Publications

2010

• Design of magnetic concentrators for high sensitivity anisotropic magnetoresistor devices
  
  • Mansour Malik
  • Coillot Christophe
  • Chanteur Gérard
  • Roux A.
  • Nguyen van Dau Frédéric
  Journal of Applied Physics, American Institute of Physics, 2010, 107, pp.09E707. In this work, a very promising shape of magnetic concentrators taking advantage of the symmetrical flux leakage of Mn-Zn ferrite magnetic cores is presented. This configuration consists of two ferromagnetic rods separated by two air gaps allowing to place anisotropic magnetoresistance sensors in the core axis. Results from three-dimensional finite elements modeling are presented. We show that an appropriate shape optimization of core extremities enables to improve significantly the amplification factor without any increase in length. (10.1063/1.3337747)
  DOI : 10.1063/1.3337747
• Simultaneous FAST and Double Star TC1 observations of broadband electrons during a storm time substorm
  
  • Nakajima A.
  • Shiokawa K.
  • Seki K.
  • Nakamura R.
  • Keika K.
  • Baumjohann W.
  • Takada T.
  • Mcfadden J. P.
  • Carlson C. W.
  • Fazakerley A.
  • Rème H.
  • Dandouras I.
  • Strangeway R. J.
  • Le Contel Olivier
  • Cornilleau-Wehrlin Nicole
  • Yearby K. H.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115, pp.7217. Broadband electrons (BBEs) exhibit remarkable electron flux enhancements over a broad energy range (0.03-30 keV) near the equatorward edge of the auroral oval during geomagnetic storms. Here, we report a BBE event observed by the Fast Auroral Snapshot (FAST) satellite at 1355-1359 UT, 61°-66° invariant latitudes, 0600 magnetic local time (MLT), and 3800 km altitude during a storm on 25 July 2004. The Double Star (DS) TC1 satellite was located near the magnetic equator at L = 5.7, close to the same local time as FAST. We investigate the acceleration process of BBEs from the inner magnetosphere to near the ionosphere by comparing electron data obtained by FAST and DS TC1. We also investigate both plasma and field variations in the inner magnetosphere associated with substorm onset using DS TC1 data to examine the relationship between the BBEs and the storm time substorm. Ground geomagnetic field data show a positive H-bay at 1349 UT at 0600 MLT, indicating that a storm time substorm started just before the appearance of the BBEs. At 1350 UT, a tailward ion flow was observed by DS TC1. Then, DS TC1 observed a local dipolarization and a drastic ion density enhancement at 1351 UT, indicating that particle heating associated with the substorm was occurring in the inner magnetosphere. From 1352 UT, electron fluxes were isotropically enhanced at energies above 0.5 keV as observed by DS TC1. On the other hand, the pitch angle distribution of BBEs at the FAST altitude showed field-aligned lower-energy electrons below 0.5 keV and isotropic higher-energy electrons above 0.5 keV. From these data, it was inferred that the BBEs might consist of two energy components due to the acceleration or heating of electrons at different altitudes in association with the storm time substorm. (10.1029/2009JA014907)
  DOI : 10.1029/2009JA014907
• Design criteria and validation of a vacuum load current multiplier on a mega-ampere microsecond inductive storage generator
  
  • Chuvatin Alexandre S.
  • Kim A. A.
  • Kokshenev V. A.
  • Kovalchuk Boris M.
  • Lassalle Francis
  • Calamy Hervé
  • Krishnan M.
  Laser and Particle Beams, Cambridge University Press (CUP), 2010, 28 (3), pp.361-369. The load current multiplier concept (LCM) was suggested for improving the energy transfer efficiency from pulse power generators to loads. The concept was initially demonstrated at atmospheric pressure and dielectric insulation on a compact, 100 kA, microsecond capacitor bank. This paper reports on the LCM design criteria for mega-ampere vacuum pulse power when the LCM comprises a large-inductance magnetic flux extruder cavity without a magnetic core. The analytical and numerical design approach presented was experimentally validated on GIT12 mega-ampere inductive energy storage generator with a constant-inductance load. The LCM technique increased the peak load current from typically 4.6 MA at 1.87 µs on this generator, to 6.43 MA at 2.0 µs. The electromagnetic power into a ~10 nH load increased from 100 GW to 230 GW. This result is in good agreement with the presented numerical simulations and it corresponds to a 95% increase of the achievable magnetic pressure at 8 cm radius in the load. The compact, LCM hardware allows the GIT12 generator to operate more efficiently without modifying the stored energy or architecture. The demonstrated load power and energy increase using the LCM concept is of importance for further studies on power amplification in vacuum and high energy density physics. (10.1017/S0263034610000224)
  DOI : 10.1017/S0263034610000224
• The WHISPER Relaxation Sounder and the CLUSTER Active Archive
  
  • Trotignon Jean-Gabriel
  • Décréau Pierrette
  • Rauch Jean-Louis
  • Vallières Xavier
  • Rochel A.
  • Kougblénou S.
  • Lointier G.
  • Facskó G.
  • Canu Patrick
  • Darrouzet F.
  • Masson A.
  • Taylor M.
  • Escoubet C. Philippe
  , 2010, pp.185-208. The Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation (WHISPER) instrument is part of the Wave Experiment Consortium (WEC) of the CLUSTER mission. With the help of the long double sphere antennae of the Electric Field and Wave (EFW) instrument and the Digital Wave Processor (DWP), it delivers active (sounding) and natural (transmitter off) electric field spectra, respectively from 4 to 82 kHz, and from 2 to 80 kHz. These frequency ranges have been chosen to include the electron plasma frequency, which is closely related to the total electron density, in most of the regions encountered by the CLUSTER spacecraft. Presented here is an overview of the WHISPER data products available in the CLUSTER Active Archive (CAA). The instrument and its performance are first recalled. The way the WHISPER products are obtained is then described, with particular attention being paid to the density determination. Both sounding and natural measurements are commonly used in this process, which depends on the ambient plasma regime. This is illustrated using drawings similar to the Bryant plots commonly used in the CLUSTER master science plan. These give a clear overview of typical density values and the parts of the orbits where they are obtained. More information on the applied software or on the quality/reliability of the density determination can also be highlighted. (10.1007/978-90-481-3499-1_12)
  DOI : 10.1007/978-90-481-3499-1_12
• Three dimensional anisotropic k-spectra of turbulence at sub-proton scales in the solar wind
  
  • Sahraoui Fouad
  • Goldstein M.L.
  • Belmont Gérard
  • Canu Patrick
  • Rezeau Laurence
  Physical Review Letters, American Physical Society, 2010 (105), pp.131101. We show the first three dimensional (3D) dispersion relations and k spectra of magnetic turbulence in the solar wind at subproton scales. We used the Cluster data with short separations and applied the k-filtering technique to the frequency range where the transition to subproton scales occurs. We show that the cascade is carried by highly oblique kinetic Alfve´n waves with !plas 0:1!ci down to k?i 2. Each k spectrum in the direction perpendicular to B0 shows two scaling ranges separated by a breakpoint (in the interval ½0:4; 1k?i): a Kolmogorov scaling k1:7 ? followed by a steeper scaling k4:5 ? . We conjecture that the turbulence undergoes a transition range, where part of the energy is dissipated into proton heating via Landau damping and the remaining energy cascades down to electron scales where electron Landau damping may predominate. (10.1103/PhysRevLett.105.131101)
  DOI : 10.1103/PhysRevLett.105.131101
• Plasmas de Fusion Magnétique
  
  • Hennequin Pascale
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.25-26. ISSN : 1775-0385
• Formation of a sodium ring in Mercury's magnetosphere
  
  • Yagi Manabu
  • Seki K.
  • Matsumoto Y.
  • Delcourt Dominique C.
  • Leblanc François
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A10), pp.A10253. We have performed a statistical analysis of exospheric sodium ion paths in Mercury's magnetosphere under northward interplanetary magnetic field conditions. Electric and magnetic field models used in the simulation were obtained from a global MHD simulation model, whereas the initial conditions of test Na+ ions were derived from a sodium exosphere model. We observe the formation of a ring-shaped high-pressure region consisting of energetic sodium ions traveling around the planet close to the equatorial plane. The configuration of this "sodium ring" as well as the acceleration processes leading to its formation strongly depend on the solar wind conditions. When the dynamic pressure is low, most of the Na+ are picked up in the magnetosphere and accelerated by the large-scale convective electric field. In contrast, in the case of high dynamic pressure, ions that are picked up in the magnetosheath and penetrate into the magnetosphere significantly contribute to the sodium ring. The configuration of this ring also depends upon the intensity of the solar wind electric field. Our analysis reveals that the pressure built by the Na+ ions may be significant as compared to the MHD pressure around the planet. (10.1029/2009JA015226)
  DOI : 10.1029/2009JA015226
• Non adiabatic electron behavior through a supercritical perpendicular collisionless shock: Impact of the shock front turbulence
  
  • Savoini Philippe
  • Lembège Bertrand
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A11), pp.A11103. Adiabatic and nonadiabatic electrons transmitted through a supercritical perpendicular shock wave are analyzed with the help of test particle simulations based on field components issued from 2 − D full-particle simulation. A previous analysis (Savoini et al., 2005) based on 1 − D shock profile, including mainly a ramp (no apparent foot) and defined at a fixed time, has identified three distinct electron populations: adiabatic, overadiabatic, and underadiabatic, respectively, identified by μds/μus ≈ 1, >1 and <1, where μus and μds are the magnetic momenta in the upstream and downstream regions. Presently, this study is extended by investigating the impact of the time evolution of 2 − D shock front dynamics on these three populations. Analysis of individual time particle trajectories is performed and completed by statistics based on the use of different upstream velocity distributions (spherical shell of radius vshell and a Maxwellian with thermal velocity vthe). In all statistics, the three electron populations are clearly recovered. Two types of shock front nonstationarity are analyzed. First, the impact of the nonstationarity along the shock normal (due to the front self-reformation only) strongly depends on the values of vshell or vthe. For low values, the percentages of adiabatic and overadiabatic electrons are almost comparable but become anticorrelated under the filtering impact of the self-reformation; the percentage of the underadiabatic population remains almost unchanged. In contrast, for large values, this impact becomes negligible and the adiabatic population alone becomes dominant. Second, when 2 − D nonstationarity effects along the shock front (moving rippling) are fully included, all three populations are strongly diffused, leading to a larger heating; the overadiabatic population becomes largely dominant (and even larger than the adiabatic one) and mainly contributes to the energy spectrum. (10.1029/2010JA015381)
  DOI : 10.1029/2010JA015381
• Chorus source region localization in the Earth's outer magnetosphere using THEMIS measurements
  
  • Agapitov O
  • Krasnoselskikh V
  • Zaliznyak Yu
  • Angelopoulos V
  • Le Contel Olivier
  • Rolland G
  Annales Geophysicae, European Geosciences Union, 2010, 28, pp.1377–1386. Discrete ELF/VLF chorus emissions, the most intense electromagnetic plasma waves observed in the Earth's radiation belts and outer magnetosphere, are thought to propagate roughly along magnetic field lines from a localized source region near the magnetic equator towards the magnetic poles. THEMIS project Electric Field Instrument (EFI) and Search Coil Magnetometer (SCM) measurements were used to determine the spatial scale of the chorus source lo-calization region on the day side of the Earth's outer magne-tosphere. We present simultaneous observations of the same chorus elements registered onboard several THEMIS spacecraft in 2007 when all the spacecraft were in the same orbit. Discrete chorus elements were observed at 0.15–0.25 of the local electron gyrofrequency, which is typical for the outer magnetosphere. We evaluated the Poynting flux and wave vector distribution and obtained chorus wave packet quasi-parallel propagation to the local magnetic field. Amplitude and phase correlation data analysis allowed us to estimate the characteristic spatial correlation scale transverse to the local magnetic field to be in the 2800–3200 km range. Keywords. Electromagnetics (Random media and rough surfaces) – Magnetospheric physics (Plasma waves and in-stabilities) – Radio science (Remote sensing) (10.5194/angeo-28-1377-2010)
  DOI : 10.5194/angeo-28-1377-2010
• Observation and theoretical modeling of electron scale solar wind turbulence
  
  • Sahraoui Fouad
  • Belmont Gérard
  • Goldstein M. L.
  • Kiyani K. H.
  • Robert Patrick
  • Canu Patrick
  , 2010.
• Wave-particle interactions in the equatorial source region of whistler-mode emissions
  
  • Santolík Ondrej
  • Gurnett D. A.
  • Pickett J. S.
  • Grimald S.
  • Décréau Pierrette
  • Parrot Michel
  • Cornilleau-Wehrlin Nicole
  • El-Lemdani Mazouz Farida
  • Schriver D.
  • Meredith N. P.
  • Fazakerley A.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A8). Wave-particle interactions can play a key role in the process of transfer of energy between different electron populations in the outer Van Allen radiation belt. We present a case study of wave-particle interactions in the equatorial source region of whistler-mode emissions. We select measurements of the Cluster spacecraft when these emissions are observed in the form of random hiss with only occasional discrete chorus wave packets, and where the wave propagation properties are very similar to previously analyzed cases of whistler-mode chorus. We observe a positive divergence of the Poynting flux at minima of the magnetic field modulus along the magnetic field lines, indicating the central position of the source. In this region we perform a linear stability analysis based on the locally measured electron phase space densities. We find two unstable electron populations. The first of them consists of energy-dispersed and highly anisotropic injected electrons at energies of a few hundreds eV to a few keV, with the perpendicular temperature more than 10 times higher than the parallel temperature with respect to the magnetic field line. Another unstable population is formed by trapped electrons at energies above 10 keV. We show that the injected electrons at lower energies can be responsible for a part of the waves that propagate obliquely at frequencies above one half of the electron cyclotron frequency. Our model of the trapped electrons at higher energies gives insufficient growth of the waves below one half of the electron cyclotron frequency and a nonlinear generation mechanism might be necessary to explain their presence even in this simple case. (10.1029/2009JA015218)
  DOI : 10.1029/2009JA015218
• Observations multi-satellitaires de l'interaction Vent Solaire - Magnétosphère
  
  • Sahraoui Fouad
  • Cornilleau-Wehrlin Nicole
  Flash X - La revue scientifique de l'Ecole polytechnique, Ecole polytechnique, 2010, 12, pp.33-34. ISSN : 1775-0385
• RPWS_ViToS
  
  • Piberne Rodrigue
  • Canu Patrick
  , 2010. RPWS_ViToS is an IDL software for data processing and visualization of the RPW instrument of the Cassini mission.
• Scientific objectives and instrumentation of Mercury Plasma Particle Experiment (MPPE) onboard MMO
  
  • Saito Y.
  • Sauvaud J.-A.
  • Hirahara M.
  • Barabash S.
  • Delcourt Dominique C.
  • Takashima T.
  • Asamura K.
  Planetary and Space Science, Elsevier, 2010, 58 (1-2), pp.182-200. Mercury is one of the least explored planets in our solar system. Until the recent flyby of Mercury by MESSENGER, no spacecraft had visited Mercury since Mariner 10 made three flybys: two in 1974 and one in 1975. In order to elucidate the detailed plasma structure and dynamics around Mercury, an orbiter BepiColombo MMO (Mercury Magnetospheric Orbiter) is planned to be launched in 2013 as a joint mission between ESA and ISAS/JAXA. Mercury Plasma Particle Experiment (MPPE) was proposed in order to investigate the plasma/particle environment around Mercury. MPPE is a comprehensive instrument package for plasma, high-energy particle and energetic neutral atom measurements. It consists of seven sensors: two Mercury electron analyzers (MEA1 and MEA2), Mercury ion analyzer (MIA), Mercury mass spectrum analyzer (MSA), high-energy particle instrument for electron (HEP-ele), high-energy particle instrument for ion (HEP-ion), and energetic neutrals analyzer (ENA). Since comprehensive full three-dimensional simultaneous measurements of low to high-energy ions and electrons around Mercury as well as measurements of energetic neutral atoms will not be realized before BepiColombo/MMO's arrival at Mercury, it is expected that many unresolved problems concerning the Mercury magnetosphere will be elucidated by the MPPE observation. (10.1016/j.pss.2008.06.003)
  DOI : 10.1016/j.pss.2008.06.003
• A simple model of intrinsic rotation in high confinement regime tokamak plasmas
  
  • Gürcan Özgür D.
  • Diamond P.H.
  • Mcdevitt C.J.
  • Hahm T.S.
  Physics of Plasmas, American Institute of Physics, 2010, 17, pp.032509. A simple unified model of intrinsic rotation and momentum transport in high confinement regime (H-mode) tokamak plasmas is presented. Motivated by the common dynamics of the onset of intrinsic rotation and the L-H transition, this simple model combines E×B shear-driven residual stress in the pedestal with a turbulent equipartition pinch to yield rotation profiles. The residual stress is the primary mechanism for buildup of intrinsic rotation in the H-mode pedestal, while the pinch drives on-axis peaking of rotation profiles. Analytical estimates for pedestal flow velocities are given in terms of the pedestal width, the pedestal height, and various model parameters. The predicted scaling of the toroidal flow speed with pedestal width is found to be consistent with the International Tokamak Physics Activity database global scaling of the flow speed on-axis with the total plasma stored energy. (10.1063/1.3339909)
  DOI : 10.1063/1.3339909
• Operation of a load current multiplier on a nanosecond mega-ampere pulse forming line generator
  
  • Chuvatin Alexandre S.
  • Kantsyrev Viktor L.
  • Rudakov Leonid I.
  • Cuneo Michael E.
  • Astanovitskiy A. L.
  • Presura Radu
  • Safronova Alla S.
  • Cline W.
  • Williamson Kenneth M.
  • Shrestha Ishor
  • Osborne Glenn C.
  • Le Galloudec B.
  • Nalajala Vidya
  • Pointon T. D.
  • Mikkelson K. A.
  Physical Review Special Topics: Accelerators and Beams, American Physical Society, 2010, 13 (1), pp.010401. We investigate the operation of a load current multiplier (LCM) on a pulse-forming-line nanosecond pulse-power generator. Potential benefits of using the LCM technique on such generators are studied analytically for a simplified case. A concrete LCM design on the Zebra accelerator (1.9 Ohm, &#8764;1&#8201;&#8201;MA, 100 ns) is described. This design is demonstrated experimentally with high-voltage power pulses having a rise time of dozens of nanoseconds. Higher currents and magnetic energies were observed in constant-inductance solid-state loads when a better generator-to-load energy coupling was achieved. The load current on Zebra was increased from the nominal 0.80.9 MA up to about 1.6 MA. This result was obtained without modifying the generator energetics or architecture and it is in good agreement with the presented numerical simulations. Validation of the LCM technique at a nanosecond time scale is of importance for the high-energy-density physics research. (10.1103/PhysRevSTAB.13.010401)
  DOI : 10.1103/PhysRevSTAB.13.010401
• A comparison of global models for the solar wind interaction with Mars
  
  • Brain D.
  • Barabash S.
  • Boesswetter A.
  • Bougher S.
  • Brecht S.
  • Chanteur Gérard
  • Hurley D.
  • Dubinin Eduard
  • Fang X.
  • Fraenz M.
  • Halekas J.
  • Harnett E.
  • Holmstrom M.
  • Kallio E.
  • Lammer H.
  • Ledvina S.
  • Liemohn M.
  • Liu K.
  • Luhmann J.
  • Ma Y.
  • Modolo Ronan
  • Nagy A.
  • Motschmann U.
  • Nilsson Hans
  • Shinagawa H.
  • Simon Sunil
  • Terada N.
  Icarus, Elsevier, 2010, 206 (1), pp.139-151. We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the models and run to steady state. Model output was compared in three ways to determine how pressure was partitioned and conserved in each model, the location and asymmetry of plasma boundaries and pathways for planetary ion escape, and the total escape flux of planetary oxygen ions. The two participating MHD models provided similar results, while the five sets of multi-fluid and hybrid results were different in many ways. All hybrid results, however, showed two main channels for oxygen ion escape (a pickup ion 'plume' in the hemisphere toward which the solar wind convection electric field is directed, and a channel in the opposite hemisphere of the central magnetotail), while the MHD models showed one (a roughly symmetric channel in the central magnetotail). Most models showed a transition from an upstream region dominated by plasma dynamic pressure to a magnetosheath region dominated by thermal pressure to a low altitude region dominated by magnetic pressure. However, calculated escape rates for a single ion species varied by roughly an order of magnitude for similar input conditions, suggesting that the uncertainties in both the current and integrated escape over martian history as determined by models are large. These uncertainties are in addition to those associated with the evolution of the Sun, the martian dynamo, and the early atmosphere, highlighting the challenges we face in constructing Mars' past using models. (10.1016/j.icarus.2009.06.030)
  DOI : 10.1016/j.icarus.2009.06.030
• THEMIS analysis of observed equatorial electron distributions responsible for the chorus excitation
  
  • Li W.
  • Thorne R. M.
  • Nishimura Y.
  • Bortnik J.
  • Angelopoulos V.
  • Mcfadden J. P.
  • Larson D. E.
  • Bonnell J. W.
  • Le Contel Olivier
  • Roux A.
  • Auster U.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2010, 115 (A6). A statistical survey of plasma densities and electron distributions (0.5-100 keV) is performed using data obtained from the Time History of Events and Macroscale Interactions During Substorms spacecraft in near-equatorial orbits from 1 July 2007 to 1 May 2009 in order to investigate optimum conditions for whistler mode chorus excitation. The plasma density calculated from the spacecraft potential, together with in situ magnetic field, is used to construct global maps of cyclotron and Landau resonant energies under quiet, moderate, and active geomagnetic conditions. Statistical results show that chorus intensity increases at higher AE index, with the strongest waves confined to regions where the ratio between the plasma frequency and gyrofrequency, f<SUB>pe</SUB>/f<SUB>ce</SUB>, is less than 5. On the nightside, large electron anisotropies and intense chorus emissions indicate remarkable consistency with the confinement to 8 R<SUB>E</SUB>. Furthermore, as injected plasma sheet electrons drift from midnight through dawn toward the noon sector, their anisotropy increases and peaks on the dayside at 7 < L < 9, which is well correlated with intense chorus emissions observed in the prenoon sector. These statistical results are generally consistent with the generation of both lower-band and upper-band chorus through cyclotron resonant interactions with suprathermal electrons (1-100 keV). Two typical events on the nightside and dayside are studied in greater detail and additional interesting features are identified. Pancake distributions of electrons with energy below 2 keV, which could be responsible for the excitation of upper-band chorus, are observed at lower L shells (<7) on the nightside and at larger L shells (>6) on the dayside. In addition, very isotropic distributions at a few keV, which may be produced by Landau resonance and contribute to the formation of the typical gap in the chorus spectrum near 0.5 f<SUB>ce</SUB>, are commonly observed on the dayside. (10.1029/2009JA014845)
  DOI : 10.1029/2009JA014845
• Measurements of stray antenna capacitance in the STEREO/WAVES instrument: Comparison of the measured voltage spectrum with an antenna electron shot noise model
  
  • Zouganelis I.
  • Maksimovic M.
  • Meyer-Vernet N.
  • Bale S. D.
  • Eastwood Jonathan P.
  • Zaslavsky A.
  • Dekkali M.
  • Goetz K.
  • Kaiser M. L.
  Radio Science, American Geophysical Union, 2010, 45, pp.1005. One of the most accurate techniques for in situ measuring the electron density and temperature in space plasmas is the quasi-thermal noise spectroscopy, which uses the voltage fluctuation spectrum on an electric antenna. This technique has been used successfully on the WIND and ULYSSES spacecraft; however, on STEREO this technique may only work in high-density filamentary structures, where the Debye length is small, because the STEREO/WAVES antennas have a large surface area, so that the resulting shot noise spectrum in the solar wind dominates the power at lower frequencies. In the unperturbed solar wind, we can use instead the electron shot noise to infer the plasma density. For doing so, we use well calibrated WIND particle data to deduce the stray capacitance of the STEREO/WAVES antenna system in a special configuration when the STEREO-B spacecraft was just downstream of WIND. This stray capacitance is also compared to ground experiments done on the flight spare equipment and independent calibrations performed using the galactic radio background. (10.1029/2009RS004194)
  DOI : 10.1029/2009RS004194
• Comparison of the use of SQUID an Hall effect sensors in NDE
  
  • Bettaieb L.
  • Kokabi H.
  • Poloujadoff M.
  • Sentz A.
  • Krause H. J
  • Coillot Christophe
  Materials Evaluation, American Society for Nondestructive Testing, 2010, 68 (5), pp.535-554. ...
• Electric Current Systems in the Earths Environment
  
  • Amory-Mazaudier Christine
  Nigerian Journal of Space Research, National space research and development agency, 2010, 8, pp.178-255. ...
• Cluster observations of outflowing electron distributions and broadband electrostatic emissions above the polar cap
  
  • Teste A.
  • Fontaine Dominique
  • Canu Patrick
  • Belmont Gérard
  Geophysical Research Letters, American Geophysical Union, 2010, 37, pp.3103. We investigate the excellent correlation between ionospheric upgoing electron beams and broadband electrostatic emissions (0-6 kHz) observed by Cluster, at 5 to 9 Earth's radii above the polar cap. In the absence of detailed, high time resolution waveform data in that region, we precisely analyzed several electron beams to obtain information concerning wave-particle interactions. Our results indicate that these beams are extremely variable and occasionally show multiple components. The processes involved might then occur on very short time scales, of the order of or shorter than sampling rates, typically 100 ms. We suggest that non linearities are at the origin of the spread of the frequency range of the waves simultaneously observed, as well as of the beam variability. We conclude that these electron beams are likely to destabilize Langmuir waves and, by the non-linear evolution of the electron bump-on-tail instability, could be responsible for the appearance of electrostatic solitary waves above the polar cap. (10.1029/2009GL041593)
  DOI : 10.1029/2009GL041593
• Residual parallel Reynolds stress due to turbulence intensity gradient in tokamak plasmas
  
  • Gürcan Özgür D.
  • Diamond P.H.
  • Hennequin Pascale
  • Mcdevitt C.J.
  • Garbet X.
  • Bourdelle C.
  Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112309. A novel mechanism for driving residual stress in tokamak plasmas based on k&#8741; symmetry breaking by the turbulence intensity gradient is proposed. The physics of this mechanism is explained and its connection to the wave kinetic equation and the wave-momentum flux is described. Applications to the H-mode pedestal in particular to internal transport barriers, are discussed. Also, the effect of heat transport on the momentum flux is discussed. (10.1063/1.3503624)
  DOI : 10.1063/1.3503624
• ECRH for JET: A feasibility study
  
  • Lennholm M.
  • Giruzzi G.
  • Parkin A.
  • Bouquey F.
  • Braune H.
  • Bruschi A.
  • Luna Elena de La
  • Denisov G.
  • Edlington T.
  • Farina D.
  • Farthing J.
  • Figini Lorenzo
  • Garavaglia S.
  • Garcia J.
  • Gerbaud Thomas
  • Granucci G.
  • Henderson M.
  • Horton L.
  • Kasparek W.
  • Khilar P.
  • Jennison M.
  • Kirneva N.
  • Kislov D.
  • Kuyanov A.
  • Litaudon X.
  • Litvak A.
  • Moro A.
  • Nowak S.
  • Parail V.
  • Plaum B.
  • Rimini F.
  • Saibene G.
  • Sips A. C. C.
  • Sozzi C.
  • Spaeh P.
  • Trukhina E.
  • Vaccaro A.
  • Vdovin V.
  Fusion Engineering and Design, Elsevier, 2010, 6-8, pp.805 - 809. For JET to fulfil its mission in preparing ITER operation, the installation of an electron cyclotron resonance heating system on JET would be desirable. The study described in this paper has investigated the feasibility of installing such a system on JET. The principal goals of such a system are: current drive over a range of radii for NTM stabilization, sawtooth control and current profile tailoring and central electron heating to equilibrate electron and ion temperatures in high performance discharges. The study concluded that a 12 gyrotron, 10 MW, system at the ITER frequency (170 GHz) adapted for fields of 2.7-3.3 T would be appropriate for the operation planned in JET. An antenna allowing toroidal and poloidal steering over a wide range is being designed, using the ITER upper launcher steering mechanism. The use of ITER diamond windows and transmission line technology is suggested while power supply solutions partially reusing existing JET power supplies are proposed. Detailed planning shows that such a system can be operational in about 5 years from the time that the decision to proceed is taken. The cost and required manpower associated with implementing such a system on JET has also been estimated. (C) 2011 EURATOM. Published by Elsevier B.V. All rights reserved.Commiss European Communities, B-1049 Brussels, Belgium.IRFM, CEA, F-13108 St Paul Les Durance, France.Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.EURATOM, Max Planck IPP, D-17491 Greifswald, Germany.EURATOM, CNR, Ist Fis Plasma, I-20125 Milan, Italy.Asociac EURATOM CIEMAT, Lab Nacl Fus, Madrid 28040, Spain.Inst Appl Phys, Nizhnii Novgorod 603155, Russia.Ecole Polytech, LPTP, F-91128 Palaiseau, France.ITER Org, F-13108 St Paul Les Durance, France.Univ Stuttgart, IPF, Stuttgart, Germany.RRC Kurchatov Inst, Moscow, Russia.Fus Energy, Barcelona 08019, Spain.Karlsruhe Inst Technol, Karlsruhe, Germany. (10.1016/j.fusengdes.2011.01.136)
  DOI : 10.1016/j.fusengdes.2011.01.136
• Poloidal rotation and its relation to the potential vorticity flux
  
  • Mcdevitt C.J.
  • Diamond P.H.
  • Gürcan Özgür D.
  • Hahm T.S.
  Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112509. A kinetic generalization of a Taylor identity appropriate to a strongly magnetized plasma is derived. This relation provides an explicit link between the radial mixing of a fourdimensional (4D) gyrocenter fluid and the poloidal Reynolds stress. This kinetic analog of a Taylor identity is subsequently utilized to link the turbulent transport of poloidal momentum to the mixing of potential vorticity. A quasilinear calculation of the flux of potential vorticity is carried out, yielding diffusive, turbulent equipartition, and thermoelectric convective components. Self-consistency is enforced via the quasineutrality relation, revealing that for the case of a stationary small amplitude wave population, deviations from neoclassical predictions of poloidal rotation can be closely linked to the growth/damping profiles of the underlying drift wave microturbulence. (10.1063/1.3490253)
  DOI : 10.1063/1.3490253