Publications

2014

• Mars-Solar Wind Interaction: Coupling Between Hybrid, Ionospheric, Thermospheric and Exospheric Models
  
  • Leblanc François
  • Chaufray Jean-Yves
  • Modolo Ronan
  • Hess Sebastien
  • Yagi M.
  • Mancini M.
  • Forget François
  • Gonzalez-Galindo Francisco
  • Lorenzato L.
  • Mazelle Christian
  • Chanteur Gérard
  , 2014. The solar wind interaction with the Martian neutral envi- ronment is investigated by means of three dimensional hybrid magnetospheric simulations. In such formal- ism, ions have a kinetic description while electrons are treated as an inertialess fluid, ensuring the neutrality of the plasma and contributing to currents and pressure terms. This model has been successfully used to de- scribe the near ionized environment of Mars
• Experimental and numerical study of fast gas heating and O atom production in a capillary nanosecond discharge
  
  • Klochko A.V.
  • Salmon A.
  • Lemainque J.
  • Popov N.A.
  • Booth Jean-Paul
  • Xiong Z.
  • Kushner M.J.
  • Starikovskaia Svetlana
  , 2014, pp.2014-1030.
• Ignition of CH4:O2:Ar and n-C4H10:O2:Ar(N2) mixtures with initial temperatures between 650-950 K by a surface pulsed discharge
  
  • Stepanyan S.A.
  • Boumehdi M.A.
  • Vanhove G.
  • Desgroux Pascale
  • Starikovskaia Svetlana
  • Popov N.A.
  , 2014. (10.2514/6.2014-0665)
  DOI : 10.2514/6.2014-0665
• Adsorption, desorption and reactivity of O and N atoms on SiO2 surface
  
  • Rousseau Antoine
  , 2014.
• New ferromagnetic core shapes for induction sensors
  
  • Coillot Christophe
  • Moutoussamy Joël
  • Boda Mathieu
  • Leroy Paul
  Journal of Sensors and Sensor Systems, Copernicus Publ, 2014, pp.1-8. Induction sensors are used in a wide range of scientific and industrial applications. One way to improve these is rigorous modelling of the sensor combined with a low voltage and current input noise preamplifier aiming to optimize the whole induction magnetometer. In this paper, we explore another way, which consists in the use of original ferromagnetic core shapes of induction sensors, which bring substantial improvements. These new configurations are the cubic, orthogonal and coiled-core induction sensors. For each of them we give modelling elements and discuss their benefits and drawbacks with respect to a given noise-equivalent magnetic induction goal. Our discussion is supported by experimental results for the cubic and orthogonal configurations, while the coiled-core configuration remains open to experimental validation. The transposition of these induction sensor configurations to other magnetic sensors (fluxgate and giant magneto-impedance) is an exciting prospect of this work. (10.5194/jsss-3-1-2014)
  DOI : 10.5194/jsss-3-1-2014
• Multi Water Bag modelling of drift kinetic electrons and ions plasmas
  
  • Morel Pierre
  • Dreydemy Ghiro Florent
  • Berionni Vincent
  • Gürcan Özgür D.
  , 2014.
• Spatial Propagation of Turbulence and Formation of Mesoscopic Structures in Plasma Turbulence
  
  • Dif-Pradalier Guilhem
  • Ghendrih Ph.
  • Diamond P.H.
  • Garbet X.
  • Grandgirard V.
  • Norscini C.
  • Palermo F.
  • Sarazin Y.
  • Abiteboul J.
  • Dong Yue
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Morel Pierre
  • Vermare Laure
  • Kosuga Y.
  , 2014.
• Radiation sources with planar wire arrays and planar foils for inertial confinement fusion and high energy density physics research
  
  • Kantsyrev Viktor L.
  • Chuvatin Alexandre S.
  • Safronova Alla S.
  • Rudakov Leonid I.
  • Esaulov A. A.
  • Velikovich A. L.
  • Shrestha Ishor
  • Astanovitsky A.
  • Osborne Glenn C.
  • Shlyaptseva V. V.
  • Weller Michael E.
  • Keim S.
  • Stafford A.
  • Cooper M. C.
  Physics of Plasmas, American Institute of Physics, 2014, 21 (03), pp.031204. This article reports on the joint success of two independent lines of research, each of them being a multi-year international effort. One of these is the development of innovative sources, such as planar wire arrays (PWAs). PWAs turned out to be a prolific radiator, which act mainly as a resistor, even though the physical mechanism of efficient magnetic energy conversion into radiation still remains unclear. We review the results of our extensive studies of PWAs. We also report the new results of the experimental comparison PWAs with planar foil liners (another promising alternative to wire array loads at multi-mega-ampere generators). Pioneered at UNR, the PWA Z-pinch loads have later been tested at the Sandia National Laboratories (SNL) on the Saturn generator, on GIT-12 machine in Russia, and on the QiangGuang-1 generator in China, always successfully. Another of these is the drastic improvement in energy efficiency of pulsed-power systems, which started in early 1980s with Zucker's experiments at Naval Research Laboratory (NRL). Successful continuation of this approach was the Load Current Multiplier (LCM) proposed by Chuvatin in collaboration with Rudakov and Weber from NRL. The 100 ns LCM was integrated into the Zebra generator, which almost doubled the plasma load current, from 0.9 to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum radiation source for ICF, as jointly proposed by SNL and UNR [Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The first successful proof-of-the-principle experimental implementation of new hohlraum concept at university-scale generator Zebra/LCM is demonstrated. A numerical simulation capability with VisRaD code (from PRISM Co.) established at UNR allowed for the study of hohlraum coupling physics and provides the possibility of optimization of a new hohlraum. Future studies are discussed. (10.1063/1.4865367)
  DOI : 10.1063/1.4865367
• Turbulence elasticity-A new mechanism for transport barrier dynamics
  
  • Guo Z. B.
  • Diamond P.H.
  • Kosuga Y.
  • Gürcan Özgür D.
  Physics of Plasmas, American Institute of Physics, 2014, 21 (9). We present a new, unified model of transport barrier formation in ``elastic'' drift wave-zonal flow (DW-ZF) turbulence. A new physical quantity-the delay time (i.e., the mixing time for the DW turbulence)-is demonstrated to parameterize each stage of the transport barrier formation. Quantitative predictions for the onset of limit-cycle-oscillation (LCO) among DW and ZF intensities (also denoted as I-mode) and I-mode to high-confinement mode (H-mode) transition are also given. The LCO occurs when the ZF shearing rate (vertical bar < u >(ZF)'vertical bar) enters the regime Delta omega(k) < vertical bar < V >(ZF)'vertical bar < tau(-1)(cr), where Delta omega(k) is the local turbulence decorrelation rate and tau(cr) is the threshold delay time. In the basic predator-prey feedback system, tau(cr) is also derived. The I-H transition occurs when vertical bar < V >(ExB)'vertical bar > tau(-1)(cr), where the mean E x B shear flow driven by ion pressure ``locks'' the DW-ZF system to the H-mode by reducing the delay time below the threshold value. (C) 2014 AIP Publishing LLC. (10.1063/1.4894695)
  DOI : 10.1063/1.4894695
• Complete multi-field characterization of the geodesic acoustic mode in the TCV tokamak
  
  • de Meijere C. A.
  • Coda S.
  • Huang Z.
  • Vermare Laure
  • Vernay T.
  • Vuille V.
  • Brunner Stephan
  • Dominski J.
  • Hennequin Pascale
  • Kraemer-Flecken A.
  • Merlo G.
  • Porte L.
  • Villard Laurent
  Plasma Physics and Controlled Fusion, IOP Publishing, 2014, 56 (7), pp.072001. The geodesic acoustic mode (GAM) is a coherently oscillating zonal flow that may regulate turbulence in toroidal plasmas. Uniquely, the complete poloidal and toroidal structure of the magnetic component of the turbulence-driven GAM has been mapped in the TCV tokamak. Radially localized measurements of the fluctuating density, ECE radiative temperature and poloidal flow show that the GAM is a fully coherent, radially propagating wave. These observations are consistent with electrostatic, gyrokinetic simulations. (10.1088/0741-3335/56/7/072001)
  DOI : 10.1088/0741-3335/56/7/072001
• The FIELDS Instrument Suite on MMS: Scientific Objectives, Measurements, and Data Products
  
  • Torbert R. B.
  • Russell C. T.
  • Magnes W.
  • Ergun R. E.
  • Lindqvist P.-A.
  • Le Contel Olivier
  • Vaith H.
  • Macri J.
  • Myers S.
  • Rau D.
  • Needell J.
  • King B.
  • Granoff M.
  • Chutter M.
  • Dors I.
  • Olsson G.
  • Khotyaintsev Y. V.
  • Eriksson A.
  • Kletzing C. A.
  • Bounds S.
  • Anderson B.
  • Baumjohann W.
  • Steller M.
  • Bromund K.
  • Le G.
  • Nakamura R.
  • Strangeway R. J.
  • Leinweber H. K.
  • Tucker S.
  • Westfall J.
  • Fischer D.
  • Plaschke F.
  • Porter J.
  • Lappalainen K.
  Space Science Reviews, Springer Verlag, 2014, pp.1-31. Not Available (10.1007/s11214-014-0109-8)
  DOI : 10.1007/s11214-014-0109-8
• Circulation of Heavy Ions and Their Dynamical Effects in the Magnetosphere: Recent Observations and Models
  
  • Kronberg E. A.
  • Ashour-Abdalla M.
  • Dandouras I.
  • Delcourt Dominique C.
  • Grigorenko E. E.
  • Kistler L. M.
  • Kuzichev I. V.
  • Liao J.
  • Maggiolo R.
  • Malova H. V.
  • Orlova K. G.
  • Peroomian V.
  • Shklyar D. R.
  • Shprits Y. Y.
  • Welling D. T.
  • Zelenyi L. M.
  Space Science Reviews, Springer Verlag, 2014, 184 (1-4), pp.173-235. Knowledge of the ion composition in the near-Earths magnetosphere and plasma sheet is essential for the understanding of magnetospheric processes and instabilities. The presence of heavy ions of ionospheric origin in the magnetosphere, in particular oxygen (O ), influences the plasma sheet bulk properties, current sheet (CS) thickness and its structure. It affects reconnection rates and the formation of Kelvin-Helmholtz instabilities. This has profound consequences for the global magnetospheric dynamics, including geomagnetic storms and substorm-like events. The formation and demise of the ring current and the radiation belts are also dependent on the presence of heavy ions. In this review we cover recent advances in observations and models of the circulation of heavy ions in the magnetosphere, considering sources, transport, acceleration, bulk properties, and the influence on the magnetospheric dynamics. We identify important open questions and promising avenues for future research. (10.1007/s11214-014-0104-0)
  DOI : 10.1007/s11214-014-0104-0
• On the origin of falling-tone chorus elements in Earth's inner magnetosphere
  
  • Breuillard H
  • Agapitov O
  • Artemyev A
  • Krasnoselskikh V
  • Le Contel Olivier
  • Cully C. M.
  • Angelopoulos V
  • Zaliznyak Y
  • Rolland G
  Annales Geophysicae, European Geosciences Union, 2014, 32, pp.1477-1485. Generation of extremely/very low frequency (ELF/VLF) chorus waves in Earth's inner magnetosphere has received increased attention recently because of their significance for radiation belt dynamics. Though past theoretical and numerical models have demonstrated how rising-tone chorus elements are produced, falling-tone chorus element generation has yet to be explained. Our new model proposes that weak-amplitude falling-tone chorus elements can be generated by magnetospheric reflection of rising-tone elements. Using ray tracing in a realistic plasma model of the inner magnetosphere, we demonstrate that rising-tone elements originating at the magnetic equator propagate to higher latitudes. Upon reflection there, they propagate to lower L-shells and turn into oblique falling tones of reduced power, frequency, and bandwidth relative to their progenitor rising tones. Our results are in good agreement with comprehensive statistical studies of such waves, notably using magnetic field measurements from THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft. Thus, we conclude that the proposed mechanism can be responsible for the generation of weak-amplitude falling-tone chorus emissions. (10.5194/angeo-32-1477-2014)
  DOI : 10.5194/angeo-32-1477-2014
• Ion flux asymmetry in radiofrequency capacitively-coupled plasmas excited by sawtooth-like waveforms
  
  • Bruneau Bastien
  • Novikova T.
  • Lafleur Trevor
  • Booth Jean-Paul
  • Johnson E.V.
  Plasma Sources Science and Technology, IOP Publishing, 2014, 23 (6), pp.065010. Using particle-in-cell simulations, we predict that it is possible to obtain a significant difference between the ion flux to the powered electrode and that to the grounded electrode?with about 50% higher ion flux on one electrode?in a geometrically symmetric, radiofrequency capacitively-coupled plasma reactor by applying a non-sinusoidal, ?Tailored? voltage waveform. This sawtooth-like waveform presents different rising and falling slopes over one cycle. We show that this effect is due to differing plasma sheath motion in front of each electrode, which induces a higher ionization rate in front of the electrode which has the fastest positive rising voltage. Together with the higher ion flux comes a lower voltage drop across the sheath, and therefore a reduced maximum ion bombardment energy; a result in contrast to typical process control mechanisms. (10.1088/0963-0252/23/6/065010)
  DOI : 10.1088/0963-0252/23/6/065010
• Plasma-assisted ignition and combustion: nanosecond discharges and development of kinetic mechanisms
  
  • Starikovskaia Svetlana
  Journal of Physics D: Applied Physics, IOP Publishing, 2014, 47 (35), pp.353001 (34pp). This review covers the results obtained in the period 20062014 in the field of plasma-assisted combustion, and in particular the results on ignition and combustion triggered or sustained by pulsed nanosecond discharges in different geometries. Some benefits of pulsed high voltage discharges for kinetic study and for applications are demonstrated. The necessity of and the possibility of building a particular kinetic mechanism of plasma-assisted ignition and combustion are discussed. The most sensitive regions of parameters for plasmacombustion kinetic mechanisms are selected. A map of the pressure and temperature parameters (PT diagram) is suggested, to unify the available data on ignition delay times, ignition lengths and densities of intermediate species reported by different authors. (10.1088/0022-3727/47/35/353001)
  DOI : 10.1088/0022-3727/47/35/353001
• What is the size of a floating sheath?
  
  • Chabert Pascal
  Plasma Sources Science and Technology, IOP Publishing, 2014, 23 (6), pp.065042. The size of the positive space charge sheath that forms in front of an object immersed in a plasma and not dc-connected to ground with an external circuit (a floating sheath) is calculated numerically. If the sheath edge is defined as the position at which the ion fluid speed equals the Bohm speed, it is shown that the sheath size varies significantly with the discharge parameters, typically from s float &#8776; 7 &#955; Des to s float &#8776; 14 &#955; Des , where s float is the floating sheath size and &#955; Des is the Debye length at the sheath edge. However, if the sheath edge is defined as a significant departure from quasi-neutrality, then the floating sheath size is almost independent of the discharge parameters and may be approximated by s float &#8776; 5 &#955; Des . (10.1088/0963-0252/23/6/065042)
  DOI : 10.1088/0963-0252/23/6/065042
• Evolution of Turbulence in the Expanding Solar Wind, a Numerical Study
  
  • Dong Yue
  • Verdini Andrea
  • Grappin Roland
  The Astrophysical Journal, American Astronomical Society, 2014, 793, pp.118. We study the evolution of turbulence in the solar wind by solving numerically the full three-dimensional (3D) magnetohydrodynamic (MHD) equations embedded in a radial mean wind. The corresponding equations (expanding box model or EBM) have been considered earlier but never integrated in 3D simulations. Here, we follow the development of turbulence from 0.2 AU up to about 1.5 AU. Starting with isotropic spectra scaling as k <SUP>-1</SUP>, we observe a steepening toward a k <SUP>-5/3</SUP> scaling in the middle of the wave number range and formation of spectral anisotropies. The advection of a plasma volume by the expanding solar wind causes a non-trivial stretching of the volume in directions transverse to radial and the selective decay of the components of velocity and magnetic fluctuations. These two effects combine to yield the following results. (1) Spectral anisotropy: gyrotropy is broken, and the radial wave vectors have most of the power. (2) Coherent structures: radial streams emerge that resemble the observed microjets. (3) Energy spectra per component: they show an ordering in good agreement with the one observed in the solar wind at 1 AU. The latter point includes a global dominance of the magnetic energy over kinetic energy in the inertial and f <SUP>-1</SUP> range and a dominance of the perpendicular-to-the-radial components over the radial components in the inertial range. We conclude that many of the above properties are the result of evolution during transport in the heliosphere, and not just the remnant of the initial turbulence close to the Sun. (10.1088/0004-637X/793/2/118)
  DOI : 10.1088/0004-637X/793/2/118
• The influence of the geometry and electrical characteristics on the formation of the atmospheric pressure plasma jet
  
  • Sobota Ana
  • Guaitella Olivier
  • Rousseau Antoine
  Plasma Sources Science and Technology, IOP Publishing, 2014, 23, pp.025016. An extensive electrical study was performed on a coaxial geometry atmospheric pressure plasma jet source in helium, driven by 30 kHz sine voltage. Two modes of operation were observed, a highly reproducible low-power mode that features the emission of one plasma bullet per voltage period and an erratic high-power mode in which micro-discharges appear around the grounded electrode. The minimum of power transfer efficiency corresponds to the transition between the two modes. Effective capacitance was identified as a varying property influenced by the discharge and the dissipated power. The charge carried by plasma bullets was found to be a small fraction of charge produced in the source irrespective of input power and configuration of the grounded electrode. The biggest part of the produced charge stays localized in the plasma source and below the grounded electrode, in the range 1.23.3 nC for ground length of 38 mm. (10.1088/0963-0252/23/2/025016)
  DOI : 10.1088/0963-0252/23/2/025016
• BV technique for investigating 1-D interfaces
  
  • Dorville Nicolas
  • Belmont Gérard
  • Rezeau Laurence
  • Aunai Nicolas
  • Retinò Alessandro
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2014, 119, pp.1709-1720. To investigate the internal structure of the magnetopause with spacecraft data, it is crucial to be able to determine its normal direction and to convert the measured time series into spatial profiles. We propose here a new single-spacecraft method, called the BV method, to reach these two objectives. Its name indicates that the method uses a combination of the magnetic field (B) and velocity (V) data. The method is tested on simulation and on Cluster data, and a short overview of the possible products is given. We discuss its assumptions and show that it can bring a valuable improvement with respect to previous methods. (10.1002/2013JA018926)
  DOI : 10.1002/2013JA018926
• Compact hohlraum configuration with parallel planar-wire-array x-ray sources at the 1.7-MA Zebra generator
  
  • Vesey R. A.
  • Kantsyrev Viktor L.
  • Chuvatin Alexandre S.
  • Rudakov Leonid I.
  • Velikovich A. L.
  • Shreshta I. K.
  • Esaulov A. A.
  • Safronova Alla S.
  • Shlyaptseva V. V.
  • Osborne Glenn C.
  • Astanovitsky A. L.
  • Weller Michael E.
  • Stafford A.
  • Schultz K. A.
  • Cooper M. C.
  • Cuneo Michael E.
  • Jones B.
  Physical Review E, American Physical Society (APS), 2014, 90 (6), pp.063101. A compact Z-pinch x-ray hohlraum design with parallel-driven x-ray sources is experimentally demonstrated in a configuration with a central target and tailored shine shields at a 1.7-MA Zebra generator. Driving in parallel two magnetically decoupled compact double-planar-wire Z pinches has demonstrated the generation of synchronized x-ray bursts that correlated well in time with x-ray emission from a central reemission target. Good agreement between simulated and measured hohlraum radiation temperature of the central target is shown. The advantages of compact hohlraum design applications for multi-MA facilities are discussed. (10.1103/PhysRevE.90.063101)
  DOI : 10.1103/PhysRevE.90.063101
• A model of the magnetosheath magnetic field during magnetic clouds
  
  • Turc Lucile
  • Fontaine Dominique
  • Savoini Philippe
  • Kilpua E.K.J.
  Annales Geophysicae, European Geosciences Union, 2014, 32 (2), pp.157-173. Magnetic clouds (MCs) are huge interplanetary structures which originate from the Sun and have a paramount importance in driving magnetospheric storms. Before reaching the magnetosphere, MCs interact with the Earth's bow shock. This may alter their structure and therefore modify their expected geoeffectivity. We develop a simple 3-D model of the magnetosheath adapted to MCs conditions. This model is the first to describe the interaction of MCs with the bow shock and their propagation inside the magnetosheath. We find that when the MC encounters the Earth centrally and with its axis perpendicular to the Sun–Earth line, the MC's magnetic structure remains mostly unchanged from the solar wind to the magnetosheath. In this case, the entire dayside magnetosheath is located downstream of a quasi-perpendicular bow shock. When the MC is encountered far from its centre, or when its axis has a large tilt towards the ecliptic plane, the MC's structure downstream of the bow shock differs significantly from that upstream. Moreover, the MC's structure also differs from one region of the magnetosheath to another and these differences vary with time and space as the MC passes by. In these cases, the bow shock configuration is mainly quasi-parallel. Strong magnetic field asymmetries arise in the mag-netosheath; the sign of the magnetic field north–south component may change from the solar wind to some parts of the magnetosheath. We stress the importance of the B x component. We estimate the regions where the magnetosheath and magnetospheric magnetic fields are anti-parallel at the mag-netopause (i.e. favourable to reconnection). We find that the location of anti-parallel fields varies with time as the MCs move past Earth's environment, and that they may be situated near the subsolar region even for an initially northward magnetic field upstream of the bow shock. Our results point out the major role played by the bow shock configuration in modifying or keeping the structure of the MCs unchanged. Note that this model is not restricted to MCs, it can be used to describe the magnetosheath magnetic field under an arbitrary slowly varying interplanetary magnetic field. (10.5194/angeo-32-157-2014)
  DOI : 10.5194/angeo-32-157-2014
• Langmuir probe analysis in electronegative plasmas
  
  • Bredin Jérôme
  • Chabert Pascal
  • Aanesland Ane
  Physics of Plasmas, American Institute of Physics, 2014, 21 (12), pp.123502. This paper compares two methods to analyze Langmuir probe data obtained in electronegative plasmas. The techniques are developed to allow investigations in plasmas, where the electronegativity &#945;0&#8201;=&#8201;n/ne (the ratio between the negative ion and electron densities) varies strongly. The first technique uses an analytical model to express the Langmuir probe current-voltage (I-V) characteristic and its second derivative as a function of the electron and ion densities (ne, n , n), temperatures (Te, T , T), and masses (me, m , m). The analytical curves are fitted to the experimental data by adjusting these variables and parameters. To reduce the number of fitted parameters, the ion masses are assumed constant within the source volume, and quasi-neutrality is assumed everywhere. In this theory, Maxwellian distributions are assumed for all charged species. We show that this data analysis can predict the various plasma parameters within 510%, including the ion temperatures when &#945;0&#8201;>&#8201;100. However, the method is tedious, time consuming, and requires a precise measurement of the energy distribution function. A second technique is therefore developed for easier access to the electron and ion densities, but does not give access to the ion temperatures. Here, only the measured I-V characteristic is needed. The electron density, temperature, and ion saturation current for positive ions are determined by classical probe techniques. The electronegativity &#945;0 and the ion densities are deduced via an iterative method since these variables are coupled via the modified Bohm velocity. For both techniques, a Child-Law sheath model for cylindrical probes has been developed and is presented to emphasize the importance of this model for small cylindrical Langmuir probes. (10.1063/1.4903328)
  DOI : 10.1063/1.4903328
• NO oxidation on plasma pretreated Pyrex: the case for a distribution of reactivity of adsorbed O atoms
  
  • Guerra V.
  • Marinov Daniil
  • Guaitella Olivier
  • Rousseau Antoine
  Journal of Physics D: Applied Physics, IOP Publishing, 2014, 47 (22), pp.224012. The formation of NO 2 molecules on a Pyrex surface, as a result of NO oxidation by adsorbed O atoms on the wall, is experimentally demonstrated and quantified. The measurements reveal that the characteristic times of heterogeneous NO 2 production and NO gas phase decay change from ?60 to ?1500 s as the gas phase concentration of NO introduced in a tube pretreated with an oxygen radiofrequency discharge increases from 10 13 to 10 15 cm ?3 . Moreover, a clear variation of the characteristic loss frequency of NO molecules when small amounts of NO are successively injected in the tube is detected, between ?7 × 10 ?2 and ?5 × 10 ?3 s ?1 . The complex surface kinetics observed is studied and interpreted with the help of a mesoscopic surface model accounting for Eley?Rideal NO oxidation and slow NO 2 adsorption, confirming the existence of adsorption sites possessing a distribution of reactivity on the surface. (10.1088/0022-3727/47/22/224012)
  DOI : 10.1088/0022-3727/47/22/224012
• Electron transport parameters in NF<SUB>3</SUB>
  
  • Lisovskiy V. A.
  • Yegorenkov V. D.
  • Ogloblina P.
  • Booth Jean-Paul
  • Martins S.
  • Landry K.
  • Douai D.
  • Cassagne V.
  Journal of Physics D: Applied Physics, IOP Publishing, 2014, 47 (11), pp.115203. We present electron transport parameters (the first Townsend coefficient, the dissociative attachment coefficient, the fraction of electron energy lost by collisions with NF 3 molecules, the average and characteristic electron energy, the electron mobility and the drift velocity) in NF 3 gas calculated from published elastic and inelastic electron?NF 3 collision cross-sections using the BOLSIG code. Calculations were performed for the combined RB (Rescigno 1995 Phys. Rev. E 52 [http://dx.doi.org/10.1103/PhysRevA.52.329] 329 , Boesten et al 1996 J. Phys. B: At. Mol. Opt. Phys. 29 [http://dx.doi.org/10.1088/0953-4075/29/22/022] 5475 ) momentum-transfer cross-section, as well as for the JB (Joucoski and Bettega 2002 J. Phys. B: At. Mol. Opt. Phys. 35 [http://dx.doi.org/10.1088/0953-4075/35/4/303] 783 ) momentum-transfer cross-section. In addition, we have measured the radio frequency (rf) breakdown curves for various inter-electrode gaps and rfs, and from these we have determined the electron drift velocity in NF 3 from the location of the turning point in these curves. These drift velocity values are in satisfactory agreement with those calculated by the BOLSIG code employing the JB momentum-transfer cross-section. (10.1088/0022-3727/47/11/115203)
  DOI : 10.1088/0022-3727/47/11/115203
• Radio-frequency capacitively coupled plasmas in hydrogen excited by tailored voltage waveforms: comparison of simulations with experiments
  
  • Diomede P.
  • Economou D. J.
  • Lafleur Trevor
  • Booth Jean-Paul
  • Longo S.
  Plasma Sources Science and Technology, IOP Publishing, 2014, 23 (6), pp.065049. A combined computational-experimental study was performed of a geometrically symmetric capacitively coupled plasma in hydrogen sustained by tailored voltage waveforms consisting of the sum of up to three harmonics. Predictions of a particle-in-cell with Monte Carlo collisions/fluid hybrid model were in reasonably good agreement compared to data from an array of experimental plasma diagnostics. The plasma was electrically asymmetric, with a dc self-bias developed, for all but a sinusoidal voltage waveform. Hydrogen ions (H<SUP> </SUP>,H <SUP> </SUP><SUB>2</SUB>,H <SUP> </SUP><SUB>3</SUB>) bombarding the electrodes exhibited different ion flux-distribution functions due to their different masses and collisionality in the sheath. Plasma density, ion flux and absolute value of the dc self-bias all increased with increasing the number of harmonics. The energy of ions bombarding the substrate electrode may be controlled by switching the applied voltage waveform from (positive) peaks to (negative) valleys. (10.1088/0963-0252/23/6/065049)
  DOI : 10.1088/0963-0252/23/6/065049