Publications

2015

• Consistent multi-internal-temperature models for vibrational and electronic nonequilibrium in hypersonic nitrogen plasma flows
  
  • Guy Aurélien
  • Bourdon Anne
  • Perrin Marie-Yvonne
  Physics of Plasmas, American Institute of Physics, 2015, 22 (4), pp.043507. In this work, a state-to-state vibrational and electronic collisional model is developed to investigate nonequilibrium phenomena behind a shock wave in an ionized nitrogen flow. In the ionization dynamics behind the shock wave, the electron energy budget is of key importance and it is found that the main depletion term corresponds to the electronic excitation of N atoms, and conversely the major creation terms are the electron-vibration term at the beginning, then replaced by the electron ions elastic exchange term. Based on these results, a macroscopic multi-internal-temperature model for the vibration of N2 and the electronic levels of N atoms is derived with several groups of vibrational levels of N2 and electronic levels of N with their own internal temperatures to model the shape of the vibrational distribution of N2 and of the electronic excitation of N, respectively. In this model, energy and chemistry source terms are calculated self-consistently from the rate coefficients of the state-to-state database. For the shock wave condition studied, a good agreement is observed on the ionization dynamics as well as on the atomic bound-bound radiation between the state-to-state model and the macroscopic multi-internal temperature model with only one group of vibrational levels of N2 and two groups of electronic levels of N. (10.1063/1.4917338)
  DOI : 10.1063/1.4917338
• Current Status of MPPE (Mercury Plasma Particle Experiment) onBepiColombo/MMO
  
  • Saito Yoshifumi
  • Hirahara Masafumi
  • Barabash Stas
  • Delcourt Dominique
  • André Nicolas
  • Takashima Takeshi
  • Asamura Kazushi
  , 2015, 17. Mercury's plasma/particle environment has gradually become clear thanks to the new observations made by MESSENGER spacecraft orbiting around Mercury. However, it is also true that many questions will be left unsolved. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is going to be launched in 2016 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of 7 sensors: two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). Currently, the MPPE sensors are on the MMO spacecraft under system integration test at ISAS/JAXA (Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency). Evaluation of the sensor calibration data and the final check of the onboard processing software are being made in order to realize the flawless future plasma/particle observations around Mercury.
• La magnétosphère : du vent solaire au feuillet neutre
  
  • Fontaine Dominique
  , 2015.
• Fluid simulation of reactive atmospheric pressure discharges
  
  • Bourdon Anne
  , 2015.
• Synthetic Doppler backscattering diagnostic for fluid turbulent simulations
  
  • Leybros Robin
  • Ciraolo G.
  • Colin C.
  • Hennequin Pascale
  • Marandet Y.
  • Morel Pierre
  • Tamain P.
  • Vermare Laure
  , 2015.
• Turbulence de particules piégées dans les plasmas de Tokamak, modèles en couches et modèle LDM
  
  • Xu Shaokang
  • Morel Pierre
  • Gürcan Özgür D.
  , 2015.
• Signatures of solar event at middle and low latitudes in the europe-african sector, during geomagnetic storms october 2013
  
  • Azzouzi Ilyasse
  • Migoya-Orue Yenca
  • Amory-Mazaudier Christine
  • Fleury Rolland
  • Radicella Sandro Maria
  • Touzani Abdellatif
  , 2015. This paper presents the variability of the total electron content, VTEC, the ROTI index (proxy of the scintillation index) and the transient variations of the Earth's magnetic field associated to the impacts of solar events during October 2013. The observations are from middle and low latitudes in European African longitude sector. During October 2013, there are four solar events reaching the Earth. The two first events, on October 2 and October 8 are CME, the third event on October 14, is a jet of fast solar wind flowing from a solar coronal hole, and the last event on October 30 is a slow solar wind with southward excursions of the Bz component of the interplanetary magnetic field, associated to CME passing near the Earth. For the four events, the variation of VTEC at middle latitudes is the same and presents an increase of VTEC at the time of the impact followed by a decrease of VTEC, lasting one or several days. At low latitudes, no clear common pattern for all the events appears. For the four events the variation of the ROTI index over Africa is different showing the asymmetry between West and East Africa. For the first event, on October 2, the scintillations are not inhibited, for the second and the fourth events on October 8 and 30, the scintillations are inhibited on East Africa and for the third event (high speed solar wind stream), on October 14, the scintillations are inhibited over the whole Africa. The available data allow the full explanation of the observations of October 14, indeed, on this day, there is no post sunset increase of the virtual height h 0 F2 at Ascension Island. There is no Pre Reversal Enhancement (PRE) of the eastward electric field; it is this electric field which moves up the F layer, the necessary condition for the existence of scintillation. The analysis of the variations of the Earth's magnetic field at low latitudes highlights the presence of the ionospheric disturbance dynamo on October 14, which produces a decrease of the Equatorial Electrojet, several hours after the impact of the high speed solar wind. The disturbance dynamo electric field (DDEF) is westward during the day and till after sunset and turns eastward around 22.30LT. So, on October 14, the westward DDEF inhibits the eastward regular electric field.
• Sun impacts on ionized layers and transient variations of the earth's magnetic field Members of the Groupe International de Recherche en Géophysique Europe Afrique Asie
  
  • Amory-Mazaudier Christine
  , 2015. During the last decade in the projects IHY (International Heliophysical Year) 2005-2009 and ISWI (International Space Weather Initiative) 2010-2012, knowledge of the sun and its impacts on the ionized layers considerably progress following different ways: - Connecting the physical process from the sun to the ionosphere - Analysis of long series of ionospheric data over several solar cycles - Deployment of instruments (magnetometers and GPS) on the African continent in regions where measurements were nonexistent, thus leading to the revision of certain models. The research network GIRGEAA developed studies of equatorial Ionosphere in Africa and Asia. This presentation includes results on: - The time variations of ionosphere in Africa and Asia - The impacts of CME or high speed solar wind streams related to coronal holes on ionized layers (GPS/TEC measurements), - The magnetic DP2 current system related to the prompt penetration of magnetospheric convection electric field - The magnetic disturbance Ddyn associated to storm winds generated by Joule heating in the auroral zone: data analysis and modeling - The equatorial electrojet - etc.
• Signatures of solar event at middle and low latitudes in the Europe-African sector, during geomagnetic storms, October 2013
  
  • Azzouzi Ilyasse
  • Migoya-Orue Yenca
  • Amory-Mazaudier Christine
  • Fleury Rolland
  • Radicella S.
  • Touzani A.
  , 2015. In this study we investigate the ionospheric and magnetic disturbances during four magnetic storms of October 2013. The Earth was under the influence of solar events as CMEs, interplanetary shock wave and high speed solar wind stream flowing from coronal holes. The variation of the disturbed magnetic observations and GPS-TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS_TEC, GPS_ROTI (Rate of TEC Index) and magnetic disturbances due to the solar events. We use multi-instruments as GPS station at middle and low latitudes for Africa longitudes. At the beginning of each storm our data highlight the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storms, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. We observe the time variation of the ROTI index during these consecutive days associated to magnetic data. We see the disappearance of the scintillations (low values of ROTI) in Africa at all longitudes on the day of October 14, 2013. The 2 possible causes to explain this observation (large scale disturbance due to the solar wind magnetosphere dynamo source or local physical source) are investigated.
• Polarization analysis of CuXX-lines emitted from X-pinch
  
  • Baronova Elena
  • Larour Jean
  • Rosmej Frank
  • Khattak Fida
  , 2015, 653 (12), pp.012145. Soft x-ray emission from CuXX L-shell lines emitted by a dense X-pinch plasma have been investigated with high-resolution curved Bragg crystals at different angles of orientation. Single shot time integrated spectra show clear evidences of polarization for the Ne-like spectral lines 2s22p6 1S0 -> 2s22p53s 1P1 (lambda = 12.570 Ang), 2s22p6 1S0 -> 2s22p53s 3P1 (lambda = 12.8277 Ang). The variation of the intensity ratio of these two well-separated L-shell lines is discussed in view of its application for suprathermal electron characterization under real experimental conditions of pinch plasmas. We demonstrated that the simultaneous use of two different polarization spectrometers (means 4 Bragg crystals) permitted a high level of confidence for the analysis of the variation of the line ratios due to polarization.
• GPS in Africa
  
  • Amory-Mazaudier Christine
  , 2015. Presentation of the GPS networks in Africa in 2015
• A numerical strategy to discretize and solve the Poisson equation on dynamically adapted multiresolution grids for time-dependent streamer discharge simulations
  
  • Duarte Max
  • Bonaventura Zdenek
  • Massot Marc
  • Bourdon Anne
  Journal of Computational Physics, Elsevier, 2015, 289, pp.129-148. We develop a numerical strategy to solve multi-dimensional Poisson equations on dynamically adapted grids for evolutionary problems disclosing propagating fronts. The method is an extension of the multiresolution finite volume scheme used to solve hyperbolic and parabolic time-dependent PDEs. Such an approach guarantees a numerical solution of the Poisson equation within a user-defined accuracy tolerance. Most adaptive meshing approaches in the literature solve elliptic PDEs level-wise and hence at uniform resolution throughout the set of adapted grids. Here we introduce a numerical procedure to represent the elliptic operators on the adapted grid, strongly coupling inter grid relations that guarantee the conservation and accuracy properties of multiresolution finite volume schemes. The discrete Poisson equation is solved at once over the entire computational domain as a completely separate process. The accuracy and numerical performance of the method is assessed in the context of streamer discharge simulations. (10.1016/j.jcp.2015.02.038)
  DOI : 10.1016/j.jcp.2015.02.038
• Relations TERRE SOLEIL METEOROLOGIE DE LESPACE/ GNSS
  
  • Amory-Mazaudier Christine
  , 2015. Conférence Grand Public SOLEIL et SYSTÈME SOLAIRE LE SOLEIL et ses perturbations Protubérances, éruptions solaires Ejection de masse coronale Taches solaires -> champ magnétique solaire LA TERRE et son champ magnétique SOLEIL-TERRE / particules SOLEIL-TERRE/radiations Vie de tous les jours
• TRAINING ON SPACE WEATHER IN DEVELOPING COUNTRIES
  
  • Amory-Mazaudier Christine
  , 2015. In this paper we present the following items: Definition of Space Weather Use of GPS Impact of Coronal Mass Ejections on Total Electron Content measured by GPS Training on GPS Training on Sun Earths Physics Methodology : Schools, PhD, Teams of research
• Magnétosphère Terrestre: un apercu de la dynamique magnétosphérique
  
  • Fontaine Dominique
  , 2015.
• Alternate extraction and acceleration of positive and negative ions from a gridded plasma source
  
  • Lafleur Trevor
  • Rafalskyi D.V.
  • Aanesland Ane
  Plasma Sources Science and Technology, IOP Publishing, 2015, 24 (1), pp.15005. By applying a square-wave voltage with frequencies between 10 kHz to 1 MHz to a set of grids terminating an ion-ion plasma source, we experimentally demonstrate the alternate extraction and acceleration of high energy (100's of eV) positive and negative ion beams. In addition, the ratio of positive-to-negative ion beam current can be controlled by adjusting the applied square-wave duty cycle. Temporally-resolved floating potential measurements of a target show that the downstream potential can be controlled and sufficiently reduced at high applied frequencies (∼ 200 kHz), indicating that space-charge compensation can be achieved to prevent beam stalling. (10.1088/0963-0252/24/1/015005)
  DOI : 10.1088/0963-0252/24/1/015005
• Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995–1997
  
  • Tanoh K. S.
  • Adohi B. J.-P.
  • Coulibaly I. S.
  • Amory-Mazaudier Christine
  • Kobea A. T.
  • Assamoi P.
  Annales Geophysicae, European Geosciences Union, 2015, 33 (1), pp.143-157. In this paper, we report on the night-time equatorial F-layer height behaviour at Korhogo (9.2° N, 5° W; 2.4° S dip lat), Ivory Coast, in the West African sector during the solar minimum period 1995–1997. The data were collected from quarter-hourly ionograms of an Ionospheric Prediction Service (IPS) 42-type vertical sounder. The main focus of this work was to study the seasonal changes in the F-layer height and to clarify the equinox transition process recently evidenced at Korhogo during 1995, the year of declining solar flux activity. The F-layer height was found to vary strongly with time, with up to three main phases. The night-to-night variability of these morphological phases was then analysed. The early post-sunset slow rise, commonly associated with rapid chemical recombination processes in the bottom part of the F layer, remained featureless and was observed regardless of the date. By contrast, the following event, either presented like the post-sunset height peak associated with the evening E × B drift, or was delayed to the midnight sector, thus involving another mechanism. The statistical analysis of the occurrence of these events throughout the solar minimum period 1995–1997 revealed two main F-layer height patterns, each characteristic of a specific season. The one with the post-sunset height peak was associated with the northern winter period, whereas the other, with the midnight height peak, characterized the northern summer period. The transition process from one pattern to the other took place during the equinox periods and was found to last only a few weeks. We discuss these results in the light of earlier works. (10.5194/angeo-33-143-2015)
  DOI : 10.5194/angeo-33-143-2015
• Pourquoi la résolution de l'équation de Poisson doit être précise et rapide pour les simulations plasmas froids ?
  
  • Pechereau François
  • Bourdon Anne
  , 2015.
• Physics of the propagation in a dielectric tube, in the open air, and interaction of the plasma with a water surface
  
  • Rousseau Antoine
  , 2015.
• EXPERIMENTAL AND MODELING STUDIES OF LOW-PRESSURE CAPACITIVE OXYGEN PLASMAS EXCITED BY TAILORED VOLTAGE WAVEFORMS
  
  • Derszi Aranka
  • Lafleur Trevor
  • Korolov Ihor
  • Booth Jean-Paul
  • Donko Zoltan
  , 2015.
• Quantitative Diagnostics of Inductive Plasmas in Cl<SUB>2</SUB>, O<SUB>2</SUB> AND Cl<SUB>2</SUB>/O<SUB>2</SUB> Mixtures
  
  • Booth Jean-Paul
  • Foucher Mickaël
  • Marinov Daniil
  • Chabert Pascal
  , 2015. Inductively-coupled plasmas in molecular, electronegative gases are widely used for plasma processing of surfaces, for instance in CMOS manufacture. The complexity of these systems is such that they can only be described by multi-physics models which describe both the plasma physics and the molecular collisional processes. However, there has been little rigorous validation of these models by comparison to quantitative measurements of particle densities over a wide range of parameter space. We have chosen to study the Cl2/O2 system partly because of the industrial process relevance but also because methods exist to measure the density of many of the particles present. Electron densities were measured by microwave hairpin resonator. Absolute Cl and O atom densities were determined by Two-photon Absorption Laser-Induced Fluorescence. We have constructed a new ultra-low noise broadband UV-visible absorption bench, which allows the measurement of the densities of ground state Cl2 molecules and ClxOy reaction products, as well as vibrationally excited states of Cl2 and O2.
• Strong Ionization Asymmetry in a Geometrically Symmetric Radio Frequency Capacitively Coupled Plasma Induced by Sawtooth Voltage Waveforms
  
  • Bruneau Bastien
  • Gans T.
  • O'Connell D.
  • Greb Arthur
  • Johnson E.V.
  • Booth Jean-Paul
  Physical Review Letters, American Physical Society, 2015, 114, pp.125002. The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric waveforms induce spatial asymmetries and offer control of the spatiotemporal dynamics of electron heating and associated ionization structures. Sawtooth waveforms with different rise and fall rates are employed using truncated Fourier series approximations of an ideal sawtooth. Experimental PROES results obtained in argon plasmas are compared with PIC simulations, showing excellent agreement. With waveforms comprising a fast voltage drop followed by a slower rise, the faster sheath expansion in front of the powered electrode causes strongly enhanced ionization in this region. The complementary waveform causes an analogous effect in front of the grounded electrode. (10.1103/PhysRevLett.114.125002)
  DOI : 10.1103/PhysRevLett.114.125002
• Predator-prey model for the self-organization of stochastic oscillators in dual populations.
  
  • Moradi S.
  • Anderson J.
  • Gürcan Özgür D.
  Physical Review E, American Physical Society (APS), 2015, 92, pp.06293. A predator-prey model of dual populations with stochastic oscillators is presented. A linear cross-coupling between the two populations is introduced following the coupling between the motions of a Wilberforce pendulum in two dimensions: one in the longitudinal and the other in torsional plain. Within each population a Kuramoto-type competition between the phases is assumed. Thus, the synchronization state of the whole system is controlled by these two types of competitions. The results of the numerical simulations show that by adding the linear cross-coupling interactions predator-prey oscillations between the two populations appear, which results in self-regulation of the system by a transfer of synchrony between the two populations. The model represents several important features of the dynamical interplay between the drift wave and zonal flow turbulence in magnetically confined plasmas, and a novel interpretation of the coupled dynamics of drift wave-zonal flow turbulence using synchronization of stochastic oscillator is discussed. (10.1103/PhysRevE.92.062930)
  DOI : 10.1103/PhysRevE.92.062930
• Magnetic noise contribution of the ferromagnetic core of induction magnetometers
  
  • Coillot C
  • El Moussalim M
  • Brun E
  • Rhouni A
  • Lebourgeois R
  • Sou Gérard
  • Mansour Malik
  Journal of Sensors and Sensor Systems, Copernicus Publ, 2015, 4, pp.229 - 237. The performance of induction magnetometers, in terms of resolution, depends both on the induction sensor and the electronic circuit. To investigate accurately the sensor noise sources, an induction sensor, made of a ferrite ferromagnetic core, is combined with a dedicated low voltage and current noise preamplifier, designed in CMOS 0.35 µm technology. A modelling of the contribution of the ferromagnetic core to the noise through the complex permeability formalism is performed. Its comparison with experimental measurements highlight another possible source for the dominating noise near the resonance. (10.5194/jsss-4-229-2015)
  DOI : 10.5194/jsss-4-229-2015
• Wide-banded NTC radiation: local to remote observations by the four Cluster satellites
  
  • Décréau Pierrette
  • Aoutou S.
  • Denazelle A.
  • Galkina I.
  • Rauch Jean-Louis
  • Vallières Xavier
  • Canu Patrick
  • Rochel Grimald S.
  • El-Lemdani Mazouz Farida
  • Darrouzet F.
  Annales Geophysicae, European Geosciences Union, 2015, 33 (10), pp.1285-1300. The Cluster multi-point mission offers a unique collection of non-thermal continuum (NTC) radio waves observed in the 2-80 kHz frequency range over almost 15 years, from various view points over the radiating plasmasphere. Here we present rather infrequent case events, such as when primary electrostatic sources of such waves are embedded within the plasmapause boundary far from the magnetic equatorial plane. The spectral signature of the emitted electromagnetic waves is structured as a series of wide harmonic bands within the range covered by the step in plasma frequency encountered at the boundary. Developing the concept that the frequency distance df between harmonic bands measures the magnetic field magnitude B at the source (df = F<SUB>ce</SUB>, electron gyrofrequency), we analyse three selected events. The first one (studied in Grimald et al., 2008) presents electric field signatures observed by a Cluster constellation of small size (~ 200 to 1000 km spacecraft separation) placed in the vicinity of sources. The electric field frequency spectra display frequency peaks placed at frequencies fs = n df (n being an integer), with df of the order of F<SUB>ce</SUB> values encountered at the plasmapause by the spacecraft. The second event, taken from the Cluster tilt campaign, leads to a 3-D view of NTC waves ray path orientations and to a localization of a global source region at several Earth radii (R<SUB>E</SUB>) from Cluster (Décréau et al., 2013). The measured spectra present successive peaks placed at fs ~ (n 1/2) df. Next, considering if both situations might be two facets of the same phenomenon, we analyze a third event. The Cluster fleet, configured into a constellation of large size (~ 8000 to 25 000 km spacecraft separation), allows us to observe wide-banded NTC waves at different distances from their sources. Two new findings can be derived from our analysis. First, we point out that a large portion of the plasmasphere boundary layer, covering a large range of magnetic latitudes, is radiating radio waves. The radio waves are issued from multiple sources of small size, each related to a given fs series and radiating inside a beam of narrow cone angle, referred to as a beamlet. The beamlets illuminate different satellites simultaneously, at different characteristic fs values, according to the latitude at which the satellite is placed. Second, when an observing satellite moves away from its assumed source region (the plasmapause surface), it is illuminated by several beamlets, issued from nearby sources with characteristic fs values close to each other. The addition of radio waves blurs the spectra of the overall received electric field. It can move the signal peaks such that their position fs satisfiesfs = (n alpha) df, with 0 < alpha < 1. These findings open new perspectives for the interpretation of NTC events displaying harmonic signatures. (10.5194/angeo-33-1285-2015)
  DOI : 10.5194/angeo-33-1285-2015