Publications

2020

• Magnetospheric Multiscale Observations of the Off-equatorial Dipolarization Front Dynamics in the Terrestrial Magnetotail
  
  • Li Huimin
  • Zhu Congkuan
  • Guo Lixin
  • Cheng Qi
  • Le Contel O.
  The Astrophysical Journal, American Astronomical Society, 2020, 899 (2), pp.125. (10.3847/1538-4357/aba8a7)
  DOI : 10.3847/1538-4357/aba8a7
• Observations of Particle Acceleration in Magnetic Reconnection–driven Turbulence
  
  • Ergun R.
  • Ahmadi N.
  • Kromyda L.
  • Schwartz S.
  • Chasapis A.
  • Hoilijoki S.
  • Wilder F.
  • Stawarz J.
  • Goodrich K. A
  • Turner D.
  • Cohen I.
  • Bingham S.
  • Holmes J.
  • Nakamura R.
  • Pucci F.
  • Torbert R.
  • Burch J.
  • Lindqvist P.-A.
  • Strangeway R.
  • Le Contel O.
  • Giles B.
  The Astrophysical Journal, American Astronomical Society, 2020, 898 (2), pp.154. (10.3847/1538-4357/ab9ab6)
  DOI : 10.3847/1538-4357/ab9ab6
• Les étudiants à distance en télétravail ?!
  
  • Rezeau Laurence
  , 2020.
• Time Evolution of the Dissociation Fraction in rf CO 2 Plasmas: Impact and Nature of Back-Reaction Mechanisms
  
  • Morillo-Candas Ana Sofia
  • Guerra Vasco
  • Guaitella Olivier
  Journal of Physical Chemistry C, American Chemical Society, 2020, 124 (32), pp.17459-17475. (10.1021/acs.jpcc.0c03354)
  DOI : 10.1021/acs.jpcc.0c03354
• Iodine plasmas : experimental and numerical studies. Application to electric propulsion
  
  • Marmuse Florian
  , 2020. Iodine is an alternative propellant for the electric propulsion of satellites, offering performances comparable to xenon. As of 2020, propulsion systems running on iodine are already on the market. These good performances are linked to the very low dissociation energy of I2, leading to a plasma similar to an atomic xenon plasma. To which extent can the molecular and electronegative nature of iodine plasmas be neglected? An existing global model for I2 plasmas is further developed and fully recoded in python, to enable fast parametric studies, uncertainty quantification, and integrate electronegative effects. Tools and processes are developed to ensure the safety of operators and experimental setups during iodine experiments. Four optical diagnostics are developed and installed on the ionization chamber of the PEGASES thruster. They lead for the first time to the density and temperature of I, and the density of I2: emission spectroscopy, laser absorption coupled to Doppler-free saturated absorption spectroscopy at 10969 cm−1 and 11036 cm−1, laser absorption spectroscopy at 7603 cm−1, and broadband absorption spectroscopy from 480nm to 500nm. Langmuir probe measurements yield the electron density and temperature. Confronting this data to the model shows that the model overestimates the molecular dissociation and the electron density. These discrepancies can be partly explained by underestimated power losses phenomena in the plasma, possibly linked to its molecular and electronegative nature. This work gives leads for future theoretical work and diagnostics on I2 plasmas. It proposes an updated model and a set of new diagnostics for use to further develop propulsion systems.
• Geomagnetic Activity Control of Irregularities Occurrences Over the Crests of the African EIA
  
  • Amaechi Paul O
  • Oyeyemi Elijah O
  • Akala A. O
  • Amory-Mazaudier Christine
  Earth and Space Science, American Geophysical Union/Wiley, 2020, 7 (7). The user has requested enhancement of the downloaded file. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as (10.1029/2020EA001183)
  DOI : 10.1029/2020EA001183
• Kinetic Scale Slow Solar Wind Turbulence in the Inner Heliosphere: Coexistence of Kinetic Alfvén Waves and Alfvén Ion Cyclotron Waves
  
  • Huang S.
  • Zhang J.
  • Sahraoui F.
  • He J.
  • Yuan Z.
  • Andrés N.
  • Hadid L.
  • Deng X.
  • Jiang K.
  • Yu L.
  • Xiong Q.
  • Wei Y.
  • Xu S.
  • Bale S.
  • Kasper J.
  The Astrophysical Journal Letters, Bristol : IOP Publishing, 2020, 897 (1), pp.L3. (10.3847/2041-8213/ab9abb)
  DOI : 10.3847/2041-8213/ab9abb
• Comparison between IRI-2012, IRI-2016 models and F2 peak parameters in two stations of the EIA in Vietnam during different solar activity periods
  
  • Pham Thi Thu Hong
  • Amory-Mazaudier Christine
  • Le Huy Minh
  • Nguyen Thanh Dung
  • Luu Viet Hung
  • Luong Thi Ngoc
  • Hozumi Kornyanat
  • Le Truong Thanh
  Advances in Space Research, Elsevier, 2020, pp.(in press). This paper presents observations of the F2-layer critical frequency (foF2) and height (hmF2) obtained at Phu Thuy (21.03°N, 105.95°E) and Bac Lieu (9.28°N, 105.73°E) observatories in Vietnam. The data have been examined for all seasons, during high and low solar activities, and compared with the foF2 and hmF2 of the International Reference Ionosphere model (IRI-2012, IRI-2016 two options: AMTB, SHU). Phu Thuy observatory is located at the Northern Crest of the EIA and Bac Lieu in the trough of the EIA, therefore the foF2 values at Phu Thuy are higher than at Bac Lieu. The results show that the IRI-2012 model estimates well the observed foF2 at both stations during high and low solar activities. During high solar activity, models estimate well the calculated hmF2 in summer for both stations. At Phu Thuy in equinoxes AMTB reproduces the night peak better than IRI-2012 and SHU, but higher and later about 2-3 hours, in winter the performance of AMTB is worst. At Bac Lieu, the IRI-2016 options reproduce the night peak and underestimates it, but IRI-2012 does not do it. The pre-noon peaks are underestimated by all the models, except IRI-2012 which overestimates the hmF2 pre-noon peaks at Bac Lieu. At Phu Thuy the pre-noon hmF2 peak is higher than the post-dusk one. At Bac Lieu the post-dusk peak is higher except in summer. During low solar activity, the IRI models estimate relatively well the shape of the calculated hmF2 at both stations. The IRI-2012 models explained better the observed foF2 (deviation of 2.5%) during solstices than during equinoxes (14.2%) for high solar activity. The IRI-2012 model explained better the observed foF2 in spring (7.8%) than in autumn (19.9%), matched better the calculated hmF2 in solstice (5.4%) than during equinoxes (11.8%). The performance of AMTB is worst at both stations for both the high and low solar activity periods except in autumn at Bac Lieu for the low solar year. IRI-2012 is best at the stations for both high and low solar activity periods, except in summer for the high solar activiy year when SHU is the best at Phu Thuy. These results can be used to improve the future IRI model. (10.1016/j.asr.2020.07.017)
  DOI : 10.1016/j.asr.2020.07.017
• A Plausible Model of Inflation Driven by Strong Gravitational Wave Turbulence
  
  • Galtier Sebastien
  • Laurie Jason
  • Nazarenko Sergey
  Universe, MDPI, 2020, 6 (7), pp.98. (10.3390/universe6070098)
  DOI : 10.3390/universe6070098
• Lower-Hybrid Drift Waves Driving Electron Nongyrotropic Heating and Vortical Flows in a Magnetic Reconnection Layer
  
  • Chen L.-J.
  • Wang S.
  • Le Contel O.
  • Rager A. C
  • Hesse M.
  • Drake J.
  • Dorelli J.
  • Ng J.
  • Bessho N.
  • Graham D.
  • Wilson Lynn
  • Moore T.
  • Giles B.
  • Paterson W.
  • Lavraud B.
  • Genestreti K. J
  • Nakamura R.
  • Khotyaintsev Yu. v.
  • Ergun R. e.
  • Torbert R. b.
  • Burch J.
  • Pollock C.
  • Russell C. t.
  • Lindqvist P.-A.
  • Avanov L.
  Physical Review Letters, American Physical Society, 2020, 125 (2). (10.1103/PhysRevLett.125.025103)
  DOI : 10.1103/PhysRevLett.125.025103
• Collisionless ion modeling in Hall thrusters: Analytical axial velocity distribution function and heat flux closures
  
  • Boccelli S.
  • Charoy Thomas
  • Alvarez-Laguna Alejandro
  • Chabert P.
  • Bourdon Anne
  • Magin T.
  Physics of Plasmas, American Institute of Physics, 2020, 27 (7), pp.073506. (10.1063/5.0006258)
  DOI : 10.1063/5.0006258
• Aerosols-plasma interaction in Titan’s ionosphere
  
  • Chatain Audrey
  , 2020. The climatic system of Saturn’s moon Titan is governed by the intense production of organic aerosols in its upper atmosphere. This phenomenon also certainly happened on Earth at the beginning of life. These two points strongly motivate research on the formation and evolution processes of the aerosols in the atmosphere of Titan. The aerosols form and stay several weeks in the ionosphere, between ~900-1200 km of altitude. This atmospheric layer is ionized by UV solar rays and energetic particles coming from Saturn’s magnetosphere, forming a plasma with very reactive species: radicals, excited species, ions and electrons. In such an environment, the main question I tackle is how the organic aerosols interact with the plasma species.The phenomenon is simulated in the laboratory with a plasma setup developed on purpose: analogues of Titan aerosols are exposed to a N2-H2 plasma discharge. Both an evolution of the solid and the gas phase are observed. H and N atoms chemically interact with the aerosols. Then, hydrogen cyanide (HCN) and other organic molecules are ejected in the gas phase by ion sputtering. These results highlight an important contribution of heterogeneous processes in Titan’s upper atmosphere.My re-analysis of the Cassini Langmuir probe data revealed the presence of an unexpected electron population in the ionosphere, below 1200 km and on the day-side, where heavy ions are also detected. These electrons could be emitted by the aerosols, after collision with a photon, and/or heating by the active ion chemistry.
• Saturation of the magnetic confinement in weakly ionized plasma
  
  • Lucken Romain
  • Tavant Antoine
  • Bourdon Anne
  • Lieberman Mike
  • Chabert Pascal
  Plasma Sources Science and Technology, IOP Publishing, 2020, 29, pp.065014. Plasma transport in magnetized discharges is a long-standing problem because it strongly depends on instabilities whose properties and influence on the plasma transport are difficult to predict. 
 A magnetized plasma column is investigated with 2D PIC simulations in the plane transverse to the magnetic field, at gas pressures between 3 and 12 mTorr and magnetic field intensities between 0 and 40 mT. At high magnetic field, instabilities develop and rotate in the diamagnetic drift direction. It is shown theoretically and by simulation that the magnetic field confinement is destroyed by the instability. Predictive formulas of the main parameters of the instability-enhanced plasma transport such as the edge-to-center plasma density ratio (or h factor), and the effective collision frequency are provided and successfully compared with the PIC simulations. (10.1088/1361-6595/ab38b2)
  DOI : 10.1088/1361-6595/ab38b2
• A comparison between kinetic theory and particle-in-cell simulations of anomalous electron transport in E × B plasma discharges
  
  • Charoy Thomas
  • Lafleur Trevor
  • Tavant Antoine
  • Chabert Pascal
  • Bourdon A.
  Physics of Plasmas, American Institute of Physics, 2020. Understanding anomalous electron transport in E × B discharges remains a key challenge in the development of self-consistent models of these systems. It has been shown that short-wavelength, high-frequency, instabilities in the azimuthal E × B direction may be responsible for increased electron transport due to an enhanced electron-ion friction force. Although a theoretical model based on quasi-linear kinetic theory has previously been proposed to describe this friction force, it has so far only undergone limited validation testing. Here we rigorously assess this theoretical model by comparison with the friction force self-consistently obtained from 2D axial-azimuthal particle-in-cell simulations. The simulation geometry is based on a recently established benchmark configuration for E × B discharges, and a broad parametric study is performed by varying the magnetic field strength, the discharge current density, and the presence of different neutral collisional processes. Overall the theory is found to be in very good agreement with the simulation results for all cases studied; verifying the underlying physical mechanisms leading to enhanced electron transport. We demonstrate however that the friction force depends sensitively on the shape of the electron velocity distribution function, thus posing significant challenges to fully self-consistent, first principles, modelling of anomalous transport in fluid simulations. (10.1063/5.0003978)
  DOI : 10.1063/5.0003978
• Plasma Wave Investigation (PWI) Aboard BepiColombo Mio on the Trip to the First Measurement of Electric Fields, Electromagnetic Waves, and Radio Waves Around Mercury
  
  • Kasaba Yasumasa
  • Kojima Hirotsugu
  • Moncuquet Michel
  • Wahlund Jan-Erik
  • Yagitani Satoshi
  • Sahraoui Fouad
  • Henri Pierre
  • Karlsson Tomas
  • Kasahara Yoshiya
  • Kumamoto Atsushi
  • Ishisaka Keigo
  • Issautier Karine
  • Wattieaux Gaëtan
  • Imachi Tomohiko
  • Matsuda Shoya
  • Lichtenberger János
  • Usui Hideyuki
  Space Science Reviews, Springer Verlag, 2020, 216 (4), pp.65. The Plasma Wave Investigation (PWI) aboard the BepiColombo Mio (Mercury Magnetospheric Orbiter, MMO) will enable the first observations of electric fields, plasma waves, and radio waves in and around the Hermean magnetosphere and exosphere. The PWI has two sets of receivers (EWO with AM2P, SORBET) connected to two electric field sensors (MEFISTO and WPT) and two magnetic field sensors (SCM: LF-SC and DB-SC). After the launch on October 20, 2018, we began initial operations, confirmed that all receivers were functioning properly, and released the launch locks on the sensors. Those sensors are not deployed during the cruising phase, but the PWI is still capable performing magnetic field observations. After full deployment of all sensors following insertion into Mercury orbit, the PWI will start its measurements of the electric field from DC to 10 MHz using two dipole antennae with a 32-m tip-to-tip length in the spin plane and the magnetic field from 0.3 Hz to 20 kHz using a three-axis sensor and from 2.5 kHz to 640 kHz using a single-axis sensor at the tip of a 4.5-m solid boom extended from the spacecraft’s side panel. Those receivers and sensors will provide (1) in-situ measurements of electron density and temperature that can be used to determine the structure and dynamics of the Hermean plasma environment; (2) in-situ measurements of the electron and ion scale waves that characterize the energetic processes governed by wave–particle interactions and non-MHD interactions; (3) information on radio waves, which can be used to remotely probe solar activity in the heliocentric sector facing Mercury, to study electromagnetic-energy transport to and from Mercury, and to obtain crustal information from reflected electromagnetic waves; and (4) information concerning dust impacts on the spacecraft body detected via potential disturbances. This paper summarizes the characteristics of the overall PWI, including its significance, its objectives, its expected performance specifications, and onboard and ground data processing. This paper also presents the detailed design of the receiver components installed in a unified chassis. The PWI in the cruise phase will observe magnetic-field turbulence during multiple flybys of Earth, Venus, and Mercury. After the Mercury-orbit insertion planned at the end of 2025, we will deploy all sensors and commence full operation while coordinating with all payloads onboard the Mio and MPO spacecraft. (10.1007/s11214-020-00692-9)
  DOI : 10.1007/s11214-020-00692-9
• Role of the Coronal Environment in the Formation of Four Shocks Observed without Coronal Mass Ejections at Earth’s Lagrangian Point L1
  
  • Pick M.
  • Magdalenić J.
  • Cornilleau-Wehrlin N.
  • Grison B.
  • Schmieder B.
  • Bocchialini K.
  The Astrophysical Journal, American Astronomical Society, 2020, 895 (2), pp.144. The main goal of this study is to determine the solar origin of four single shocks observed at the Lagrange point L1 and followed by storm sudden commencements (SSCs) during 2002. We look for associated coronal mass ejections (CMEs), starting from estimates of the transit time from Sun to Earth. For each CME, we investigate its association with a radio type II burst, an indicator of the presence of a shock wave. For three of the events, the type II burst is shown to propagate along the same, or a similar, direction as the fastest segment of the CME leading edge. We analyze for each event the role of the coronal environment in the CME development, the shock formation, and their propagation, to finally identify its complex evolution. The ballistic velocity of these shocks during their propagation from the corona to L1 is compared to the shock velocity at L1. Based on a detailed analysis of the shock propagation and possible interactions up to 30 solar radii, we find a coherent velocity evolution for each event, in particular for one event, the 2002 April 14 SSC, for which a previous study did not find a satisfactory CME source. For the other three events, we observe the formation of a white-light shock overlying the different sources associated with those events. The localization of the event sources over the poles, together with an origin of the shocks being due to encounters of CMEs, can explain why at L1 we observe only single shocks and not interplanetary CMEs. (10.3847/1538-4357/ab8fae)
  DOI : 10.3847/1538-4357/ab8fae
• Connecting the global H-mode power threshold to the local radial electric field at ASDEX Upgrade
  
  • Cavedon M.
  • Birkenmeier G.
  • Pütterich T.
  • Ryter F.
  • Viezzer E.
  • Wolfrum E.
  • Dux R.
  • Happel T.
  • Hennequin Pascale
  • Plank U.
  • Stroth U.
  • Willensdorfer M.
  Nuclear Fusion, IOP Publishing, 2020, 60 (6), pp.066026. (10.1088/1741-4326/ab8777)
  DOI : 10.1088/1741-4326/ab8777
• The Relationship Between Electron-Only Magnetic Reconnection and Turbulence in Earth’s Magnetosheath
  
  • Stawarz Julia
  • Eastwood Jonathan
  • Phan Tai
  • Gingell Imogen
  • Mallet Alfred
  • Shay Michael
  • Sharma Pyakurel Prayash
  • Burch James
  • Ergun Robert
  • Giles Barbara
  • Gershman Daniel
  • Le Contel Olivier
  • Lindqvist Per-Arne
  • Strangeway Robert
  • Torbert Roy
  • Argall Matthew
  • Fischer David
  • Magnes Werner
  , 2020. <p>The Earth’s magnetosheath is filled with small-scale current sheets arising from turbulent dynamics in the plasma. Previous observations and simulations have provided evidence that such current sheets can be sites for magnetic reconnection. Recently, observations from the Magnetospheric Multiscale (MMS) mission have revealed that a novel form of “electron-only” reconnection can occur at these small-scale, turbulence-driven current sheets, in which ions do not appear to couple to the reconnected magnetic field to form ion jets. The presence of electron-only reconnection may facilitate dissipation of the turbulence, thereby influencing the partition of energy between ions and electrons, and can alter the nonlinear dynamics of the turbulence itself. In this study, we perform a survey of turbulent intervals in the Earth’s magnetosheath as observed by MMS in order to determine how common magnetic reconnection is in the turbulent magnetosheath and how it impacts the small-scale turbulent dynamics. The magnetic correlation length, which dictates the length of the turbulent current sheets, is short enough in most of the examined intervals for reconnection with reduced or absent ion jets to occur. Magnetic reconnection is found to be a common feature within these intervals, with a significant fraction of reconnecting current sheets showing evidence of sub-Alfvénic ion jets and super- Alfvénic electron jets, consistent with electron-only reconnection. Moreover, a subset of the intervals exhibit changes in the behavior of the small-scale magnetic power spectra, which may be related to the reconnecting current sheets. The results of the survey are compared with recent theoretical work on electron-only reconnection in turbulent plasmas.</p> (10.5194/egusphere-egu2020-5692)
  DOI : 10.5194/egusphere-egu2020-5692
• In situ evidence of firehose instability in multiple magnetic reconnection
  
  • Alexandrova Alexandra
  • Retinò Alessandro
  • Divin Andrey
  • Matteini Lorenzo
  • Le Contel Olivier
  • Breuillard Hugo
  • Catapano Filomena
  • Cozzani Giulia
  • Deca Jan
  , 2020. <p>Energy conversion via reconnecting current sheets is common in space and astrophysical plasma. Frequently, current sheets disrupt at multiple reconnection sites, leading to the formation of plasmoid structures between the sites, which might affect energy conversion. We present in situ observations of multiple reconnection in the Earth’s magnetotail. The observed highly accelerated proton beams parallel to magnetic field and the ion-scale wave-like fluctuations of the whistler type imply the development of firehose instability between two active reconnection sites. The linear wave dispersion relation estimated for the measured plasma parameters, indicates a positive growth rate of the firehose-related electromagnetic fluctuations. The detailed time-space evolution of the plasmoid is obtained by reconstruction of observations with the 2.5D implicit particle-in-cell simulations. In course of time, plasma on the periphery of the plasmoid becomes anisotropic and as it overcomes the firehose marginal stability threshold, the corresponding magnetic field fluctuations arise. The results of observations and simulations suggest that the firehose instability operating between reconnection sites, converts plasma energy of the proton temperature anisotropy to the energy of magnetic field fluctuations, counteracting with the conversion of magnetic energy to the energy of plasma in reconnection sites.</p> (10.5194/egusphere-egu2020-18188)
  DOI : 10.5194/egusphere-egu2020-18188
• MMS/Cluster joint measurements at the vicinity of the plasma sheet boundary layer
  
  • Le Contel Olivier
  • Retino Alessandro
  • Alexandrova Alexandra
  • Chust Thomas
  • Steinvall Konrad
  • Alqeeq Soboh
  • Canu Patrick
  • Fontaine Dominique
  • Dandouras Iannis
  • Carr Christopher
  • Toledo Sergio
  • Fazakerley Andrew
  • Doss Natasha
  • Kiehas Stefan
  • Nakamura Rumi
  • Khotyaintsev Yuri
  • Wilder Frederick
  • Ahmadi Narges
  • Gershman Daniel
  • Strangeway Robert
  , 2020. <p>On 28th of August 2018 at 5:30 UT, MMS and Cluster were located in the magnetotail at about 16 earth radii (RE). They both suddenly crossed plasma interfaces. Located in the post midnight sector, Cluster transitioned from a cold plasma sheet to a hot plasma sheet whereas MMS, located at 4 RE duskward of Cluster, transitioned from a similar cold plasma sheet to the lobe region via a very short period in a hot plasma sheet. At 05:50 UT MMS returned to a hot plasma sheet and detected a quasi-parallel earthward flow ~ 400 km/s and increased energetic ion and electron fluxes. We use measurements from both missions during this conjunction to describe the possible macroscale evolution of the magnetotail as well as some associated kinetic processes. In particular, we analyze fast and slow non linear electrostatic waves propagating tailward which are detected in the so called electron boundary layer as well as in the hot plasma sheet. We discuss their possible generation mechanisms and link with the large scale evolution of the magnetotail. Finally, we investigate possible effects related to the dawn-dusk asymmetry of the magnetotail.</p> (10.5194/egusphere-egu2020-18357)
  DOI : 10.5194/egusphere-egu2020-18357
• Geomagnetic Response to a Chain of Interplanetary Coronal Mass Ejections
  
  • Akhavan-Tafti Mojtaba
  • Fontaine Dominique
  • Le Contel Olivier
  • Slavin James
  , 2020. <p>The most geoeffective storms in the Space Age have been driven solely by the sheath preceding an interplanetary coronal mass ejection (ICME) or by a combination of the sheath and an ICME magnetic cloud. In the present study, the magnetospheric response to a chain of three independent and well-spaced ICMEs (P<sub>dyn</sub> > 15 nPa and Sym-H < -50 nT) spanning one month (December 12, 2015 – January 12, 2016) is investigated using WIND, Cluster, and MMS fields and plasma measurements. The first of the three ICMEs consists of a sheath preceding an ICME (ICME-SH). The latter two ICMEs are preceded by a combination of the sheath and an ICME magnetic cloud (ICME-SH-MC).</p><p>Following the passage of the first ICMEs (ICME-SH) the interplanetary environment was made up of moderate Alfvenic Mach number (M<sub>A</sub> ~ 10) and average magnetopause standoff distance (R<sub>MP</sub> ~ 11 R<sub>E</sub>). The arrival of the ICME-SH-MC then initiated a sudden storm commencement (SSC) phase. During the SSC, the storm index (Sym-H ~ +50 nT) remained positive through the ICME shock and sheath regions. The storm index and the Alfvenic Mach number sharply declined (Sym-H~ -200 nT and M<sub>A</sub> ~ 1.0, respectively) with the arrival of the leading edge of the magnetic cloud (B<sub>IMF, core</sub> ~ 20 nT) and the associated sharp IMF B<sub>z</sub> reversal (B<sub>z</sub><0). The Alfvenic Mach number and IMF B<sub>z</sub> are found to directly correlate with the Sym-H index. ICME-SH-MC compressed the magnetopause standoff distance (∂R<sub>MP</sub>/∂t ~ -1 R<sub>E</sub>/min), resulting in a sudden reduction in the total magnetospheric volume (∂V<sub>MP</sub>/∂t ~ -3×10<sup>2</sup> R<sub>E</sub><sup>3</sup>/min), as determined by cross-scale observations. In particular, the sharp drops in the magnetospheric volume (relative change in volume >30%) with the arrival of each of the three independent ICMEs are shown to start with the SSC and remain low through the main phase, before slowly recovering (∂V<sub>MP</sub>/∂t ~ +1 R<sub>E</sub><sup>3</sup>/min) to the pre-ICME conditions during the recovery phase.</p> (10.5194/egusphere-egu2020-10717)
  DOI : 10.5194/egusphere-egu2020-10717
• The Search-Coil Magnetometer onboard the ESA JUICE mission
  
  • Retino Alessandro
  , 2020. The JUpiter ICy moons Explorer (JUICE) mission is the first large-class (L1) mission in ESA Cosmic Vision. JUICE is planned for launch in 2022 with arrival at Jupiter in 2029 and will spend at least four years making detailed observations of Jupiter's magnetosphere and of three of its largest moons (Ganymede, Callisto and Europa). The Radio and Plasma Wave Investigation (RPWI) consortium will carry the most advanced set of electric and magnetic fields sensors ever flown in Jupiter's magnetosphere, which will allow to characterize the radio emission and plasma wave environment of Jupiter and its icy moons. Here we present the scientific objectives and the technical features of the Search Coil Magnetometer (SCM) of RPWI. SCM will provide for the first time high-quality three-dimensional measurements of magnetic field fluctuations' vector in the frequency range 0.1 Hz - 20 kHz within Jupiter's magnetosphere. High sensitivity (~ 4 fT / √Hz at 4 kHz) will be assured by combining an optimized (20 cm long) magnetic transducer with a low-noise (4 nV / √Hz ) ASICs pre-amplifier for the front-end electronics. Perturbations by the spacecraft are strongly reduced by accommodating SCM more at ~ 10 m away from the spacecraft on the JUICE magnetometer boom. The combination of high sensitivity and high cleanliness of SCM measurements will allow unpreceded studies of waves and turbulence down to kinetic scales, in particular in key regions such as the magnetopause, the auroral region and the magnetotail current sheet of Ganymede's magnetosphere. This will lead to important advances in understanding wave-particle interaction and particle energization mechanisms in Jupiter's magnetosphere.
• Analysis of energy conversion processes at kinetic scales associated with a series of dipolarization fronts observed by MMS during a substorm
  
  • Alqeeq Soboh
  • Le Contel Olivier
  • Canu Patrick
  • Retinò Alessandro
  • Chust Thomas
  • Mirioni Laurent
  , 2020. <p>In July 2017, the MMS constellation was in the magnetotail with an apogee of 25 Earth radii<br>and an average inter-satellite distance of 10 km (i.e. at electron scales). On 23 July around<br>16:19 UT, MMS was located at the edge of the current sheet which was in a quasi-static<br>state. Then, MMS suddenly entered in the central plasma sheet and detected the local onset<br>of a small substorm as indicated by the AE index (~400 nT). Fast earthward plasma flows<br>were measured for about 1 hour starting with a period of quasi-steady flow and followed by<br>a saw-tooth like series of fast flows associated with dipolarization fronts. This plasma<br>transport sequence finished with a flow reversal still occurring close to the magnetic<br>equator. In the present study, we investigate the energy conversion processes at ion and<br>electron scales for these different phases with particular attention on the processes in the<br>vicinity of the dipolarization fronts.</p> (10.5194/egusphere-egu2020-19750)
  DOI : 10.5194/egusphere-egu2020-19750
• MMS Observations of Short-Period Current Sheet Flapping
  
  • Richard Louis
  • Khotyaintsev Yuri
  • Graham Daniel
  • Russell Christopher
  • Le Contel Olivier
  , 2020. <p>Flapping motions of current sheets are commonly observed in the magnetotail. Various wave modes can correspond to these oscillations such as kink-like flapping or steady flapping (e.g Wei2019). The period of such oscillating phenomena is usually longer than 100s and a typical observations consist only of a few crossings (e.g. Zhang2002). Here, we present a short period (T≈25s) flapping event observed by Magnetospheric Multiscale (MMS) mission at the dusk side plasmasheet on September 14, 2019. Using the multispacecraft observations, the direction of flapping as well as the direction of propagation of the current sheet are determined using the minimum variance, the timing method and the spatiotemporal derivative (Shi2005). It appears that the three methods give similar results with a direction of propagation of the current sheet which mainly lies in the ecliptic plane with a flapping velocity up to 500km/s. Based on the obtained wavelength and the variations of the direction of propagation we discuss which of the wave modes can explain the flapping.</p> (10.5194/egusphere-egu2020-8693)
  DOI : 10.5194/egusphere-egu2020-8693
• Evolution of Turbulence in the Kelvin-Helmholtz Instability mediated by the Magnetopause and its Boundary Layer
  
  • Di Mare Francesca
  • Sorriso-Valvo Luca
  • Retino A.
  • Malara Francesco
  • Hasegawa Hiroshi
  , 2020. The turbulence at the interface between the solar wind and the Earth's magnetosphere, mediated by the magnetopause and its boundary layer are investigated by using Geotail and THEMIS spacecraft data during ongoing Kelvin-Helmholtz instability (KHI). The efficient transfer of energy across scales for which the turbulence is responsible, achieves the connection between the macroscopic flow and the microscopic dissipation of this energy. This boundary layer is thought to be the result of the observed plasma transfer, driven by the development of the KHI, originating from the velocity shear between the solar wind and the almost static near-Earth plasma. A collection of 20 events spatially located on the tail-flank magnetopause, selected from previously studied by Hasegawa et al. 2006 and Lin et al. 2014, have been tested against standard diagnostics for intermittent turbulence. In light of the results obtained, we have investigated the behaviour of several parameters as a function of the progressive departure along the Geocentric Solar Magnetosphere coordinates, which roughly represent the direction in which we expect the KHI vortices to evolve towards fully developed turbulence. It appears that a fluctuating behaviour of the parameters exist, visible as a decreasing, quasi-periodic modulation with an associated periodicity, estimated to correspond to approximately 6.4 Earth Radii. Such observed wavelength is consistent with the estimated vortices roll-up wavelength reported in the literature for these events. If the turbulence is pre-existent, it is possible that the KHI modulates its properties along the magnetosheath, as we observed. On the other hand, if we assume that the KHI has been initiated near the magnetospheric nose and develops along the flanks, then the different intervals we study may be sampling the plasma at different stages of evolution of the KH-generated turbulence, after the instability has injected energy in a cascading process as large-scale structures.