Publications

2019

• Measurement of the tilt angle of turbulent structures in magnetically confined plasmas using Doppler reflectometry
  
  • Pinzon Javier
  • Estrada Teresa
  • Happel T.
  • Hennequin Pascale
  • Blanco E.
  • Stroth Ulrich
  Plasma Physics and Controlled Fusion, IOP Publishing, 2019. The mean tilt angle of turbulent structures is a key element for describing the turbulence and its interplay with plasma flows in magnetically confined plasmas. It is a quantity predicted by theories and gyrokinetic simulations, which can provide information on the type of the dominant micro-instability, and also on the turbulence anisotropy induced by sheared flows. A new method for measuring the tilt angle of turbulent structures using Doppler reflectometry has been recently introduced [J R Pinzón <i>et al</i> 2019 Nucl. Fusion 59 074002]. It is based on the time delay of the cross-correlation between microwaves backscattered at radially displaced positions. In this paper, the method is presented in detail and is successfully applied on the ASDEX Upgrade tokamak and the TJ-II stellarator. Measurements of the tilt angle in the core of both machines are reported, in the TJ-II case, for the first time. (10.1088/1361-6587/ab394d)
  DOI : 10.1088/1361-6587/ab394d
• Turbulence and Microprocesses in Inhomogeneous Solar Wind Plasmas
  
  • Krafft C.
  • Volokitin A. S.
  • Gauthier Gaétan
  Fluids, MDPI, 2019, 4 (2), pp.69. The random density fluctuations observed in the solar wind plasma crucially influence on the Langmuir wave turbulence generated by energetic electron beams ejected during solar bursts. Those are powerful phenomena consisting of a chain of successive processes leading ultimately to strong electromagnetic emissions. The small-scale processes governing the interactions between the waves, the beams and the inhomogeneous plasmas need to be studied to explain such macroscopic phenomena. Moreover, the complexity induced by the plasma irregularities requires to find new approaches and modelling. Therefore theoretical and numerical tools were built to describe the Langmuir wave turbulence and the beams dynamics in inhomogeneous plasmas, in the form of a self-consistent Hamiltonian model including a fluid description for the plasma and a kinetic approach for the beam. On this basis, numerical simulations were performed in order to shed light on the impact of the density fluctuations on the beam dynamics, the electromagnetic wave radiation, the generation of Langmuir wave turbulence, the waves coupling and decay phenomena involving Langmuir and low frequency waves, the acceleration of beam electrons, their diffusion mechanisms, the modulation of the Langmuir waveforms and the statistical properties of the radiated fields distributions. The paper presents the main results obtained in the form of a review. (10.3390/fluids4020069)
  DOI : 10.3390/fluids4020069
• The Role of Upper Hybrid Waves in the Magnetotail Reconnection Electron Diffusion Region
  
  • Jiang K.
  • Huang S. Y.
  • Yuan Z. G.
  • Sahraoui Fouad
  • Deng X. H.
  • Yu X. D.
  • He L. H.
  • Deng D.
  • Wei Y. Y.
  • Xu S. B.
  The Astrophysical Journal Letters, Bristol : IOP Publishing, 2019, 881 (2), pp.L28. Plasma waves are believed to play an important role during magnetic reconnection. However, the specific role of upper hybrid (UH) waves in the electron diffusion region (EDR) remains elusive, owing to the absence of high-resolution measurements. We analyze one EDR event in the magnetotail on 2017 July 11 observed by the Magnetospheric Multiscale (MMS) mission. To the best of our knowledge, this is the first time that intense UH waves have been observed in the EDR by MMS. The agyrotropic crescent-shaped electron distributions could result in the observed UH waves. Concomitant with the observations of UH waves, the agyrotropy parameter of the electrons decreases, implying that the UH waves could effectively scatter the electrons in the EDR. The good accordance of positive energy conversion (, likely dissipation) and the observed UH waves indicates that UH waves may contribute to the energy conversion from the magnetic fields to the plasma particles during magnetic reconnection. (10.3847/2041-8213/ab36b9)
  DOI : 10.3847/2041-8213/ab36b9
• Fluidization of collisionless plasma turbulence
  
  • Meyrand Romain
  • Kanekar Anjor
  • Dorland William
  • Schekochihin Alexander A.
  Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2019, 116, pp.1185. In a collisionless, magnetized plasma, particles may stream freely alongmagnetic field lines, leading to ?phase mixing? of their distributionfunction and consequently, to smoothing out of any ?compressive?fluctuations (of density, pressure, etc.). This rapid mixing underliesLandau damping of these fluctuations in a quiescent plasma?one of themost fundamental physical phenomena that makes plasma different from aconventional fluid. Nevertheless, broad power law spectra of compressivefluctuations are observed in turbulent astrophysical plasmas (mostvividly, in the solar wind) under conditions conducive to strong Landaudamping. Elsewhere in nature, such spectra are normally associated withfluid turbulence, where energy cannot be dissipated in the inertial-scale range and is, therefore, cascaded from large scales to small. Bydirect numerical simulations and theoretical arguments, it is shown herethat turbulence of compressive fluctuations in collisionless plasmasstrongly resembles one in a collisional fluid and does have broad powerlaw spectra. This ?fluidization? of collisionless plasmas occurs,because phase mixing is strongly suppressed on average by ?stochasticechoes,? arising due to nonlinear advection of the particle distributionby turbulent motions. Other than resolving the long-standing puzzle ofobserved compressive fluctuations in the solar wind, our results suggesta conceptual shift for understanding kinetic plasma turbulencegenerally: rather than being a system where Landau damping plays therole of dissipation, a collisionless plasma is effectivelydissipationless, except at very small scales. The universality of?fluid? turbulence physics is thus reaffirmed even for a kinetic,collisionless system. (10.1073/pnas.1813913116)
  DOI : 10.1073/pnas.1813913116
• Energy Cascade Rate Measured in a Collisionless Space Plasma with MMS Data and Compressible Hall Magnetohydrodynamic Turbulence Theory
  
  • Andrés Nahuel
  • Sahraoui Fouad
  • Galtier Sébastien
  • Hadid Lina
  • Ferrand R.
  • Huang S.Y.
  Physical Review Letters, American Physical Society, 2019, 123 (24), pp.055102. The first complete estimation of the compressible energy cascade rate lεCl at magnetohydrodynamic (MHD) and subion scales is obtained in Earth’s magnetosheath using Magnetospheric MultiScale spacecraft data and an exact law derived recently for compressible Hall MHD turbulence. A multispacecraft technique is used to compute the velocity and magnetic gradients, and then all the correlation functions involved in the exact relation. It is shown that when the density fluctuations are relatively small, lεCl identifies well with its incompressible analog jεIj at MHD scales but becomes much larger than jεIj at subion scales. For larger density fluctuations, lεCl is larger than jεIj at every scale with a value significantly higher than for smaller density fluctuations. Our study reveals also that for both small and large density fluctuations, the nonflux terms remain always negligible with respect to the flux terms and that the major contribution to lεCl at subion scales comes from the compressible Hall flux. (10.1103/PhysRevLett.123.245101)
  DOI : 10.1103/PhysRevLett.123.245101
• Oxygen (<SUP>3</SUP>P) atom recombination on a Pyrex surface in an O<SUB>2</SUB> plasma
  
  • Booth Jean-Paul
  • Guaitella Olivier
  • Chatterjee Abhyuday
  • Drag Cyril
  • Guerra V.
  • Lopaev Dmitry
  • Zyryanov Sergey
  • Rakhimova Tatyana
  • Voloshin Dmitry
  • Mankelevich Y.
  Plasma Sources Science and Technology, IOP Publishing, 2019, 28 (5), pp.055005. The recombination of O (3P) atoms on the surface of a Pyrex tube containing a DC glow discharge in pure O2 was studied over a wide range of pressure (0.210 Torr) and discharge current (1040 mA) for two fixed surface temperatures ( 50 °C and 5 °C). The recombination probability, &#947;, was deduced from the observed atom loss rate (dominated by surface recombination) determined by time-resolved optical emission actinometry in partially-modulated (amplitude ~15%17%) discharges. The value of &#947; increased with discharge current at all pressures studied. As a function of pressure it passes through a minimum at ~0.75 Torr. At pressures above this minimum &#947; is well-correlated with the gas temperature, T g, (determined from the rotational structure of the O2 (b1&#931;g , v = 0) &#8594; O2(X3&#931;g &#8722;, v = 0) emission spectrum) which increases with pressure and current. The temperature of the atoms incident at the surface was deduced from a model, calibrated by measurements of the spatially-averaged gas temperature and validated by radial temperature profile measurements. The value of &#947; follows an Arrhenius law depending on the incident atom temperature, with an activation energy in the range 0.130.16 eV. At the higher surface temperature the activation energy is the same, but the pre-exponential factor is smaller. Under conditions where the O flux to the surface is low &#947; falls below this Arrhenius law. These results are well explained by an EleyRideal (ER) mechanism with incident O atoms recombining with both chemisorbed and more weakly bonded physisorbed atoms on the surface, with the kinetic energy of the incident atoms providing the energy to overcome the activation energy barrier. A phenomenological ER model is proposed that explains both the decrease in recombination probability with surface temperature as well as the deviations from the Arrhenius law when the O flux is low. At pressures below 0.75 Torr &#947; increases significantly, and also increases strongly with the discharge current. We attribute this effect to incident ions and fast neutrals arriving with sufficient energy to clean or chemically modify the surface, generating new adsorption sites. Discharge modeling confirms that at pressures below ~0.3 Torr a noticeable fraction of the ions arriving at the surface have adequate kinetic energy to break surface chemical bonds (>35 eV). (10.1088/1361-6595/ab13e8)
  DOI : 10.1088/1361-6595/ab13e8
• Linear discriminant analysis based predator-prey analysis of hot electron effects on the X-pinch plasma produced K-shell Aluminum spectra
  
  • Fatih Yilmaz Mehmet
  • Danisman Yusuf
  • Larour Jean
  • Arantchouk Léonid
  Scientific Reports, Nature Publishing Group, 2019, 9, pp.11867. In this study, Linear Discriminant Analysis (LDA) is applied to investigate the electron beam effects on the X-pinch produced K-shell Aluminum plasma. The radiating plasma is produced by the explosion of two 25-μm Al wires on a compact L-C (40 kV, 200 kA and 200 ns) generator, and the time integrated spectra are recorded using de Broglie spectrographs. The ion and electron oscillations of K-shell Al plasma are extracted using LDA of spectral database of non-LTE K-shell Al model. A three dimensional representation of LDA shows that the presence of electron beam exhibits outward spirals of Langmuir turbulence and the center region of the spirals recieves lower electron temperatures of 50–100 eV. These spirals then are modeled by logistic growth of predator-prey model. This modeling suggests that the ions (LD1: most dominant eigenvector of LDA) and electrons (LD2: second most dominant eigenvector of LDA) represent the predators and preys, respectively. Besides, addition of electron beams transforms evanescent oscillations to the standing ones. (10.1038/s41598-019-47997-6)
  DOI : 10.1038/s41598-019-47997-6
• Universality of Lower Hybrid Waves at Earth's Magnetopause
  
  • Graham D. B.
  • Khotyaintsev Yu. V.
  • Norgren C.
  • Vaivads A.
  • André M.
  • Drake J. F.
  • Egedal J.
  • Zhou M.
  • Le Contel O.
  • Webster J. M.
  • Lavraud B.
  • Kacem I.
  • Génot V.
  • Jacquey C.
  • Rager A. C.
  • Gershman D. J.
  • Burch J. L.
  • Ergun R. E.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2019, 124, pp.8727-8760. Waves around the lower hybrid frequency are frequently observed at Earth's magnetopause and readily reach very large amplitudes. Determining the properties of lower hybrid waves is crucial because they are thought to contribute to electron and ion heating, cross-field particle diffusion, anomalous resistivity, and energy transfer between electrons and ions. All these processes could play an important role in magnetic reconnection at the magnetopause and the evolution of the boundary layer. In this paper, the properties of lower hybrid waves at Earth's magnetopause are investigated using the Magnetospheric Multiscale mission. For the first time, the properties of the waves are investigated using fields and direct particle measurements. The highest-resolution electron moments resolve the velocity and density fluctuations of lower hybrid waves, confirming that electrons remain approximately frozen in at lower hybrid wave frequencies. Using fields and particle moments, the dispersion relation is constructed and the wave-normal angle is estimated to be close to 90° to the background magnetic field. The waves are shown to have a finite parallel wave vector, suggesting that they can interact with parallel propagating electrons. The observed wave properties are shown to agree with theoretical predictions, the previously used single-spacecraft method, and four-spacecraft timing analyses. These results show that single-spacecraft methods can accurately determine lower hybrid wave properties. (10.1029/2019JA027155)
  DOI : 10.1029/2019JA027155
• Evidence of Electron Acceleration at a Reconnecting Magnetopause
  
  • Fu H.S.
  • Peng F. Z.
  • Liu C. M.
  • Burch J. L.
  • Gershman D. G.
  • Le Contel Olivier
  Geophysical Research Letters, American Geophysical Union, 2019, 46 (11), pp.5645-5652. It is still unknown nowadays whether magnetic reconnection−-a process occurring both in the magnetotail and at the magnetopause−-can intrinsically accelerate energetic electrons. Observations in the Earth's magnetotail usually indicate strong electron acceleration during magnetic reconnection, while observations at the Earth's magnetopause rarely show such features. With the recently launched Magnetospheric Multiscale (MMS) mission, here we report the first evidence of energetic-electron acceleration at a reconnecting magnetopause. We find that the acceleration of electrons, with energy up to 70 times their thermal energy, occurs in the magnetosheath side of the ion diffusion region and is associated with strong whistler waves. Such acceleration−-not contaminated by the magnetospheric population−-is attributed to nonadiabatic wave-particle interactions, as supported by analyses of the resonance condition. It manifests that energetic-electron acceleration can happen at the reconnecting magnetopause, like that in the tail. (10.1029/2019GL083032)
  DOI : 10.1029/2019GL083032
• Electron-Driven Dissipation in a Tailward Flow Burst
  
  • Chen Z. Z.
  • Fu H.S.
  • Liu C. M.
  • Wang T. Y.
  • Ergun R. E.
  • Cozzani Giulia
  • Huang S. Y.
  • Khotyaintsev Y. V.
  • Le Contel Olivier
  • Giles B. L.
  • Burch J. L.
  Geophysical Research Letters, American Geophysical Union, 2019, 46 (11), pp.5698-5706. Traditionally, the magnetotail flow burst outside the diffusion region is known to carry ions and electrons together (V<SUB>i</SUB> = V<SUB>e</SUB>), with the frozen-in condition well satisfied (E V<SUB>e</SUB> × B = 0). Such picture, however, may not be true, based on our analyses of the high-resolution MMS (Magnetospheric Multiscale mission) data. We find that inside the flow burst the electrons and ions can be decoupled (V<SUB>e</SUB> != V<SUB>i</SUB>), with the electron speed 5 times larger than the ion speed. Such super-Alfvenic electron jet, having scale of 10 d<SUB>i</SUB> (ion inertial length) in X<SUB>GSM</SUB> direction, is associated with electron demagnetization (E V<SUB>e</SUB> × B != 0), electron agyrotropy (crescent distribution), and O-line magnetic topology but not associated with the flow reversal and X-line topology; it can cause strong energy dissipation and electron heating. We quantitatively analyze the dissipation and find that it is primarily attributed to lower hybrid drift waves. These results emphasize the non-MHD (magnetohydrodynamics) behaviors of magnetotail flow bursts and the role of lower hybrid drift waves in dissipating energies. (10.1029/2019GL082503)
  DOI : 10.1029/2019GL082503
• Stationarity of I-mode operation and I-mode divertor heat fluxes on the ASDEX Upgrade tokamak
  
  • Happel T.
  • Griener M.
  • Silvagni D.
  • Freethy S. J.
  • Hennequin Pascale
  • Janky F.
  • Manz P.
  • Prisiazhniuk D.
  • Ryter F.
  • Bernert M.
  • Brida D.
  • Eich T.
  • Faitsch M.
  • Gil L.
  • Guimarais L.
  • Merle A.
  • Nille D.
  • Pinzón J R
  • Sieglin B.
  • Stroth U.
  • Viezzer E.
  Nuclear Materials and Energy, Elsevier, 2019, 18, pp.159 - 165. Recent I-mode investigations from the ASDEX Upgrade tokamak are reported. It is shown that neutral-beam-injection heated I-modes can be stationary, which is important in terms of extrapolability towards future fusion devices. Furthermore, detailed studies on the weakly coherent mode are reported. In particular, experimental observations point towards its existence in L-mode, before I-mode starts. Moreover, its impact on density and temperature fluctuations is evaluated. Studies of stationary divertor heat fluxes show that in I-mode, the upstream power fall-off length is between those observed in L-mode and H-mode, and it is connected to the scrape-off layer temperature fall-off length. Moreover, analysis of transient divertor heat loads shows that intermittent turbulent events, observed in the confinement region and linked to the weakly coherent mode, are responsible for a significant part of divertor heat loads. (10.1016/j.nme.2018.12.022)
  DOI : 10.1016/j.nme.2018.12.022
• A rotational Raman study under non-thermal conditions in pulsed CO2−N2 and CO2−O2 glow discharges
  
  • Grofulovic Marija
  • Klarenaar Bart
  • Guaitella Olivier
  • Guerra V.
  • Engeln Richard
  Plasma Sources Science and Technology, IOP Publishing, 2019, 28 (4), pp.045014. This work employs in situ rotational Raman spectroscopy to study the effect of N2 and O2 addition to CO2 in pulsed glow discharges in the mbar range. The spatiotemporally resolved measurements are performed in CO2 and 25%, 50% and 75% of N2 or O2 admixture, in a 510 ms on-off cycle, 50 mA plasma current and 6.7 mbar total pressure. The rotational temperature profile is not affected by adding N2, ranging from 400 to 850 K from start to end of the discharge pulse, while the addition of O2 decreases the temperature at corresponding time points. Molecular number densities of CO2, CO, O2 and N2 are determined, showing the spatial homogeneity along the axis of the reactor and uniformity during the cycle. The measurements in the N2 containing mixtures show that CO2 conversion factor &#945; increases from 0.15 to 0.33 when the content of N2 is increased from 0% to 75%, demonstrating the potential of N2 addition to enhance the vibrational pumping of CO2 and its beneficial effect on CO2 dissociation. Furthermore, the influence of admixtures on CO2 vibrations is examined by analysing the vibrationally averaged nuclear spin degeneracy. The difference between the fitted odd averaged degeneracy and the calculated odd degeneracy assuming thermal conditions increases with the addition of N2, demonstrating the growth of vibrational temperatures in CO2. On the other hand, the addition of O2 leads to a decrease of &#945;, which might be attributed to quenched vibrations of CO2, and/or to the influence of the back reaction in the presence of O2. (10.1088/1361-6595/ab1240)
  DOI : 10.1088/1361-6595/ab1240
• Whistler Waves Driven by Field-Aligned Streaming Electrons in the Near-Earth Magnetotail Reconnection
  
  • Ren Y.
  • Dai L.
  • Li W.
  • Tao X.
  • Wang C.
  • Tang B.
  • Lavraud B.
  • Wu Y.
  • Burch J. L.
  • Giles B. L.
  • Le Contel Olivier
  • Torbert R. B.
  • Russell C. T.
  • Strangeway R. J.
  • Ergun R. E.
  • Lindqvist P.-A.
  Geophysical Research Letters, American Geophysical Union, 2019, 46 (10), pp.5045-5054. We analyze Magnetospheric Multiscale Mission observations of whistler waves and associated electron field-aligned crescent distribution in the vicinity of the magnetotail near-Earth X-line. The whistler waves propagate outward from the X-line in the neutral sheet. The associated field-aligned streaming electrons exhibit a crescent-like shape, with an inverse slope (df/d|v<SUB>||</SUB>|>0) at 1-5 keV. The parallel phase velocity of the waves is in the range (1-5 keV) of the inverse slope of the field-aligned crescents in the velocity space. We demonstrate that the observed whistler waves are driven by the electron field-aligned crescents through Landau resonance. The cyclotron resonance is at the high-energy tail with negligible free energy of pitch angle anisotropy in these events. (10.1029/2019GL083283)
  DOI : 10.1029/2019GL083283
• Erratum: Multi frequency matching for voltage waveform tailoring <A href="/abs/">(2018 Plasma Sources Sci. Technol. 27 095012</A>)
  
  • Schmidt Frederik
  • Schulze Julian
  • Johnson Erik
  • Booth Jean-Paul
  • Keil Douglas
  • French David M.
  • Trieschmann Jan
  • Mussenbrock Thomas
  Plasma Sources Science and Technology, IOP Publishing, 2019, 28, pp.019601. (10.1088/1361-6595/aaeb4b)
  DOI : 10.1088/1361-6595/aaeb4b
• Electron Distribution Functions Around a Reconnection X-Line Resolved by the FOTE Method
  
  • Wang Z.
  • Fu H. S.
  • Liu C. M.
  • Liu Y. Y.
  • Cozzani G.
  • Giles B. L.
  • Hwang K. -J.
  • Burch J. L.
  Geophysical Research Letters, American Geophysical Union, 2019, 46, pp.1195. Using data from the MMS mission and the First-Order Taylor Expansion(FOTE) method, here we reveal electron distribution functions around areconnection X-line at the Earth's magnetopause. We find cigardistribution of electrons in both the magnetosphere-side andmagnetosheath-side inflow regions, isotropic distribution of electronsat the separatrix, and loss of high-energy electrons in the antiparalleldirection in the magnetosheath-side inflow region. We interpret theformation of cigar distribution in the inflow regions using the Fermimechanism?as suggested in previous simulations, the loss of high-energyelectrons in the magnetosheath side using the parallel electricfields?which evacuate electrons to escape the diffusion region along theantiparallel direction, and the isotropic distribution at the separatrixusing the pitch angle scattering by whistler waves?which existfrequently at the separatrix. We also find that the electrondistribution functions can change rapidly (within 60 ms) from isotropicto cigar as the spacecraft moves slightly away from the separatrix. (10.1029/2018GL081708)
  DOI : 10.1029/2018GL081708
• Sign singularity of the local energy transfer in space plasma turbulence
  
  • Sorriso-Valvo L.
  • de Vita Gaetano
  • Fraternale Federico
  • Gurchumelia Alexandre
  • Perri S.
  • Nigro Giuseppina
  • Catapano F.
  • Retinò Alessandro
  • Chen Christopher H. K.
  • Yordanova E.
  • Pezzi O.
  • Chargazia Khatuna
  • Kharshiladze Oleg
  • Kvaratskhelia Diana
  • Vásconez Christian L.
  • Marino Raffaele
  • Le Contel Olivier
  • Giles B. L.
  • Moore T. E.
  • Torbert Roy B.
  • Burch James L.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2019, 7, pp.108. In weakly collisional space plasmas, the turbulent cascade provides most of the energy that is dissipated at small scales by various kinetic processes. Understanding the characteristics of such dissipative mechanisms requires the accurate knowledge of the fluctuations that make energy available for conversion at small scales, as different dissipation processes are triggered by fluctuations of a different nature. The scaling properties of different energy channels are estimated here using a proxy of the local energy transfer, based on the third-order moment scaling law for magnetohydrodynamic turbulence. In particular, the sign-singularity analysis was used to explore the scaling properties of the alternating positive-negative energy fluxes, thus providing information on the structure and topology of such fluxes for each of the different type of fluctuations. The results show the highly complex geometrical nature of the flux, and that the local contributions associated with energy and cross-helicity nonlinear transfer have similar scaling properties. Consequently, the fractal properties of current and vorticity structures are similar to those of the Alfvénic fluctuations. (10.3389/fphy.2019.00108)
  DOI : 10.3389/fphy.2019.00108
• Evolution of Turbulence in the Kelvin-Helmholtz Instability in the Terrestrial Magnetopause
  
  • Di Mare Francesca
  • Sorriso-Valvo L.
  • Retinò Alessandro
  • Malara Francesco
  • Hasegawa H.
  Atmosphere, MDPI, 2019, 10 (9), pp.561. The dynamics occurring at the terrestrial magnetopause are investigated by using Geotail and THEMIS spacecraft data of magnetopause crossings during ongoing KelvinHelmholtz instability. Properties of plasma turbulence and intermittency are presented, with the aim of understanding the evolution of the turbulence as a result of the development of KelvinHelmholtz instability. The data have been tested against standard diagnostics for intermittent turbulence, such as the autocorrelation function, the spectral analysis and the scale-dependent statistics of the magnetic field increments. A quasi-periodic modulation of different scaling exponents may exist along the direction of propagation of the KelvinHelmholtz waves along the Geocentric Solar Magnetosphere coordinate system (GSM), and it is visible as a quasi-periodic modulation of the scaling exponents we have studied. The wave period associated with such oscillation was estimated to be approximately 6.4 Earth Radii ( RE ). Furthermore, the amplitude of such modulation seems to decrease as the measurements are taken further away from the Earth along the magnetopause, in particular after X(GSM)&#8818;&#8722;15RE . The observed modulation seems to persist for most of the parameters considered in this analysis. This suggests that a kind of signature related to the development of the KelvinHelmholtz instabilities could be present in the statistical properties of the magnetic turbulence. (10.3390/atmos10090561)
  DOI : 10.3390/atmos10090561
• Groupe de Travail Soleil Heliosphere-Magnetospheres (SHM)
  
  • Auchère F.
  • Astafyeva E.
  • Baudin F.
  • Briand C.
  • Brun S.
  • Célestin Sebastien
  • Génot V.
  • Kretzschmar Matthieu
  • Leblanc François
  • Rouillard A.
  • Sahraoui F.
  CNES: Rapport du Groupe de Travail Soleil Heliosphere-Magnetospheres (SHM), 2019, pp.1-28. Les grandes questions scientifiques abordées dans le cadre de la thématique Soleil Héliosphère et Magnétosphères (SHM) couvrent l'ensemble des problématiques liées aux relations entre notre étoile et le système solaire. Cela commence par l'étude de la structure interne du Soleil à travers l'observation multi-spectrales, l'hélio-sismologie et la modélisation ; par l'étude de l'origine de la couronne solaire, son chauffage et l'accélération du vent solaire et des particules énergétiques solaires lors d'événements énergétiques solaires ; et enfin par l'étude de la propagation du vent solaire et des mécanismes de chauffage de celui-ci par dissipation turbulente.