Publications

2016

• Highly vibrationally excited O<SUB>2</SUB> molecules in low pressure oxygen plasmas: 2. Self-consistent model
  
  • Annusova Adriana
  • Guerra V.
  • Silva M. Lino Da
  • Lopez B.
  • Foucher Mickaël
  • Marinov Daniil
  • Booth Jean-Paul
  , 2016. The high degree of vibraitonal excitation of O2(X) molecules recently observed in ICP discharges is investigated and interpreted using a detailed self-consistent 0D global model for oxygen plasmas. The theoretical calculations are compared with measurements performed at 10 and 80 mTorr. The origin of these highly excited molecules is explained on the basis of creation and destruction rates of the most important processes for the vibration, controlled by eV, VT O2-O and e O2(X,v)&#61614;O O processes.
• Some thoughts on plasma turbulence in the magnetosheath adn the solar wind
  
  • Sahraoui Fouad
  , 2016.
• Charged and neutral particle dynamics in low pressure chlorine and oxygen plasmas: the role of collisional processes
  
  • Gibson Andrew
  • Foucher Mickaël
  • Marinov Daniil
  • Chabert Pascal
  • Gans T.
  • Guerra V.
  • Kushner M.J.
  • Booth Jean-Paul
  , 2016. The modelling of low pressure industrial plasmas is strongly reliant upon fundamental data describing particle collisions in the gas phase and with surfaces. Such data include electron-heavy particle collision cross sections, surface loss coefficients of reactive neutral species (&#947;) and thermal energy accommodation coefficients for heavy particle interactions with surfaces (&#945;). The methods required, both theoretically and experimentally, to generate the above data are extremely varied and as such the degree to which these data are known for a given plasma system varies significantly from process to process. Self-consistent plasma simulations provide a strong test for the accuracy of the complete set of fundamental collision data for a given system as the final result often hinges on the accuracy of the data for many different processes in concert. This work seeks to evaluate the state-of-the art of knowledge of a range of fundamental collision data by comparing the results of a self-consistent 2-D plasma simulation (HPEM [1]) and a range of experimental measurements in chlorine and oxygen inductively coupled plasmas. For both gases, it is found that the simulation is sensitive to the electron impact cross section set used as well as the surface coefficients &#947; and &#945;. In both cases &#947; determines in large part the density of the reactive atomic species (either atomic chlorine or oxygen), &#945; determines the neutral gas temperature and the electron impact cross sections define the electron density and temperature. Through comparison between the simulated and experimentally measured values of the discussed parameters the most appropriate collision data set for use in self-consistent plasma simulations is inferred. It is hoped that this work with stimulate further direct measurements and calculations of the discussed collision data. [1] M. J. Kushner, J. Phys. D: Appl. Phys., 42, 194013 (2009) Acknowledgement: Funding is acknowledged through the LABEX Plas@Par project, ANR-11-IDEX-0004-02, UK EPSRC Manufacturing Grant (EP/K018388/1) and the York-Paris Collaborative Research Centre.
• Density profile and turbulence evolution during L-H transition studied with the Ultra-fast swept reflectometer on ASDEX Upgrade
  
  • Medvedeva Anna
  • Birkenmeier G.
  • Bottereau C.
  • Cavedon M.
  • Clairet F.
  • Conway G. D.
  • Hennequin Pascale
  • Heuraux S.
  • Molina D.
  • Silva A.
  • Stroth U.
  • Asdex Upgrade Team The
  , 2016, 40A, pp.P1.032.
• Characterization by complementary diagnostics of plasma jets in interaction with targets relevant for biomedical applications
  
  • Robert E.
  • Damany X.
  • Darny T.
  • Iseni S.
  • Douat Claire
  • Dozias S.
  • Pouvesle Jm
  • Viegas Pedro
  • Bourdon Anne
  , 2016.
• Modelling and experimental validation of capacitively coupled plasmas in hydrogen
  
  • Diomede D.
  • Bruneau Bastien
  • Lafleur Trevor
  • Economou D. J.
  • Longo S.
  • Gans T.
  • O'Connell D.
  • Greb Arthur
  • Johnson E.V.
  • Booth Jean-Paul
  , 2016. Parallel plate capacitively coupled plasmas (CCPs) are commonly used for material processing applications such as deposition and etching of thin films. Since hydrogen is the most abundant component used as a diluent in a variety of gas mixtures, pure H2 plasma dynamics is to be investigated first. A one-dimensional in space, three-dimensional in velocity hybrid model described in detail in [1-3] was used to investigate CCPs in H2. The hybrid model couples self-consistently a particle-in-cell model with Monte Carlo collisions for charged species (electrons, H , H2 , H3 and H&#8722; ions), with a reactiondiffusion fluid model for neutrals (14 vibrational levels of the electronic ground state of H2, and H atoms). In the past, the model was compared with experimental results found in literature for the classical sinusoidal voltage [1, 2] and, more recently, it has been used in several combined computational-experimental studies to investigate plasmas sustained by tailored voltage waveforms (TVWs) composed of multiple harmonics [3, 4]. The excitation dynamics and ion flux asymmetry and many quantities of paramount importance for plasma processing, including the ones not accessible through experimental investigations, have been analysed for different TVWs, thus allowing an improvement of the model and giving a better insight into this very new kind of discharge excitation. References [1] P. Diomede, M. Capitelli, S. Longo, Plasma Sources Sci. Technol., 14, 459-466 (2005) [2] P. Diomede, S. Longo, D. J. Economou and M. Capitelli, J. Phys. D: Appl. Phys., 45, 175204 (14pp) (2012) [3] P. Diomede, D. J. Economou, T. Lafleur, J.-P. Booth and S. Longo, Plasma Sources Sci. Technol., 23, 065049 (11pp) (2014) [4] B. Bruneau, P. Diomede, D. J. Economou, S. Longo, T. Gans, D. OConnell, A. Greb, E. Johnson, J.-P. Booth, submitted to Plasma Sources Sci. Technol.
• Isotope effect on confinement unraveled for L-mode in dimensionless &#961;&#8902; scan
  
  • Schneider Philip
  • Bustos Andreas
  • Hennequin Pascale
  • Ryter F.
  • Bernert M.
  • Cavedon Marco
  , 2016, 40A, pp.O4.135.
• The I-mode confinement regime at ASDEX Upgrade: global properties and characterization of strongly intermittent density fluctuations
  
  • Happel T.
  • Manz P.
  • Ryter F.
  • Bernert M.
  • Dunne M.
  • Hennequin Pascale
  • Hetzenecker A.
  • Stroth G.
  • Conway G. D.
  • Guimarais L.
  • Honoré Cyrille
  • Viezzer E.
  • Asdex Upgrade Team The
  , 2016, pp.I1.101.
• O- and X-mode Radial Correlation Doppler Reflectometry in 2D Full Wave Simulations and Experiments
  
  • Pinzon Javier
  • Happel T.
  • Hennequin Pascale
  • Blanco E.
  • Estrada T.
  • Stroth U.
  , 2016, 40A, pp.P1.052.
• Characterization of plasma jets in interaction with targets relevant for biomedical applications by complementary diagnostics
  
  • Robert Eric
  • Damany Xavier
  • Darny Thibault
  • Iséni Sylvain
  • Douat Claire
  • Dozias Sébastien
  • Pouvesle Jean-Michel
  • Viegas Pedro
  • Bourdon Anne
  , 2016. In the last decade, plasma jets generated in ambient air at room temperature have found an impressive number of material processing and biomedical applications [1, 2]. While being generated in simple discharge reactors, dielectric barrier discharge or miniaturized plasma torch, it has been rapidly evidenced that their reliable operation and diagnostics was quite challenging and strongly application dependent. In this invited lecture, we will emphasize on the necessity and benefit first to perform plasma diagnostics not only in situation of free jet expansion but more informatively with including target used or mimicking those involved for plasma jet in operation for any dedicated application. It is also crucial to perform combined diagnostics to entangle the number and cross correlated physico chemical phenomena inherent with plasma jet delivery. Recent measurements including gas flow diagnostics with or without plasma operation through Schlieren visualization, species density assessment with IR laser absorption or laser induced fluorescence techniques [3], plasma propagation dynamics and emission diagnostics with fast, eventually wavelength filtered, ICCD imaging, but also electric field measurements [4] will be presented. The necessity to combine various experimental data but also the confrontation with simulation results [5] will be enlighten in the diagnostics of electric fields, radical generation over surface, helium metastable generation and discharge propagation and counter propagation on metallic targets. Acknowledgments X.D. is supported through a Région Centre Val de Loire/INEL PhD fellowship. References [1]Penkov O.V. et al, J. Coat. Technol. Res., 12 (2), 225-23 (2015) [2]Laroussi M , IEEE Trans. Plas.Sci., 43 (3), 703-712 (2015) [3]Ries D. et al, J. Phys. D: Appl. Phys. 47 275401 (2014) [4]Robert E. et al, Phys. Plasmas, 22, 122,007 (2015) [5]Bourdon A. et al, accepted PSST (2016)
• Sq solar variation at Medea Observatory (Algeria), from 2008 to 2011
  
  • Anad F.
  • Amory-Mazaudier Christine
  • Hamoudi M.
  • Bourouis S.
  • Abtout A.
  • Yizengaw E.
  Advances in Space Research, Elsevier, 2016. This paper presents the regular variations of terrestrial magnetic field recorded by a new magnetic observatory Medea, Algeria (geographic latitude: 36.85 • N, geographic longitude: 2.93 • E, geomagnetic latitude: 27.98 • N, geomagnetic longitude: 77.7 • E) during 2008-2011. The diurnal and seasonal variations of the solar quiet (Sq) variations are analyzed. The results show differences in the diurnal pattern of the northward-component Sq variation (SqX) at different seasons. The seasonal variation of SqX is similar in different years. The diurnal pattern of SqX from July through September cannot be explained by an equivalent current system that is symmetric about the noon time sector. The observations indicate that the major axis of the elliptic current system is tilted towards the equator in the morning hours during those months. The diurnal pattern of SqY indicates southward currents in the morning and northward currents in the afternoon, except during February-March 2009 when there is apparently no southward current during the morning. For the other months, the observations indicate that the maximum northward current intensity in the afternoon tends to be greater than the maximum southward current intensity in the morning. This is because of the UT variation of the Sq current system. That is, the pattern and strength of the Sq current system are different when SqY is measured in the morning around 8 UT and in the afternoon around 14 UT. The amplitude of these extreme varies linearly with the solar cycle. For the SqY component, the changes in the morning maximum have an annual variation while that of the afternoon minimum has a semi-annual variation. These variations are attributed to seasonal variations in the ionospheric E-region conductivity and atmospheric tidal winds. The field-aligned currents can also contribute to the seasonal variation of SqY. However, the two-dimensional approach used in this article does not allow us to quantitatively determine their influences. (10.1016/j.asr.2016.06.029)
  DOI : 10.1016/j.asr.2016.06.029
• Inter-hourly variability of total electron content during the quiet condition over Nigeria, within the equatorial ionization anomaly region
  
  • Ayorinde T.T.
  • Rabiu A. B
  • Amory-Mazaudier Christine
  Journal of Atmospheric and Solar-Terrestrial Physics, Elsevier, 2016, 145, pp.21-33. The inter-hourly variability (IHV) of the Total Electron Content (TEC) over Nigeria during the quiet days (Ap<4) of the year 2013 was examined using ground-based GPS receivers installed at seven (7) different locations across Nigeria by the Nigerian Global Navigation Satellite Systems (GNSS) Reference Network (NIGNET) operated by the office of the surveyor general of Nigeria. Nigeria is a country that lies within equatorial ionospheric anomaly (EIA) region. The IHV was calculated by converting the observed hourly slant TEC (STEC) value into the hourly vertical TEC (VTEC) and the differencing (∆TEC) with its corresponding hourly value from the previous day. There is a clear variation which depicts the expected temporal variability. The IHV in TEC in all the stations ranges between 0-20 TECU (TEC Units). The seasonal variation of the IHV of TEC over Nigeria maximizes (5-20 TECU) during Equinoctial months and minimizes (1-10 TECU) during the Solstice months. The IHV of TEC in September equinox period is higher than that of March equinox. Minimum value of IHV (~7 TECU at equinoxes and ~5 TECU at Solstice) was recorded at the Office of Surveyor General of the Federation (OSGF) station and the maximum value (~12 TECU at equinoxes and ~16 TECU at Solstice) was recorded at the Birni Kebbi Federal Polytechnic (BKFP) station which may be due to the fact that BKFP at 0.72° dip latitude is closer to the dip equator. (10.1016/j.jastp.2016.04.005)
  DOI : 10.1016/j.jastp.2016.04.005
• Whistler mode waves and Hall fields detected by MMS during a dayside magnetopause crossing
  
  • Le Contel Olivier
  • Retinò Alessandro
  • Breuillard Hugo
  • Mirioni L.
  • Robert Patrick
  • Chasapis A.
  • Lavraud B.
  • Chust Thomas
  • Rezeau Laurence
  • Wilder D.
  • Graham D.
  • Argall M.
  • Gershman D.
  • Lindqvist P.-A.
  • Khotyaintsev Y.
  • Marklund G.
  • Ergun R. E.
  • Goodrich K. A.
  • Burch L.
  • Torbert R. B.
  • Needell J.
  • Chutter M.
  • Rau D.
  • Dors I.
  • Russell C. T.
  • Magnes W.
  • Strangeway R. J.
  • Bromund K. R.
  • Le H. K.
  • Plaschke F.
  • Fischer D.
  • Anderson B. J.
  • Le G.
  • Moore T. E.
  • Pollock C. J.
  • Giles L.
  • Dorelli J. C.
  • Avanov L.
  • Saito Y.
  Geophysical Research Letters, American Geophysical Union, 2016, 43 (12), pp.5943 - 5952. (10.1002/2016GL068968)
  DOI : 10.1002/2016GL068968
• Occurrence and impact of the spatial chaos of magnetic field lines
  
  • Firpo Marie-Christine
  , 2016. Magnetic field lines are spatially chaotic at a given time when the space Hamiltonian from which they derive is non integrable. As the minimal number of degrees of freedom required for the possible emergence of chaos is three, situations or models involving only two effective space dimensions cannot develop a spatial chaos of magnetic field lines. The question behind this presentation will be: What is the impact of the spatial chaos of magnetic field lines in hot magnetized plasmas? Two situations will be addressed: i) in tokamak sawteeth, that can be viewed as a laboratory prototype of magnetic reconnection, evidence will be given that magnetic field lines are spatially chaotic during the fast crash (reconnection) phase. ii) the spatial chaos of magnetic field lines will be shown to occur even for the low values of the magnetic perturbation &#948;B/B devoted to magnetic turbulence that have been experimentally measured in toroidal magnetic devices.
• Heating dynamics and control of energy distribution functions in capacitive discharges driven by tailored voltage waveforms
  
  • Schulze J.
  • Berger B.
  • Brandt S.
  • Koepke M.
  • Mussenbrock T.
  • Bruneau Bastien
  • Johnson Erik
  • Lafleur Trevor
  • Booth Jean-Paul
  • O'Connell D.
  • Gans T.
  • Korolov Ihor
  • Derzsi A.
  • Donkó Z.
  , 2016. The spatio-temporal electron impact excitation dynamics in capacitive RF discharges driven by tailored voltage waveforms in Ar and CF4 is investigated experimentally and by PIC simulations. In the experiment, the discharge is driven by up to three consecutive harmonics of 13.56 MHz with individually adjustable harmonics amplitudes and phases based on a novel RF supply system at different pressures (3 Pa - 200 Pa)1-3. The excitation dynamics is investigated by Phase Resolved Optical Emission Spectroscopy for different shapes of the driving voltage waveform (peaks/valleys/sawtooth). The DC self bias and the ion energy distribution function at the electrodes are measured. It is demonstrated that the mean ion energy can be controlled and the excitation dynamics can be tailored on a nanosecond timescale by adjusting the harmonics phases. In CF4, strongly different excitation dynamics are observed compared to Ar and understood based on the simulation results3,4. The plasma is divided spatially into two different halves of strongly different electronegativity for specific driving voltage waveforms. This asymmetry can be reversed by inverting the driving waveform. For Sawtooth waveforms, an electron heating mode transition occurs as the pressure is increased, leading to a reversed discharge asymmetry and sign of the DC self bias. References: 1. J. Franek et al., Rev. Sci. Instr., 86, 053504, (2015). 2. B. Berger et al., J. Appl. Phys., 118, 223302, (2015) 3. S. Brandt et al., Plasma Sourc. Sci. Technol., submitted 4. B. Bruneau et al., Plasma Sourc. Sci. Technol., 25, 01LT02 (2016)
• Response of the ionosphere to high-speed solar wind streams during 20-31August 2010
  
  • Zaourar Naima
  • Amory-Mazaudier Christine
  • Fleury Rolland
  , 2016. This study is the first attempt to analyze the latitudinal response to geomagnetic activity driven by high speed solar wind streams (HSSs) which emanates from a transition coronal hole. After the HSS hits the earths magnetic field on 24 August 2010, it was observed during four days. We study the magnetic and ionospheric disturbance using ground magnetic and GPS data at conjugate latitude stations, in various longitude sectors. The asymmetry between northern hemisphere (NH) and southern hemisphere (SH) magnetic and ionospheric disturbances are examined. The magnetic disturbances reveal that different large electrodynamics perturbations produced by HSSs event last during four days in the different latitude sectors. Our results show that hemispheric asymmetries in ground response patterns between the conjugate locations increase significantly to higher latitudes where the magnetosphere ionosphere are coupled in a more complex mechanism
• Ionospheric Disturbance Dynamo Associated to coronal hole during Geomagnetic Storm 1-5 August 2002
  
  • Fathy Ibrahim
  • Amory-Mazaudier Christine
  • Mahrous A. M.
  , 2016. In this paper we study the ionosphericmagnetic disturbance during a magnetic storm on 2 August 2002 associated to a coronal hole. The Earth was under the influence of a high speed solar wind and IMF was southward. We separate the magnetic disturbance associated to the ionospheric disturbance dynamo (Ddyn) from the magnetic disturbance associated to the prompt penetration of magnetospheric electric field (DP2).We used three Stations (AAE, GUA and HUA) from INTERMAGNET Magnetometers in the equatorial regions at different longitude sectors (African, Asian and American respectively). At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field (DP2). During the recovery phase of the storm, we observe the signature of ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti-Sq circulation on magnetic data in agreement with the Blanc and Richmonds model of ionospheric disturbance dynamo. The strongest effect is observed in the American sector
• Sun Earth Connections
  
  • Amory-Mazaudier Christine
  , 2016. Sun and Earth : Variabilities The Main Dynamos Solar dynamo Solar wind magnetosphere dynamo Ionospheric dynamo Earths dynamo The Electric current systems Magnetospheric current systems Ionospheric current systems Electrodynamic coupling between high and low latitudes PPEF : Prompt penetration of magnetospheric convection DDEF : Ionospheric disturbance dynamo
• Mixed double planar wire arrays on Michigan's Ltd generator
  
  • Kantsyrev Viktor L.
  • Safronova Alla S.
  • Shlyaptseva V. V.
  • Shreshta I.
  • Schmidt-Petersen M. T.
  • Stafford A.
  • Lorance M. Y.
  • Cooper M. C.
  • Steiner A. M.
  • Yager-Elorriaga D. A.
  • Jordan N. M.
  • Gilgenbach R. M.
  • Chuvatin Alexandre S.
  , 2016. Double Planar Wire Arrays (DPWA), which consist of two parallel rows of wires, have previously demonstrated high radiation efficiency, compact size, and usefulness for various applications in experiments on a University-scale high-impedance Z-pinch generator1. Recently, we successfully performed two experimental campaigns with PWAs on the University of Michigan's low-impedance MAIZE (Linear Transformer Driver (LTD)-driven generator, 0.1ohm, 0.5-1 MA, 100-180 ns) in collaboration with the UM team. The details and the analysis of the results of the first experimental campaign can be found in Ref. [2]. The second experimental campaign was focused on studying the implosion and radiative characteristics of DPWAs using a diagnostic set similar to the first campaign, including: filtered X-ray diodes, X-ray spectrographs and pinhole cameras, and a new four-frame shadowgraphy system with 2-ns, 532 nm frequency doubled Nd:YAG laser. Here we present the results of four, mixed-DPWA shots with the load consisting of one plane with 6 Al wires of 10¿¿m diameter and another plane of 6 stainless steel wires of 5.1 ¿¿m diameter. The rise-time of the current varies between 175 and 225 ns and shadowgraphy images cover the broad span of time from as early as 116 ns to as late as 304 ns. The shadowgraphy images show ablating and imploding mixed DPWAs that are very different from the images of uniform DPWAs. There is a clearly observed asymmetry of implosions of two wire array planes dependent on the material of each plane, (early time images in particular), captured also by X-ray pinhole images. WADM is used for the analysis of shadowgraphy images. X-ray spectra display both K-shell Al and L-shell Fe features analyzed with non-LTE modeling. Advantages of using mixed wire arrays are discussed. [1] V. L. Kantsyrev et al, Phys. Plasmas 15, 030704 (2008). [2] A.S. Safronova, V.L. Kantsyrev, M.E. Weller, V.V. Shlyaptseva, I.K. Shrestha, M. Lorance, M. Schmidt-Petersen, A. Stafford. M. Cooper, A.M. Steiner, D.A. Yager-Elorriaga, S.G. Patel, N.M. Jordan, R.M. Gilgenbach, A.S. Chuvatin, IEEE TPS, Special Issue on Plenary and Invited papers from ICOPS 2015, to be published, April 2016. * This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984. (10.1109/PLASMA.2016.7534391)
  DOI : 10.1109/PLASMA.2016.7534391
• ELECTRON POWER ABSORPTION DYNAMICS AND ION ENERGY DISTRIBUTIONS IN CAPACITIVE DISCHARGES DRIVEN BY CUSTOMIZED VOLTAGE WAVEFORMS IN ARGON AND CF<SUB>4</SUB>
  
  • Berger B.
  • Brandt S.
  • Franek J.
  • Shuengel E.
  • Koepke M.
  • Schulze J.
  • Mussenbrock T.
  • Bruneau Bastien
  • Johnson E.V.
  • Lafleur Trevor
  • Booth Jean-Paul
  • O'Connell D.
  • Gans T.
  • Korolov Ihor
  • Derzsi A.
  • Donkó Z.
  , 2016.
• Experimental study of counter propagating radiative shocks
  
  • Singh Raj Laxmi
  • Stehlé Chantal
  • Suzuki-Vidal Francisco
  • Kozlová Michaela
  • Larour Jean
  • Chaulagain Uddhab
  • Clayson Thomas
  • Nejdl Jaroslav
  • Krus Miroslav
  • Dostál Jan
  • Dudzak R.
  • Barroso Patrice
  • Acef Ouali
  • Cotelo M.
  • Rodriguez R.
  • Gil J. M.
  , 2016. S 04 Atelier général PNPS Radiative shocks are present at different stages of stellar evolution, for instance in the stellar infancy when matter is accreted from the stellar disk to the photosphere of the young star and is also ejected in the form of stellar jets, up to the final stages as supernovae and the interaction of their remnants with the interstellar medium. Such shocks are strongly influenced by the radiation through its coupling with hydrodynamics. Thus their topology and dynamics are quite complex. Generating such hypersonic shocks in the laboratory, with controlled conditions, is thus an adequate tool to study the influence of radiation and to compare them with numerical simulations. So far, such laboratory astrophysics studies are performed on large-scale laser facilities, addressing hydrodynamic radiative shocks, in Xenon with very high velocity (50 - 150 km/s) and moderate pressure (0.1 - 1 bar). These experiments advance the understanding of the effect of radiation on the different shock components (radiative precursors, shock collapse, walls heating etc.). In continuation of these laboratory experiments, we recently performed experiments at PALS laser facility to study a fairly new topic focusing on the interaction of two counter propagating shocks. The objective is to understand the influence of one radiative precursor onto another, to achieve higher temperature in the compressed medium. In the astrophysical context, aforementioned studies are relevant for instance, collision of supernovae remnants and more indirectly the interaction of supernovae remnants with dense molecular clouds and the impact of accretion flows on a stellar atmosphere. The experiments have been able to launch shocks with different shock speeds (~30-55 km/s and 10-25 km/s), in varying gases (Ar, Xe) and pressures (~0.1-0.3 bar). Optical interferometry allowed us to estimate several physical parameters such as shock speed and electron density in the precursor, XUV spectroscopy allowed to give information about the shock temperature. We will present some preliminary results together with numerical simulations.
• Kinetic simulations of collisionless magnetic reconnection
  
  • Aunai N.
  • Dargent Jérémy
  • Lavraud B.
  • Ciardi Andrea
  • Drouin M.
  • Smets Roch
  , 2016, pp.157-161. This paper focuses on magnetic reconnection and its role in magnetospheric physics, where collisions are inexistant. In this context, the presence of a very cold ion population of ionospheric origin is known to have an important contribution to the particle density at the magnetopause. However, besides this mass loading effect, consequences of their extremely low temperature, and therefore of their must smaller gyroscale, have not yet been addressed from a modeling viewpoint. This study presents two fully kinetic simulations with and without cold ions in the magnetosphere and highlights how their small Larmor radius can change signatures expected to be proxy of the X line in spacecraft measurements. In a second part, this paper addresses shortly the problem of the X line orientation in an asymmetric system. Using this time hybrid kinetic simulations, we show the X line aligned with the bisector of upstream magnetic field vectors results in faster reconnection rate. This have consequences regarding where reconnection at the magnetopause, although models here do not include large scale dynamics. We conclude with perspectives regarding future developments to address multi-scale magnetic reconnection dynamics at the magnetopause.
• 2D Particle-in-cell simulations of the electron-cyclotron instability and associated anomalous transport in Hall-effect thrusters
  
  • Croes Vivien
  • Lafleur Trevor
  • Bonaventura Z.
  • Bourdon Anne
  • Chabert Pascal
  , 2016. In this work we study the electron-cyclotron instability in Hall-effect thrusters (HETs) using a 2D electrostatic particle-in-cell (PIC) simulation. The simulation is configured with a Cartesian coordinate system where the magnetic field, *B0*, is aligned along the x-axis (*radial direction*, including absorbing walls), a constant applied electric field, *E0*, along the z-axis (perpendicular to the simulation plane), and the ExB direction along the y-axis (*Theta direction*, which uses periodic boundaries). Although electron transport can be well described by classical electron-neutral collision theory for low plasma densities, at sufficiently high densities (typical of those measured in HETs), a strong instability can be observed that enhances the electron mobility, even in the absence of electron-neutral collisions. The instatbility generates high frequency (of the order of MHz) and short wavelength (of the order of mm) fluctuations in both the electric field and charged particle densities, and we investigate the correlation between these fluctuations and the role they play in anomalous electron transport; work which compliments previous 1D simulations. Wall effects on the instability are studied here in the case where the plasma is self-consistently heated by the instability. Since the instability does not reach saturation in an infinitely long 2D system, saturation is achieved through the implementation of a finite axial length that models convection in the *E0* direction (i.e. perpendicular to the simulation plane).
• Dynamique prédateur proie dans les plasmas de fusion magnétique
  
  • Morel Pierre
  • Kobayashi Sumire
  • Donnel Peter
  • Berionni Vincent
  • Honoré Cyrille
  • Pisarev V.
  • Hennequin Pascale
  • Gürcan Özgür D.
  , 2016.
• Comparaisons simulation expérience : application d'un diagnostic synthétique de Rétro-Diffusion Doppler au plasma Tore Supra #45511 simulé par le code gyrocinétique GYSELA
  
  • Morel Pierre
  • Gassama Banda
  • Leybros Robin
  • Dif-Pradalier Guilhem
  • Hennequin Pascale
  • Vermare Laure
  • Gürcan Özgür D.
  • Grandgirard V.
  • Latu G.
  • Sarazin Y.
  • Ghendrih Ph.
  • Garbet X.
  , 2016.