Publications

2012

• Radiofrequency plasma antenna generated by femtosecond laser filaments in air
  
  • Brelet Yohann
  • Houard Aurélien
  • Point Guillaume
  • Prade Bernard
  • Arantchouk Léonid
  • Carbonnel Jérôme
  • André Yves-Bernard
  • Pellet Michel
  • Mysyrowicz André
  Applied Physics Letters, American Institute of Physics, 2012, 101 (26), pp.264106. We demonstrate tunable radiofrequency emission from a meter-long linear plasma column produced in air at atmospheric pressure. A short-lived plasma column is initially produced by femtosecond filamentation and subsequently converted into a long-lived discharge column by application of an external high voltage field. Radiofrequency excitation is fed to the plasma by induction and detected remotely as electromagnetic radiation by a classical antenna. (10.1063/1.4773492)
  DOI : 10.1063/1.4773492
• Cl atom spin-orbit excited densities in a Cl<SUB>2</SUB> ICP determined by TALIF
  
  • Booth Jean-Paul
  • Sirse Nishant
  • Indelicato P.
  • Surzhykov A.
  • Wang Y.
  • Zatsarinny Oleg
  • Bartschat Klaus
  • Kushner M.J.
  , 2012.
• Cl atom spin-orbit excited densities in a Cl2 ICP determined by TALIF
  
  • Booth Jean-Paul
  • Sirse Nishant
  • Indelicato P.
  • Wang Y.
  • Zatsarinny Oleg
  • Bartschatt K.
  • Kushner M.J.
  , 2012.
• Caractérisation des magnétomètres à induction
  
  • Alison Dominique
  • Coillot Christophe
  • Chust Thomas
  • Le Contel Olivier
  , 2012. Ce document présente une séance de travaux pratiques de caractérisation d'un magnétomètre à induction haute performance destinée aux étudiants de M2 OSAE de l'Observatoire de Meudon. Ce TP se déroule sur une journée et nécessite du matériel spécifique (bobines Helmholtz, analyseur de spectre). Le TP a pour but de comparer deux modes de fonctionnement du magnétomètre inductif permettant de s'affranchir de la résonance: la contre-réaction de flux et l'amplification en courant. Le TP permet de réaliser des caractérisations en champ magnétique et donner un cadre concret à des caractérisations de bruit.
• Magnetosphere-ionosphere coupling at high latitude during periods of Northward IMF
  
  • Maggiolo R.
  • Echim M.
  • Fear R.
  • Fontaine Dominique
  • Simon Wedlund C.
  • Zhang Y.
  , 2012, 21, pp.05. During periods of northward IMF, auroral features are observed above the polar caps. These polar cap arcs are the signature of magnetosphere-ionosphere coupling processes occurring at high latitudes. Recent observations from the Cluster satellites at high altitude (5-7 RE) and from spacecraft imagers give new insight on these processes. Polar cap arcs can occur on a variety of scales, from large-scale arcs called 'transpolar arcs' or 'theta aurora' to small-scale isolated arcs. There is strong evidence that large-scale transpolar arcs are located on field lines that have been closed by magnetotail reconnection but remain embedded within the lobes. This is further confirmed by recent observations from the IMAGE and Cluster satellites. Small scale structures consisting in a succession of current sheets with opposite polarity are also observed above the polar caps during periods of northward IMF. Cluster and TIMED observations reveal that they are associated with thin polar cap arcs. The upward current is carried by upflowing ionospheric ions and precipitating electrons accelerated by quasi-static electric fields. The precipitating electrons are cold and likely of solar wind origin. However, for half of the events, plasmasheet-like isotropic ions are detected simultaneously. Consequently the magnetic field lines do not neatly fit into either a closed and open configuration. A detailed review of these observations is proposed, which are subsequently used to constrain ideas on magnetosphere-ionosphere interactions and on magnetospheric configuration at high latitudes during prolonged periods of northward IMF.
• Hybrid simulation of the Solar wind interaction with the Martian ionosphere and magnetic field
  
  • Modolo Ronan
  • Hess Sebastien
  • Richer Emilie
  • Mancini Marco
  • Leblanc François
  • Chaufray Jean-Yves
  • Chanteur Gérard
  • Mazelle Christian Xavier
  • Grimald Sandrine
  • Forget François
  • Gonzalez-Galindo Francisco
  , 2012. In the frame of the HELIOSARES project (PI F.Leblanc) dedicated to the modeling of Mars environment (neutral and charged species) from the lower atmosphere to the solar wind, a modeling effort has been conducted to parallelize a multi-species hybrid simulation code. This code now provides a kinetic description of the ions with a rather improved spatial resolution (smaller than the ion inertial length). The latest progresses are reported and simulations results with a uniform spatial resolution of 80 km are presented. This fully parallelized code describes both the dynamics and physical and chemical processes involved in the interaction. Photoproduction, charge exchange and electron impact ionization are computed dynamically through the simulation domain. The Martian ionosphere can be described either by external profile -- e.g. by coupling with the result of ionosphere-exosphere simulations -- or internally computed profiles obtained by assuming an equilibrium between several chemical processes (in which case transport is neglected). Moreover, the Martian crustal field can be integrated in our model to study its influence on the interaction dynamic and the ionosphere escape rate. We hereby show the results of simulations of the interaction between the martian atmosphere and the solar wind, which shows how the interaction is modified by the presence of the crustal field modifies and how it is modulated with the planetary rotation.
• Étude de fonctions électroniques en technologie ASIC pour instruments dédiés à l'étude des plasmas spatiaux
  
  • Rhouni Amine
  , 2012. La couronne solaire est la source d'un vent de plasma qui interagit avec les divers objets du système solaire : planètes, comètes et astéroïdes. Le développement des instruments destinés à être embarqués à bord de satellites et de sondes spatiales permet d'étudier, in situ, les relations soleil Terre et plus généralement le vent solaire et les environnements ionisés planétaires. L'étude de ces phénomènes nécessite la combinaison d'instruments permettant de caractériser à la fois les ondes et leurs particules. Nous nous sommes intéressés à l'intégration de l'électronique des instruments spatiaux, et notamment la chaine d'amplification analogique de magnétomètres à induction et la chaîne d'amplification / discrimination de détecteurs de particules, en technologie standard CMOS 0.35 m. Les circuits étudiés, associés respectivement au magnétomètre à induction et au détecteur de particules, permettent l'amplification faible bruit à basse fréquence et l'amplification ultrasensible de charge sur une large gamme. Ces circuits doivent en outre répondre aux exigences du spatial en terme de consommation, tenue en température et en radiation. Le mémoire de thèse s'articule autour de la présentation de l'environnement ionisé de la Terre, la présentation des instruments scientifiques (magnétomètre spatial et détecteur de particules), la description des architectures des circuits CMOS permettant d'atteindre des performances inédites. Un travail important sur les structures d'amplifications a été mené afin de réduire considérablement la consommation et augmenter la sensibilité de la chaine électronique de traitement du détecteur de particules. Ainsi, la faisabilité d'une électronique intégrée multivoie pour l'analyseur de particules à optique hémisphérique contenant jusqu'à 256 pixels a été prouvée. Réduire le niveau de bruit en basse fréquence (de quelques 100 mHz à quelque 10 kHz) des circuits à base de composants MOS a toujours été une tache fastidieuse, puisque ce type de composants n'est à la base, pas destiné à une telle gamme de fréquence. Il a été donc nécessaire de concevoir des structures d'amplification originales par la taille non habituelle, voir à la limite autorisée par les procédés de fabrication, de leur transistors d'entrée. Cette solution a permis de réduire considérablement le niveau de bruit vu à l'entrée de l'électronique d'amplification des fluxmètres. L'avantage d'utiliser une technologie CMOS est le faible bruit en courant, la faible consommation et résoudre le problème de l'encombrement. Les résultats obtenus lors des tests de validations et en radiations sont très satisfaisants. Ils permettent d'ouvrir une éventuelle voie pour l'électronique intégrée au sein de l'instrumentation spatiale. Les performances obtenues notamment lors d'un tir fusée a renforcé la fiabilité d'une telles conceptions pour le domaine spatial.
• Statistical study of the equatorial F2 layer critical frequency at Ouagadougou during solar cycles 20, 21 and 22, using Legrand and Simon's classification of geomagnetic activity
  
  • Ouattara Frédéric Martial
  • Amory-Mazaudier Christine
  Journal of Space Weather and Space Climate, EDP sciences, 2012, pp.1-10. This paper presents the statistical analysis of the diurnal variations of the F layer at the equatorial station of Ouagadougou (Lat: 12.4 N; Long: 358.5 E; dip: 5.9 ) from 1966 to 1998 (=> ~11 680 days). We consider three main factors of variability: (1) the season (spring, summer, autumn and winter), (2) the phase of the sunspot cycle (ascending, maximum, descending and minimum) and (3) the geomagnetic activity classified by Legrand and Simon in four groups: slow solar wind, high solar wind streams, fluctuating solar wind and shock activity. We easily identify the influence of the solar wind speed and shock activity on the diurnal pattern of the F layer. Shock and recurrent activities tend to enhance or diminish the morning or afternoon maximum of the F2 layer critical frequency. The difference of the diurnal foF2 variation during the increasing and decreasing phases of the sunspot solar cycle is explained by different solar wind regimes. The slow solar wind dominates during the increasing phase of the sunspot cycle and the fluctuating solar wind dominates during the decreasing phase of the sunspot cycle. This paper demonstrates that it is possible using a large database, to bring up significant morphologies of the diurnal variation of the foF2 critical frequency as a function of (1) different solar events such as quiet solar wind, fluctuating wind, recurrent high stream wind and Coronal Mass Ejections (CMEs); (2) solar cycle phases and (3) seasons. It is an approach directly connecting the critical frequency of the F2 layer to the solar parameters. (10.1051/swsc/2012019)
  DOI : 10.1051/swsc/2012019
• Space Weather in Africa : capacity buildind and involved students
  
  • Amory-Mazaudier Christine
  , 2012.
• Développement du propulseur PEGASES : source inductive à haute performance et accélération successive de faisceaux d'ions positifs et d'ions négatifs.
  
  • Popelier Lara
  , 2012. PEGASES est un nouveau propulseur conçu et développé au LPP. Un propulseur électrique classique éjecte de la matière positive à grande vitesse depuis un plasma électropositif pour générer la poussée. La nouveauté introduite par PEGASES est le fait que la poussée est générée par l'accélération successive d'ions positifs et d'ions négatifs issus d'un plasma ion-ion continu. Le propulseur PEGASES est composé de trois étages: (i) un étage d'ionisation constitué d'une source radiofréquence (rf) pour le couplage inductif d'un plasma électronégatif à partir d'un gaz contenant des halogènes, (ii) un étage de filtrage magnétique des électrons pour obtenir un plasma ion-ion, et (iii) l'étage d'accélération des ions utilisant des grilles polarisées alternativement pour créer un champ électrique dont le sens varie dans le temps. Durant ma thèse, j'ai travaillé essentiellement sur les premier et troisième étages sur deux prototypes de PEGASES. Un plasma ion-ion a été obtenu dans le premier prototype à partir de SF6 grâce à un filtrage magnétique important. Mais des limitations inhérentes et significatives rendent les performances insuffisantes pour le processus d'accélération voulu. Afin d'obtenir une source d'ions électriquement performante, le second prototype utilise une source inductive plane avec une bobine à noyau de ferrite et une boîte d'accord d'impédance comportant un transformateur à faibles pertes. Le couplage capacitif parasite a été réduit en optimisant la boîte d'accord et les progrès sont évalués grâce à la mesure du spectre du potentiel plasma par sonde capacitive. Le plasma est étudié à l'aide de sondes de Langmuir et d'un analyseur de l'énergie des ions (RFEA) dans les deux prototypes. Le potentiel d'un plasma ion-ion peut être contrôlé par une électrode polarisée en contact avec le plasma. L'accélération des ions issus du plasma ion-ion est étudiée dans le cas continu où la polarisation des grilles est fixée puis en imposant une tension créneau d'amplitude comprise entre 0 et ± 350 V avec une fréquence de 1 kHz. Dans le cas alternatif, les ions positifs et les ions négatifs sont accélérés durant les demi-périodes de polarisation positive et négative respectivement. L'énergie respective des deux populations d'ions peut être contrôlée indépendamment, en continu et en alternatif. Avec ces résultats est démontrée la faisabilité du concept PEGASES et l'étude du propulseur peut passer à l'étape de développement et réalisation.
• Cluster spacecraft observations of reconnection jet fronts/braking regions and associated electron energization at multiple scales
  
  • Retinò Alessandro
  • Vaivads A.
  • Zieger B.
  • Nakamura R.
  • Fujimoto M.
  • Kasahara S.
  , 2012.
• Interactions of CMEs/magnetic clouds with the terrestrial environment
  
  • Fontaine Dominique
  , 2012.
• Experiments and Numerical Simulation on a New Hohlraum Configuration with Planar Wire Array Sources at the 1.7 MA Zebra Generator
  
  • Kantsyrev Viktor L.
  • Chuvatin Alexandre S.
  • Rudakov Leonid I.
  • Safronova Alla S.
  • Esaulov A. A.
  • Shrestha Ishor
  • Osborne Glenn C.
  • Shlyaptseva V. V.
  • Weller Michael E.
  • Keim S. F.
  • Stafford A.
  • Jones B.
  • Vesey R. A.
  , 2012, 57 (12), pp.BO5.00008. In new hohlraum configuration, multiple mm-size planar wire array (PWA) sources surround a central cavity [B. Jones et al., PRL, v.104 (2010)]. This might provide a hotter hohlraum for ICF than the prior double-ended scheme with cylindrical arrays. The current redistribution in two magnetically decoupled compact Z-pinches (0.75-0.82 MA each) was demonstrated at 1.7 MA UNR Zebra generator. Yield measurements from two cages with PWA sources show that such plasma dissipates the magnetic energy at stagnation as a resistor. For the first time, strong EUV radiation, that time-correlated with sub-keV source bursts, was registered from central cavity. The experimental cavity radiation temperature of 37-45 eV correlates well with 39 eV from VisRaD code (PRISM Co.) simulation. First results of new configuration optimization are reported. The possible applications for 30-60 MA ICF experiments are discussed. This work was supported by NNSA under DOE Coop. Agr. DE-FC52-06NA27586, 06NA27588, and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
• Plasma deposition processes excited using Tailored Voltage Waveforms: from microcrystalline silicon thin films to devices
  
  • Johnson E.V.
  • Pouliquen S.
  • Delattre Pierre-Alexandre
  • Booth Jean-Paul
  , 2012.
• Theoretical Investigation of Radiation Characteristics of Silver Z-pinch Arrays with Applications
  
  • Weller Michael E.
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Esaulov A. A.
  • Shrestha Ishor
  • Osborne Glenn C.
  • Shlyaptseva V. V.
  • Keim S. F.
  • Stafford A.
  • Petkov E. E.
  • Chuvatin Alexandre S.
  • Apruzese J. P.
  • Golovkin I. E.
  • Macfarlane J. J.
  , 2012, 57 (12), pp.BO5.00007.
• Analysis of Precursor Properties of mixed Al/Alumel Cylindrical Wire Arrays
  
  • Stafford A.
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Esaulov A. A.
  • Weller Michael E.
  • Shrestha Ishor
  • Osborne G.C.
  • Shlyaptseva V. V.
  • Keim S. F.
  • Coverdale C.
  • Chuvatin Alexandre S.
  , 2012, 57 (12), pp.TP8.00138.
• Benefits and drawbacks of low magnetic shears on the confinement in magnetic fusion toroidal devices
  
  • Firpo Marie-Christine
  • Constantinescu D.
  , 2012. http://adsabs.harvard.edu/abs/2012APS..DPPPO7011F The issue of confinement in magnetic fusion devices is addressed within a purely magnetic approach. As it is well known, the magnetic field being divergence-free, the equations of its field lines can be cast in Hamiltonian form. Using then some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is demonstrated. Away from resonances, it induces a drastic enhancement of magnetic confinement that favors robust internal transport barriers (ITBs) and turbulence reduction. However, when low-shear occurs for values of the winding of the magnetic field lines close to low-order rationals, the amplitude thresholds of the resonant modes that break internal transport barriers by allowing a radial stochastic transport of the magnetic field lines may be much lower than the ones obtained for strong shear profiles. The approach can be applied to assess the robustness versus magnetic perturbations of general almost-integrable magnetic steady states, including non-axisymmetric ones such as the important single helicity steady states. This analysis puts a constraint on the tolerable mode amplitudes compatible with ITBs and may be proposed as a possible explanation of diverse experimental and numerical signatures of their collapses.
• DYNAMICS OF ION-SCALE COHERENT MAGNETIC STRUCTURES AND COUPLING WITH WHISTLER WAVES DURING SUBSTORMS.
  
  • Tenerani Anna
  , 2012. A new model of the self-consistent coupling between low frequency, ion-scale coherent magnetic structures and high frequency whistler waves is proposed in order to interpret space data gathered by Cluster satellites during substorm events, in the night sector of the Earth's magnetosphere. The coupling provides a mechanism to spatially confine and transport whistler waves by means of a highly oblique, propagating nonlinear carrier wave. The present study relies on a combination of data analysis of original in situ measurements, theoretical modeling and numerical investigation. During substorms, the magnetosphere undergoes strong magnetic and electric field fluctuations ranging from low frequencies, of the order or less than the typical ion-time scales, to higher frequencies, of the order or higher than the typical electron time-scales. To understand basic plasma physical processes which characterize the magnetosphere dynamics during substorms an analysis of whether, and by which mechanism, waves occurring at these different time scales are coupled, is of fundamental interest. Low frequency magnetic structures are commonly detected in environments such as the magnetosheath and the solar wind, as well as in the dusk magnetosphere, possibly correlated with higher frequency whistler waves. In this Thesis it is shown that similar magnetic structures, correlated with whistler waves, are observed in the magnetospheric plasma sheet during substorms. The interesting question arises as to how the inhomogeneity associated with such magnetic structures affects the propagation of higher frequency waves. The Cluster mission, thanks to its four satellites in tetrahedron configuration and high temporal resolution measurements, provides a unique opportunity on the one hand to explore the spatial structure of stationary and propagating perturbations observed at low frequencies and on the other hand to study dynamics occurring at higher temporal scales, via whistler mode waves. With regard to this, I will describe the Cluster spacecraft detection of large amplitude whistler wave packets inside coherent ion-scale magnetic structures embedded in a fast plasma flow during the August 17th 2003 substorm event. In this period the Cluster satellites were located in the plasma sheet region and separated by a distance which is less than the magnetotail typical ion-scale lengths, namely the ion gyroradius and the ion inertial length. The observed whistler emissions are correlated with magnetic field structures showing magnetic depletions associated with density humps. As a first step, the latter have been modeled as one dimensional nonlinear slow waves which spatially confine and transport whistlers, in the framework of a two-fluid approximation. This schematic model is investigated through a theoretical and numerical study by means of a two-fluid code, and it is shown that the proposed model goes quite well with data interpretation. Its possible role in substorm dynamics is also discussed. This new trapping mechanism, studied here by using a highly oblique slow magnetosonic soliton as a guide for whistler waves, is of more general interest beyond the specific context of the observations reported in this Thesis. Other nonlinear structures showing similar features, for example highly oblique nonlinear Alfvén waves or kinetic Alfvén waves in high beta plasmas, can in principle act as wave carriers. The model proposed provides an explanation for the recurrent detection of whistlers inside ion-scale magnetic structures which is alternative to usual models of stationary magnetic structures acting as channels. Moreover, the study described in this Thesis addresses more general questions of basic plasma physics, such as wave propagation in inhomogeneous plasmas and the interaction between wave modes at different temporal scales.
• Inductively-coupled plasmas in pure chlorine: comparison experiments/HPEM
  
  • Booth Jean-Paul
  • Sirse Nishant
  • Azamoum Yasmina
  • Chabert Pascal
  , 2012.
• Electron temperature and plasma density distribution measurement along magnetic barrier in the PEGASES thruster
  
  • Bredin Jérôme
  • Aanesland Ane
  • Chabert Pascal
  • Godyak Valery
  , 2012.
• Plasma Excitation using Tailored Voltage Waveforms for the Deposition of Thin Film Silicon for Photovoltaics: From Plasma Physics to Devices
  
  • Johnson E.V.
  • Delattre Pierre-Alexandre
  • Lafleur Trevor
  • Booth Jean-Paul
  , 2012.
• Plasma characteristics in non-sinusoidally excited CCP discharges
  
  • Lafleur Trevor
  • Booth Jean-Paul
  , 2012.
• Tailored Voltage Waveform Capacitively-Coupled Plasmas
  
  • Booth Jean-Paul
  • Lafleur Trevor
  • Delattre Pierre-Alexandre
  • Johnson E.V.
  , 2012.
• Modelling of atmospheric pressure capacitive discharges
  
  • Chabert Pascal
  , 2012.
• Ozone kinetics in low-pressure discharges
  
  • Guerra V.
  • Marinov Daniil
  • Guaitella Olivier
  • Rousseau Antoine
  , 2012.