001},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.110.175001},
  doi = {10.1103/PhysRevLett.110.175001}
}
"Coherent wake emission spectroscopy as a probe of steep plasma density profiles"
Malvache A, Borot A, Quéré F and Lopez-Martens R, Physical Review E., Vol. 87, pp. 035101. American Physical Society - March, (2013).
Abstract: Precise knowledge of the plasma density gradient created by an intense laser field at the surface of a solid is essential for understanding and controlling the resulting laser-plasma interaction. We present a novel experimental method for determining the scale length of such a gradient in a single shot, based on the spectral analysis of coherent wake emission by a laser-induced solid density plasma, using an analytical model of this emission process. We illustrate this approach in a pump-probe experiment, where it is used to measure the expansion velocity of a plasma into a vacuum.
BibTeX:
@article{citeulike:12177820,
  author = {Malvache, A. and Borot, A. and Quéré, F and Lopez-Martens, R.},
  title = {Coherent wake emission spectroscopy as a probe of steep plasma density profiles},
  journal = {Physical Review E},
  publisher = {American Physical Society},
  year = {2013},
  volume = {87},
  pages = {035101},
  url = {http://dx.doi.org/10.1103/physreve.87.035101},
  doi = {10.1103/physreve.87.035101}
}
"Charge Equilibrium of a Laser-Generated Carbon-Ion Beam in Warm Dense Matter"
Gauthier M, Chen SN, Levy A, Audebert P, Blancard C, Ceccotti T, Cerchez M, Doria D, Floquet V, Lamour E, Peth C, Romagnani L, Rozet J-P, Scheinder M, Shepherd R, Toncian T, Vernhet D, Willi O, Borghesi M, Faussurier G and Fuchs J, Phys. Rev. Lett., Vol. 110, pp. 135003. American Physical Society - Mar, (2013).
Abstract: Using ion carbon beams generated by high intensity short pulse lasers we perform measurements of single shot mean charge equilibration in cold or isochorically heated solid density aluminum matter. We demonstrate that plasma effects in such matter heated up to 1 eV do not significantly impact the equilibration of carbon ions with energies 0.045-0.5 MeV/nucleon. Furthermore, these measurements allow for a first evaluation of semiempirical formulas or ab initio models that are being used to predict the mean of the equilibrium charge state distribution for light ions passing through warm dense matter.
BibTeX:
@article{PhysRevLett.110.135003,
  author = {Gauthier, M. and Chen, S. N. and Levy, A. and Audebert, P. and Blancard, C. and Ceccotti, T. and Cerchez, M. and Doria, D. and Floquet, V. and Lamour, E. and Peth, C. and Romagnani, L. and Rozet, J.-P. and Scheinder, M. and Shepherd, R. and Toncian, T. and Vernhet, D. and Willi, O. and Borghesi, M. and Faussurier, G. and Fuchs, J.},
  title = {Charge Equilibrium of a Laser-Generated Carbon-Ion Beam in Warm Dense Matter},
  journal = {Phys. Rev. Lett.},
  publisher = {American Physical Society},
  year = {2013},
  volume = {110},
  pages = {135003},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.110.135003},
  doi = {10.1103/PhysRevLett.110.135003}
}
2012
"Attosecond control of collective electron motion in plasmas"
Borot A, Malvache A, Chen X, Jullien A, Geindre J-P, Audebert P, Mourou G, Quere F and Lopez-Martens R, Nature Physics., Vol. 8(5), pp. 416-421 - May, (2012).
Abstract: Today, light fields of controlled and measured waveform can be used to guide electron motion in atoms and molecules with attosecond precision. Here, we demonstrate attosecond control of collective electron motion in plasmas driven by extreme intensity (≈1018 W cm−2) light fields. Controlled few-cycle near-infrared waves are tightly focused at the interface between vacuum and a solid-density plasma, where they launch and guide subcycle motion of electrons from the plasma with characteristic energies in the multi-kiloelectronvolt range-two orders of magnitude more than has been achieved so far in atoms and molecules. The basic spectroscopy of the coherent extreme ultraviolet radiation emerging from the light-plasma interaction allows us to probe this collective motion of charge with sub-200 as resolution. This is an important step towards attosecond control of charge dynamics in laser-driven plasma experiments.
BibTeX:
@article{Borot2012,
  author = {Borot, Antonin and Malvache, Arnaud and Chen, Xiaowei and Jullien, Aurelie and Geindre, Jean-Paul and Audebert, Patrick and Mourou, Gerard and Quere, Fabien and Lopez-Martens, Rodrigo},
  title = {Attosecond control of collective electron motion in plasmas},
  journal = {Nature Physics},
  year = {2012},
  volume = {8},
  number = {5},
  pages = {416--421},
  doi = {10.1038/NPHYS2269}
}
"First measurements of laser-accelerated proton induced luminescence"
Floquet V, Ceccotti T, Dobosz Dufrénoy S, Bonnaud G, Gremillet L, Monot P and Martin P, Physics of Plasmas., Vol. 19(9), pp. 094501 - September, (2012).
Abstract: We present our first results about laser-accelerated proton induced luminescence in solids. In the first part, we describe the optimization of the proton source as a function of the target thickness as well as the laser pulse duration and energy. Due to the ultra high contrast ratio of our laser beam, we succeeded in using targets ranging from the micron scale down to nanometers thickness. The two optimal thicknesses we put in evidence are in good agreement with numerical simulations. Laser pulse duration shows a small influence on proton maximum energy, whereas the latter turns out to vary almost linearly as a function of laser energy. Thanks to this optimisation work, we have been able to acquire images of the proton energy deposition in a solid scintillator.
BibTeX:
@article{Floquet2012,
  author = {Floquet, V. and Ceccotti, T. and Dobosz Dufrénoy, S. and Bonnaud, G. and Gremillet, L. and Monot, P. and Martin, Ph.},
  title = {First measurements of laser-accelerated proton induced luminescence},
  journal = {Physics of Plasmas},
  year = {2012},
  volume = {19},
  number = {9},
  pages = {094501},
  doi = {10.1063/1.4753939}
}
"Attosecond Lighthouses: How To Use Spatiotemporally Coupled Light Fields To Generate Isolated Attosecond Pulses"
Vincenti H and Quere F, Physical Review Letters., Vol. 108(11), pp. 113904 - March, (2012).
Abstract: Under the effect of even simple optical components, the spatial properties of femtosecond laser beams can vary over the duration of the light pulse. We show how using such spatiotemporally coupled light fields in high harmonic generation experiments (e.g., in gases or dense plasmas) enables the production of attosecond lighthouses, i.e., sources emitting a collection of angularly well-separated light beams, each consisting of an isolated attosecond pulse. This general effect opens the way to a new generation of light sources, particularly suitable for attosecond pump-probe experiments, and provides a new tool for ultrafast metrology, for instance, giving direct access to fluctuations of the carrier-envelope relative phase of even the most intense ultrashort lasers.
BibTeX:
@article{Vincenti2012c,
  author = {Vincenti, H. and Quere, F.},
  title = {Attosecond Lighthouses: How To Use Spatiotemporally Coupled Light Fields To Generate Isolated Attosecond Pulses},
  journal = {Physical Review Letters},
  year = {2012},
  volume = {108},
  number = {11},
  pages = {113904},
  doi = {10.1103/PhysRevLett.108.113904}
}
"Attosecond lighthouses"
Vincenti H, Wheeler J, Monchoce S, Borot A, Malvache A, Lopez-Martens R and Quere F, 2012 Conference on Lasers and Electro-Optics (CLEO). , pp. IEEE Photonics Soc. - (2012).
Abstract: We show how to use spatio-temporally coupled light fields to generate isolated attosecond pulses. This general effect provides an ideal scheme for attosecond pump-probe experiments, and constitutes a powerful new tool for ultrafast metrology.
BibTeX:
@article{Vincenti2012,
  author = {Vincenti, H. and Wheeler, J. and Monchoce, S. and Borot, A. and Malvache, A. and Lopez-Martens, R. and Quere, F.},
  title = {Attosecond lighthouses},
  journal = {2012 Conference on Lasers and Electro-Optics (CLEO)},
  year = {2012},
  pages = {IEEE Photonics Soc.},
  doi = {10.1364/QELS.2012.QTu3H.2}
}
"Attosecond lighthouses from plasma mirrors"
Wheeler JA, Borot A, Monchoce S, Vincenti H, Ricci A, Malvache A, Lopez-Martens R and Quere F, Nature Photonics., Vol. 6(12), pp. 828-832 - December, (2012).
Abstract: The nonlinear interaction of an intense femtosecond laser pulse with matter can lead to the emission of a train of sub-laser-cycle-attosecond-bursts of short-wavelength radiation1, 2. Much effort has been devoted to producing isolated attosecond pulses, as these are better suited to real-time imaging of fundamental electronic processes3, 4, 5, 6. Successful methods developed so far rely on confining the nonlinear interaction to a single sub-cycle event7, 8, 9. Here, we demonstrate for the first time a simpler and more universal approach to this problem10, applied to nonlinear laser-plasma interactions. By rotating the instantaneous wavefront direction of an intense few-cycle laser field11, 12 as it interacts with a solid-density plasma, we separate the nonlinearly generated attosecond pulse train into multiple beams of isolated attosecond pulses propagating in different and controlled directions away from the plasma surface. This unique method produces a manifold of isolated attosecond pulses, ideally synchronized for initiating and probing ultrafast electron motion in matter
BibTeX:
@article{Wheeler2012a,
  author = {Wheeler, Jonathan A. and Borot, Antonin and Monchoce, Sylvain and Vincenti, Henri and Ricci, Aurelien and Malvache, Arnaud and Lopez-Martens, Rodrigo and Quere, Fabien},
  title = {Attosecond lighthouses from plasma mirrors},
  journal = {Nature Photonics},
  year = {2012},
  volume = {6},
  number = {12},
  pages = {828--832},
  doi = {10.1038/NPHOTON.2012.284}
}
"Attosecond lighthouses from plasma mirrors"
Wheeler J, Borot A, Malvache A, Ricci A, Jullien A, Lopez-Martens R, Monchoce S, Vincenti H and Quere F, 2012 Conference on Lasers and Electro-Optics (CLEO). , pp. IEEE Photonics Soc. - (2012).
Abstract: We demonstrate for the first time experimentally a universal method - attosecond lighthouse effect - for producing temporally synchronized and spatially isolated attosecond light pulses, applied to a few-cycle laser-driven plasma mirror.
BibTeX:
@article{Wheeler2012b,
  author = {Wheeler, J. and Borot, A. and Malvache, A. and Ricci, A. and Jullien, A. and Lopez-Martens, R. and Monchoce, S. and Vincenti, H. and Quere, F.},
  title = {Attosecond lighthouses from plasma mirrors},
  journal = {2012 Conference on Lasers and Electro-Optics (CLEO)},
  year = {2012},
  pages = {IEEE Photonics Soc.},
  doi = {10.1364/QELS.2012.QTh5B.9}
}
2011
"High-harmonic generation from plasma mirrors at kilohertz repetition rate"
Borot A, Malvache A, Chen X, Douillet D, Iaquianiello G, Lefrou T, Audebert P, Geindre J-P, Mourou G, Quere F and Lopez-Martens R, Optics Letters., Vol. 36(8), pp. 1461-1463 - April, (2011).
Abstract: We report the first demonstration of high-harmonic generation from plasma mirrors at a 1kHz repetition rate. Harmonics up to nineteenth order are generated at peak intensities close to 10 18W/cm 2 by focusing 1mJ , 25fs laser pulses down to 1.7μm FWHM spot size without any prior wavefront correction onto a moving target. We minimize target surface motion with respect to the laser focus using online interferometry to ensure reproducible interaction conditions for every shot and record data at 1kHz with unprecedented statistics. This allows us to unambiguously identify coherent wake emission as the main generation mechanism.
BibTeX:
@article{Borot2011c,
  author = {Borot, Antonin and Malvache, Arnaud and Chen, Xiaowei and Douillet, Denis and Iaquianiello, Gregory and Lefrou, Thierry and Audebert, Patrick and Geindre, Jean-Paul and Mourou, Gerard and Quere, Fabien and Lopez-Martens, Rodrigo},
  title = {High-harmonic generation from plasma mirrors at kilohertz repetition rate},
  journal = {Optics Letters},
  year = {2011},
  volume = {36},
  number = {8},
  pages = {1461--1463},
  doi = {10.1364/OL.36.001461}
}
"Short pulse laser interaction with micro-structured targets: simulations of laser absorption and ion acceleration"
Klimo O, Psikal J, Limpouch J, Proska J, Novotny F, Ceccotti T, Floquet V and Kawata S, New Journal of Physics., Vol. 13, pp. 053028 - May, (2011).
The interaction of an ultrashort intense laser pulse with thin foil targets is accompanied by the acceleration of ions from the target surface. To make this ion source suitable for application, it is of particular importance to increase the efficiency of laser energy transformation into accelerated ions and the maximum ion energy. This can be achieved by using a thin foil target with a microscopic structure on the front, laser-irradiated surface. The influence of the microscopic structure on the target surface on the laser target interaction and subsequent ion acceleration is studied here using numerical simulations. The influence of the shape and size of the microstructure, the density profile and the laser pulse incidence angle is also studied. Based on the simulation results, we propose to construct the target for ion acceleration experiments by depositing a monolayer of polystyrene microspheres of a size similar to the laser wavelength on the front surface of a thin foil.
BibTeX:
@article{Klimo2011,
  author = {Klimo, O. and Psikal, J. and Limpouch, J. and Proska, J. and Novotny, F. and Ceccotti, T. and Floquet, V. and Kawata, S.},
  title = {Short pulse laser interaction with micro-structured targets: simulations of laser absorption and ion acceleration},
  journal = {New Journal of Physics},
  year = {2011},
  volume = {13},
  pages = {053028},
  doi = {10.1088/1367-2630/13/5/053028}
}
"Field ionization model implemented in Particle In Cell code and applied to laser-accelerated carbon ions"
Nuter R, Gremillet L, Lefebvre E, Levy A, Ceccotti T and Martin P, Physics of Plasmas., Vol. 18(3), pp. 033107 - March, (2011).
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.
BibTeX:
@article{Nuter2011,
  author = {Nuter, R. and Gremillet, L. and Lefebvre, E. and Levy, A. and Ceccotti, T. and Martin, P.},
  title = {Field ionization model implemented in Particle In Cell code and applied to laser-accelerated carbon ions},
  journal = {Physics of Plasmas},
  year = {2011},
  volume = {18},
  number = {3},
  pages = {033107},
  doi = {10.1063/1.3559494}
}
  
"Modular EUV Source for the Next Generation Lithography"
Sublemontier O, Rosset-Kos M, Ceccotti T, Hergott J-F, Auguste T, Normand D, Schmidt M, Beaumont F, Farcage D, Cheymol G, Le Caro J-M, Cormont P, Mauchien P, Thro P-Y, Skrzypczak J, Muller S, Marquis E, Barthod B, Gaurand I, Davenet M and Bernard R, Journal of Laser Micro Nanoengineering., Vol. 6(2), pp. 113-118 - September, (2011).
Abstract: The present work, performed in the frame of the EXULITE project, was dedicated to the design and characterization of a laser-plasma-produced extreme ultraviolet (EUV) source prototype at 13.5 nm for the next generation lithography. It was conducted in cooperation with two laboratories from CEA, ALCATEL and THALES. One of our approach originalities was the laser scheme modularity. Six Nd:YAG laser beams were focused at the same time on a xenon filament jet to generate the EUV emitting plasma. Multiplexing has important industrial advantages and led to interesting source performances in terms of in-band power, stability and angular emission properties with the filament jet target. A maximum conversion efficiency (CE) value of 0.44% in 2$ sr and 2% band-width was measured, which corresponds to a maximum in band EUV mean power of 7.7 W at a repetition rate of 6 kHz. The EUV emission was found to be stable and isotropic in these conditions.
BibTeX:
@article{Sublemontier2011,
  author = {Sublemontier, Olivier and Rosset-Kos, Marylene and Ceccotti, Tiberio and Hergott, Jean-Francois and Auguste, Thierry and Normand, Didier and Schmidt, Martin and Beaumont, Francois and Farcage, Daniel and Cheymol, Guy and Le Caro, Jean-Marc and Cormont, Philippe and Mauchien, Patrick and Thro, Pierre-Yves and Skrzypczak, Jacky and Muller, Sophie and Marquis, Emanuel and Barthod, Benoit and Gaurand, Isabelle and Davenet, Magali and Bernard, Roland},
  title = {Modular EUV Source for the Next Generation Lithography},
  journal = {Journal of Laser Micro Nanoengineering},
  year = {2011},
  volume = {6},
  number = {2},
  pages = {113--118},
  doi = {10.2961/jlmn.2011.02.0004}
}
2010
"Towards Laser-Driven, Quasi-Monochromatic Ion Bunches via Ultrathin Targets Nano-Structuring?"
Betti S, Giulietti A, Giulietti D, Gizzi LA, Vaselli M, Cecchetti CA, Gamucci A, Koester P, Labate L, Pathak N, Levato T, Andreev AA, Ceccotti T, Martin P and Monot P, 2nd International Conference On Ultra-intense Laser Interaction Science. Vol. 1209, pp. Lab Nazl Frascati, Ist Nazl Fisca Nucl; Ist Processi Chimico FisiciEOLEOLConsiglio Nazl Ric; Inst IRAMIS Commissariat Energie Atomique; AmplitudeEOLEOLTechnol; CVI Melles Griot; Thales Laser; Unibiomedics - (2010).
Abstract: The conditions for achieving the laser acceleration of quasi-monochromatic ion bunches with present-day, fs laser systems are theoretically discussed. The study suggests the possibility of achieving quasi-monochromaticity via irradiation of double-layer, nano-structured foils and the conjecture is numerically confirmed by means of two dimensional, Particle-In-Cell (PIC) simulations. A feasible setup in order to experimentally validate this approach is thus proposed.
BibTeX:
@article{Betti2010,
  author = {Betti, S. and Giulietti, A. and Giulietti, D. and Gizzi, L. A. and Vaselli, M. and Cecchetti, C. A. and Gamucci, A. and Koester, P. and Labate, L. and Pathak, N. and Levato, T. and Andreev, A. A. and Ceccotti, T. and Martin, P. and Monot, P.},
  title = {Towards Laser-Driven, Quasi-Monochromatic Ion Bunches via Ultrathin Targets Nano-Structuring?},
  journal = {2nd International Conference On Ultra-intense Laser Interaction Science},
  year = {2010},
  volume = {1209},
  pages = {Lab Nazl Frascati, Ist Nazl Fisca Nucl; Ist Processi Chimico FisiciEOLEOLConsiglio Nazl Ric; Inst IRAMIS Commissariat Energie Atomique; AmplitudeEOLEOLTechnol; CVI Melles Griot; Thales Laser; Unibiomedics},
  doi = {10.1063/1.3326308}
}
"Results of a laser-driven electron acceleration experiment and perspectives of application for nuclear studies"
Gamucci A, Bourgeois N, Ceccotti T, Davoine X, Dobosz Dufrénoy S, D'Oliveira P, Galimberti M, Galy J, Giulietti A, Giulietti D, Gizzi LA, Hamilton DJ, Labate L, Lefebvre E, Marques JR, Martin P, Monot P, Popescu H, Reau F, Sarri G and Tomassini P, Radiation Effects and Defects In Solids. Vol. 165(6-10), pp. Messina Univ; Inst Nazl Fis Nucl; Salento Univ Lecce; Bonino Pulejo FdnEOLEOLMessina - (2010).
Abstract: High-energy electrons can be produced in interactions of intense, ultra-short laser pulses with plasmas. Experiments conducted in the regime of moderate laser power (a few terawatts [TW]) are attracting increasing attention for their possibility of optimizing the acceleration process. Here we report the successful production of several-MeV electron bunches in interactions of femtosecond laser pulses from a 10 TW tabletop laser with supersonic gas-jets. The laser-plasma interaction and the obtained electron bunches have been characterized in detail, and conditions for stable and reproducible acceleration have been found. The accelerated electron bunches have been characterized by means of the measurement of the induced photo-activation of a gold sample via bremsstrahlung-generation of photons with suitable energy. The obtained result opens up a wide range of possible applications of the compact electron source for the concerns of nuclear physics studies. Some of them are briefly considered in this paper.
BibTeX:
@article{Gamucci2010,
  author = {Gamucci, A. and Bourgeois, N. and Ceccotti, T. and Davoine, X. and Dobosz Dufrénoy, S. and D'Oliveira, P. and Galimberti, M. and Galy, J. and Giulietti, A. and Giulietti, D. and Gizzi, L. A. and Hamilton, D. J. and Labate, L. and Lefebvre, E. and Marques, J. R. and Martin, P. and Monot, P. and Popescu, H. and Reau, F. and Sarri, G. and Tomassini, P.},
  title = {Results of a laser-driven electron acceleration experiment and perspectives of application for nuclear studies},
  journal = {Radiation Effects and Defects In Solids},
  year = {2010},
  volume = {165},
  number = {6-10},
  pages = {Messina Univ; Inst Nazl Fis Nucl; Salento Univ Lecce; Bonino Pulejo FdnEOLEOLMessina},
  doi = {10.1080/10420151003731983}
}
"Laser-IORT: a laser-driven source of relativistic electrons suitable for Intra-Operative Radiation Therapy of tumors"
Gamucci A, Bourgeois N, Ceccotti T, Davoine X, Dobosz Dufrénoy S, D'Oliveira P, Galimberti M, Galy J, Giulietti A, Giulietti D, Gizzi LA, Hamilton DJ, Labate L, Lefebvre E, Marques JR, Monot P, Popescu H, Reau F, Sarri G, Tomassini P and Martin P, 2nd International Conference On Ultra-intense Laser Interaction Science. Vol. 1209, pp. Lab Nazl Frascati, Ist Nazl Fisca Nucl; Ist Processi Chimico FisiciEOLEOLConsiglio Nazl Ric; Inst IRAMIS Commissariat Energie Atomique; AmplitudeEOLEOLTechnol; CVI Melles Griot; Thales Laser; Unibiomedics - (2010).
Abstract: In a recent experiment [1] a high efficiency regime of stable electron acceleration to kinetic energies ranging from 10 to 40 MeV has been achieved. The main parameters of the electron bunches are comparable with those of bunches provided by commercial Radio-Frequency based Linacs currently used in Hospitals for Intra-Operative Radiation Therapy (IORT). IORT is an emerging technique applied in operating theaters during the surgical treatment of tumors. Performances and structure of a potential laser-driven Hospital accelerator are compared in detail with the ones of several commercial devices. A number of possible advantages of the laser based technique are also discussed.
BibTeX:
@article{Gamucci2010a,
  author = {Gamucci, A. and Bourgeois, N. and Ceccotti, T. and Davoine, X. and Dobosz Dufrénoy, S. and D'Oliveira, P. and Galimberti, M. and Galy, J. and Giulietti, A. and Giulietti, D. and Gizzi, L. A. and Hamilton, D. J. and Labate, L. and Lefebvre, E. and Marques, J. R. and Monot, P. and Popescu, H. and Reau, F. and Sarri, G. and Tomassini, P. and Martin, Ph.},
  title = {Laser-IORT: a laser-driven source of relativistic electrons suitable for Intra-Operative Radiation Therapy of tumors},
  journal = {2nd International Conference On Ultra-intense Laser Interaction Science},
  year = {2010},
  volume = {1209},
  pages = {Lab Nazl Frascati, Ist Nazl Fisca Nucl; Ist Processi Chimico FisiciEOLEOLConsiglio Nazl Ric; Inst IRAMIS Commissariat Energie Atomique; AmplitudeEOLEOLTechnol; CVI Melles Griot; Thales Laser; Unibiomedics},
  doi = {10.1063/1.3326314}
}
"High-order harmonic and attosecond pulse generation on plasma mirrors: basic mechanisms"
Thaury C and Quere F, Journal of Physics B-atomic Molecular and Optical Physics., Vol. 43(21), pp. 213001 - November, (2010).
Abstract: When an intense femtosecond laser pulse hits an optically polished surface, it generates a dense plasma that itself acts as a mirror, known as the plasma mirror. As this mirror reflects the high-intensity laser field, its nonlinear temporal response can lead to a periodic temporal distortion of the reflected wave, associated with a train of attosecond light pulses, and, in the frequency domain, to the generation of high-order harmonics of the laser. This tutorial presents detailed theoretical and numerical analysis of the two dominant harmonic generation mechanisms identified so far, coherent wake emission and the relativistic oscillating mirror. Parametric studies of the emission efficiency are presented for these two regimes, and the phase properties of the corresponding harmonics are discussed. This theoretical study is complemented by a synthesis of recent experimental results, which establishes that these two mechanisms indeed dominate harmonic generation on plasma mirrors.
BibTeX:
@article{Thaury2010a,
  author = {Thaury, C. and Quere, F.},
  title = {High-order harmonic and attosecond pulse generation on plasma mirrors: basic mechanisms},
  journal = {Journal of Physics B-atomic Molecular and Optical Physics},
  year = {2010},
  volume = {43},
  number = {21},
  pages = {213001},
  doi = {10.1088/0953-4075/43/21/213001}
}
"Intrinsic phase of high order harmonics generated on plasma mirrors"
Thaury C, Quere F, George H, Geindre JP, Bonnaud G and Martin P, Light At Extreme Intensities: Opportunities and Technological Issues of the Extreme Light Infrastructure. Vol. 1228, pp. Int Consortium Extreme Light Infrastruct; Natl Inst Laser, Plasma \&EOLEOLRadiat Phys; Inst Plasmas \& Fusao Nucl; Natl Author Sci Res; EmbassyEOLEOLFrance Romania; Transilvania Univ Brasov - (2010).
Abstract: We study numerically and experimentally the intrinsic phase of Coherent Wake Emission harmonics. We first use 1D3V particle-in-cell simulations to identify the origin of the phase. Then we present experimental results showing that it can be controlled by tailoring the laser pulse, and measured precisely using an interferometric technique.
BibTeX:
@article{Thaury2010,
  author = {Thaury, C. and Quere, F. and George, H. and Geindre, J. -. P. and Bonnaud, G. and Martin, Ph.},
  title = {Intrinsic phase of high order harmonics generated on plasma mirrors},
  journal = {Light At Extreme Intensities: Opportunities and Technological Issues of the Extreme Light Infrastructure},
  year = {2010},
  volume = {1228},
  pages = {Int Consortium Extreme Light Infrastruct; Natl Inst Laser, Plasma &EOLEOLRadiat Phys; Inst Plasmas & Fusao Nucl; Natl Author Sci Res; EmbassyEOLEOLFrance Romania; Transilvania Univ Brasov},
  doi = {10.1063/1.3426078}
}
2009
"Proton Maximum Energy Cutoff Scaling Laws For Bulk Targets"
Passoni M, Bertagna L, Ceccotti T and Martin P, Laser-driven Relativistic Plasmas Applied To Science, Industry and Medicine. : 2nd International Symposium - Date:19–23 January 2009 - Location: Kyoto (Japan) - (2009).
Abstract: In this work we experimentally and theoretically report on the energy cutoff scaling law for proton generation from bulk targets over one decade of intensity ranging from 5?1018 to 5?1019 W/cm2 in the ultra-short pulse duration regime (25 fs). Assuming the same experimental conditions and that the physics does not change for higher intensities, we extrapolate that 100 MeV could be reached using 500 TW ultra-high-contrast-ultra short laser pulses.
BibTeX:
@article{Passoni2009,
  author = {Passoni, M. and Bertagna, L. and Ceccotti, T. and Martin, P.},
  title = {Proton Maximum Energy Cutoff Scaling Laws For Bulk Targets},
  journal = {Laser-driven Relativistic Plasmas Applied To Science, Industry and Medicine},
  year = {2009},
  doi = {10.1063/1.3204520}
}
"Ultrafast science: Attosecond plasma optics"
Quere F, Nature Physics., Vol. 5(2), pp. 93-94 - February, (2009).
Abstract: Using dense plasmas instead of atomic or molecular gases could enable the generation of attosecond light pulses with higher energy, shorter durations and more energetic photons.
BibTeX:
@article{Quere2009a,
  author = {Quere, Fabien},
  title = {Ultrafast science: Attosecond plasma optics},
  journal = {Nature Physics},
  year = {2009},
  volume = {5},
  number = {2},
  pages = {93--94},
  doi = {10.1038/nphys1191}
}
"Attosecond and femtosecond metrology for plasma mirrors"
Quere F, George H and Martin P, Harnessing Relativistic Plasma Waves As Novel Radiation Sources From Terahertz To X-rays and Beyond. Vol. 7359, pp. SPIE Europe - (2009).
Abstract: When an intense ultrashort laser pulse impinges on an initially-solid target, it creates a dense plasma at the surface, which reflects a large fraction of the incident light. At high enough intensities, high-order harmonics of the incident laser frequency, associated in the time domain to trains of attosecond pulses, are generated in the light beam specularly reflected by this "plasma mirror". The mechanisms leading to this generation are now relatively well-established, and the first experimental evidence for attosecond pulses generated on plasma mirrors has recently been reported. An accurate characterization of the temporal structure of the light reflected by plasma mirrors, down to the attosecond scale, however remains an experimental challenge. In this paper, we describe three different methods that could be used for such temporal measurements, from the femtosecond to the attosecond time scale. Two of them are interferometric techniques which only require measurements of photons, while the third one is a new configuration of a now well-established method, developed for attosecond pulses generated in gases, and based on photoelectron spectroscopy.
BibTeX:
@article{Quere2009,
  author = {Quere, F. and George, H. and Martin, Ph.},
  title = {Attosecond and femtosecond metrology for plasma mirrors},
  journal = {Harnessing Relativistic Plasma Waves As Novel Radiation Sources From Terahertz To X-rays and Beyond},
  year = {2009},
  volume = {7359},
  pages = {SPIE Europe},
  doi = {10.1117/12.822010}
}
"Internal frequency conversion extreme ultraviolet interferometer using mutual coherence properties of two high-order-harmonic sources"
Dobosz Dufrénoy S, Stabile H, Tortora A, Monot P, Reau F, Bougeard M, Merdji H, Carre B, Martin P, Joyeux D, Phalippou D, Delmotte F, Gautier J and Mercier R, Review of Scientific Instruments., Vol. 80(11), pp. 113102 - November, (2009).
Abstract: We report on an innovative two-dimensional imaging extreme ultraviolet (XUV) interferometer operating at 32 nm based on the mutual coherence of two laser high order harmonics (HOH) sources, separately generated in gas. We give the first evidence that the two mutually coherent HOH sources can be produced in two independent spatially separated gas jets, allowing for probing centimeter-sized objects. A magnification factor of 10 leads to a micron resolution associated with a subpicosecond temporal resolution. Single shot interferograms with a fringe visibility better than 30% are routinely produced. As a test of the XUV interferometer, we measure a maximum electronic density of 3x10(20) cm(-3) 1.1 ns after the creation of a plasma on aluminum target.
BibTeX:
@article{Dobosz2009a,
  author = {Dobosz Dufrénoy, S. and Stabile, H. and Tortora, A. and Monot, P. and Reau, F. and Bougeard, M. and Merdji, H. and Carre, B. and Martin, Ph. and Joyeux, D. and Phalippou, D. and Delmotte, F. and Gautier, J. and Mercier, R.},
  title = {Internal frequency conversion extreme ultraviolet interferometer using mutual coherence properties of two high-order-harmonic sources},
  journal = {Review of Scientific Instruments},
  year = {2009},
  volume = {80},
  number = {11},
  pages = {113102},
  doi = {10.1063/1.3257676}
}
"Mechanisms of forward laser harmonic emission from thin overdense plasmas"
George H, Quere F, Thaury C, Bonnaud G and Martin P, New Journal of Physics., Vol. 11, pp. 113028 - November, (2009).
Abstract: As a high-intensity laser pulse impinges a thin solid foil, high-order harmonics of the incident frequency can be observed at the rear (non-illuminated) side of this foil. Using numerical simulations, we show that these harmonics can be generated either at the front or at the rear side of the target. We analyze the mechanisms responsible for these two types of emission, and discuss their connection with those involved in the generation of harmonics detected on the front side. The combined measurements of spectra on both sides of the target constitute a powerful, but often nontrivial, probe of the ultrafast plasma dynamics.
BibTeX:
@article{George2009,
  author = {George, H. and Quere, F. and Thaury, C. and Bonnaud, G. and Martin, Ph},
  title = {Mechanisms of forward laser harmonic emission from thin overdense plasmas},
  journal = {New Journal of Physics},
  year = {2009},
  volume = {11},
  pages = {113028},
  doi = {10.1088/1367-2630/11/11/113028}
}
"Tracking propagation of ultrashort intense laser pulses in gases via probing of ionization"
Gizzi LA, Betti S, Galimberti M, Giulietti A, Giulietti D, Labate L, Levato T, Tomassini P, Monot P, Ceccotti T, D'Oliveira P and Martin P, Physical Review E., Vol. 79(5), pp. 056405 - May, (2009).
Abstract: We use optical interferometry to study the propagation of femtosecond laser pulses in gases. We show the measurements of propagation in a nitrogen gas jet and we compare the results with propagation in He under the same irradiation conditions. We find that in the case of nitrogen, the detailed temporal structure of the laser pulse can be tracked and visualized by measuring the phase and the resulting electron-density map. A dramatically different behavior occurs in He gas jets, where no details of the temporal structure of the laser pulse are visible. These observations are explained in terms of the ionization dynamics of nitrogen compared to helium. These circumstances make N2 gas sensitive to variations in the electric field and, therefore, allow the laser-pulse temporal and spatial structures to be visualized in detail.
BibTeX:
@article{Gizzi2009,
  author = {Gizzi, L. A. and Betti, S. and Galimberti, M. and Giulietti, A. and Giulietti, D. and Labate, L. and Levato, T. and Tomassini, P. and Monot, P. and Ceccotti, T. and De Oliveira, P. and Martin, Ph.},
  title = {Tracking propagation of ultrashort intense laser pulses in gases via probing of ionization},
  journal = {Physical Review E},
  year = {2009},
  volume = {79},
  number = {5},
  pages = {056405},
  doi = {10.1103/PhysRevE.79.056405}
}
"Ion acceleration in ultra-high contrast regime"
Levy A, Ceccotti T, Popescu H, Reau F, D'Oliveira P, Monot P, Martin P, Geindre JP and Lefebvre E , European Physical Journal-special Topics., Vol. 175, pp. 111-116 - August, (2009).
Abstract: In this work, we demonstrate that the contrast of high intensity laser pulses is a key issue for many problems dealing with high-field interaction with solid-density matter. As an example, we will discuss the interaction of an Ultra-High-Contrast (UHC), Ultra-Intense, 65 fs laser pulse with an overdense plasma through the proton acceleration from ultra-thin foils (from 0.08 μm to 105 μm). The symmetric feature of the ion beams emitted from both faces of the target will be demonstrated as well as the dominant role of the p component of the electric field rather than the ponderomotive force. Simulations performed with a 2D particle-in-cell code are in close agreement with all experimental data. UHC experiments prove to be a good as benchmarks for theories and models.
BibTeX:
@article{Levy2009,
  author = {Levy, A. and Ceccotti, T. and Popescu, H. and Reau, F. and D'Oliveira, P. and Monot, P. and Martin, Ph. and Geindre, J. P. and Lefebvre, E.},
  title = {Ion acceleration in ultra-high contrast regime},
  journal = {European Physical Journal-special Topics},
  year = {2009},
  volume = {175},
  pages = {111--116},
  doi = {10.1140/epjst/e2009-01126-3}
}
"Effect of a nanometer scale plasma on laser-accelerated ion beams"
Levy A, Nuter R, Ceccotti T, Combis P, Drouin M, Gremillet L, Monot P, Popescu H, Reau F, Lefebvre E and Martin P, New Journal of Physics., Vol. 11, pp. 093036 - September, (2009).
Abstract: Energies of laser-accelerated ions from thin foils in the so-called 'ultra-high-contrast' regime have been measured for various preformed plasma sizes on the non-irradiated foil surface. Whereas energies of protons accelerated in the laser counter-propagating direction remain almost constant for plasma scale length up to 300?nm, we found that plasmas as short as a few tens of nanometers reduce the maximum energy of ions accelerated in the laser direction. These experimental measurements are numerically confirmed with two-dimensional particle-in-cell simulations coupled to hydrodynamic calculation. Moreover, our experimental results, supported by simulations, provide evidence for the occurrence of ion wave breaking, and demonstrate its ability to mitigate the ion energy reduction due to the plasma gradient. This wave breaking is observed and characterized for both proton and carbon ion components.
BibTeX:
@article{Levy2009a,
  author = {Levy, A. and Nuter, R. and Ceccotti, T. and Combis, P. and Drouin, M. and Gremillet, L. and Monot, P. and Popescu, H. and Reau, F. and Lefebvre, E. and Martin, P.},
  title = {Effect of a nanometer scale plasma on laser-accelerated ion beams},
  journal = {New Journal of Physics},
  year = {2009},
  volume = {11},
  pages = {093036},
  doi = {10.1088/1367-2630/11/9/093036}
}
"Enhanced ion acceleration with extremely thin foils"
Loch R.A, Levy A, Ceccotti T, Quere F, Thaury C, George H, Bijkerk F, Boller K.J and Martin P, European Physical Journal-special Topics., Vol. 175, pp. 133-138 - August, (2009).
Abstract: Enhanced backward-acceleration of ions is experimentally observed when ultra-short, high-intensity and ultra-high-contrast laser pulses interact with thin foils having thicknesses in the order of the penetration depth of the laser light. Below the experimentally observed optimum foil thickness for the maximum ion energy versus thickness, there arises a second peak. 1D simulations on foils with an initial plasma density gradient show a similar trend as the experiment. It appears that in this regime of extremely thin foils it is important to take into account the limited expansion of the plasma that is formed by ultra-high-contrast pulses.
BibTeX:
@article{Loch2009a,
  author = {Loch, R. A. and Levy, A. and Ceccotti, T. and Quere, F. and Thaury, C. and George, H. and Bijkerk, F. and Boller, K. -. J. and Martin, Ph.},
  title = {Enhanced ion acceleration with extremely thin foils},
  journal = {European Physical Journal-special Topics},
  year = {2009},
  volume = {175},
  pages = {133--138},
  doi = {10.1140/epjst/e2009-01130-7}
}
i>"High-Order Harmonic And Fast Ion Generation In High Intensity Laser-Solid Interactions"
Loch R.A, Martin P, Ceccotti T, Monot P, Quere F, George H, Bougeard M, Reau F, D'Oliveira P and Boller K.J, Laser-driven Relativistic Plasmas Applied To Science, Industry and Medicine: 2nd International Symposium - Date: 19–23 January 2009 - Location Kyoto (Japan) - (2009).
Abstract: Experiments on high-order harmonic generation and ion acceleration are performed with the new installed 100 TW, 25 fs laser in Saclay (UHI100). These experiments require a very high laser pulse contrast. The suppression of prepulse energy is achieved by using a double plasma mirror, which results in a contrast of 1013.
BibTeX:
@article{Loch2009,
  author = {Loch, R. A. and Martin, Ph. and Ceccotti, T. and Monot, P. and Quere, F. and George, H. and Bougeard, M. and Reau, F. and D'Oliveira, P. and Boller, K. -. J.},
  title = {High-Order Harmonic And Fast Ion Generation In High Intensity Laser-Solid Interactions},
  journal = {Laser-driven Relativistic Plasmas Applied To Science, Industry and Medicine},
  year = {2009},
  volume = {1153},
  pages = {Japan Atom Energy Agcy, Photo-Med Valley & Photo-Med Res Ctr; Inst JapanEOLEOLAtom Energy Agcy, Adv Photon Res Ctr & Kansai Photon Sci; Minist Educ,EOLEOLCulture, Sports, Sci & Technol Japan; Japan Soc Promot Sci Core-to-CoreEOLEOLProgram; Int Collaborat High Dens Energy Sci; Japan Soc Promot Sci Res;EOLEOLOsaka Univ, Inst Laser Engn; Int Sci & Technol Ctr; Consortium PhotonEOLEOLSci & Technol},
  doi = {10.1140/epjst/e2009-01115-6}
}
"High-order harmonic generation from plasma mirrors"
Thaury C, Quere F, George H, Geindre JP, Monot P and Martin P, European Physical Journal-special Topics., Vol. 175, pp. 43-48 - August, (2009).
Abstract: We discuss the two mechanisms involved in high-order harmonic generation from plasma mirrors, and show that they can be clearly identified experimentally. The very different phase properties of the corresponding harmonics lead to light beams with different divergences. This can be exploited to select a particular type of harmonic by spatial filtering in the far-field.
BibTeX:
@article{Thaury2009,
  author = {Thaury, C. and Quere, F. and George, H. and Geindre, J. P. and Monot, P. and Martin, Ph.},
  title = {High-order harmonic generation from plasma mirrors},
  journal = {European Physical Journal-special Topics},
  year = {2009},
  volume = {175},
  pages = {43--48},
  doi = {10.1140/epjst/e2009-01115-6}
}
"Probing the dynamics of plasma mirrors on the attosecond time scale"
Thaury C, Quere F, George H, Loch RA, Geindre JP, Monot P and Martin P, Ultrafast Phenomena Xvi. Vol. 92, pp. 93-95 (2009).
Abstract: We demonstrate that the generation of high-order harmonics (HHG) of a laser on plasma mirrors preserves the coherence of the laser. We then exploit this coherence to study the dynamics of the plasma electrons.
BibTeX:
@article{Thaury2009a,
  author = {Thaury, C. and Quere, F. and George, H. and Loch, R. A. and Geindre, J. -. P. and Monot, P. and Martin, Ph.},
  title = {Probing the dynamics of plasma mirrors on the attosecond time scale},
  journal = {Ultrafast Phenomena Xvi},
  year = {2009},
  volume = {92},
  pages = {93--95},
  doi = {10.1007/978-3-540-95946-5_31}
}
2008
"Fast-ion energy-flux enhancement from ultrathin foils irradiated by intense and high-contrast short laser pulses."
Andreev A, Levy A, Ceccotti T, Thaury C, Platonov K, Loch RA and Martin P, Physical review letters., Vol. 101(15), pp. 155002-155002 - October, (2008).
Abstract: Recent significant improvements of the contrast ratio of chirped pulse amplified pulses allows us to extend the applicability domain of laser accelerated protons to very thin targets. In this framework, we propose an analytical model particularly suitable to reproducing ion laser acceleration experiments using high intensity and ultrahigh contrast pulses. The model is based on a self-consistent solution of the Poisson equation using an adiabatic approximation for laser generated fast electrons which allows one to find the target thickness maximizing the maximum proton (and ion) energies and population as a function of the laser parameters. Model furnished values show a good agreement with experimental data and 2D particle-in-cell simulation results.
BibTeX:
@article{Andreev2008,
  author = {Andreev, A. and Levy, A. and Ceccotti, T. and Thaury, C. and Platonov, K. and Loch, R. A. and Martin, Ph},
  title = {Fast-ion energy-flux enhancement from ultrathin foils irradiated by intense and high-contrast short laser pulses.},
  journal = {Physical review letters},
  year = {2008},
  volume = {101},
  number = {15},
  pages = {155002--155002},
  doi = {10.1103/PhysRevLett.101.155002}
}
"TNSA in the ultra-high contrast regime"
Ceccotti T, Levy A, Reau F, Popescu H, Monot P, Lefebvre E and Martin P, Plasma Physics and Controlled Fusion., December, 2008. Vol. 50(12), pp. European Phys Soc - (2008).
Abstract: We present some of the results obtained when an ultra-high-intensity (~5 * 1018W?cm-2), ultra-high contrast (>1010) laser pulse interacts with thins foils. Under such conditions, protons accelerated by the target normal sheat acceleration mechanism are observed from both sides of the target and show quasi-symmetric features which have been corroborated by extensive 1D and 2D particle-in-cell simulations. Moreover, we show that due to the very steep gradient of the laser-irradiated surface, the Brunel effect is the main laser energy coupling mechanism.
BibTeX:
@article{Ceccotti2008,
  author = {Ceccotti, T. and Levy, A. and Reau, F. and Popescu, H. and Monot, P. and Lefebvre, E. and Martin, Ph},
  title = {TNSA in the ultra-high contrast regime},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2008},
  volume = {50},
  number = {12},
  pages = {European Phys Soc},
  doi = {10.1088/0741-3335/50/12/124006}
}
"Non-adiabatic cluster expansion after ultrashort laser interaction"
Faenov AY, Magunov AI, Pikuz TA, Skobelev IY, Giulietti D, Betti S, Galimberti M, Gamucci A, Giulietti A, Gizzi LA, Labate L, Levato T, Tomassini P, Marques JR, Bourgeois N, Dobosz Dufrénoy S, Ceccotti T, Monot P, Reau F, Popescu H, D'Oliveira P, Martin P, Fukuda Y, Boldarev AS, Gasilov SV and Gasilov VA, Laser and Particle Beams., Vol. 26(1), pp. 69-81 - March, (2008).
Abstract: We used X-ray spectroscopy as a diagnostic tool for investigating the properties of laser-cluster interactions at the stage in which non-adiabatic cluster expansion takes place and a quasi-homogeneous plasma is produced. The experiment was carried out with a 10 TW, 65 fs Ti:Sa laser focused on CO 2 cluster jets. The effect of different laser-pulse contrast ratios and cluster concentrations was investigated. The X-ray emission associated to the Rydberg transitions allowed us to retrieve, through the density and temperature of the emitting plasma, the time after the beginning of the interaction at which the emission occurred. The comparison of this value with the estimated time for the "homogeneous" plasma formation shows that the degree of adiabaticity depends on both the cluster concentration and the pulse contrast. Interferometric measurements support the X-ray data concerning the plasma electron density.
BibTeX:
@article{Faenov2008,
  author = {Faenov, A. Ya. and Magunov, A. I. and Pikuz, T. A. and Skobelev, I. Yu. and Giulietti, D. and Betti, S. and Galimberti, M. and Gamucci, A. and Giulietti, A. and Gizzi, L. A. and Labate, L. and Levato, T. and Tomassini, P. and Marques, J. R. and Bourgeois, N. and Dobosz Dufrénoy, S and Ceccotti, T. and Monot, P. and Reau, F. and Popescu, H. and D'Oliveira, P. and Martin, Ph. and Fukuda, Y. and Boldarev, A. S. and Gasilov, S. V. and Gasilov, V. A.},
  title = {Non-adiabatic cluster expansion after ultrashort laser interaction},
  journal = {Laser and Particle Beams},
  year = {2008},
  volume = {26},
  number = {1},
  pages = {69--81},
  doi = {10.1017/S0263034608000104}
}
"Advanced diagnostics applied to a laser-driven electron-acceleration experiment"
Gamucci A, Bourgeois N, Ceccotti T, Dobosz Dufrénoy S, D'Oliveira P, Galimberti M, Galy J, Giulietti A, Giulietti D, Gizzi LA, Hamilton DJ, Labate L, Marques J-R, Monot P, Popescu H, Reau F, Sarri G, Tomassini P and Martin P, Ieee Transactions On Plasma Science., Vol. 36(4), pp. 1699-1706 - August, (2008).
Abstract: In this paper, the interaction of 10-TW laser pulses, focused at moderately relativistic intensity, with a supersonic helium gas-jet has been investigated by varying gas density and jet nozzle. We have successfully tested several advanced diagnostic devices to characterize the plasma and the accelerated electron bunches. Plasma densities have been measured by means of a femtosecond high-resolution interferometer, while the electron beams were analyzed with a stack of radiochromic films, a beam-profile monitor, a magnetic spectrometer, and a nuclear activation setup based on gamma-ray generation via electron bremsstrahlung. We present the results as well as the basic features and relevant details of such diagnostics whose performances can fit a large class of experiments.
BibTeX:
@article{Gamucci2008,
  author = {Gamucci, Andrea and Bourgeois, Nicolas and Ceccotti, Tiberio and Dobosz Dufrénoy, Sandrine and D'Oliveira, Pascal and Galimberti, Marco and Galy, Jean and Giulietti, Antonio and Giulietti, Danilo and Gizzi, Leomda A. and Hamilton, David J. and Labate, Luca and Marques, Jean-Raphael and Monot, Pascal and Popescu, Horia and Reau, Fabrice and Sarri, Gianluca and Tomassini, Paolo and Martin, Philippe},
  title = {Advanced diagnostics applied to a laser-driven electron-acceleration experiment},
  journal = {Ieee Transactions On Plasma Science},
  year = {2008},
  volume = {36},
  number = {4},
  pages = {1699--1706},
  doi = {10.1109/TPS.2008.2000898}
}
"Intense gamma-ray source in the giant-dipole-resonance range driven by 10-TW laser pulses."
Giulietti A, Bourgeois N, Ceccotti T, Davoine X, Dobosz Dufrénoy S, D'Oliveira P, Galimberti M, Galy J, Gamucci A, Giulietti D, Gizzi LA, Hamilton DJ, Lefebvre E, Labate L, Marques JR, Monot P, Popescu H, Reau F, Sarri G, Tomassini P and Martin P, Physical review letters., Vol. 101(10), pp. 105002-105002 - September, (2008).
Abstract: A gamma-ray source with an intense component around the giant dipole resonance for photonuclear absorption has been obtained via bremsstrahlung of electron bunches driven by a 10-TW tabletop laser. 3D particle-in-cell simulation proves the achievement of a nonlinear regime leading to efficient acceleration of several sequential electron bunches per each laser pulse.
BibTeX:
@article{Giulietti2008,
  author = {Giulietti, A. and Bourgeois, N. and Ceccotti, T. and Davoine, X. and Dobosz Dufrénoy, S. and D'Oliveira, P. and Galimberti, M. and Galy, J. and Gamucci, A. and Giulietti, D. and Gizzi, L. A. and Hamilton, D. J. and Lefebvre, E. and Labate, L. and Marques, J. R. and Monot, P. and Popescu, H. and Reau, F. and Sarri, G. and Tomassini, P. and Martin, P.},
  title = {Intense gamma-ray source in the giant-dipole-resonance range driven by 10-TW laser pulses.},
  journal = {Physical review letters},
  year = {2008},
  volume = {101},
  number = {10},
  pages = {105002--105002},
  doi = {10.1103/PhysRevLett.101.105002}
}
"Proton acceleration with high-intensity laser pulses in ultrahigh contrast regime"
Levy A, Ceccotti T, Popescu H, Reau F, D'Oliveira P, Monot P, Martin P, Geindre J-P and Lefebvre E, Ieee Transactions On Plasma Science., Vol. 36(4), pp. 1808-1811 - August, (2008).
Abstract: We investigate the interaction of a high-intensity (~5.1018 W/cm2) and short (~65 fs) laser pulse with thin foils (from 0.08 to 105 μm) in a regime of ultrahigh contrast (> 1010). This paper shows that for thicknesses less than about 10 μm, proton acceleration from both sides of the target presents quite symmetric features. Proton bunches emitted from each side show similar maximum energies and spatial characteristics. Moreover, we show that for ultrahigh-contrast pulses, the efficient acceleration mechanism is related to the Brunel effect and not to the ponderomotive force. Simulations performed with a 2-D particle-in-cell code are in close agreement with all experimental data.
BibTeX:
@article{Levy2008,
  author = {Levy, Anna and Ceccotti, Tiberio and Popescu, Horia and Reau, Fabrice and D'Oliveira, Pascal and Monot, Pascal and Martin, Philippe and Geindre, Jean-Paul and Lefebvre, Erik},
  title = {Proton acceleration with high-intensity laser pulses in ultrahigh contrast regime},
  journal = {Ieee Transactions On Plasma Science},
  year = {2008},
  volume = {36},
  number = {4},
  pages = {1808--1811},
  doi = {10.1109/TPS.2008.2001188}
}
"Phase properties of laser high-order harmonics generated on plasma mirrors."
Quere F, Thaury C, Geindre JP, Bonnaud G, Monot P and Martin P, Physical review letters., Vol. 100(9), pp. 095004-095004 - March, (2008).
Abstract: As a high-intensity laser-pulse reflects on a plasma mirror, high-order harmonics of the incident frequency can be generated in the reflected beam. We present a numerical study of the phase properties of these individual harmonics, and demonstrate experimentally that they can be coherently controlled through the phase of the driving laser field. The harmonic intrinsic phase, resulting from the generation process, is directly related to the coherent sub-laser-cycle dynamics of plasma electrons, and thus constitutes a new experimental probe of these dynamics.
BibTeX:
@article{Quere2008c,
  author = {Quere, F. and Thaury, C. and Geindre, J. -. P. and Bonnaud, G. and Monot, P. and Martin, Ph},
  title = {Phase properties of laser high-order harmonics generated on plasma mirrors.},
  journal = {Physical review letters},
  year = {2008},
  volume = {100},
  number = {9},
  pages = {095004--095004},
  doi = {10.1103/PhysRevLett.100.095004}
}
"Comment on "transition to the relativistic regime in high order harmonic generation"."
Quere F, Thaury C, Geindre JP and Martin P, Physical review letters., Vol. 100(8), pp. 089402-089401 - February, (2008).
Abstract: A Comment on the Letter by Alexander Tarasevitch et al.,
BibTeX:
@article{Quere2008h,
  author = {Quere, F. and Thaury, C. and Geindre, J. -. P. and Martin, Ph},
  title = {Comment on "transition to the relativistic regime in high order harmonic generation".},
  journal = {Physical review letters},
  year = {2008},
  volume = {100},
  number = {8},
  pages = {089402--089401;},
  doi = {10.1103/PhysRevLett.100.089401}
}
"Basic mechanisms of laser high-order harmonic generation from plasma mirrors"
Quere F, Thaury C, George H, Geindre JP, Lefebvre E, Bonnaud G, Hueller S, Monot P and Martin P, Journal of Modern Optics. Vol. 55(16), pp. 2711-2721 - (2008).
Abstract: We discuss the two mechanisms involved in high-order harmonic generation from plasma mirrors, which can be clearly identified in numerical simulations: the coherent wake emission (CWE) and the relativistic oscillating mirror (ROM) processes. Using high-contrast multi-TeraWatt ultrashort laser pulses, harmonics originating from these two processes can also be distinguished experimentally.
BibTeX:
@article{Quere2008b,
  author = {Quere, F. and Thaury, C. and George, H. and Geindre, J. P. and Lefebvre, E. and Bonnaud, G. and Hueller, S. and Monot, P. and Martin, Ph.},
  title = {Basic mechanisms of laser high-order harmonic generation from plasma mirrors},
  journal = {Journal of Modern Optics},
  year = {2008},
  volume = {55},
  number = {16},
  pages = {2711--2721},
  doi = {10.1080/09500340802187381}
}
"High-order harmonic generation using plasma mirrors"
Quere F, Thaury C, George H, Geindre JP, Lefebvre E, Bonnaud G, Monot P and Martin P, Plasma Physics and Controlled Fusion., Vol. 50(12), pp. European Phys Soc - December, (2008).
Abstract: We discuss the two mechanisms involved in high-order harmonic generation from plasma mirrors, which can be clearly identified in numerical simulations: the coherent wake emission (CWE) and the relativistic oscillating mirror (ROM) processes. Using high-contrast multi-terawatt ultrashort laser pulses, harmonics originating from these two processes can also be distinguished experimentally.
BibTeX:
@article{Quere2008e,
  author = {Quere, F. and Thaury, C. and George, H. and Geindre, J. P. and Lefebvre, E. and Bonnaud, G. and Monot, P. and Martin, Ph},
  title = {High-order harmonic generation using plasma mirrors},
  journal = {Plasma Physics and Controlled Fusion},
  year = {2008},
  volume = {50},
  number = {12},
  pages = {European Phys Soc},
  doi = {10.1088/0741-3335/50/12/124007}
}
"High-order harmonic generation in high intensity laser-solid interactions"
Quere F, Thaury C, George H, Geindre JP, Levy A, Ceccotti T, Monot P, Marjoribanks R, Audebert P and Martin P, 2008 Quantum Electronics and Laser Science Conference (QELS)., pp. 2 pp.-2 - January, (2008).
Abstract: We will discuss the two mechanisms involved in high-order harmonic generation from plasma mirrors, and show that they can be clearly identified experimentally. The phase and coherence properties of these harmonics will be analyzed.
BibTeX:
@article{Quere2008a,
  author = {Quere, F. and Thaury, C. and George, H. and Geindre, J. P. and Levy, A. and Ceccotti, T. and Monot, P. and Marjoribanks, R. and Audebert, P. and Martin, P.},
  title = {High-order harmonic generation in high intensity laser-solid interactions},
  journal = {2008 Quantum Electronics and Laser Science Conference (QELS)},
  year = {2008},
  pages = {2 pp.--2},
  doi = {10.1109/QELS.2008.4552898}
}
"Coherent dynamics of plasma mirrors"
Thaury C, George H, Quere F, Loch R, Geindre JP, Monot P and Martin P, Nature Physics., Vol. 4(8), pp. 631-634 - August, (2008).
Abstract: Coherent ultrashort X-ray pulses provide new ways to probe matter and its ultrafast dynamics1, 2, 3. One of the promising paths to generate these pulses consists of using a nonlinear interaction with a system to strongly and periodically distort the waveform of intense laser fields, and thus produce high-order harmonics. Such distortions have so far been induced by using the nonlinear polarizability of atoms, leading to the production of attosecond light bursts4, short enough to study the dynamics of electrons in matter3. Shorter and more intense attosecond pulses, together with higher harmonic orders, are expected5, 6 by reflecting ultraintense laser pulses on a plasma mirror-a dense (1023 electrons cm-3) plasma with a steep interface. However, short-wavelength-light sources produced by such plasmas are known to generally be incoherent7. In contrast, we demonstrate that like in usual low-intensity reflection, the coherence of the light wave is preserved during harmonic generation on plasma mirrors. We then exploit this coherence for interferometric measurements and thus carry out a first study of the laser-driven coherent dynamics of the plasma electrons.
BibTeX:
@article{Thaury2008,
  author = {Thaury, C. and George, H. and Quere, F. and Loch, R. and Geindre, J. -. P. and Monot, P. and Martin, Ph.},
  title = {Coherent dynamics of plasma mirrors},
  journal = {Nature Physics},
  year = {2008},
  volume = {4},
  number = {8},
  pages = {631--634},
  doi = {10.1038/nphys986}
}
"Radiothérapie miniature"
Michaut C, La Recherche - technologie - 01/11/2008 par Cécile Michaut dans mensuel n°424 à la page 26 - (2008).
Abstract: Le domaine médical a lui aussi ses accélérateurs de particules : il s'agit d'accélérateurs d'électrons, utilisés dans le traitement de certains cancers par radiothérapie. Très encombrants, ces derniers mesurent près de deux mètres de haut. Des chercheurs français et italiens tentent donc de les remplacer par un système à base de laser, plus petit et d'utilisation plus simple [1] .

La radiothérapie est une méthode qui permet d'éviter les récidives d'une tumeur après son ablation. Elle consiste à irradier la zone opérée, à l'aide d'électrons énergétiques qui détruisent les cellules cancéreuses restantes. Ce geste se déroule pendant l'opération, d'oů son nom de radiothérapie intra-opératoire ou IORT. Mais il nécessite l'installation d'un accélérateur d'électrons au sein même des blocs opératoires, ce qui, compte tenu des contraintes d'utilisation et d'encombrement, en limite la diffusion. Or, depuis quelques années, on sait accélérer des électrons par un autre moyen : les lasers. Le principe : des impulsions laser très brèves et très intenses sont envoyées sur un jet de gaz, ici du xénon, et éjectent une partie des électrons, formant un plasma. L'oscillation de ce plasma accélère les électrons à des vitesses proches de celle de la lumière [2, 3] .

Antonio Giulietti et ses collaborateurs, du Commissariat à l'énergie atomique CEA à Saclay, dans l'Essonne, et du Conseil italien de la recherche, à Pise, viennent de montrer que cette technique pourrait s'appliquer à la production d'électrons à usage médical. << Jusqu'à présent, les recherches étaient en quête de record : elles visaient à obtenir les électrons les plus énergétiques possibles, au détriment de leur nombre, commente Philippe Martin, l'un des auteurs de ce travail, du CEA de Saclay. Mais pour les applications médicales en IORT, des électrons moyennement énergétiques, de 10 à 20 mégaélectronvolts, suffisent. à ces énergies, il est plus facile d'en produire beaucoup, environ 1010 électrons par joule. C'est ce que nous avons fait, avec un laser commercial qui tient sur une table. » L'autre difficulté est de produire des électrons de manière reproductible, notamment en énergie. << C'est surtout en jouant sur la densité du gaz et la position du foyer du laser dans le jet de gaz que l'on atteint cette stabilité », indique Philippe Martin.

Ce dispositif n'est pas encore testé médicalement. En cas de succès, il permettrait, outre les économies espérées sur la taille et le coűt des installations, de soigner plusieurs personnes en parallèle, puisque le faisceau laser peut être transporté en même temps dans plusieurs salles. Et comme le laser est situé hors de la salle d'opération, la maintenance est assurée sans nuire à la stérilité des salles.

BibTeX:
@article{Michaut2008,
  author = {Michaut, Cécile},
  title = {Radiothérapie miniature},
  journal = {La Recherche - technologie - 01/11/2008 par Cécile Michaut dans mensuel n°424 à la page 26},
  year = {2008},
  url = {http://www.larecherche.fr/actualite/technologie/radiotherapie-miniature-01-11-2008-85830}
}
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