Publications

2014

• Characteristics of the flank magnetopause: Cluster observations
  
  • Haaland S.
  • Reistad J.
  • Tenfjord P.
  • Gjerloev J.
  • Maes Lukas
  • de Keyser J.
  • Maggiolo R.
  • Anekallu C.
  • Dorville Nicolas
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2014, 119, pp.9019-9037. The magnetopause is a current sheet forming the boundary between the geomagnetic field on one side and the shocked solar wind on the other side. This paper discusses properties of the low-latitude dawn and dusk flanks of the magnetopause. The reported results are based on a large number of measurements obtained by the Cluster satellites during magnetopause traversals. Using a combination of single-spacecraft and multispacecraft techniques, we calculated macroscopic features such as thickness, location, and motion of the magnetopause. The results show that the typical flank magnetopause is significantly thicker than the dayside magnetopause and also possesses a pronounced and persistent dawn-dusk asymmetry. Thicknesses vary from 150 to 5000 km, with an median thickness of around 1400 km at dawn and around 1150 km at dusk. Current densities are on average higher on dusk, suggesting that the total current at dawn and dusk are similar. Solar wind conditions and the interplanetary magnetic field cannot fully explain the observed dawn-dusk asymmetry. For a number of crossings we were also able to derive detailed current density profiles. The profiles show that the magnetopause often consists of two or more adjacent current sheets, each current sheet typically several ion gyroradii thick and often with different current direction. This demonstrates that the flank magnetopause has a structure that is more complex than the thin, one-dimensional current sheet described by a Chapman-Ferraro layer. (10.1002/2014JA020539)
  DOI : 10.1002/2014JA020539
• Planetary Science Virtual Observatory architecture
  
  • Erard S.
  • Cecconi B.
  • Le Sidaner P.
  • Berthier J.
  • Henry F.
  • Chauvin C.
  • André N.
  • Génot V.
  • Jacquey C.
  • Gangloff M.
  • Bourrel N.
  • Schmitt B.
  • Capria M.-Th.
  • Chanteur Gérard
  Astronomy and Computing, Elsevier, 2014, 7-8, pp.71-80. In the framework of the Europlanet-RI program, a prototype of Virtual Observatory dedicated to Planetary Science was defined. Most of the activity was dedicated to the elaboration of standards to retrieve and visualize data in this field, and to provide light procedures to teams who wish to contribute with on-line data services. The architecture of this VO system and selected solutions are presented here, together with existing demonstrators. (10.1016/j.ascom.2014.07.005)
  DOI : 10.1016/j.ascom.2014.07.005
• Elasticity in drift-wave-zonal-flow turbulence
  
  • Guo Z. B.
  • Diamond P.H.
  • Kosuga Y.
  • Gürcan Özgür D.
  Physical Review E, American Physical Society (APS), 2014, 89 (4). We present a theory of turbulent elasticity, a property of drift-wave-zonal-flow (DW-ZF) turbulence, which follows from the time delay in the response of DWs to ZF shears. An emergent dimensionless parameter vertical bar < v >'vertical bar/Delta omega(k) is found to be a measure of the degree of Fickian flux-gradient relation breaking, where vertical bar < v >'vertical bar is the ZF shearing rate and Delta omega(k) is the turbulence decorrelation rate. For vertical bar < v >'vertical bar/Delta omega(k) > 1, we show that the ZF evolution equation is converted from a diffusion equation, usually assumed, to a telegraph equation, i.e., the turbulent momentum transport changes from a diffusive process to wavelike propagation. This scenario corresponds to a state very close to the marginal instability of the DW-ZF system, e.g., the Dimits shift regime. The frequency of the ZF wave is Omega(ZF) = /-gamma(1/2)(d)gamma(1/2)(modu), where gamma(d) is the ZF friction coefficient and gamma(modu) is the net ZF growth rate for the case of the Fickian flux-gradient relation. This insight provides a natural framework for understanding temporally periodic ZF structures in the Dimits shift regime and in the transition from low confined mode to high confined mode in confined plasmas. (10.1103/PhysRevE.89.041101)
  DOI : 10.1103/PhysRevE.89.041101
• Phase space structures in gyrokinetic simulations of plasma turbulence
  
  • Ghendrih Philippe
  • Norscini C.
  • Cartier-Michaud T.
  • Dif-Pradalier Guilhem
  • Abiteboul J.
  • Dong Yue
  • Garbet X.
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Grandgirard Virginie
  • Latu G.
  • Morel Pierre
  • Sarazin Y.
  • Storelli A.
  • Vermare Laure
  The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2014, 68 (10), pp.303. Gyrokinetic simulations of fusion plasmas give extensive information in 5D on turbulence and transport. This paper highlights a few of these challenging physics in global, flux driven simulations using experimental inputs from Tore Supra shot TS45511. The electrostatic gyrokinetic code GYSELA is used for these simulations. The 3D structure of avalanches indicates that these structures propagate radially at localised toroidal angles and then expand along the field line at sound speed to form the filaments. Analysing the poloidal mode structure of the potential fluctuations (at a given toroidal location), one finds that the low modes m = 0 and m = 1 exhibit a global structure; the magnitude of the m = 0 mode is much larger than that of the m = 1 mode. The shear layers of the corrugation structures are thus found to be dominated by the m = 0 contribution, that are comparable to that of the zonal flows. This global mode seems to localise the m = 2 mode but has little effect on the localisation of the higher mode numbers. However when analysing the pulsation of the latter modes one finds that all modes exhibit a similar phase velocity, comparable to the local zonal flow velocity. The consequent dispersion like relation between the modes pulsation and the mode numbers provides a means to measure the zonal flow. Temperature fluctuations and the turbulent heat flux are localised between the corrugation structures. Temperature fluctuations are found to exhibit two scales, small fluctuations that are localised by the corrugation shear layers, and appear to bounce back and forth radially, and large fluctuations, also readily observed on the flux, which are associated to the disruption of the corrugations. The radial ballistic velocity of both avalanche events if of the order of 0.5&#961;&#8727;c0 where &#961;&#8727; = &#961;0/a, a being the tokamak minor radius and &#961;0 being the characteristic Larmor radius, &#961;0 = c0/&#937;0. c0 is the reference ion thermal velocity and &#937;0 = qiB0/mi the reference ion Larmor frequency for the characteristic amplitude of the magnetic field B0, qi and mi being, respectively, the ion charge and mass. The electric drift velocity is also found to exhibit a poloidal pattern, with maximum amplitude of the fluctuations either in the top or in the bottom regions of the machine depending on the sign of the zonal flow shear. This effect is found to be correlated to the stopping capability of the corrugation structures. The neoclassical properties stemming from the trapped particle drifts lead to large distortion of the distribution function. As expected, these prevail at the outer part of the simulation region despite the large collisionality. The distribution function fluctuations appear to be aligned along the v&#8741; = const. lines at constant poloidal angle. A specific symmetry is observed regarding the interplay of turbulence with the trapped-passing region. (10.1140/epjd/e2014-50210-8)
  DOI : 10.1140/epjd/e2014-50210-8
• On the electron diffusion region in planar, asymmetric, systems
  
  • Hesse Michael
  • Aunai Nicolas
  • Sibeck David G.
  • Birn Joachim
  Geophysical Research Letters, American Geophysical Union, 2014, 41, pp.8673-8680. Particle-in-cell simulations and analytical theory are employed to study the electron diffusion region in asymmetric reconnection, which is taking place in planar configurations without a guide field. The analysis presented here focuses on the nature of the local reconnection electric field and on differences from symmetric configurations. Further emphasis is on the complex structure of the electron distribution in the diffusion region, which is generated by the mixing of particles from different sources. We find that the electric field component that is directly responsible for flux transport is provided not by electron pressure-based, "quasi-viscous," terms but by inertial terms. The quasi-viscous component is shown to be critical in that it is necessary to sustain the required overall electric field pattern in the immediate neighborhood of the reconnection X line. (10.1002/2014GL061586)
  DOI : 10.1002/2014GL061586
• A Kolmogorov-like exact relation for compressible polytropic turbulence
  
  • Banerjee Supratik
  • Galtier Sébastien
  Journal of Fluid Mechanics, Cambridge University Press (CUP), 2014, 742, pp.230-242. Compressible hydrodynamic turbulence is studied under the assumption of a polytropic closure. Following Kolmogorov, we derive an exact relation for some two-point correlation functions in the asymptotic limit of a high Reynolds number. (10.1017/jfm.2013.657)
  DOI : 10.1017/jfm.2013.657
• Wave number determination of Pc 1-2 mantle waves considering He++ ions: A Cluster study
  
  • Grison B.
  • Escoubet C. Philippe
  • Santolík O.
  • Cornilleau-Wehrlin Nicole
  • Khotyaintsev Y. V.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2014, 119 (9), pp.7601-7614. The present case study concerns narrowband electromagnetic emission detected in the distant cusp region simultaneously with upgoing plasma flows. The wave properties match the usual properties of the Pc 12 mantle waves: small angle between the wave vector and the magnetic field line, left-hand polarization, and propagation toward the ionosphere. We report here the first direct wave vector measurement of these waves (about 1.2&#8201;×&#8201;10&#8722;&#8201;2&#8201;rad/km) through multi spacecraft analysis using the three magnetic components and, at the same time, through single spacecraft analysis based on the refractive index analysis using the three magnetic components and two electric components. The refractive index analysis offers a simple way to estimate wave numbers in this frequency range. Numerical calculations are performed under the observed plasma conditions. The obtained results show that the ion distribution functions are unstable to ion cyclotron instability at the observed wave vector value, due to the large ion temperature anisotropy. We thus show that these electromagnetic ion cyclotron (EMIC) waves are amplified in the distant cusp region. The Poynting flux of the waves is counterstreaming with respect to the plasma flow. This sense of propagation is consistent with the time necessary to amplify the emissions to the observed level. We point out the role of the wave damping at the He gyrofrequency to explain that such waves cannot be observed from the ground at the cusp foot print location. (10.1002/2013JA019719)
  DOI : 10.1002/2013JA019719
• Coherent structures in ion temperature gradient turbulence-zonal flow
  
  • Singh Rameswar
  • Singh R.
  • Kaw P.
  • Gürcan Özgür D.
  • Diamond P.H.
  Physics of Plasmas, American Institute of Physics, 2014, 21 (10), pp.102306. Nonlinear stationary structure formation in the coupled ion temperature gradient (ITG)-zonal flow system is investigated. The ITG turbulence is described by a wave-kinetic equation for the action density of the ITG mode, and the longer scale zonal mode is described by a dynamic equation for the m&#8201;=&#8201;n&#8201;=&#8201;0 component of the potential. Two populations of trapped and untrapped drift wave trajectories are shown to exist in a moving frame of reference. This novel effect leads to the formation of nonlinear stationary structures. It is shown that the ITG turbulence can self-consistently sustain coherent, radially propagating modulation envelope structures such as solitons, shocks, and nonlinear wave trains. (10.1063/1.4898207)
  DOI : 10.1063/1.4898207
• Modelling of JET hybrid scenarios with GLF23 transport model: E x B shear stabilization of anomalous transport
  
  • Voitsekhovitch I.
  • Belo P.
  • Citrin Jonathan
  • Fable E.
  • Ferreira Jorge
  • Garcia J.
  • Garzotti L.
  • Hobirk J.
  • Hogeweij G.M.D.
  • Joffrin E.
  • Koechl F.
  • Litaudon X.
  • Moradi S.
  • Nabais F.
  • Jet-Efda Contributors
  • Eu-Itm Iter Scenario Modelling Grp
  Nuclear Fusion, IOP Publishing, 2014, 54 (9). The E x B shear stabilization of anomalous transport in JET hybrid discharges is studied via self-consistent predictive modelling of electron and ion temperature, ion density and toroidal rotation velocity performed with the GLF23 model. The E x B shear stabilization factor (parameter alpha E in the GLF23 model) is adjusted to predict accurately the four simulated quantities under different experimental conditions, and the uncertainty in aE determined by 15% deviation between simulated and measured quantities is estimated. A correlation of aE with toroidal rotation velocity and E x B shearing rate is found in the low density plasmas, suggesting that the turbulence quench rule may be more complicated than assumed in the GLF23 model with constant alpha(E). For the selected discharges the best predictive accuracy is obtained by using weak/no E x B shear stabilization (i.e. alpha(E) approximate to 0) at low toroidal angular frequency (Omega < 60 krad s(-1)), even in the scenarios with the current overshoot, and alpha(E) = 0.9 at high frequency (Omega > 100 krad s(-1)). Interestingly, a weak E x B shear stabilization of anomalous transport is found in the medium density strongly rotating discharge. An importance of linear beta(e) stabilization in this discharge is estimated and compared to the low density discharge with equally high beta(e). The toroidal rotation velocity is well predicted here by assuming that the momentum diffusion coefficient is a fraction of thermal ion diffusivity. Taking into account the alpha(E) and Prandtl number with their uncertainties determined in the modelling of JET hybrid discharges, the performance of ITER hybrid scenario with optimized heat mix (33 MW of NBI and 20 MW of ECCD) is estimated showing the importance of toroidal rotation for achieving Q > 5. (10.1088/0029-5515/54/9/093006)
  DOI : 10.1088/0029-5515/54/9/093006
• Plasma-catalyst coupling for volatile organic compound removal and indoor air treatment: a review
  
  • Thévenet Frédéric
  • Sivachandiran Loganathan
  • Guaitella Olivier
  • Barakat Christelle
  • Rousseau Antoine
  Journal of Physics D: Applied Physics, IOP Publishing, 2014, 47 (22), pp.224011. The first part of the review summarizes the problem of air pollution and related air-cleaning technologies. Volatile organic compounds in particular have various effects on health and their abatement is a key issue. Different ways to couple non-thermal plasmas with catalytic or adsorbing materials are listed. In particular, a comparison between in-plasma and post-plasma coupling is made. Studies dealing with plasma-induced heterogeneous reactivity are analysed, as well as the possible modifications of the catalyst surface under plasma exposure. As an alternative to the conventional and widely studied plasmacatalyst coupling, a sequential approach has been recently proposed whereby pollutants are first adsorbed onto the material, then oxidized by switching on the plasma. Such a sequential approach is reviewed in detail. (10.1088/0022-3727/47/22/224011)
  DOI : 10.1088/0022-3727/47/22/224011
• The quasi-electrostatic mode of chorus waves and electron nonlinear acceleration
  
  • Agapitov O. V.
  • Artemyev A.V.
  • Mourenas D
  • Krasnoselskikh V
  • Bonnell J
  • Le Contel Olivier
  • Cully C. M.
  • Angelopoulos V
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2014, 119, pp.1606-1626. Selected Time History of Events and Macroscale Interactions During Substorms observations at medium latitudes of highly oblique and high-amplitude chorus waves are presented and analyzed. The presence of such very intense waves is expected to have important consequences on electron energization in the magnetosphere. An analytical model is therefore developed to evaluate the efficiency of the trapping and acceleration of energetic electrons via Landau resonance with such nearly electrostatic chorus waves. Test-particle simulations are then performed to illustrate the conclusions derived from the analytical model, using parameter values consistent with observations. It is shown that the energy gain can be much larger than the initial particle energy for 10 keV electrons, and it is further demonstrated that this energy gain is weakly dependent on the density variation along field lines. (10.1002/2013JA019223)
  DOI : 10.1002/2013JA019223
• Global (volume-averaged) model of inductively coupled chlorine plasma: Influence of Cl wall recombination and external heating on continuous and pulse-modulated plasmas
  
  • Kemaneci Efe
  • Carbone Emile
  • Booth Jean-Paul
  • Graef Wouter
  • van Dijk Jan
  • Kroesen G.
  Plasma Sources Science and Technology, IOP Publishing, 2014, 23 (4), pp.045002. An inductively coupled radio-frequency plasma in chlorine is investigated via a global (volume-averaged) model, both in continuous and square wave modulated power input modes. After the power is switched off (in a pulsed mode) an ion?ion plasma appears. In order to model this phenomenon, a novel quasi-neutrality implementation is proposed. Several distinct Cl wall recombination probability measurements exist in the literature, and their effect on the simulation data is compared. We also investigated the effect of the gas temperature that was imposed over the range 300?1500 K, not calculated self-consistently. Comparison with published experimental data from several sources for both continuous and pulsed modes shows good agreement with the simulation results. (10.1088/0963-0252/23/4/045002)
  DOI : 10.1088/0963-0252/23/4/045002
• Modelling Ganymede's neutral environment: A 3D test-particle simulation
  
  • Turc Lucile
  • Leclercq Ludivine
  • Leblanc François
  • Modolo Ronan
  • Chaufray Jean-Yves
  Icarus, Elsevier, 2014, 229, pp.157-169. In this paper, we present a 3D parallelized test-particle model of Ganymede's neutral environment. The atmosphere sources are assumed to be the sputtering and the sublimation of water-ice, the former taking place in the polar regions and the latter near the subsolar point. It appears that Ganymede's atmosphere is deeply structured by these two processes, leading to a strong dichotomy between polar and subsolar regions. The densest part of the atmosphere is found in the vicinity of the subsolar point, where sublimated H2O is the predominant species near the surface. At higher latitudes and on the nightside, O2 prevails at low altitude, whereas the high altitudes are primarily populated by H2 everywhere in the atmosphere. An estimation of the number of collisions shows that the atmosphere is mostly collisionless, except a small region near the subsolar point. The O2 column density in our model is in good agreement with the observations. However, it appears that we underestimate the H density. This could suggest that the sublimation rates are significantly underestimated but not the sputtering. The escape rates of the different species are essentially lower than those previously obtained by Marconi (2007). The effects of varying surface emission fluxes are investigated in order to simulate Ganymede's passing into the shadow of Jupiter or in the plasma sheet. We estimate that the sublimated H2O peak in the subsolar region would disappear within one hour in the shadow of Jupiter. Likewise, the variation of the sputtering fluxes alters the atmospheric structure in a similar time scale. (10.1016/j.icarus.2013.11.005)
  DOI : 10.1016/j.icarus.2013.11.005
• 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.
• 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
• 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
• 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
• 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
• 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
• 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
• Multi Water Bag modelling of drift kinetic electrons and ions plasmas
  
  • Morel Pierre
  • Dreydemy Ghiro Florent
  • Berionni Vincent
  • Gürcan Özgür D.
  , 2014.
• 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
• 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&#8201;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