Publications

2010

• Multi-Scale Observations of Magnetic Reconnection at the Subsolar Magnetopause
  
  • Retinò Alessandro
  • Vaivads A.
  • Khotyaintsev Y. V.
  • Nakamura R.
  • Sahraoui Fouad
  • Baumjohann W.
  • Fujimoto M.
  , 2010, pp.B1878.
• Evidence of ion Foreshock in Full-particle 2-D Simulations of a Supercritical Curved Collisionless Shock
  
  • Stienlet J.
  • Savoini Philippe
  • Lembège Bertrand
  , 2010. Ion foreshock filled in with energized particles backstreaming from a curved shock is analyzed with the help of a 2-D full particle simulations (PIC). Full curvature and time of flight effects, and both electrons and ions dynamics are fully described by a self consistent approach. The analysis is restricted within a quasi-perpendidular shock with 90° ≥ θBn 45°, where θBn is the angle between the shock normal and the upstream magnetostatic field. It is for the first time to our knowledge, that the formation of both electron and ion foreshock is evidenced within a full self-consistent approach. Herein, we focuss only on the ion foreshock and more particularly, on the different populations of backstreaming ions observed in the upstream region. Present preliminary results show that, in agreement with experimental data, two distinct ion populations are observed : (i) the field-aligned beams (FAB) which consist of ions collimated along the IMF and (ii) the gyro-phase bunch ions (hereafter named GPB) characterized by a non-vanishing perpendicular bulk velocity and a global gyration around the magnetic field. More precisely, (a) the FAB population is observed at the edge of the foreshock and near the shock front, while GPB population is observed deeper in the foreshock and further from the shock shock; (b) both backstreaming populations can be identified versus their individual interaction time τ int with the shock front. In particular, GBP population shows a short interaction time (τ int ≈ 1-2 τci) while the FAB population evidences a larger time range (from 1 τci to 10 τci); (iv) FAB population may have different origins, and is composed with ions coming from the shock front itself but also from "leaked" ions (issued from the downstream region)
• Properties of Equatorial Noise and its Connection with Disturbances in the Solar Wind Using Data from the Cluster Mission
  
  • Hrbackova Z.
  • Santolík O.
  • Pickett J. S.
  • Gurnett D. A.
  • Cornilleau-Wehrlin Nicole
  , 2010, 11, pp.1718. The four spacecraft of the Cluster mission collected a unique data set between 2002 and 2009. These data are unique not only because of their quantity but mainly because the spacecraft changed their orbits during their eight-year operational phase and therefore we have data from a large area around the Earth. We focus our analysis on observations of equatorial noise (EN) which is an intense wave emission generated by unstable ion distributions. It occurs in the inner magnetosphere and propagates close to the geomagnetic equator at frequencies between the local proton cyclotron and local lower hybrid frequencies. We use onboard analyzed data from the STAFF-SA instrument and high-resolution measurements of the WBD instrument. Furthermore we investigate connection of events in the solar wind with subsequent changes of the properties of EN such as location of the source region and the intensity of magnetic and electric fields.
• Overview of Emic Triggered Chorus Emissions in Cluster Data
  
  • Grison B.
  • Pickett J. S.
  • Omura Y.
  • Santolík O.
  • Engebretson M. J.
  • Dandouras I. S.
  • Masson A.
  • Décréau Pierrette
  • Adrian M. L.
  • Cornilleau-Wehrlin Nicole
  , 2010, 21, pp.02. Electromagnetic ion cyclotron (EMIC) triggered emissions have been recently observed onboard the Cluster spacecraft close to the plasmapause in the equatorial region of the magnetosphere (Pickett et al., 2010). The nonlinear mechanism of the wave amplification is the same as for the well known whistler-mode chorus emissions (Omura et al., 2010). The EMIC triggered emissions appear as risers: electromagnetic structures that have a positive frequency drift with time. They can thus be considered as the EMIC analogue of rising frequency whistler-mode chorus emissions. In addition, they propagate away from the magnetic equator. These EMIC risers are not common in Cluster data. We present an overview of the properties of all the identified cases. Risers can be sorted out in two groups: in the first one the starting frequency of EMIC emissions is close to one half of the local proton gyrofrequency and the risers have a clear left-hand polarization. In the second group the risers have an opposite polarization with a starting frequency close to one half of the He gyrofrequency. Most of the cases have been detected close to 22 MLT (magnetic local time). This dependence will be investigated to determine if it is linked to the orbit effects or if there is a physical cause.
• Chorus emissions measured by Cluster spacecraft at different L-shells
  
  • Macusova E.
  • Santolík O.
  • Pickett J. S.
  • Gurnett D. A.
  • Cornilleau-Wehrlin Nicole
  , 2010, 14, pp.07. Whistler mode chorus emissions are intense magnetospheric waves composed of discrete wave packets with variable frequencies that sometimes change into shapeless hiss. Chorus probably accelerates electrons in the outer radiation belts to energies greater than 1 MeV through wave-particle interactions. Chorus wave packets usually consist of rising tones, but falling tones and more complicated structures have also been observed. Measurements provided by Wideband and STAFF-SA instruments onboard Cluster spacecraft give us information about the source region, propagation and spectral structures. Previous measurements of Cluster spacecraft show that most of the intense chorus can be found at L-shells between 4 and 5, but recent studies based on Themis and Double Star TC-1 observations provide evidence of intense emissions at much larger L-shells. Owing to a recent change of the Cluster orbit we can observed chorus over a larger range of radial distances. We observe banded chorus with a gap localized at the one half of electron cyclotron frequency close to the geomagnetic equator in entire L-shell interval between 4 and 10. We show the influence of the L-shell on spectral shapes and intensity of chorus emissions.
• Contribution of alpha particles to the interaction of the Solar wind with Mars
  
  • Chanteur Gérard
  • Modolo Ronan
  • Dubinin E.
  • Richer Emilie
  , 2010, 41, pp.abstract id.SM41B-1864. When the solar wind interacts with a small obstacle like Mars, protons and alpha particles behave quite differently at scales of the order of the size of the obstacle. Although alpha particles can contribute up to about 20% to the solar wind momentum and energy flux their contribution to the interaction has not yet been investigated. Meanwhile recent observations by Mars Express indicate that penetration boundaries could be different for alphas and protons. We use both test particle simulations and global hybrid simulations including self-consistently solar wind alpha particles to investigate their behaviour at the bow shock and evaluate their contribution to the transfer of momentum and energy to the Martian induced magnetosphere.
• Titan's induced magnetosphere from plasma wave and magnetometer observations
  
  • Modolo Ronan
  • Bertucci C.
  • Canu Patrick
  • Piberne Rodrigue
  • Edberg N. J.
  • Kurth W. S.
  • Gurnett D. A.
  • Dougherty M. K.
  , 2010, 41, pp.1871. Plasma wave observations are combined with the magnetometer measurements to investigate Titan's induced magnetosphere. Electric field emissions close to Titan are identified as upper hybrid resonance emissions and therefore can provide a density estimate of Titan's cold plasma. Some of Titan's flybys show a very strong asymmetry between two flybys performed in similar geographical conditions. Good examples are the Ta and Tb flybys, which have a similar trajectory in the Titan interaction coordinate system and even though they have the same illumination conditions, the density profiles present major differences. Thermal plasma observations are displayed for the nominal mission flybys in a draping coordinate system where the average ambient magnetic field, the ideal flow direction and the motional electric field correspond to the main axis of the system. This coordinate system organizes the cold plasma observations and provides information on the envelop of the induced magnetosphere and its global asymmetry.
• Magnetic compressibility and Isotropic Scale-Invariant Dissipation of Solar Wind Turbulence
  
  • Kiyani K. H.
  • Chapman S. C.
  • Khotyaintsev Y. V.
  • Hnat B.
  • Sahraoui Fouad
  , 2010, pp.B1801.
• RF waveform tailoring to control film morphology during nanocrystalline silicon PECVD
  
  • Booth Jean-Paul
  • Johnson E.V.
  • Verbeke T.
  • Vanel J-C
  , 2010.
• Turbulent Generation of Poloidal Rotation
  
  • Gürcan Özgür D.
  , 2010.
• Sheath and electron density dynamics in the normal and self-pulsing regime of a micro hollow cathode discharge in argon gas
  
  • Lazzaroni Claudia
  • Chabert Pascal
  • Rousseau A.
  • Sadeghi N.
  The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2010, 60, pp.555-563. A microplasma is generated in the microhole (400 μm diameter) of a molybdenum-alumina-molybdenum sandwich (MHCD type) at medium pressure (30-200 Torr) in pure argon. Imaging and emission spectroscopy have been used to study the sheath and electron density dynamics during the stationary normal regime and the self-pulsing regime. Firstly, the evolution of the microdischarge structure is studied by recording the emission intensity of the Ar (5 p[3/2]1-4 s[3/2]1) line at 427.217 nm, and Ar+ (4 p' 2P3/2-4 s' 2D_{5/2}) line at 427.752 nm. The maximum of the Ar+ line is located in the vicinity of the sheath-plasma edge. In both regimes, the experimental observations are consistent with the position of the sheath edge calculated with an ionizing sheath model. Secondly, the electron density is recorded by monitoring the Stark broadening of the H_β-line. In the self-pulsing regime at 150 Torr, the electron density reaches its maximum value of 4 × 1015 cm-3, a few tens of ns later than the discharge current maximum. The electron density then decays with a characteristic decay time of about 2 μs, while the discharge current vanishes twice faster. The electron density in the steady-state regime is two orders of magnitude lower, at about 6-8 × 1013 cm-3. (10.1140/EPJD/E2010-00259-4)
  DOI : 10.1140/EPJD/E2010-00259-4
• Lien entre cisaillement magnétique et résonances dans des dispositifs de fusion par confinement magnétique
  
  • Firpo Marie-Christine
  , 2010.
• The Negative Ion Mean Free Path And Its Possible Implications
  
  • Bacal M.
  • Mcadams R.
  • Lepetit Bruno
  , 2011, 1390, pp.13-21. The knowledge of the mean free path (mfp) of the negative ions is important for many purposes, e.g. evaluating the distance from which the ions can be extracted, or understanding the significance of experimental results. We will present the mfp for similar conditions in volume and caesium seeded sources. It appears that the mfp is longer in the caesium seeded source than in the volume source under identical conditions.
• Numerical Analysis of the Extraction of Negative Hydrogen Ion in the Extraction Region of Negative Ion Source
  
  • Wada S.
  • Kuppel S.
  • Fukuyama Y.
  • Miyamoto K.
  • Hatayama A.
  • Bacal M.
  , 2011, 1390, pp.58-67. The optimization of H− extraction from the source is one of the most important issues for developing negative ion sources. The following effects on the total extracted H− current IH− are systematically studied with the 2D3V PIC (Particle in Cell) modeling in a H− volume production source: 1) width of the extraction slit and 2) extraction grid voltage. The PIC modeling results make clear the dependence of IH− on these important parameters. The results also give useful physics understanding about the processes leading to the extraction of H− ions from the source and its optimization.
• Electronegative plasmas and Ion-Ion plasmas applied to the semiconductor industry, fusion and space propulsion
  
  • Aanesland Ane
  , 2010.
• Control of plasma potential in an ion-ion plasma for negative ion acceleration
  
  • Popelier Lara
  • Aanesland Ane
  • Chabert Pascal
  , 2010.
• First Analysis of Radiative Properties of Moderate-atomic-number Planar Wire Arrays on Zebra at UNR at Higher Current of 1.7 MA
  
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Esaulov A. A.
  • Astanovitskiy A. L.
  • Legalloudec B.
  • Presura Radu
  • Shrestha Ishor
  • Williamson Kenneth M.
  • Shlyaptseva V. V.
  • Weller Michael E.
  • Ouart N. D.
  • Keim S. F.
  • Osborne Glenn C.
  • Chuvatin Alexandre S.
  • Coverdale C.
  , 2010, 55 (15), pp.PO5.00005.
• Innovative Approach for Enhancing Shaped X-ray Production in Z-pinches
  
  • Kantsyrev Viktor L.
  • Safronova Alla S.
  • Esaulov A. A.
  • Kindel J. M.
  • Williamson Kenneth M.
  • Shrestha Ishor
  • Osborne G.C.
  • Weller Michael E.
  • Ouart N. D.
  • Shlyaptseva V. V.
  • Chuvatin Alexandre S.
  • Rudakov Leonid I.
  • Velikovich A. L.
  , 2010, 55 (15), pp.PO5.00006.
• Physique et physicochimie des Plasmas excites par radio-frequence
  
  • Booth Jean-Paul
  , 2010.
• Magnetospheric charged particle observations and modeling at Mercury
  
  • Delcourt Dominique
  , 2010.
• Experimental study and simulation of a micro-discharge with limited cathode area
  
  • Dufour Thierry
  • J. Overzet Lawrence
  • Dussart Remi
  • Pitchford L. C.
  • Sadeghi N
  • Lefaucheux P
  • Kulsreshath M
  • Ranson P
  The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2010, 60, pp.565-574. We report in this paper simulation results and experimental measurements to characterize a micro-discharge generated in a single micro cavity device operating in helium. By spatially limiting the cathode surface area using a dielectric layer, we demonstrate the ability of the micro-discharge to work in a steady-state abnormal glow regime. The physical properties of this regime are discussed. (10.1140/epjd/e2010-00273-6)
  DOI : 10.1140/epjd/e2010-00273-6
• Integrated micro-plasmas in silicon operating in helium
  
  • Dussart Remi
  • J. Overzet Lawrence
  • Lefaucheux Philippe
  • Dufour Thierry
  • Kulsreshath Mukesh
  • Mandra Monali
  • Tillocher Thomas
  • Aubry Olivier
  • Dozias Sébastien
  • Ranson Pierre
  • Lee Jeong Bong
  • Goeckner Matthew
  The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2010, 60, pp.601-608. Microplasma arrays operating in helium in a DC regime have been produced in silicon microre-actors. Cathode boundary layer (CBL) type microdevices were elaborated using clean room facilities and semiconductor processing techniques. Ignition of the micro-discharge arrays having either 50 or 100 µm diameter cavities was studied. Two different structures (isotropically etched or anisotropically etched cavity) and various conditions (the two different voltage polarities, pressures etc.) were investigated. 100 microdis-charges of 50 µm diameter could be ignited in parallel at 1000 torr. At high current, some parasitic and transient sparks appeared at the edge of the sample. When the polarization was reversed (cathode side corresponding the opened electrode), more current was needed to light all the microdischarges. A thermally affected zone around the hole on the anode side was obtained after operation. (10.1140/epjd/e2010-00272-7)
  DOI : 10.1140/epjd/e2010-00272-7
• RF impedance measurements of DC atmospheric micro-discharges
  
  • J. Overzet Lawrence
  • Jung D.
  • Mandra Monali
  • Goeckner Matthew
  • Dufour Thierry
  • Dussart Remi
  • Lefaucheux Philippe
  The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2010, 60, pp.449-454. The available diagnostics for atmospheric micro-plasmas remain limited and relatively complex to implement; so we present a radio-frequency technique for diagnosing a key parameter here. The technique allows one to estimate the dependencies of the electron density by measuring the RF-impedance of the micro-plasma and analyzing it with an appropriate equivalent circuit. This technique is inexpensive, can be used in real time and gives reasonable results for argon and helium DC micro-plasmas in holes over a wide pressure range. The electron density increases linearly with current in the expected range consistent with normal glow discharge behavior. (10.1140/epjd/e2010-00274-5)
  DOI : 10.1140/epjd/e2010-00274-5
• Nanocrystalline silicon film growth morphology control through RF waveform tailoring
  
  • Booth Jean-Paul
  • Johnson E.V.
  • Verbeke T.
  • Vanel J-C
  , 2010.
• Inductive plasmas in Cl<SUB>2</SUB>/Ar :Comparison of hybrid model results with experimental measurements
  
  • Booth Jean-Paul
  • Despiau-Pujo Emilie
  • Chabert Pascal
  • Sarot Rodolphe
  , 2010.