J. Faure

Lund University, Lund, Skåne, Sweden

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Publications (118)384.85 Total impact

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    ABSTRACT: Using particle-in-cell simulations, we study the interaction of few-mJ–few-cycle laser pulses with an underdense plasma at resonant density. In this previously unexplored regime, it is found that group velocity dispersion is a key ingredient of the interaction. The concomitant effects of dispersion and plasma nonlinearities cause a deceleration of the wakefield phase velocity, which becomes sub-relativistic. Electron injection in this sub-relativistic wakefield is enhanced and leads to the production of a femtosecond electron bunch with a picocoulomb of charge in the 5–10 MeV energy range. Such an electron bunch is of great interest for application to ultrafast electron diffraction. In addition, in this dispersion dominated regime, it is shown that positively chirped laser pulses can be used as a tuning knob for compensating for plasma dispersion, increasing the laser amplitude during self-focusing and optimizing the trapped charge.
    New Journal of Physics 02/2014; 16(2):023023. · 4.06 Impact Factor
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    ABSTRACT: We demonstrate electron diffraction from a polycrystalline aluminum foil using 100 keV electron bunches from a high repetition rate laser wakefield accelerator. Our proof-of-principle experiment shows the potential of such source for ultrafast electron diffraction applications.
    CLEO: QELS_Fundamental Science; 06/2013
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    ABSTRACT: We report on an experimental demonstration of laser wake field electron acceleration using few-milijoule laser pulses tightly focused on a 100 μm scale gas target. Using a comparatively low energy pulse has the benefit of a more compact system with a high repetition rate (typically kHz), which can prove useful for both practical applications and better statistical studies of laser plasma interactions. A proof-of-principle experiment was conducted to demonstrate the applicability of such electron sources from laser plasma wake field accelerator for ultrafast electron diffraction.
    Proc SPIE 05/2013;
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    ABSTRACT: Spectral measurements of visible coherent transition radiation produced by a laser-plasma-accelerated electron beam are reported. The significant periodic modulations that are observed in the spectrum result from the interference of transition radiation produced by multiple bunches of electrons. A Fourier analysis of the spectral interference fringes reveals that electrons are injected and accelerated in multiple plasma wave periods, up to at least 10 periods behind the laser pulse. The bunch separation scales with the plasma wavelength when the plasma density is changed over a wide range. An analysis of the spectral fringe visibility indicates that the first bunch contains most of the charge.
    Physical Review Letters 02/2013; 110(6):065005. · 7.73 Impact Factor
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    ABSTRACT: We show that electron bunches in the 50–100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.
    Applied Physics Letters. 01/2013; 102(6):064104-064104-4.
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    ABSTRACT: Betatron x-ray emission in laser-plasma accelerators is a promising compact source that may be an alternative to conventional x-ray sources, based on large scale machines. In addition to its potential as a source, precise measurements of betatron emission can reveal crucial information about relativistic laser-plasma interaction. We show that the emission length and the position of the x-ray emission can be obtained by placing an aperture mask close to the source, and by measuring the beam profile of the betatron x-ray radiation far from the aperture mask. The position of the x-ray emission gives information on plasma wave breaking and hence on the laser non-linear propagation. Moreover, the measurement of the longitudinal extension helps one to determine whether the acceleration is limited by pump depletion or dephasing effects. In the case of multiple injections, it is used to retrieve unambiguously the position in the plasma of each injection. This technique is also used to study how, in a capillary discharge, the variations of the delay between the discharge and the laser pulse affect the interaction. The study reveals that, for a delay appropriate for laser guiding, the x-ray emission only occurs in the second half of the capillary: no electrons are injected and accelerated in the first half.
    Plasma Physics and Controlled Fusion 11/2012; 54(12). · 2.37 Impact Factor
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    ABSTRACT: To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research.
    Medical Physics 06/2012; 39(6):3501-8. · 2.91 Impact Factor
  • Physical Review Letters 02/2012; 108(6). · 7.73 Impact Factor
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    ABSTRACT: Laser plasma accelerators produce today ultra short, quasi-monoenergetic and collimated electron beams with potential applications in material science, chemistry and medicine. The laser plasma accelerator used to produce such an electron beam is presented. The design of a laser based accelerator designed to produce more energetic electron beams with a narrow relative energy spread is also proposed here. This compact approach should permit a miniaturization and cost reduction of future accelerators and associated X-Free Electrons Lasers (XFEL).
    International Journal of Modern Physics B 01/2012; 21(03n04). · 0.46 Impact Factor
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    ABSTRACT: We show that the control and the mapping of the x-ray emission reveals unique features of the laser-plasma accelerator physics, including strong correlations between electron and x-ray beams, and density-dependence of electron injection position.
    Lasers and Electro-Optics (CLEO), 2012 Conference on; 01/2012
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    ABSTRACT: The features of Betatron x-ray emission produced in a laser-plasma accelerator are closely linked to the properties of the relativistic electrons which are at the origin of the radiation. While in interaction regimes explored previously the source was by nature unstable, following the fluctuations of the electron beam, we demonstrate in this Letter the possibility to generate x-ray Betatron radiation with controlled and reproducible features, allowing fine studies of its properties. To do so, Betatron radiation is produced using monoenergetic electrons with tunable energies from a laser-plasma accelerator with colliding pulse injection [J. Faure et al., Nature (London) 444, 737 (2006)]. The presented study provides evidence of the correlations between electrons and x-rays, and the obtained results open significant perspectives toward the production of a stable and controlled femtosecond Betatron x-ray source in the keV range.
    Physical Review Letters 12/2011; 107(25):255003. · 7.73 Impact Factor
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    ABSTRACT: The x-ray emission in laser-plasma accelerators can be a powerful tool to understand the physics of relativistic laser-plasma interaction. It is shown here that the mapping of betatron x-ray radiation can be obtained from the x-ray beam profile when an aperture mask is positioned just beyond the end of the emission region. The influence of the plasma density on the position and the longitudinal profile of the x-ray emission is investigated and compared to particle-in-cell simulations. The measurement of the x-ray emission position and length provides insight on the dynamics of the interaction, including the electron self-injection region, possible multiple injection, and the role of the electron beam driven wakefield.
    Physical Review Letters 11/2011; 107(21):215004. · 7.73 Impact Factor
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    ABSTRACT: Gamma-ray beams with optimal and tuneable size, temperature, and dose are of great interest for a large variety of applications. These photons can be produced by the conversion of energetic electrons through the bremsstrahlung process in a dense material. This work presents the experimental demonstration of 30 μm resolution radiography of dense objects using an optimized gamma-ray source, produced with a high-quality electron beam delivered by a compact laser-plasma accelerator.
    Applied Physics Letters 06/2011; 98(26):264101-264101-3. · 3.52 Impact Factor
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    ABSTRACT: Demonstrations of high-quality electron beams driven by compact and 10 Hz repetition rate lasers have been recently achieved by several research teams. We report in this paper numerical study results of an optimized conversion of these energetic electrons into high-energy photons, through the bremsstrahlung process in a dense material. Dedicated optimizations of the spectral and optical qualities of such resulting photon beams are carried out by Monte Carlo simulations and by considering typical measurements of electron beams obtained with a 30 TW–30 fs laser. These results of simulations show the possibility of production of gamma-ray sources with optimal and tunable dose, temperature, size and angular divergence. Gamma sources with size below 50 μm are expected to be produced using such compact laser-plasma accelerators.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2011; 629(1):382-386. · 1.14 Impact Factor
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    ABSTRACT: Particle accelerators driven by the interaction of ultraintense and ultrashort laser pulses with a plasma can generate accelerating electric fields of several hundred gigavolts per metre and deliver high-quality electron beams with low energy spread, low emittance and up to 1GeV peak energy. Moreover, it is expected they may soon be able to produce bursts of electrons shorter than those produced by conventional particle accelerators, down to femtosecond durations and less. Here we present wide-band spectral measurements of coherent transition radiation which we use for temporal characterization. Our analysis shows that the electron beam, produced using controlled optical injection, contains a temporal feature that can be identified as a 15pC, 1.4-1.8fs electron bunch (root mean square) leading to a peak current of 3-4kA depending on the bunch shape. We anticipate that these results will have a strong impact on emerging applications such as short-pulse and short-wavelength radiation sources, and will benefit the realization of laboratory-scale free-electron lasers.
    Nature Physics 01/2011; 7(3):219-222. · 19.35 Impact Factor
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    Cell Death & Disease 09/2010; 1:e73. · 6.04 Impact Factor
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    ABSTRACT: The injection of quasimonoenergetic electron beams into a laser wakefield accelerator is demonstrated experimentally using density gradients at the edges of a plasma channel. In the experiment, two laser pulses are used; the main laser pulse drives a wakefield, while a second countercrossing laser beam produces a plasma whose expansion creates a channel with significant density gradients. Local injection of electrons in the wakefield is triggered by wave breaking in the density ramp. The injection is localized spatially and leads to the generation of collimated and narrow energy spread relativistic electron beams at the 100 MeV level, with charges in the range of 20–100 pC. The stability of this injection process is compared to the stability of the colliding pulse injection process and is found to be inferior for our experimental conditions. On the other hand, it is found that as the electron beam divergence is smaller in the case of gradient injection, the transverse emittance might be better.
    Physics of Plasmas 08/2010; 17(8):083107-083107-8. · 2.38 Impact Factor
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    ABSTRACT: In this study, electrons were injected into a laser plasma accelerator using colliding laser pulses. By varying the parameters of the injection laser pulse, the amount of charge accelerated in the plasma wave could be controlled. This external control of the injected load was used to investigate beam loading of the accelerating structure and especially its influence on the electron beam energy and energy spread. Information on the accelerating structure and bunch duration was then derived from these experimental observations.
    New Journal of Physics 04/2010; 12(4):045023. · 4.06 Impact Factor
  • Victor Malka, Jérôme Faure, Yann A Gauduel
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    ABSTRACT: Deeply understanding the basic mechanisms of radiation damage in vitro and on living cells, starting from the early radical and molecular processes to mutagenic DNA lesions, cell signalling, genomic instability, apoptosis, microenvironment and Bystander effects, radio sensitivity should have many practical consequences such as the customization of cancer radiotherapy or radioprotection protocols. In this context, innovative laser-plasma accelerators provide ultra-short particle beams (electrons, protons) with parameters of interest for radiation biology and medical physics. This review article approaches some complex links that exist between radiation physics of new pulsed irradiation sources and potential biomedical applications. These links concern mainly the understanding of spatio-temporal events triggered by a radiation, within a fluctuating lapse of time from the initial energy deposition to primary damages of biological interest.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 01/2010; 704(1-3):142-51. · 3.90 Impact Factor
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    ABSTRACT: Beam loading is the phenomenon which limits the charge and the beam quality in plasma based accelerators. An experimental study conducted with a laser-plasma accelerator is presented. Beam loading manifests itself through the decrease of the beam energy, the reduction of dark current, and the increase of the energy spread for large beam charge. 3D PIC simulations are compared to the experimental results and confirm the effects of beam loading. It is found that, in our experimental conditions, the trapped electron beams generate decelerating fields on the order of 1 (GV/m)/pC and that beam loading effects are optimized for trapped charges of about 20 pC.
    Physical Review Letters 11/2009; 103(19):194804. · 7.73 Impact Factor

Publication Stats

2k Citations
384.85 Total Impact Points


  • 2013
    • Lund University
      • Department of Physics
      Lund, Skåne, Sweden
  • 2004–2013
    • ENSTA Bretagne
      Brest, Brittany, France
  • 2009
    • Atomic Energy and Alternative Energies Commission
      Fontenay, Île-de-France, France
  • 2008–2009
    • Università degli Studi di Milano-Bicocca
      Milano, Lombardy, Italy
  • 2000–2009
    • École Polytechnique
      • LULI Laboratoire Pour l'Utilisation des Lasers Intenses
      Lutetia Parisorum, Île-de-France, France
  • 2001–2002
    • Pierre and Marie Curie University - Paris 6
      • Laboratoire pour l'Utilisation des Lasers Intenses (LULI)
      Lutetia Parisorum, Île-de-France, France