Publications

2010

• Shell Models and the possibility of application to fusion plasmas
  
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Garbet X.
  • Diamond P.H.
  • Vermare Laure
  • Casati A.
  • Falchetto G.
  , 2010 (oral).
• Météorologie de l'Espace en Afrique : les programmes Année 2010 Egypte France et ISWI
  
  • Damé Luc
  • Marhous Ayman
  • Amory-Mazaudier Christine
  • Petitdidier Monique
  • Hady Ahmed
  , 2010, pp.8 p..
• Modelling of chlorine inductive discharges
  
  • Chabert Pascal
  • Despiau-Pujo Emilie
  , 2010.
• Effect of low-frequency power on electron density and ion flux in dual-frequency capacitive radiofrequency discharges
  
  • Booth Jean-Paul
  • Curley G.
  • Chabert Pascal
  , 2010.
• Nonstationarity of two / three - dimensional supercritical perpendicular shocks: nonlinear whistler emission versus shock front self-reformation
  
  • Lembège Bertrand
  • Savoini Philippe
  • Hellinger P.
  • Travnicek P. M.
  , 2010.
• Measurements and Modeling of Turbulent Transport in the Tore Supra Tokamak
  
  • Garbet X.
  • Abiteboul J.
  • Benkadda S.
  • Bourdelle C.
  • Casati A.
  • Clairet F.
  • Dubuit N.
  • Falchetto G.
  • Fenzi C.
  • Futatani S.
  • Grandgirard V.
  • Guirlet R.
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Heuraux S.
  • Hoang G.T.
  • Honoré Cyrille
  • Sabot R.
  • Sarazin Y.
  • Ségui J.-L.
  • Smolyakov A.
  • Trier Elisée
  • Vermare Laure
  • Villegas D.
  , 2010, 1308, pp.75-84. This paper presents an overview of recent advances in modeling and measurements of turbulence in Tore Supra plasmas. Spatio‐temporal properties of turbulence are discussed in relation with transport models. An explanation is proposed for the k−3 decay of wave number spectra, which are observed by using both coherent laser scattering and Doppler reflectometry. Also the interplay between turbulence and flows has been investigated. It is shown that toroidal rotation results from a competition between neoclassical and turbulence flow generation. Finally a new method has been proposed to determine the transport coefficients of impurities. These coefficients are usually well above the neoclassical prediction. (10.1063/1.3526165)
  DOI : 10.1063/1.3526165
• Surface discharges: possible applications for plasma-assisted ignition and electric field measurements (AIAA 2010-1587)
  
  • Starikovskaia Svetlana
  • Allegraud Katia
  • Guaitella Olivier
  • Kosarev I.N.
  • Mintoussov E.I.
  • Pendleton S.J.
  • Popov N.A.
  • Sagulenko P.N.
  • Rousseau Antoine
  , 2010.
• Bilan et Perspective 2006 - 2009, Programme National Soleil Terre
  
  • Fontaine Dominique
  • Vilmer N.
  , 2010.
• Bepi-Colombo : Mercury Exploration
  
  • Chanteur Gérard
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.32-33. ISSN : 1775-0385
• Plasmas Naturels : Le Programme National Soleil - Terre
  
  • Fontaine Dominique
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.27-31. ISSN : 1775-0385
• Plasmas froids
  
  • Booth Jean-Paul
  • Chabert Pascal
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.3-5. ISSN : 1775-0385
• Plasma assisted ignition and combustion
  
  • Starikovskaia Svetlana
  • Starikovskii A.Yu.
  , 2010, pp.71-93.
• Modelling of an afterglow plasma in air produced by a pulsed discharge
  
  • Pintassilgo C.D.
  • Guerra V.
  • Guaitella Olivier
  • Rousseau Antoine
  Plasma Sources Science and Technology, IOP Publishing, 2010, 19, pp.055001. A kinetic model is developed to study the afterglow plasma of a pulsed discharge in air. This model includes a detailed analysis of the temporal evolution of heavy species during the pulse, followed by their relaxation in the afterglow. The predicted results are compared with two experimental sets performed in the time afterglow of a pulsed discharge in N220%O2 at a pressure p = 133 Pa involving the measurements of (i) N2(B) and N2(C) fluorescences for a discharge current I = 40 mA and a pulse duration τ = 200 µs and 10 ms, together with (ii) the absolute concentration of NO(X) for I = 40 and 80 mA with τ varying from 1 to 4 ms. The results of the model agree reasonably well with the measurements of N2(B) and N2(C) decays. It is shown that under these experimental conditions, N2(B) is always populated mainly via the process N2(A) N2(X, 5 ≤ v ≤ 14) → N2(B) N2(X, v = 0), while the relaxation of N2(C) is dominated by the pooling reaction N2(A) N2(A) → N2(C) N2(X, v = 0). An almost constant concentration of NO(X) is experimentally observed until the remote afterglow, but the present model is only capable of predicting the same order of magnitude for afterglow times t 0.05 s. Several hypotheses are discussed and advanced in order to explain this discrepancy. (10.1088/0963-0252/19/5/055001)
  DOI : 10.1088/0963-0252/19/5/055001
• Planar Wire-Array Z-Pinch Implosion Dynamics and X-Ray Scaling at Multiple-MA Drive Currents for a Compact Multisource Hohlraum Configuration
  
  • Jones B.
  • Ampleford D. J.
  • Vesey R. A.
  • Cuneo Michael E.
  • Coverdale C. A.
  • Waisman E. M.
  • Jones M. C.
  • Fowler W. E.
  • Stygar W. A.
  • Serrano J. D.
  • Vigil M. P.
  • Esaulov A. A.
  • Kantsyrev Viktor L.
  • Safronova Alla S.
  • Williamson Kenneth M.
  • Chuvatin Alexandre S.
  • Rudakov Leonid I.
  Physical Review Letters, American Physical Society, 2010, 104 (12), pp.125001. An indirect drive configuration is proposed wherein multiple compact Z-pinch x-ray sources surround a secondary hohlraum. Planar compact wire arrays allow reduced primary hohlraum surface area compared to cylindrical loads. Implosions of planar arrays are studied at up to 15 TW x-ray power on Saturn with radiated yields exceeding the calculated kinetic energy, suggesting other heating paths. X-ray power and yield scaling studied from 16 MA motivates viewfactor modeling of four 6-MA planar arrays producing 90 eV radiation temperature in a secondary hohlraum. (10.1103/PhysRevLett.104.125001)
  DOI : 10.1103/PhysRevLett.104.125001
• Nonlinear fan instability of electromagnetic waves
  
  • Krafft C.
  • Volokitin A.
  Physics of Plasmas, American Institute of Physics, 2010, 17, pp.102303. This paper studies the linear and nonlinear stages of the fan instability, considering electromagnetic waves of the whistler frequency range interacting resonantly with energetic electron fluxes in magnetized plasmas. The main attention is paid to determine the wave-particle interaction processes that can lead to the excitation of intense electromagnetic waves by nonequilibrium particle distributions involving suprathermal tails, and to explain under what conditions and through what mechanisms they can occur, develop, and saturate. This paper presents and discusses two main processes: (i) the linear fan instability and (ii) the nonlinear process of dynamical resonance merging, which can significantly amplify the energy carried by linearly destabilized waves after they saturate due to particle trapping. This study consists of (i) determining analytically and numerically, for parameters typical of space and laboratory plasmas, the linear growth rates of whistlers excited by suprathermal particle fluxes through the fan instability, as well as the corresponding thresholds and the physical conditions at which the instability can appear, (ii) building a theoretical self-consistent 3D model and a related numerical code for describing the nonlinear evolution of the wave-particle system, and (iii) performing numerical simulations to reveal and characterize the nonlinear amplification process at work, its conditions of development, and its consequences, notably in terms of electromagnetic wave radiation. The simulations show that when the waves have reached sufficient energy levels owing to the linear fan instability, they saturate by trapping particles and due to the complex dynamics of these particles in the electromagnetic fields, the resonant velocities' domains of the waves overlap and merge, meanwhile a strong increase of the wave energy occurs. (10.1063/1.3479829)
  DOI : 10.1063/1.3479829
• Quantum Cascade Laser Absorption Spectroscopy - a New Method to Study Molecular Plasma Components
  
  • Röpcke J.
  • Glitsch S.
  • Davies P.B.
  • Hempel F.
  • Lang N.
  • Rousseau Antoine
  • Wege S.
  • Welzel S.
  Journal of Physics: Conference Series, IOP Science, 2010, 227, pp.012005. The recent development of quantum cascade lasers (QCLs) offers an attractive new option for the monitoring and control of industrial plasma processes and for trace-gas analysis as well as for highly time-resolved studies on the kinetics of plasma processes. The contribution reviews selected examples of the application of QCLs for infrared absorption studies in basic research and for plasma monitoring and control in industry. (10.1088/1742-6596/227/1/012005)
  DOI : 10.1088/1742-6596/227/1/012005
• The WHISPER Relaxation Sounder and the CLUSTER Active Archive
  
  • Trotignon Jean-Gabriel
  • Décréau Pierrette
  • Rauch Jean-Louis
  • Vallières Xavier
  • Rochel A.
  • Kougblénou S.
  • Lointier G.
  • Facskó G.
  • Canu Patrick
  • Darrouzet F.
  • Masson A.
  • Taylor M.
  • Escoubet C. Philippe
  , 2010, pp.185-208. The Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation (WHISPER) instrument is part of the Wave Experiment Consortium (WEC) of the CLUSTER mission. With the help of the long double sphere antennae of the Electric Field and Wave (EFW) instrument and the Digital Wave Processor (DWP), it delivers active (sounding) and natural (transmitter off) electric field spectra, respectively from 4 to 82 kHz, and from 2 to 80 kHz. These frequency ranges have been chosen to include the electron plasma frequency, which is closely related to the total electron density, in most of the regions encountered by the CLUSTER spacecraft. Presented here is an overview of the WHISPER data products available in the CLUSTER Active Archive (CAA). The instrument and its performance are first recalled. The way the WHISPER products are obtained is then described, with particular attention being paid to the density determination. Both sounding and natural measurements are commonly used in this process, which depends on the ambient plasma regime. This is illustrated using drawings similar to the Bryant plots commonly used in the CLUSTER master science plan. These give a clear overview of typical density values and the parts of the orbits where they are obtained. More information on the applied software or on the quality/reliability of the density determination can also be highlighted. (10.1007/978-90-481-3499-1_12)
  DOI : 10.1007/978-90-481-3499-1_12
• Théorie des Plasmas
  
  • Firpo Marie-Christine
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.26-27. ISSN : 1775-0385
• The Plasma Wave Investigation (PWI) onboard the BepiColombo/MMO: First measurement of electric fields, electromagnetic waves, and radio waves around Mercury
  
  • Kasaba Y.
  • Bougeret J.-L.
  • Blomberg L. G.
  • Kojima H.
  • Yagitani S.
  • Moncuquet M.
  • Trotignon Jean-Gabriel
  • Chanteur Gérard
  • Kumamoto A.
  • Kasahara Y.
  • Lichtenberger J.
  • Omura Y.
  • Ishisaka K.
  • Matsumoto H.
  Planetary and Space Science, Elsevier, 2010, 58 (1-2), pp.238-278. The BepiColombo Mercury Magnetospheric Orbiter (MMO) spacecraft includes the plasma and radio wave observation system called Plasma Wave Investigation (PWI). Since the receivers for electric field, plasma waves, and radio waves are not installed in any of the preceding spacecraft to Mercury, the PWI will provide the first opportunity for conducting in-situ and remote-sensing observations of electric fields, plasma waves, and radio waves in the Hermean magnetosphere and exosphere. These observations are valuable in studying structure, dynamics, and energy exchange processes in the unique magnetosphere of Mercury. They are characterized by the key words of the non-MHD environment and the peculiar interaction between the relatively large planet without ionosphere and the solar wind with high dynamic pressure. The PWI consists of three sets of receivers (EWO, SORBET, and AM²P), connected to two sets of electric field sensors (MEFISTO and WPT) and two kinds of magnetic field sensors (LF-SC and DB-SC). The PWI will observe both waveforms and frequency spectra in the frequency range from DC to 10 MHz for the electric field and from 0.3 Hz to 640 kHz for the magnetic field. From 2008, we will start the development of the engineering model, which is conceptually consistent with the flight model design. The present paper discusses the significance and objectives of plasma/radio wave observations in the Hermean magnetosphere, and describes the PWI sensors, receivers and their performance as well as the onboard data processing. (10.1016/j.pss.2008.07.017)
  DOI : 10.1016/j.pss.2008.07.017
• MD simulations of GaN sputtering by Ar<SUP>+</SUP> ions : Ion-induced damage and near-surface modification under continuous bombardment
  
  • Despiau-Pujo Emilie
  • Chabert Pascal
  Journal of Vacuum Science & Technology A, American Vacuum Society, 2010, 28 (5), pp.1105. Results from molecular dynamics simulations of continuous 50200 eV Ar bombardment on wurtzite and zinc blende GaN surfaces are reported. A new analytical bond-order potential, originally developed for growth process studies, is used to investigate the low-energy physical sputtering of GaN compounds. Preferential sputtering of N atoms is initially observed up to 3.5×1015&#8194;ions/cm2 fluence, after which the layers reach steady state sputtering. The crystalline structure of the GaN sample does not have a major influence on the sputtering yield due to the rapid amorphization of the top surface after a few hundred impacts. Concentration depth profiles indicate a surface enrichment in gallium with a N/Ga concentration ratio equal to 0.59±0.1 for 100 eV bombardment, in agreement with published experimental studies. For the same conditions, Ga, N, and GaN species represent 25, 60, and 7% of the sputtered products. A significant fraction of those products leave the surface with kinetic energies sufficiently high to damage the passivation layers on sidewalls during etching processes dominated by physical bombardment. (10.1116/1.3460904)
  DOI : 10.1116/1.3460904
• Particle transport in low core turbulence Tore-Supra plasmas
  
  • Guirlet R.
  • Sirinelli A.
  • Parisot T.
  • Sabot R.
  • Artaud J.F.
  • Bourdelle C.
  • Garbet X.
  • Hennequin Pascale
  • Hoang G.T.
  • Imbeaux Frédéric
  • Segui J.-L.
  • Mazon D.
  • Villegas D.
  Nuclear Fusion, IOP Publishing, 2010, 50, pp.095009. Electron and impurity transport has been studied in sawtoothing plasmas in the Tore-Supra tokamak. High time and space resolution measurements of the electron density reveal the existence of a flat profile region encompassing the q = 1 surface, on which is superimposed a density peak building up between sawtooth relaxations. For the first time in this regime, we have determined the underlying transport of both nickel and electrons independently of the effect of sawteeth in the central part of the plasma. Electron transport is consistent with the neoclassical expectations only in the close vicinity of the magnetic axis. Further out, it exceeds the neoclassical values as calculated with the NCLASS code, although the turbulence level is very low in the whole central region region. In contrast, nickel transport is in good agreement with the neoclassical calculations in the same region. The neoclassical effect on trapped particles of a persisting mode due to incomplete reconnection of the magnetic surfaces is consistent with these observations. (10.1088/0029-5515/50/9/095009)
  DOI : 10.1088/0029-5515/50/9/095009
• Three-dimensional structure of electron density fluctuations in the Hall thruster plasma: ExB mode
  
  • Tsikata Sedina
  • Honoré Cyrille
  • Lemoine N.
  • Grésillon D.
  Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112110. Collective scattering measurements have been conducted on the plasma of a Hall thruster, in which the electron density fluctuations are fully characterized by the dynamic form factor. The dynamic form factor amplitude distribution has been measured depending on the k-vector spatial and frequency components at different locations. Fluctuations are seen as propagating waves. The largest amplitude mode propagates nearly along the cross-field direction but at a phase velocity that is much smaller than the E×B drift velocity. Refined directional analysis of this largest amplitude mode shows a thin angular emission diagram with a mean direction that is not strictly along the E×B direction but at small angles near it. The deviation is oriented toward the anode in the (E,E×B) plane and toward the exterior of the thruster channel in the (B,E×B) plane. The density fluctuation rate is on the order of 1%. These experimentally determined directional fluctuation characteristics are discussed with regard to the linear kinetic theory model and particle-in-cell simulation results. (10.1063/1.3499350)
  DOI : 10.1063/1.3499350
• Whistler waves guided by density depletion ducts in a magnetoplasma
  
  • Bakharev P. V.
  • Zaboronkova T. M.
  • Kudrin A. V.
  • Krafft C.
  Fizika Plazmy / Plasma Physics Reports, MAIK Nauka/Interperiodica, 2010, 36 (11), pp.919-930. The guided propagation of whistler waves along cylindrical density depletion ducts in a magneto-plasma is studied. It is shown that, under certain conditions, such ducts can support volume and surface eigenmodes. The dispersion properties and field structure of whistler modes guided by density depletion ducts are analyzed. The effect of collisional losses in the plasma on the properties of modes is discussed. (10.1134/S1063780X10110012)
  DOI : 10.1134/S1063780X10110012
• Ion dynamics during compression of Mercury's magnetosphere
  
  • Delcourt Dominique C.
  • Moore T. E.
  • Fok M.-C. H.
  Annales Geophysicae, European Geosciences Union, 2010, 28, pp.1467-1474. Because of the small planetary magnetic field as well as proximity to the Sun that leads to enhanced solar wind pressure as compared to Earth, the magnetosphere of Mercury is very dynamical and at times subjected to prominent compression. We investigate the dynamics of magnetospheric ions during such compression events. Using three-dimensional single-particle simulations, we show that the electric field induced by the time varying magnetic field can lead to significant ion energization, up to several hundreds of eVs or a few keVs. This energization occurs in a nonadiabatic manner, being characterized by large enhancements of the ion magnetic moment and bunching in gyration phase. It is obtained when the ion cyclotron period is comparable to the field variation time scale. This condition for nonadiabatic heating is realized in distinct regions of space for ions with different mass-to-charge ratios. During compression of Mercury's magnetosphere, heavy ions originating from the planetary exosphere may be subjected to such an abrupt energization, leading to loading of the magnetospheric lobes with energetic material. (10.5194/angeo-28-1467-2010)
  DOI : 10.5194/angeo-28-1467-2010
• Design of magnetic concentrators for high sensitivity anisotropic magnetoresistor devices
  
  • Mansour Malik
  • Coillot Christophe
  • Chanteur Gérard
  • Roux A.
  • Nguyen van Dau Frédéric
  Journal of Applied Physics, American Institute of Physics, 2010, 107, pp.09E707. In this work, a very promising shape of magnetic concentrators taking advantage of the symmetrical flux leakage of Mn-Zn ferrite magnetic cores is presented. This configuration consists of two ferromagnetic rods separated by two air gaps allowing to place anisotropic magnetoresistance sensors in the core axis. Results from three-dimensional finite elements modeling are presented. We show that an appropriate shape optimization of core extremities enables to improve significantly the amplification factor without any increase in length. (10.1063/1.3337747)
  DOI : 10.1063/1.3337747