M. E. Couprie

SOLEIL synchrotron, Gif, Île-de-France, France

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Publications (280)344.02 Total impact

  • M. E. Couprie · Luca Giannessi
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    ABSTRACT: Short wavelength Free Electron Lasers (FEL) may operate in the Self Amplified Spontaneous Emission (SASE) configuration, where the spontaneous radiation originated by the electron shot noise is gradually amplified. This generally leads to an output pulse consisting of uncorrelated temporal spikes with a limited longitudinal coherence length. When a FEL amplifier is seeded by a coherent light source, the coherence properties of the seed are transferred to the initial electron-beam modulation, allowing for an improved control of the longitudinal properties of the emitted radiation. The spiky structure is suppressed both in the temporal domain and spectral domain and the bunching process becomes more efficient. Associated intensity and jitter fluctuations are reduced, as well as the arrival-time jitter. In addition the use of an external seed reduces the saturation length and therefore the associated costs of the device. High order harmonics generated in gas permit to seed a FEL amplifier in the vacuum ultra-violet, enabling the direct generation of seeded-Free Electron Laser radiation directly at short wavelengths. We analyze here the basic requirements for the seed source in terms of seed level versus the electron shot noise, and the problems of coupling of the seed source to the FEL. We also review the most recent achievements with HHG seeding, in particular on SCSS Test Accelerator, SPARC and SFLASH.
    No preview · Article · Sep 2015 · Springer Series in Optical Sciences
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    ABSTRACT: More than 50 years after the laser discovery, X-ray free electron lasers (FEL), the first powerful tuneable, short pulse lasers in the X-ray spectral range, are now blooming in the world, enabling new discoveries on the ultra-fast dynamics of excited systems and imaging. LUNEX5 demonstrator project aims at investigating paths towards advanced and compact FELs. Two strategies are adopted. The first one concerns the FEL line where seeding and echo harmonic generation are implemented together with compact cryogenic in-vacuum undulators. In the second one, the electron beam is no longer provided by a conventional linear accelerator but by a laser plasma process, while a necessary particular electron beam manipulation is required to handle the electron properties to enable FEL amplification.
    Full-text · Article · Sep 2015 · Journal of Modern Optics
  • M.E. Couprie
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    ABSTRACT: The newly developed intense short wavelength light sources (from Extreme Ultra-Violet (EUV) to X-rays) have open the path to the exploration of matter for revealing structures and electronic processes and for following their evolution in time. After drawing the panorama of existing accelerator based short wavelength light sources, the new trends of evolution of short wavelengths FEL are described, with some illustrations with the example of the LUNEX5 (free electron Laser a New accelerator for the Exploitation of X-ray radiation of 5th generation) demonstrator project of advanced compact Free Electron Laser.
    No preview · Article · Sep 2015 · Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms
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    ABSTRACT: Emission of light by a single electron moving on a curved trajectory (synchrotron radiation) is one of the most well-known fundamental radiation phenomena. However experimental situations are more complex as they involve many electrons, each being exposed to the radiation of its neighbors. This interaction has dramatic consequences, one of the most spectacular being the spontaneous formation of spatial structures inside electrons bunches. This fundamental effect is actively studied as it represents one of the most fundamental limitations in electron accelerators, and at the same time a source of intense terahertz radiation (Coherent Synchrotron Radiation, or CSR). Here we demonstrate the possibility to directly observe the electron bunch microstructures with subpicosecond resolution, in a storage ring accelerator. The principle is to monitor the terahertz pulses emitted by the structures, using a strategy from photonics, time-stretch, consisting in slowing-down the phenomena before recording. This opens the way to unpreceeded possibilities for analyzing and mastering new generation high power coherent synchrotron sources.
    Full-text · Article · May 2015 · Scientific Reports
  • Conference Paper: Cryogenic undulators

    No preview · Conference Paper · May 2015
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    ABSTRACT: LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5 th generation) aims at investigating the production of short, intense, coherent Free Electron Laser (FEL) pulses in the 40-4 nm spectral range. It comprises a 400 MeV superconducting Linear Accelerator for high repetition rate operation (10 kHz), multi-FEL lines adapted for studies of advanced FEL schemes, a 0.4-1 GeV Laser Wake Field Accelerator (LWFA) for its qualification by a FEL application, a single undulator line enabling advanced seeding and pilot user applications. Different studies and R&D programs have been launched. A test experiment for the demonstration of 180 MeV LWFA based FEL amplification at 200 nm is under preparation, thanks to a proper electron beam manipulation. Specific hardware is also under development such as a cryo-ready 3 m long undulator of 15 mm period.
    Full-text · Conference Paper · May 2015
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    ABSTRACT: We consider the problem of shot-by-shot acquisition of pulse shapes at high repetition rate in accelerator-based systems. More specifically, we examine the two-step strategy consisting in (i) encoding the pulse information onto a laser pulse, and (ii) use the so-called time-stretch strategy to “slow-down” the information before recording. We thus show that the repetition rate of already existing electro-optic sampling setups can be straightforwardly increased up to the 100 ×106 pulses/s range, and make a demonstration for the detection of coherent THz pulses. The strategy is however not limited to electro-optic sampling of THz pulses or electron bunches. It can be applied to other types of wavelengths, provided the desired information (as e.g., FEL pulses or electron bunches shapes) can be imprinted onto a laser pulse.
    No preview · Conference Paper · Apr 2015
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    ABSTRACT: Abstract We report on the characteristics of coherent synchrotron radiation (CSR) as a source for spectroscopy. The optimization of the source and the resulting figures of merits in terms of flux, signal to noise, spatial distribution and spectral and temporal distribution are presented together with a spectroscopic application. The emission of THz during the slicing operation is also described. The conclusion opens up perspectives made possible by the availability of this intense and stable THz source.
    No preview · Article · Mar 2015 · Journal of Molecular Spectroscopy
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    Full-text · Technical Report · Feb 2015
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    ABSTRACT: Free-electron lasers (FELs) are a unique source of light, particularly in the x-ray domain. After the success of FELs based on conventional acceleration using radio-frequency cavities, an important challenge is the development of FELs based on electron bunching accelerated by a laser wakefield accelerator (LWFA). However, the present LWFA electron bunch properties do not permit use directly for a significant FEL amplification. It is known that longitudinal decompression of electron beams delivered by state-of-the-art LWFA eases the FEL process. We propose here a second order transverse beam manipulation turning the large inherent transverse chromatic emittances of LWFA beams into direct FEL gain advantage. Numerical simulations are presented showing that this beam manipulation can further enhance by orders of magnitude the peak power of the radiation.
    Full-text · Article · Feb 2015 · New Journal of Physics
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    ABSTRACT: Relativistic electron bunches are powerful light sources, which are largely exploited in synchrotron radiation facilities, and are crucial for most sciences. However, electrons bunches suffer from instabilities, leading to spontaneous spatial structure formation. This effect --recalling fluid turbulence issues-- represents a fundamental limitation for light sources, and simultaneously an opportunity because the structures emit high powers of terahertz radiation ($>$10000 times normal synchrotron radiation). Up to now, though crucial for understanding and mastering synchrotron sources, observations of the structures remained a largely open problem, because of their extreme evolution speed. Here we demonstrate the possibility of direct observation by adapting a technique from photonics, {\it time-strech}, consisting in "slowing-down" the phenomena prior to recording. As a main result, we present the first recording of electron bunch microstructures versus time, with submillimeter resolution, in a storage ring. This opens the way to unpreceeded possibilities for analyzing and mastering new generation light sources.
    Full-text · Article · Oct 2014
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    ABSTRACT: Microbunching instability arises in storage rings when the number of electrons in a bunch exceeds a threshold value [1, 2, 3]. Its signature, i.e. a strong and irreg-ular emission of Coherent Synchrotron Radiation (CSR) in the Terahertz (THz) domain, is studied at SOLEIL on the AILES infrared beamline [4], with the storage ring tuned in a low-alpha configuration (used to get shorter elec-tron bunch) [5, 6]. The comparison of this observed THz CSR with numerical simulations of the longitudinal elec-tron bunch dynamics permits to put in evidence that during the instability a modulation appears and drifts in the lon-gitudinal profile of the electron bunch. The understanding of this instability is important as it limits some operation of the storage rings. Indeed the induced fluctuations prevent the use of THz on the far IR beamline at high current per bunch. In addition, in normal alpha operation this instabil-ity may spoil the electron/laser interaction effects required to get femtosecond and/or coherent pulse in storage rings (with slicing [7], Coherent Harmonic Generation or Echo-Enabled Harmonic Generation schemes on storage ring).
    Full-text · Conference Paper · Oct 2014
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    Full-text · Dataset · Sep 2014
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    Conference Paper: The ThomX project status
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    ABSTRACT: HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt e a la diffusion de documents scientifiques de niveau recherche, publiés ou non emanant de etablissements d'enseignement et de recherche français oú etrangers, des laboratoires publics ou privés. *variola@lal.in2p3.fr echerche as part of the program EQUIPEX under reference ANR-10-EQPX-51, the Abstract A collaboration of seven research institutes and an industry has been set up for the ThomX project, a compact Compton Backscattering Source (CBS) based in Orsay – France. After a period of study and definition of the machine performance, a full description of all the systems has been provided. The infrastructure work has been started and the main systems are in the call for tender phase. In this paper we will illustrate the definitive machine parameters and components characteristics. We will also update the results of the different technical and experimental activities on optical resonators, RF power supplies and on the electron gun.
    Full-text · Conference Paper · Jul 2014
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    ABSTRACT: The femtoslicing project at SOLEIL is currently under commissioning. It will enable to serve several beamlines with 100 fs FWHM long pulses of soft and hard X-rays with reasonable flux and with a 1 kHz repetition rate. It is based on the interaction of a femtosecond Ti:Sa laser with electrons circulating in the magnetic field of a modulator wiggler, that provides the electron beam energy modulation on the length scale of the laser pulse. The optimization of the interaction is performed using two dedicated diagnostics stations. The first one, operating in the Infra-Red (IR) is installed in the tunnel and allows the adjustment of the temporal, spectral and spatial overlap between the laser and the electron beam. The second one, located in the IR-THz AILES beamline, measures the intensity of the terahertz (THz) radiation emitted by the local dip structure produced in the core electron beam after interaction. This second setup provides refined optimization of the interaction. This paper describes the layout of these diagnostics and gives first results and characterization of the slicing experiment at SOLEIL.
    Full-text · Article · Jul 2014
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    ABSTRACT: An out-vacuum wiggler, W164, was designed, built and installed on the SOLEIL storage ring with the double objective to produce high energy photons for the PUMA beamline (10 keV to 70 keV) and to be used as a modulator for the FEMTOSLICING project [1]. The insertion device requires simultaneously reaching high critical energy of photons (above 10 keV) and low resonant energy (1.55 eV). The wiggler is composed of 20 periods of 164.4 mm made of NdFeB magnets and Vanadium Permendur poles. The maximum total field reaches 1.85 T at the minimum gap and 1.66 T at the FEMTOSLICING operation gap. The size of the poles, the carriage and the girders were optimized to minimize the deformation resulting from the magnetic forces (8 tons at minimum gap).
    No preview · Article · Jul 2014
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    ABSTRACT: LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4-1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Transport calculation of longitudinal and transverse manipulation of a LWFA electron beam enables to provide theoretical amplification, a test experiment is under preparation.
    No preview · Article · Jul 2014
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    ABSTRACT: The aim of the Femto-Slicing project at SOLEIL is to generate 100-200 fs FWHM short X-ray pulses on two beamlines, CRISTAL and TEMPO, for pump-probe experiments in the spectral range of hard and soft X-rays. We note that this capability could be extended in the future to two or three more beamlines. Femtosecond lasers are currently in operation on TEMPO and CRISTAL beamlines, for pump-probe experiments on the ps time scale, enabling time resolved photo-emission and photo-diffraction studies, respectively. The Femto-Slicing project is based on the fs laser of the CRISTAL beamline, which can be adjusted to deliver 3 to 5 mJ pulses of 30 fs duration at 2.5 to 1 kHz, respectively. This laser beam is separated in three branches: one delivering about 2 mJ to the modulator wiggler and the other ones delivering the remaining energy to the experiments on the TEMPO and CRISTAL beamlines. This layout will yield natural synchronisation between Infra-Red (IR) laser pump and X-ray probe pulses, only affected by jitter and drift associated with beam transport. In this paper, we present the progress in the implementation and commissioning of the laser beam transport system and its characterization.
    No preview · Article · Jul 2014
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    ABSTRACT: The microbunching instability is an ubiquitous problem in storage rings at high current density. However, the in-volved fast time-scales hampered the possibility to make direct real-time recordings of theses structures. When the structures occur at a cm scale, recent works at UVSOR [1], revealed that direct recording of the coherent synchrotron radiation (CSR) electric field with ultra-high speed elec-tronics (17 ps) provides extremely precious informations on the microbunching dynamics. However, when CSR occurs at THz frequencies (and is thus out of reach of electron-ics), the problem remained largely open. Here we present a new opto-electronic strategy that enabled to record series of successive electric field pulses shapes with picosecond res-olution (including carrier and envelope), every 12 ns, over a total duration of several milliseconds. We also present the first experimental results obtained with this method at Synchrotron SOLEIL, above the microbunching instability threshold. The method can be applied to the detection of ps electric fields in other situations where high repetition rate is also an issue.
    Full-text · Conference Paper · Jun 2014
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    M.E. Couprie
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    ABSTRACT: Spectroscopy and imaging in the VUV–X-ray domain are very sensitive tools for the investigation of the properties of matter [1], [2] and [3]. Time-resolved studies enable to follow the movies of ultra-fast reactions. More than fifty years after the laser discovery [4], VUVX light sources are actively developed around the world. Among them, High order Harmonics generated in Gas, X-ray lasers, synchrotron radiation, Free electron lasers are providing a wide offer, from laboratory size sources to large scale facilities, with various features, suitable for different types of experiments. The properties of these sources are here reviewed. Quest of new performances and flexibility is also discussed.
    Preview · Article · Dec 2013 · Journal of Electron Spectroscopy and Related Phenomena

Publication Stats

2k Citations
344.02 Total Impact Points

Institutions

  • 2005-2015
    • SOLEIL synchrotron
      Gif, Île-de-France, France
  • 2011
    • RIKEN
      Вако, Saitama, Japan
  • 2008
    • Nagoya University
      Nagoya, Aichi, Japan
  • 2007
    • ENEA
      Roma, Latium, Italy
  • 1987-2007
    • Université Paris-Sud 11
      • Laboratoire de Photophysique Moléculaire
      Lutetia Parisorum, Île-de-France, France
  • 1999-2006
    • Cea Leti
      Grenoble, Rhône-Alpes, France
  • 2004
    • Technische Universiteit Eindhoven
      Eindhoven, North Brabant, Netherlands
  • 2002
    • Sincrotrone Trieste S.C.p.A.
      Trst, Friuli Venezia Giulia, Italy
  • 1996
    • École Polytechnique Fédérale de Lausanne
      Lausanne, Vaud, Switzerland
  • 1988-1991
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France