Publications

2009

Diagnosis of magnetic structures and intermittency in space-plasma turbulence using the technique of surrogate data
- Sahraoui Fouad
- Goldstein M. L.
, 2009.
Europlanet Integrated and Distributed Information Service
- Schmidt Walter
- Capria Maria Teresa
- Chanteur Gérard
- Tscherning C. C.
, 2009, 11, pp.9366. During the past decades the various disciplines in planetary sciences have developed to a very high international standard. But the collaboration between the different fields should be improved. To overcome the current fragmentation of the EU Planetary Science community and thereby to increase the scientific return of the related investment, the EU commission is funding via its Framework Program 7 the development of the "Europlanet Research Infrastructure -Europlanet RI". The Europlanet RI will consolidate the integration of the European Planetary Science community which started with Europlanet's FP6 project and will integrate major parts of the related distributed European infrastructure to be shared, fed and expanded by all planetary scientists. This infrastructure encompasses as diverse components as space exploration, ground-based observations, laboratory experiments and numerical modeling teams. Europlanet RI aims at bringing scientists from Europe and beyond together who are working in these fields, support the exchange of experts and ideas and make as many resources and data as possible available to the research community. A central part of Europlanet RI is the "Integrated and Distributed Information Service" or Europlanet-IDIS. The task of IDIS as central part of Europlanet is to provide an easy-to-use Web-based platform to locate teams and laboratories with special knowledge needed to support the own research activities, give access to the wealth of already available data, initiate new research activities needed to interpret accumulated data or to solve open questions, and to exploit synergies between space-based missions and capabilities of ground based observatories. It also offers to a wide range of teams and laboratories the possibility to share their data, advertise their capabilities and increase the scientific return by cooperation. IDIS is organized as an EU FP7 Support Activity, consisting of different access nodes which are connected by integrated search facilities, compatible structures and a common management. Each of these nodes concentrates on a special field of planetary sciences, has its own team of related international experts and is responsible for the access to information and data centres related to its area of competence. Integrated keyword-based search-possibilities direct inquiries to those node(s), most likely to return the wanted information. These nodes are hosted by the following organizations: - The Finnish Meteorological Institute (FMI) in Helsinki, Finland, hosts the Technical Node for a wide range of support activities and provides the network management. - The Institute of Planetary Research (IPR) of DLR in Berlin, Germany, hosts the Planetary Surfaces and Interiors Node, concentrating on internal structure, formation and evolution of the planets, their moons, asteroids and comets. - The Institut für Weltraumforschung, IWF (Space Research Institute) of the Austrian Academy of Sciences (OeAW) in Graz hosts the Planetary Plasma Node in close cooperation with the French space plasma data center CDPP in Toulouse. - The Institut Pierre-Simon Laplace in Paris hosts the Planetary Atmospheres Node. - The Paris Observatory hosts the Virtual Observatory Paris Data Center providing among others access to a wide range of atomic and molecular spectral databases. - The Istituto di Fisica dello Spazio Interplanetario (IFSI) in Rome hosts the Small Bodies and Dust Node, in cooperation with the ESA/ESTECs Virtual Meteor Observatory in Noordwijk, The Netherlands, concentrating on research and observations related to solar system asteroids, comets, meteors and interplanetary dust. During the next four years a set of tools for describing, accessing and combining information and data from different sources will be developed, offering finally a Virtual Observatory like access to many data essential for planetary research from European and None-European sources. Web access via any of the mentioned nodes, e.g. the Technical Node at http://www.europlanet-idis.fi
MHD wave turbulence, numerical results
- Grappin Roland
, 2009.
Titan s plasma wake geometry from RPWS and MAG observations
- Modolo Ronan
- Canu P.
- Bertucci C.
- Rosenqvist L.
- Kurth W. S.
- Gurnett D.
- Dougherty M. K.
, 2009, 11, pp.EGU2009-5912. Up to now, several tens of Titan flybys have been successfully completed by Cassini and have revealed a highly dynamic structure of the near space environment of Titan. The upstream condition of the plasma flow is expected to affect Titan's induced magnetosphere. The Titan's plasma wake has been investigated using observations from the Radio and Plasma Wave Science (RPWS) instruments (Gurnett et al, 2004) and the dual Magnetometer Technique MAG instruments (Dougherty et al, 2004). Electric field emissions were detected by the RPWS antennas during Cassini passes through Titan's wake. These narrow band emissions are identified as upper hybrid resonance emissions and therefore can provide a density estimate of the Titan's cold plasma. Some of Titan's wake flybys show a very strong asymmetry between the inbound and the outbound pass. Good examples are Ta and Tb flybys (Wahlund et al, 2005). Both flybys have a similar trajectory in Titan Interaction coordinate System (TIIS) and have the same illumination condition but the density profiles present major differences. Some of the Cassini flybys have been set back in the DRAP coordinate system (Neubauer et al, 2006) such that the upstream direction of the magnetic field is fixed, in order to determine the geometry of the plasma wake and study asymmetries. Maps of cold plasma in Titan's environment are presented. Information concerning the geometry of the wake is crucial to estimate accurately the plasma escape.
Nonstationarity of perpendicular shocks
- Hellinger P.
- Travnicek P.
- Lembège Bertrand
- Savoini Philippe
, 2009.
Heavy species kinetics in low-pressure dc pulsed discharges in air
- Pintassilgo C.D.
- Guaitella Olivier
- Rousseau Antoine
Plasma Sources Science and Technology, IOP Publishing, 2009, 18, pp.025005. A time-dependent kinetic model is presented to study low-pressure (133 and 210 Pa) pulsed discharges in air for dc currents ranging from 20 to 80mA with a pulse duration from 0.1 up to 1000 ms. The model provides the temporal evolution of the heavy species along the pulse within this range time, where the coupling between vibrational and chemical kinetics is taken into account. This work shows that the predicted values for NO(X) molecules and O(3P) atoms reproduce well previous measured data for these two species. A systematic analysis is carried out on the interpretation of experimental results. It is observed that the N2(X, v 13) + O → NO(X) + N(4S) and the reverse process NO(X) + N(4S) → N2(X, v ∼ 3) + O have practically the same rates for a pulse duration longer than 10 ms, each of them playing a dominant role in the populations of NO(X), N(4S) and, to a lesser extent, in O(3P) kinetics. Our simulations show that for shorter pulse durations, from 0.1 to 10 ms, NO(X) is produced mainly via the processes N2(A) + O → NO(X) + N(2D) and N(2D) + O2 → NO(X) + O, while the oxygen atoms are created mostly from electron impact dissociation of O2 molecules and by dissociative collisions with N2(A) and N2(B) molecules. (10.1088/0963-0252/18/2/025005)
DOI : 10.1088/0963-0252/18/2/025005
Etch process control with a deposition-tolerant planar electrostatic probe
- Booth Jean-Paul
- Keil D.
- Thorgrimsson C.
- Nagai M.
- Albarede L.
, 2009.
Physics of multiple-frequency capacitive discharges
- Chabert Pascal
- Levif P.
- Raimbault Jean-Luc
- Turner M.M.
- Lieberman M.A.
, 2009.
Analysis of energetic efficiency and kinetics of intermediates in the problem of plasma assisted ignition (AIAA-2009-692)
- Aleksandrov N.L.
- Kindusheva S.V.
- Kosarev I.N.
- Starikovskaia Svetlana
- Starikovskii A.Yu.
, 2009.
Titan's ionosphere in the magnetosheath : Cassini RPWS results during the T32 flyby
- Garnier P.
- Wahlund J.-E.
- Rosenqvist L.
- Modolo Ronan
- Agren K.
- Sergis N.
- Canu Patrick
- Andre M.
- Gurnett D.A.
- Kurth W.S.
- Krimigis S.M.
- Coates A.
- Dougherty M.
- Waite J.H
Annales Geophysicae, European Geosciences Union, 2009, 27 (11), pp.4257-4272. The Cassini mission has provided much information about the Titan environment, with numerous low altitude encounters with the moon being always inside the magnetosphere. The only encounter taking place outside the magnetopause, in the magnetosheath, occurred the 13 June 2007 (T32 flyby). This paper is dedicated to the analysis of the Radio and Plasma Wave investigation data during this specific encounter, in particular with the Langmuir probe, providing a detailed picture of the cold plasma environment and of Titan's ionosphere with these unique plasma conditions. The various pressure terms were also calculated during the flyby. The comparison with the T30 flyby, whose geometry was very similar to the T32 encounter but where Titan was immersed in the kronian magnetosphere, reveals that the evolution of the incident plasma has a significant influence on the structure of the ionosphere, with in particular a change of the exo-ionospheric shape. The electrical conductivities are given along the trajectory of the spacecraft and the discovery of a polar plasma cavity is reported. (10.5194/angeo-27-4257-2009)
DOI : 10.5194/angeo-27-4257-2009
Shape, size, velocity and field-aligned currents of dayside plasma injections: a multi-altitude study
- Marchaudon Aurelie
- Cerisier Jean-Claude
- Dunlop M.W.
- Pitout Frederic
- Bosqued Jean-Michel
- Fazakerley A. N.
Annales Geophysicae, European Geosciences Union, 2009, 27 (3), pp.1251-1266. On 20 February 2005, Cluster in the outer magnetosphere and Double Star-2 (TC-2) at mid-altitude are situated in the vicinity of the northern cusp/mantle, with Cluster moving sunward and TC-2 anti-sunward. Their magnetic footprints come very close together at about 15:28 UT, over the common field-of-view of SuperDARN radars. Thanks to this conjunction, we determine the velocity, the transverse sizes, perpendicular and parallel to this velocity, and the shape of three magnetic flux tubes of magnetosheath plasma injection. The velocity of the structures determined from the Cluster four-spacecraft timing analysis is almost purely antisunward, in contrast with the antisunward and duskward convection velocity inside the flux tubes. The transverse sizes are defined from the Cluster-TC-2 separation perpendicular to the magnetic field, and from the time spent by a Cluster spacecraft in one structure; they are comprised between 0.6 and 2 RE in agreement with previous studies. Finally, using a comparison between the eigenvectors deduced from a variance analysis of the magnetic perturbation at the four Cluster and at TC-2, we show that the upstream side of the injection flux tubes is magnetically well defined, with even a concave front for the third one giving a bean-like shape, whereas the downstream side is far more turbulent. We also realise the first quantitative comparison between field-aligned currents at Cluster calculated with the curlometer technique and with the single-spacecraft method, assuming infinite parallel current sheets and taking into account the velocity of the injection flux tubes. The results agree nicely, confirming the validity of both methods. Finally, we compare the field-aligned current distribution of the three injection flux tubes at the altitudes of Cluster and TC-2. Both profiles are fairly similar, with mainly a pair of opposite field-aligned currents, upward at low-latitude and downward at high-latitude. In terms of intensity, the field-aligned currents at Cluster are two to three times less intense than at TC-2 for the first two flux tubes, in agreement with magnetic field line convergence. For the third flux tube, the intensity is equal, which is explained by the fact that TC-2 crosses the tube on its edge. Finally, the analysis of the ion and electron moments at Cluster shows that the field-aligned currents result from a small difference between upward ion and electron fluxes. (10.5194/angeo-27-1251-2009)
DOI : 10.5194/angeo-27-1251-2009
Cascade models in plasma turbulence: The role of sheared flows
- Gürcan Özgür D.
- Garbet X.
- Hennequin Pascale
- Diamond P.H.
- Casati A.
, 2009 (oral).
Plasma sheet circulation pathways
- Moore T. E.
- Fok M.-C. H.
- Delcourt Dominique
- Slinker Steve P.
- Damiano P.
, 2009.
Plasma discharge inside water
- Ceccato P H
- Guaitella Olivier
- Rousseau Antoine
, 2009.
Electric propulsion using ion-ion plasmas
- Aanesland Ane
- Meige A.
- Chabert Pascal
Journal of Physics: Conference Series, IOP Science, 2009, 162, pp.012009. Recently, we have proposed to use both positive and negative ions for thrust in an electromagnetic space propulsion system. This concept is called PEGASES for Plasma Propulsion with Electronegative GASES and has been patented by the Ecole Polytechnique in France in 2007. The basic idea is to create a stratified plasma with an electron free (ion-ion plasma) region at the periphery of a highly ionized plasma core such that both positive and negative ions can be extracted and accelerated to provide thrust. As the extracted beam is globally neutral there is no need for a downstream neutralizer. The recombination of positive and negative ions is very efficient and will result in a fast recombination downstream of the thruster and hence there is no creation of a plasma plume downstream. The first PEGASES prototype, designed in 2007, has recently been installed in a small vacuum chamber for preliminary tests in our laboratory and the first results have been presented in several conferences. This paper reviews important work that has been used in the process of designing the first PEGASES prototype. (10.1088/1742-6596/162/1/012009)
DOI : 10.1088/1742-6596/162/1/012009
Wave emissions at half electron gyroharmonics in the equatorial plasmasphere region: CLUSTER observations and statistics
- El-Lemdani Mazouz F.
- Rauch Jean-Louis
- Décréau Pierrette
- Trotignon Jean-Gabriel
- Vallières Xavier
- Darrouzet F.
- Canu Patrick
- Suraud X.
Advances in Space Research, Elsevier, 2009, 43 (2), pp.253-264. Intense (n 1/2) fce emissions are a common phenomenon observed in the terrestrial inner magnetosphere. One of their interests is their possible effect in the pitch angle scattering of plasmasheet keV-electron, leading to diffuse auroras. In this paper, we present CLUSTERs point of view about this topic, in the equatorial region of the plasmasphere, via a statistical study using 3 years of data. Spectral characteristics of these waves, which represent an important clue concerning their generation mechanism, are obtained using WHISPER data near perigee. Details on the wave spectral signature are shown in an event study, in particular their splitting in fine frequency bands. The orbit configuration of the four spacecraft offers a complete sampling on all MLT sectors. A higher occurrence rate of the emissions in the dawn sector and their confinement to the geomagnetic equator, pointed out in previous studies, are confirmed and described with additional details. The proximity of emission sites, both to the plasmapause layer and to the geomagnetic equator surface, seems to be of great importance in the behaviour of the (n 1/2) fce wave characteristics. Our study indicates for the first time, that both the intensity of (n 1/2) fce emissions, and the number of harmonic bands they cover, are increasing as the observation point is located further away outside from the plasmapause layer. Moreover, a study of the wave intensity in the first harmonic band (near 3/2 fce) shows higher amplitude for these emissions than previous published values, these emissions can play a role in the scattering of hot electrons. Finally, geomagnetic activity influence, studied via time series of the Dst index preceding observations, indicates that (n 1/2) fce emission events are observed at CLUSTER position under moderate geomagnetic activity conditions, no specific Dst time variation being required. (10.1016/j.asr.2008.06.007)
DOI : 10.1016/j.asr.2008.06.007
A novel mechanism for exciting intrinsic toroidal rotation
- Mcdevitt C.J.
- Diamond P.H.
- Gürcan Özgür D.
- Hahm T.S.
Physics of Plasmas, American Institute of Physics, 2009, 16, pp.052302. Beginning from a phase space conserving gyrokinetic formulation, a systematic derivation of parallel momentum conservation uncovers two physically distinct mechanisms by which microturbulence may drive intrinsic rotation. The first mechanism, which emanates from E×B convection of parallel momentum, has already been analyzed [ O. D. Gurcan et al., Phys. Plasmas 14, 042306 (2007) ; R. R. Dominguez and G. M. Staebler, Phys. Fluids B 5, 3876 (1993) ] and was shown to follow from radial electric field shear induced symmetry breaking of the spectrally averaged parallel wave number. Thus, this mechanism is most likely active in regions with steep pressure gradients or strong poloidal flow shear. The second mechanism uncovered, which appears in the gyrokinetic formulation through the parallel nonlinearity, emerges due to charge separation induced by the polarization drift. This novel means of driving intrinsic rotation, while nominally higher order in an expansion of the mode frequency divided by the ion cyclotron frequency, does not depend on radial electric field shear. Thus, while the magnitude of the former mechanism is strongly reduced in regions of weak radial electric field shear, this mechanism remains unabated and is thus likely relevant in complementary regimes. (10.1063/1.3122048)
DOI : 10.1063/1.3122048
Electron transport coefficients in mixtures of CF4 and CF2 radicals
- Nikitovic Zd
- Stojanovic Vd
- Booth Jean-Paul
- Petrovic Zl
Plasma Sources Science and Technology, IOP Publishing, 2009, 18, pp.035008. Electron kinetics determines the rate of production of chemically active species in processing plasmas. Precise transport coefficients are needed to describe conditions such as those found in plasma assisted technologies for semiconductor production, but these are affected by the density of free radicals, which in themselves depend on the chemical kinetics. We present transport coefficients for electrons in mixtures of CF4 with CF2 (and we also show similar results for other radicals) for ratios of the electric field to the gas number density E/N from 1 to 1000 Td (1 Td = 10−21 V m2). Our analysis of non-conservative collisions revealed a range of E/N where electron attachment to radicals significantly changes the electron kinetics compared with pure CF4 gas. The results are obtained using simple solutions for Boltzmann's equation and exact Monte Carlo simulations. (10.1088/0963-0252/18/3/035008)
DOI : 10.1088/0963-0252/18/3/035008
Cross-scale: multi-scale coupling in space plasmas
- Schwartz S. J.
- Horbury T.
- Owen C.
- Baumjohann W.
- Nakamura R.
- Canu Patrick
- Roux A.
- Sahraoui Fouad
- Louarn P.
- Sauvaud J.-A.
- Pinçon Jean-Louis
- Vaivads A.
- Marcucci M. F.
- Anastasiadis A.
- Fujimoto M.
- Escoubet P.
- Taylor M.
- Eckersley S.
- Allouis E.
- Perkinson M.-C.
Experimental Astronomy, Springer Link, 2009, 23, pp.1001-1015. Most of the visible universe is in the highly ionised plasma state, and most of that plasma is collision-free. Three physical phenomena are responsible for nearly all of the processes that accelerate particles, transport material and energy, and mediate flows in systems as diverse as radio galaxy jets and supernovae explosions through to solar flares and planetary magnetospheres. These processes in turn result from the coupling amongst phenomena at macroscopic fluid scales, smaller ion scales, and down to electron scales. Cross-Scale, in concert with its sister mission SCOPE (to be provided by the Japan Aerospace Exploration AgencyJAXA), is dedicated to quantifying that nonlinear, time-varying coupling via the simultaneous in-situ observations of space plasmas performed by a fleet of 12 spacecraft in near-Earth orbit. Cross-Scale has been selected for the Assessment Phase of Cosmic Vision by the European Space Agency. (10.1007/s10686-008-9085-x)
DOI : 10.1007/s10686-008-9085-x
Evaluation of whistler-mode chorus intensification on the nightside during an injection event observed on the THEMIS spacecraft
- Li W.
- Thorne R. M.
- Angelopoulos V.
- Bonnell J. W.
- Mcfadden J. P.
- Carlson C. W.
- Le Contel Olivier
- Roux A.
- Glassmeier K.-H.
- Auster H.-U.
Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2009, 114. The intensification of the nightside whistler-mode chorus emissions is observed in the low-density region outside the plasmapause during the injection of anisotropic plasma sheet electrons into the inner magnetosphere. Time History of Events and Macroscale Interactions During Substorms data of the electron phase space density over the energy range between 0.1 keV and 30 keV are used to develop an analytical model for the distribution of injected suprathermal electrons. The path-integrated gain of chorus waves is then evaluated with the HOTRAY code by tracing whistler-mode chorus waves in a hot magnetized plasma. The simulated wave gain is compared to the observed wave electric field and magnetic field, respectively. The results indicate that lower-energy (<1 keV) plasma sheet electrons can penetrate deeper toward the Earth but cause little chorus intensification, while higher-energy (1 keV to tens of kiloelectron volts) electrons can be injected at relatively higher L-shells and are responsible for the intensification of lower-band and upper-band whistler-mode chorus. Compared to the lower-band chorus, a relatively higher electron anisotropy is required to generate upper-band chorus. In addition, higher plasma density results in stronger wave intensity and a broader frequency band of chorus waves. (10.1029/2008JA013554)
DOI : 10.1029/2008JA013554
Quasi-thermal noise in space plasma: ``kappa'' distributions
- Le Chat G.
- Issautier K.
- Meyer-Vernet N.
- Zouganelis I.
- Maksimovic M.
- Moncuquet M.
Physics of Plasmas, American Institute of Physics, 2009, 16, pp.102903. The transport of energy in collisionless plasmas, especially in space plasmas, is far from being understood. Measuring the temperature of the electrons and their nonthermal properties can give important clues to understand the transport properties. Quasi-thermal noise (QTN) spectroscopy is a reliable tool for measuring accurately the electron density and temperature since it is less sensitive to the spacecraft perturbations than particle detectors. This work models the plasma QTN using a generalized Lorentzian (``kappa'') distribution function for the electrons. This noise is produced by the quasi-thermal fluctuations of the electrons and by the Doppler-shifted thermal fluctuations of the ions. A sum of two Maxwellian functions has mainly been used for modeling the QTN of the electrons, but the observations have shown that the electrons are better fitted by a kappa distribution function. Pioneer work on QTN calculation only considered integer values of kappa. This paper extends these calculations to real values of kappa and gives the analytic expressions and numerical calculations of the QTN with a kappa distribution function. This paper shows some generic properties and gives some practical consequences for plasma wave measurements in space. (10.1063/1.3243495)
DOI : 10.1063/1.3243495
An Observation Linking the Origin of Plasmaspheric Hiss to Discrete Chorus Emissions
- Bortnik J.
- Li W.
- Thorne R. M.
- Angelopoulos V.
- Cully C. M.
- Bonnell J. W.
- Le Contel Olivier
- Roux A.
Science, American Association for the Advancement of Science (AAAS), 2009, 324 (5928), pp.775-778. A long-standing problem in the field of space physics has been the origin of plasmaspheric hiss, a naturally occurring electromagnetic wave in the high-density plasmasphere (roughly within 20,000 kilometers of Earth) that is known to remove the high-energy Van Allen Belt electrons that pose a threat to satellites and astronauts. A recent theory tied the origin of plasmaspheric hiss to a seemingly different wave in the outer magnetosphere, but this theory was difficult to test because of a challenging set of observational requirements. Here we report on the experimental verification of the theory, made with a five-satellite NASA mission. This confirmation will allow modeling of plasmaspheric hiss and its effects on the high-energy radiation environment. (10.1126/science.1171273)
DOI : 10.1126/science.1171273
Global Scale-Invariant Dissipation in Collisionless Plasma Turbulence
- Dunlop M. W.
- Sahraoui Fouad
- Kiyani K. H.
- Chapman S. C.
- Khotyaintsev Y. V.
Physical Review Letters, American Physical Society, 2009, 103, pp.075006. A higher-order multiscale analysis of the dissipation range of collisionless plasma turbulence is presented using in situ high-frequency magnetic field measurements from the Cluster spacecraft in a stationary interval of fast ambient solar wind. The observations, spanning five decades in temporal scales, show a crossover from multifractal intermittent turbulence in the inertial range to non-Gaussian monoscaling in the dissipation range. This presents a strong observational constraint on theories of dissipation mechanisms in turbulent collisionless plasmas. (10.1103/PhysRevLett.103.075006)
DOI : 10.1103/PhysRevLett.103.075006
Magnetic island formation between large-scale flow vortices at an undulating postnoon magnetopause for northward interplanetary magnetic field
- Cully C. M.
- Larson D. E.
- Ergun R. E.
- Roux A.
- Carlson C. W.
- Eriksson S.
- Hasegawa H.
- Teh W.-L.
- Sonnerup B. U. Ö.
- Mcfadden J. P.
- Glassmeier K.-H.
- Le Contel Olivier
- Angelopoulos V.
Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2009, 114. Time History of Events and Macroscale Interactions during Substorms multispacecraft observations are presented for a ~2-h-long postnoon magnetopause event on 8 June 2007 that for the first time indicate that the trailing (sunward) edges of Kelvin-Helmholtz (KH) waves are commonly related to small-scale <0.56 R E magnetic islands or flux transfer events (FTE) during the growth phase of these surface waves. The FTEs typically show a characteristic bipolar B N structure with enhanced total pressure at their center. Most of the small-scale FTEs are not related to any major plasma acceleration. TH-A observations of one small FTE at a transition from the low-latitude boundary layer (LLBL) into a magnetosheath plasma depletion layer were reconstructed using separate techniques that together confirm the presence of a magnetic island within the LLBL adjacent to the magnetopause. The island was associated with a small plasma vortex and both features appeared between two large-scale (~1 R E long and 2000 km wide) plasma vortices. We propose that the observed magnetic islands may have been generated from a time-varying reconnection process in a low ion plasma beta (beta i < 0.2) and low 8.3° field shear environment at the sunward edge of the growing KH waves where the local magnetopause current sheet may be compressed by the converging flow of the large-scale plasma vortices as suggested by numerical simulations of the KH instability. (10.1029/2008JA013505)
DOI : 10.1029/2008JA013505
Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations
- Casati A.
- Gerbaud T.
- Hennequin P.
- Heuraux Stéphane
Physical Review Letters, American Physical Society, 2009, 102, pp.165005. Turbulence measurements in TORE SUPRA tokamak plasmas have been quantitatively compared to predictions by nonlinear gyrokinetic simulations. For the first time, numerical results simultaneously match within experimental uncertainty (a) the magnitude of effective heat diffusivity, (b) rms values of density fluctuations, and (c) wave-number spectra in both the directions perpendicular to the magnetic field. Moreover, the nonlinear simulations help to revise as an instrumental effect the apparent experimental evidence of strong turbulence anisotropy at spatial scales of the order of ion-sound Larmor radius.

Retour aux années