Publications

1997

• Génération de hautes pressions par choc laser : application à la mesure d'équations d'état.
  
  • Benuzzi Alessandra
  , 1997. Résumé non disponible
• Channel Formation in Long Laser Pulse Interaction with a Helium Gas Jet
  
  • Malka Victor
  • de Wispelaere E.
  • Amiranoff François
  • Baton S.
  • Bonadio R.
  • Coulaud C.
  • Haroutunian R.
  • Modena A.
  • Puissant D.
  • Stenz C.
  • Hüller S.
  • Casanova M.
  Physical Review Letters, American Physical Society, 1997, 79 (16), pp.2979. Experimental realization of an electron density channel created by a low intensity laser in a helium gas jet is presented. The long (2.5 mm) plasma channel is fully ionized and thus prevents undesirable refraction effects for propagation and guiding of a subsequent high intensity laser pulse. The channel parameters are easily controlled and well suited for laser guiding. The radial plasma expansion and the temperature evolution have been measured and compared to hydrodynamic simulations which show that the plasma expansion is governed by a thermal wave during the laser pulse. (10.1103/PhysRevLett.79.2979)
  DOI : 10.1103/PhysRevLett.79.2979
• Aspects of plasma spectroscopy: Recent advances
  
  • Alexiou S
  • Calisti Annette
  • Gauthier P
  • Klein L
  • Leboucher-Dalimier E
  • Lee Rw
  • Stamm R
  • Talin B
  Journal of Quantitative Spectroscopy and Radiative Transfer, Elsevier, 1997, 58 (4-6), pp.399-413. Two important recent developments in Stark broadening are presented in this work: The first describes the Frequency Separation Technique (FST), which is motivated by the standard electron-ion separation and has important applications in that, coupled to any of a variety of methods capable of treating the intermediate ion-dynamical regime: (but not capable of treating ion impact), presents a unified and practical solution to the ion-dynamical problem. That is, this technique allows the relaxation of the quasistatic approximation. The second describes recent improvements that allow the accurate calculation of electron impact widths. (C) 1997 Published by Elsevier Science Ltd. All rights reserved. (10.1016/S0022-4073(97)00048-4)
  DOI : 10.1016/S0022-4073(97)00048-4
• Quasi-molecular emission from highly correlated plasmas
  
  • Gauthier P
  • Sauvan P
  • Angelo P
  • Alexiou S
  • Leboucher-Dalimer E
  • Poquerusse A
  • Calisti Annette
  • Talin B
  Journal of Quantitative Spectroscopy and Radiative Transfer, Elsevier, 1997, 58 (4-6), pp.597-606. The present work reports results on quasi-molecular emission from hot dense plasmas. Results from Molecular Dynamics simulations are first presented which show that a treatment of bound states in terms of two-centre wavefunctions is possible in plasmas under specific conditions. A theoretical model for describing the transient molecular behaviour in hot dense plasmas is then proposed and applied to the case of a transient F8+/F9+ molecular ion. We demonstrate that two electronic transitions (namely, using the spherical quantum numbers, 541(g)-210(u) and 650(u)-100(g)) related to this transient structure can be exhibited in experimental spectra from laser-produced plasmas implying high density conditions. These predictions are shown to be in excellent agreement with results from colliding foil experiments which have led to the exhibition of a low-energy satellite-like feature on the profile of the FLy beta line having no explanation in terms of standard line profile theories. (C) 1997 Published by Elsevier Science Ltd. All rights reserved. (10.1016/S0022-4073(97)00066-6)
  DOI : 10.1016/S0022-4073(97)00066-6
• Plasma density determination by transmission of laser-generated surface harmonics
  
  • Gibbon P.
  • Altenbernd D.
  • Teubner U.
  • Förster E.
  • Audebert Patrick
  • Geindre Jean-Paul
  • Gauthier Jean-Claude
  • Mysyrowicz André
  Physical Review E : Statistical, Nonlinear, and Soft Matter Physics [2001-2015], American Physical Society, 1997, 55 (6), pp.R6352-R6355. A diagnostic is proposed for determining the density of laser-generated plasmas. The scheme exploits surface harmonics generated by short, intense laser pulses reflected from an overdense plasma layer. At sufficiently high intensities (Iλ2>1018 W cm-2), the reflected spectrum contains harmonics well above the plasma frequency, corresponding to the maximum plasma density. The transmitted spectrum, on the other hand, exhibits a low-frequency cutoff for ω<ωp, offering a simple means of deducing the plasma density. (10.1103/PhysRevE.55.R6352)
  DOI : 10.1103/PhysRevE.55.R6352
• Frequency increase and damping of nonlinear electron plasma oscillations in cylindrical symmetry
  
  • Marques J. R.
  • Dorchies F.
  • Audebert P.
  • Geindre J. P.
  • Amiranoff François
  • Gauthier J. C.
  • Hammoniaux G.
  • Antonetti A.
  • Chessa P.
  • Mora P.
  • Antonsen T. M.
  Physical Review Letters, American Physical Society, 1997, 78 (18), pp.3463-3466. no abstract
• Second harmonic generation and its interaction with relativistic plasma waves driven by forward Raman instability in underdense plasmas
  
  • Malka Victor
  • Modena A.
  • Najmudin Z.
  • Dangor A. E.
  • Clayton C. E.
  • Marsh K. A.
  • Joshi C.
  • Danson C.
  • Neely D.
  • Walsh F. N.
  Physics of Plasmas, American Institute of Physics, 1997, 4 (4), pp.1127. High conversion efficiency (0.1%) into second harmonic light generated in the interaction of a short-pulse intense laser with underdense plasma has been observed. In this experiment the plasma is created by optical field ionization of hydrogen or helium gas. Second harmonic spectra observed in the forward direction show Stokes and anti-Stokes satellites. This is due to the interaction of the second harmonic light with large-amplitude relativistic plasmawaves. Second harmonic images taken at 30° from the propagation axis show that the radiation is generated over a length of a few times the Rayleigh length and that the origin of the second harmonic light is due to the radial electron density gradients created by the ionization process and the radial ponderomotive force. (10.1063/1.872201)
  DOI : 10.1063/1.872201