Publications

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Sont listées ci-dessous, par année, les publications figurant dans l'archive ouverte HAL.

2010

Poloidal rotation and its relation to the potential vorticity flux
- Mcdevitt C.J.
- Diamond P.H.
- Gürcan Özgür D.
- Hahm T.S.
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112509. A kinetic generalization of a Taylor identity appropriate to a strongly magnetized plasma is derived. This relation provides an explicit link between the radial mixing of a fourdimensional (4D) gyrocenter fluid and the poloidal Reynolds stress. This kinetic analog of a Taylor identity is subsequently utilized to link the turbulent transport of poloidal momentum to the mixing of potential vorticity. A quasilinear calculation of the flux of potential vorticity is carried out, yielding diffusive, turbulent equipartition, and thermoelectric convective components. Self-consistency is enforced via the quasineutrality relation, revealing that for the case of a stationary small amplitude wave population, deviations from neoclassical predictions of poloidal rotation can be closely linked to the growth/damping profiles of the underlying drift wave microturbulence. (10.1063/1.3490253)
DOI : 10.1063/1.3490253
Cluster observations of outflowing electron distributions and broadband electrostatic emissions above the polar cap
- Teste A.
- Fontaine Dominique
- Canu Patrick
- Belmont Gérard
Geophysical Research Letters, American Geophysical Union, 2010, 37, pp.3103. We investigate the excellent correlation between ionospheric upgoing electron beams and broadband electrostatic emissions (0-6 kHz) observed by Cluster, at 5 to 9 Earth's radii above the polar cap. In the absence of detailed, high time resolution waveform data in that region, we precisely analyzed several electron beams to obtain information concerning wave-particle interactions. Our results indicate that these beams are extremely variable and occasionally show multiple components. The processes involved might then occur on very short time scales, of the order of or shorter than sampling rates, typically 100 ms. We suggest that non linearities are at the origin of the spread of the frequency range of the waves simultaneously observed, as well as of the beam variability. We conclude that these electron beams are likely to destabilize Langmuir waves and, by the non-linear evolution of the electron bump-on-tail instability, could be responsible for the appearance of electrostatic solitary waves above the polar cap. (10.1029/2009GL041593)
DOI : 10.1029/2009GL041593
Residual parallel Reynolds stress due to turbulence intensity gradient in tokamak plasmas
- Gürcan Özgür D.
- Diamond P.H.
- Hennequin Pascale
- Mcdevitt C.J.
- Garbet X.
- Bourdelle C.
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112309. A novel mechanism for driving residual stress in tokamak plasmas based on k∥ symmetry breaking by the turbulence intensity gradient is proposed. The physics of this mechanism is explained and its connection to the wave kinetic equation and the wave-momentum flux is described. Applications to the H-mode pedestal in particular to internal transport barriers, are discussed. Also, the effect of heat transport on the momentum flux is discussed. (10.1063/1.3503624)
DOI : 10.1063/1.3503624
Une recherche ITER...ative
- Hennequin Pascale
Pour la science, Pour la Science, 2010 (392).
ECRH for JET: A feasibility study
- Lennholm M.
- Giruzzi G.
- Parkin A.
- Bouquey F.
- Braune H.
- Bruschi A.
- Luna Elena de La
- Denisov G.
- Edlington T.
- Farina D.
- Farthing J.
- Figini Lorenzo
- Garavaglia S.
- Garcia J.
- Gerbaud Thomas
- Granucci G.
- Henderson M.
- Horton L.
- Kasparek W.
- Khilar P.
- Jennison M.
- Kirneva N.
- Kislov D.
- Kuyanov A.
- Litaudon X.
- Litvak A.
- Moro A.
- Nowak S.
- Parail V.
- Plaum B.
- Rimini F.
- Saibene G.
- Sips A. C. C.
- Sozzi C.
- Spaeh P.
- Trukhina E.
- Vaccaro A.
- Vdovin V.
Fusion Engineering and Design, Elsevier, 2010, 6-8, pp.805 - 809. For JET to fulfil its mission in preparing ITER operation, the installation of an electron cyclotron resonance heating system on JET would be desirable. The study described in this paper has investigated the feasibility of installing such a system on JET. The principal goals of such a system are: current drive over a range of radii for NTM stabilization, sawtooth control and current profile tailoring and central electron heating to equilibrate electron and ion temperatures in high performance discharges. The study concluded that a 12 gyrotron, 10 MW, system at the ITER frequency (170 GHz) adapted for fields of 2.7-3.3 T would be appropriate for the operation planned in JET. An antenna allowing toroidal and poloidal steering over a wide range is being designed, using the ITER upper launcher steering mechanism. The use of ITER diamond windows and transmission line technology is suggested while power supply solutions partially reusing existing JET power supplies are proposed. Detailed planning shows that such a system can be operational in about 5 years from the time that the decision to proceed is taken. The cost and required manpower associated with implementing such a system on JET has also been estimated. (C) 2011 EURATOM. Published by Elsevier B.V. All rights reserved.Commiss European Communities, B-1049 Brussels, Belgium.IRFM, CEA, F-13108 St Paul Les Durance, France.Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.EURATOM, Max Planck IPP, D-17491 Greifswald, Germany.EURATOM, CNR, Ist Fis Plasma, I-20125 Milan, Italy.Asociac EURATOM CIEMAT, Lab Nacl Fus, Madrid 28040, Spain.Inst Appl Phys, Nizhnii Novgorod 603155, Russia.Ecole Polytech, LPTP, F-91128 Palaiseau, France.ITER Org, F-13108 St Paul Les Durance, France.Univ Stuttgart, IPF, Stuttgart, Germany.RRC Kurchatov Inst, Moscow, Russia.Fus Energy, Barcelona 08019, Spain.Karlsruhe Inst Technol, Karlsruhe, Germany. (10.1016/j.fusengdes.2011.01.136)
DOI : 10.1016/j.fusengdes.2011.01.136
Evidence of atomic adsorption on TiO2 under plasma exposure and related C2H2 surface reactivity
- Guaitella Olivier
- Lazzaroni Claudia
- Marinov Daniil
- Rousseau Antoine
Applied Physics Letters, American Institute of Physics, 2010, 97, pp.011502. Adsorption/reaction kinetics of C2H2 on the surface of plasma-treated SiO2 and TiO2 catalysts is studied. The catalysts are pretreated with a dc discharge in Ar, O2, N2, or air. Then 950 ppm of C2H2 in air is introduced in the closed-volume reactor. It is found that TiO2 pretreated with O2 or air plasma catalyzes C2H2 removal from the gas phase without any UV activation. During 10 min after introduction the loss of C2H2 in the whole reactor is about 5×1015 molecules. Comparison between different pretreatment procedures shows that weakly bonded oxygen atoms may remain on TiO2 long after plasma exposure (10.1063/1.3462295)
DOI : 10.1063/1.3462295
On the Boltzmann relation in a cold magnetized plasma
- Nasi L.
- Raimbault Jean-Luc
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.113513. A systematic and exact comparison between the forces acting on magnetized electrons in a current-free plasma is considered within a fluid model. We show that the Boltzmann relation is fulfilled in the drift-diffusion approximation when (hi/he)(1 he2)/(1 hi2)⪡1 where he (or hi) is the ratio of the electron (or ion) cyclotron to the collision frequency. When the nonlinear inertia terms are taken into account, the previous criterion is too rough and must be modified. In particular it is proved that the Boltzmann relation is not uniformly valid in the plasma. The case of bounded plasmas where the electron temperature must be determined self-consistently is discussed in detail. (10.1063/1.3517174)
DOI : 10.1063/1.3517174
Evidence for surface oxidation on Pyrex of NO into NO2 by adsorbed O atoms
- Guaitella Olivier
- Hübner M.
- Welzel S.
- Marinov Daniil
- Röpcke J.
- Rousseau Antoine
Plasma Sources Science and Technology, IOP Publishing, 2010, 19, pp.045026. The surface of a Pyrex discharge tube was treated by a capacitively coupled RF plasma at low pressure. In cases where the plasma contained oxygen, O atoms deposition on the tube surface could be confirmed via the time-dependent conversion of NO to NO2 in a post-plasma experiment. Inside the discharge tube, the evolution of the concentrations of NO and of NO2 was measured using quantum cascade laser absorption spectroscopy in the mid-infrared spectral range. The surface density of atomic oxygen was estimated to be about 2 × 1014 cm−2 based on NO oxidation in the closed reactor. The production rate of NO2 is in the range of 2 × 1011 molecules cm−3 s−1. (10.1088/0963-0252/19/4/045026)
DOI : 10.1088/0963-0252/19/4/045026
Comparison of the use of SQUID an Hall effect sensors in NDE
- Bettaieb L.
- Kokabi H.
- Poloujadoff M.
- Sentz A.
- Krause H. J
- Coillot Christophe
Materials Evaluation, American Society for Nondestructive Testing, 2010, 68 (5), pp.535-554. ...
THEMIS analysis of observed equatorial electron distributions responsible for the chorus excitation
- Li W.
- Thorne R. M.
- Nishimura Y.
- Bortnik J.
- Angelopoulos V.
- Mcfadden J. P.
- Larson D. E.
- Bonnell J. W.
- Le Contel Olivier
- Roux A.
- Auster U.
Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A6). A statistical survey of plasma densities and electron distributions (0.5-100 keV) is performed using data obtained from the Time History of Events and Macroscale Interactions During Substorms spacecraft in near-equatorial orbits from 1 July 2007 to 1 May 2009 in order to investigate optimum conditions for whistler mode chorus excitation. The plasma density calculated from the spacecraft potential, together with in situ magnetic field, is used to construct global maps of cyclotron and Landau resonant energies under quiet, moderate, and active geomagnetic conditions. Statistical results show that chorus intensity increases at higher AE index, with the strongest waves confined to regions where the ratio between the plasma frequency and gyrofrequency, fpe/fce, is less than 5. On the nightside, large electron anisotropies and intense chorus emissions indicate remarkable consistency with the confinement to 8 RE. Furthermore, as injected plasma sheet electrons drift from midnight through dawn toward the noon sector, their anisotropy increases and peaks on the dayside at 7 < L < 9, which is well correlated with intense chorus emissions observed in the prenoon sector. These statistical results are generally consistent with the generation of both lower-band and upper-band chorus through cyclotron resonant interactions with suprathermal electrons (1-100 keV). Two typical events on the nightside and dayside are studied in greater detail and additional interesting features are identified. Pancake distributions of electrons with energy below 2 keV, which could be responsible for the excitation of upper-band chorus, are observed at lower L shells (<7) on the nightside and at larger L shells (>6) on the dayside. In addition, very isotropic distributions at a few keV, which may be produced by Landau resonance and contribute to the formation of the typical gap in the chorus spectrum near 0.5 fce, are commonly observed on the dayside. (10.1029/2009JA014845)
DOI : 10.1029/2009JA014845
Measurements of stray antenna capacitance in the STEREO/WAVES instrument: Comparison of the measured voltage spectrum with an antenna electron shot noise model
- Zouganelis I.
- Maksimovic M.
- Meyer-Vernet N.
- Bale S. D.
- Eastwood Jonathan P.
- Zaslavsky A.
- Dekkali M.
- Goetz K.
- Kaiser M. L.
Radio Science, American Geophysical Union, 2010, 45, pp.1005. One of the most accurate techniques for in situ measuring the electron density and temperature in space plasmas is the quasi-thermal noise spectroscopy, which uses the voltage fluctuation spectrum on an electric antenna. This technique has been used successfully on the WIND and ULYSSES spacecraft; however, on STEREO this technique may only work in high-density filamentary structures, where the Debye length is small, because the STEREO/WAVES antennas have a large surface area, so that the resulting shot noise spectrum in the solar wind dominates the power at lower frequencies. In the unperturbed solar wind, we can use instead the electron shot noise to infer the plasma density. For doing so, we use well calibrated WIND particle data to deduce the stray capacitance of the STEREO/WAVES antenna system in a special configuration when the STEREO-B spacecraft was just downstream of WIND. This stray capacitance is also compared to ground experiments done on the flight spare equipment and independent calibrations performed using the galactic radio background. (10.1029/2009RS004194)
DOI : 10.1029/2009RS004194
Determination of the averaged charge-to-mass ratio of the heavy charged constituents of a magnetoplasma using whistler wave measurements
- Krafft C.
- Lundin B. V.
Annales Geophysicae, European Geosciences Union, 2010, 28, pp.2237-2247. In a cold magnetized plasma with two light ions of comparable gyrofrequencies and any species of heavy ions and/or charged dust particulates, a technique is developed to recover the relative charge density of the heavy plasma population and to estimate its effective averaged charge-to-mass ratio. Such results can be obtained without using mass spectrometer data but only the measurements of the ion plasma frequency, the electron gyro- and plasma frequencies as well as the two highest ion cutoff frequencies. (10.5194/angeo-28-2237-2010)
DOI : 10.5194/angeo-28-2237-2010
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
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
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
Plasma assisted ignition and combustion
- Starikovskaia Svetlana
- Starikovskii A.Yu.
, 2010, pp.71-93.
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
Bilan et Perspective 2006 - 2009, Programme National Soleil Terre
- Fontaine Dominique
- Vilmer N.
, 2010.
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
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
Operation of a load current multiplier on a nanosecond mega-ampere pulse forming line generator
- Chuvatin Alexandre S.
- Kantsyrev Viktor L.
- Rudakov Leonid I.
- Cuneo Michael E.
- Astanovitskiy A. L.
- Presura Radu
- Safronova Alla S.
- Cline W.
- Williamson Kenneth M.
- Shrestha Ishor
- Osborne Glenn C.
- Le Galloudec B.
- Nalajala Vidya
- Pointon T. D.
- Mikkelson K. A.
Physical Review Special Topics: Accelerators and Beams, American Physical Society, 2010, 13 (1), pp.010401. We investigate the operation of a load current multiplier (LCM) on a pulse-forming-line nanosecond pulse-power generator. Potential benefits of using the LCM technique on such generators are studied analytically for a simplified case. A concrete LCM design on the Zebra accelerator (1.9 Ohm, ∼1  MA, 100 ns) is described. This design is demonstrated experimentally with high-voltage power pulses having a rise time of dozens of nanoseconds. Higher currents and magnetic energies were observed in constant-inductance solid-state loads when a better generator-to-load energy coupling was achieved. The load current on Zebra was increased from the nominal 0.80.9 MA up to about 1.6 MA. This result was obtained without modifying the generator energetics or architecture and it is in good agreement with the presented numerical simulations. Validation of the LCM technique at a nanosecond time scale is of importance for the high-energy-density physics research. (10.1103/PhysRevSTAB.13.010401)
DOI : 10.1103/PhysRevSTAB.13.010401
Formation of a sodium ring in Mercury's magnetosphere
- Yagi Manabu
- Seki K.
- Matsumoto Y.
- Delcourt Dominique C.
- Leblanc François
Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A10), pp.A10253. We have performed a statistical analysis of exospheric sodium ion paths in Mercury's magnetosphere under northward interplanetary magnetic field conditions. Electric and magnetic field models used in the simulation were obtained from a global MHD simulation model, whereas the initial conditions of test Na+ ions were derived from a sodium exosphere model. We observe the formation of a ring-shaped high-pressure region consisting of energetic sodium ions traveling around the planet close to the equatorial plane. The configuration of this "sodium ring" as well as the acceleration processes leading to its formation strongly depend on the solar wind conditions. When the dynamic pressure is low, most of the Na+ are picked up in the magnetosphere and accelerated by the large-scale convective electric field. In contrast, in the case of high dynamic pressure, ions that are picked up in the magnetosheath and penetrate into the magnetosphere significantly contribute to the sodium ring. The configuration of this ring also depends upon the intensity of the solar wind electric field. Our analysis reveals that the pressure built by the Na+ ions may be significant as compared to the MHD pressure around the planet. (10.1029/2009JA015226)
DOI : 10.1029/2009JA015226
A simple model of intrinsic rotation in high confinement regime tokamak plasmas
- Gürcan Özgür D.
- Diamond P.H.
- Mcdevitt C.J.
- Hahm T.S.
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.032509. A simple unified model of intrinsic rotation and momentum transport in high confinement regime (H-mode) tokamak plasmas is presented. Motivated by the common dynamics of the onset of intrinsic rotation and the L-H transition, this simple model combines E×B shear-driven residual stress in the pedestal with a turbulent equipartition pinch to yield rotation profiles. The residual stress is the primary mechanism for buildup of intrinsic rotation in the H-mode pedestal, while the pinch drives on-axis peaking of rotation profiles. Analytical estimates for pedestal flow velocities are given in terms of the pedestal width, the pedestal height, and various model parameters. The predicted scaling of the toroidal flow speed with pedestal width is found to be consistent with the International Tokamak Physics Activity database global scaling of the flow speed on-axis with the total plasma stored energy. (10.1063/1.3339909)
DOI : 10.1063/1.3339909
Plasmas de Fusion Magnétique
- Hennequin Pascale
Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.25-26. ISSN : 1775-0385

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