Publications

2025

• Plasma Pressure Response to Non-Inductive Current Drive in Axisymmetric Viscoresistive MHD Steady-states
  
  • Krupka Anna
  • Firpo Marie-Christine
  Journal of Plasma Physics, Cambridge University Press (CUP), 2025, 91 (4), pp.E126. <div><p>We investigate self-consistent, steady-state axisymmetric solutions of incompressible tokamak plasma using a visco-resistive magnetohydrodynamic model. A key contribution of this work is the formulation of Poisson's equation that governs the pressure profile. Our analysis reveals that the current modeling fails to produce realistic pressure levels. To overcome this limitation, we introduce additional non-inductive current drives, akin to those generated by neutral beam injection or radio frequency heating, modeled as modifications to the toroidal current. Numerical simulations validate our enhanced model, showing significant improvements in pressure profile characteristics. In the cases examined, the effect of these current drives on the velocity profiles is moderate, except when the non-inductive current drives induce reversals in the total toroidal current density, leading to non-nested flux surfaces with internal separatrices.</p></div> (10.1017/S0022377825100743)
  DOI : 10.1017/S0022377825100743
• Pre-flight performance of the ion energy mass spectrum analyzer for the Martian Moons eXploration (MMX) mission
  
  • Yokota Shoichiro
  • Matsuoka Ayako
  • Murata Naofumi
  • Saito Yoshifumi
  • Asamura Kazushi
  • Kasahara Satoshi
  • Delcourt Dominique
  • Hadid Lina Z
  • Terada Naoki
  • Keika Kunihiro
  • Harada Yuki
  • Nakagawa Hiromu
  • Masunaga Kei
  • Sakai Shotaro
  • Futaana Yoshifumi
  • Imajo Shun
  • Seki Kanako
  • Nishino Masaki N
  • Kitamura Yuki
  Progress in Earth and Planetary Science, Springer/Japan Geoscience Union, 2025, 12 (1), pp.51. Abstract An ion energy mass spectrum analyzer was developed for the Martian Moons eXploration (MMX) mission to measure the three-dimensional velocity distribution function and mass profile of low-energy ions around the Mars-Moon system. The hemispheric field-of-view (FOV) is acquired by a pair of angular scanning deflectors, and the energy/charge and mass/charge are determined for each ion by an electrostatic analyzer and a linear-electric-field (LEF) time-of-flight (TOF) analyzer, respectively, with an enhanced mass resolution of $$m/\Delta m\sim 100$$ m / Δ m ∼ 100 . The ion analyzer, together with magnetometers, constitutes the mass spectrum analyzer (MSA), one of the scientific instruments on board the MMX spacecraft. This paper describes the instrumentation of the ion analyzer, and results of the performance tests of its flight model (FM). (10.1186/s40645-025-00718-2)
  DOI : 10.1186/s40645-025-00718-2
• Statistical properties of beam-driven upper-hybrid wave turbulence in the solar wind
  
  • Annenkov V.
  • Krafft C.
  • Volokitin A.
  • Savoini P.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2025, 699, pp.L6. We studied the statistical properties of beam-driven upper-hybrid wave turbulence in the solar wind by focusing on the probability density functions (PDFs) of electric field amplitudes, |E|. We used, for the first time, high-resolution and long-term 2D particle-in-cell simulations of the interaction of an electron beam with a magnetized plasma to calculate and analyse the skewness (degree of anisotropy) and the kurtosis (degree of flatness) of the PDFs of |E| and log|E|2 for various intensities of plasma magnetization (Ω = ωc/ωp) and average levels of random density fluctuations (ΔN). Using the Pearson classification, we show that the PDFs of log|E|2 predominantly align with Type VI Pearson distributions, with a shift towards Type I at high plasma magnetizations. In contrast, the PDFs of |E| are Type I Pearson distributions regardless of the Ω and ΔN values. Comparisons between simulation results and observations by the Solar Orbiter’s Time Domain Sampler instrument show a good agreement. This study also offers a promising method for understanding the dynamics of wave turbulence and indirectly estimating plasma magnetization. (10.1051/0004-6361/202555087)
  DOI : 10.1051/0004-6361/202555087
• Asymmetric dual cascade in gravitational wave turbulence
  
  • Gay Benoît
  • Galtier Sébastien
  Physica D: Nonlinear Phenomena, Elsevier, 2025, 477, pp.134712. (10.1016/j.physd.2025.134712)
  DOI : 10.1016/j.physd.2025.134712
• Ideal and resistive impurity parallel-velocity-gradient instability
  
  • Cuerva-Lazaro G
  • Lesur Maxime
  • Gürcan O
  • Bourgeois J
  • Maestracci C
  • Gravier E
  • Kosuga Y
  Plasma Physics and Controlled Fusion, IOP Publishing, 2025, 67 (7), pp.075019. The presence of impurity ions in magnetically confined plasmas can significantly influence micro-instabilities, impacting cross-field transport and ultimately affecting fusion performance. In particular, Parallel Velocity Gradient (PVG) instability, commonly observed at the edge of fusion devices and in linear devices, can be strongly influenced by impurities. Inspired by the drift-wave models of Hasegawa-Mima and Hasegawa-Watakani, this article develops and examines two distinct fluid models: the ideal impurity-PVG model and the resistive impurity-PVG model. These models aim to investigate the impact of impurities on key properties of the PVG instability, both in the linear and nonlinear regimes. Our findings show that non-negligible impurity concentrations change the growth rates, wave-number ranges, and nonlinear saturations of these instabilities. Notably, the degree of ionization and the relative impurity flow shear can either amplify or mitigate PVG-related turbulence, depending on the impurity and overall plasma conditions. The results underscore the need for a more comprehensive treatment of multi-ion-species plasmas, particularly when impurity fractions cannot be treated as traces. (10.1088/1361-6587/ade4fb)
  DOI : 10.1088/1361-6587/ade4fb
• Automated Nanosecond Plasma Jets for Targeted Medical Treatments
  
  • Billeau Jean-Baptiste
  • Radu Vlad-Stefanut
  • Polprasarn Kasidapa
  • Gérôme Frédéric
  • Benabid Fetah
  • Pai David
  • Seletskiy Denis
  • Reuter Stephan
  • Starikovskaia Svetlana
  , 2025, pp.MC14 : Sources de particules chargées, Plasmas.
• Spectroscopic investigations of a filament reconnecting with coronal loops during a two-ribbon solar flare
  
  • Joshi Reetika
  • Dudík Jaroslav
  • Schmieder Brigitte
  • Aulanier Guillaume
  • Chandra Ramesh
  Astronomy & Astrophysics - A&A, EDP Sciences, 2025, 698, pp.A301. Context. In the standard 2D model of eruption, the eruption of a magnetic flux rope is associated with magnetic reconnection occurring beneath it. However, in 3D, additional reconnection geometries are possible, in particular the AR – RF , where external reconnection involving the overlying arcades ( A ) and erupting flux rope ( R ) turns into another arcade and a flare loop ( F ). This process results in the drifting of the legs of the erupting flux rope. Aims. We investigate spectroscopic signatures of such AR – RF reconnection occurring in an erupting filament reconnecting with coronal arcades during a weak B3.2-class two-ribbon flare. Methods. We examined the evolution of the erupting filament eruption using imaging observations by the Atmospheric Imaging Assembly (AIA) as well as both imaging and spectroscopic observations by the Interface Region Imaging Spectrograph (IRIS). Results. As the filament rises into the corona, it reconnects with the surrounding arcade of coronal loops with localized brightenings, resulting in the disappearance of the coronal loops and formation of a hot flux rope, showing a slipping motion of its footpoints that extends to the previous footpoints of the coronal loops ( AR – RF reconnection), as was predicted by the 3D extensions to the standard solar flare model. These brightenings are accompanied by the presence of strong blueshifts in both the IRIS Si IV and Mg II lines, up to ≈200 km s −1 . The lines are also extremely wide, with nonthermal widths above 100 km s −1 . Furthermore, a strongly non-Gaussian profile of the most blueshifted component is detected at the start of the AR – RF reconnection, indicating the presence of accelerated particles and magnetohydrodynamic turbulence, and associated with the appearance of hot plasma in the AIA 94 Å passband. Results. For the first time, an observation has been reported in which the IRIS slit successfully captures AR – RF reconnection between a filament and overlying arcades, resulting in strong blueshifts and very broad line profiles. (10.1051/0004-6361/202554011)
  DOI : 10.1051/0004-6361/202554011
• Cross-Analysis of Magnetic and Current Density Field Topologies in a Quiescent High Confinement Mode Tokamak Discharge
  
  • Firpo Marie-Christine
  Foundations, MDPI, 2025.
• Initiation Route of Coronal Mass Ejections. II. The Role of Filament Mass
  
  • Xing Chen
  • Cheng Xin
  • Aulanier Guillaume
  • Ding Mingde
  The Astrophysical Journal, American Astronomical Society, 2025, 986 (1), pp.37. Abstract A thorough understanding of the initiation of coronal mass ejections (CMEs), which is manifested as a slow rise of pre-eruptive structures before the impulsive ejection in kinematics, is key for forecasting solar eruptions. In our previous work, we showed that the slow rise of a hot flux rope with coronal mass density is caused by the moderate magnetic reconnection occurring in the hyperbolic flux tube (HFT) combined with the torus instability. However, it remains unclear how the initiation process varies when a filament is present in the pre-eruptive flux rope. In this work, we reveal the complete initiation route of a CME containing filament mass with a state-of-the-art full-magnetohydrodynamics simulation. The comprehensive analyses show that the filament mass has an important impact on the CME initiation through triggering and driving the slow rise of flux rope with its drainage, besides the contributions of HFT reconnection and torus instability. Finally, in combination with our previous work, we propose that the enhanced drainage of filament mass and various features related to the HFT reconnection, such as the split of pre-eruptive structure and the preflare loops and X-ray emissions, can serve as precursors of CME initiation in observations. (10.3847/1538-4357/adceb5)
  DOI : 10.3847/1538-4357/adceb5
• Evolution of Solar Wind Turbulence during Radial Alignment of Parker Solar Probe and Solar Orbiter in 2022 December
  
  • Silwal Ashok
  • Zhao Lingling
  • Zhu Xingyu
  • Sorriso-Valvo Luca
  • Hadid Lina
  • Zank Gary
  • Li Hui
  • Badman Samuel
  • Rivera Yeimy
  • Gautam Sujan Prasad
  • Karki Monika
  • Alonso Guzman Juan
  • M. Subashchandar Nibuna
  • Jin Zeping
  The Astrophysical Journal Supplement Series, IOPscience, 2025, 278 (2), pp.40. Abstract We investigate the radial evolution of solar wind turbulence during the radial alignment of Parker Solar Probe (PSP) and Solar Orbiter (SO) on 2022 December 10, with PSP located at approximately 0.11 au and SO near 0.88 au. To identify nearly the same plasma parcel crossing both spacecraft, we apply a ballistic propagation model with time-constant acceleration constrained by in situ solar wind velocity measurements at PSP and SO. We trace the magnetic footpoint of the plasma parcel back to the photosphere using a potential field source surface model based on a Global Oscillations Network Group synoptic magnetogram. Field and plasma measurements from PSP and SO are used to analyze power spectral density (PSD), spectral scaling, magnetic compressibility, and intermittency. Our results show that (1) the trace PSD of magnetic fluctuations steepens in the inertial range and flattens in the dissipation range with increasing radial distance; (2) the spectral break shifts to lower frequencies at SO; and (3) the Castaing model reveals multifractal intermittency in the inertial range, with slightly weaker intermittency at SO. These findings based on the same plasma parcel are consistent with the results of statistical studies on the radial evolution of turbulence and provide a reference for theoretical modeling of turbulence in the inner heliosphere. (10.3847/1538-4365/add011)
  DOI : 10.3847/1538-4365/add011
• Investigation of filamentary and diffuse DBD in CO 2 by means of in-situ FTIR absorption spectroscopy
  
  • Bajon Corentin
  • Baratte Edmond
  • Sadi Dihya
  • Guaitella Olivier
  • Belinger Antoine
  • Dap Simon
  • Hoder Tomas
  • Naudé Nicolas
  , 2025. This work investigates CO2 dielectric barrier discharges at atmospheric pressure in the filamentary and diffuse regimes for the first time using in situ FTIR absorption measurements. The conversion factor of CO2 is determined and is consistent with the results obtained for DBDs in the literature. Vibrational temperatures for CO2 and CO molecules are also determined, as well as the rotational temperature. The ordering of the different temperatures is similar to the reported results for other CO2 discharges. The evolution of the measured parameters as a function of the specific energy input is discussed and a comparison of the two different regimes is carried out.
• Rapport de conjoncture de la Section 17 "SYSTÈME SOLAIRE ET UNIVERS LOINTAIN" du Comité National de la Recherche Scientifique - Mandature 2021-2025
  
  • Motte Frederique
  • Famaey Benoit
  • Lamy Laurent
  • Aghanim Nabila
  • Baklouti Donia
  • Bournaud Frédéric
  • Cambrésy L.
  • Codis Sandrine
  • Issautier Karine
  • Leconte Jérémy
  • Mirioni Laurent
  • N'Diaye Mamadou
  • Oertel Micaela
  • Palacios Ana
  • Recio-Blanco Alejandra
  • Roy Fabrice
  • Theureau Gilles
  • Savalle Renaud
  • Tibaldo Luigi
  • Tresse Laurence
  • Vincent F
  • Caffau Elisabetta
  • Douet Richard
  • Laibe Guillaume
  • Regimbau Tania
  • Reylé Céline
  , 2025. Ce rapport s'adresse à un lectorat non expert de la discipline Astrophysique, souhaitant avoir un aperçu de l'évolution de notre communauté de recherche au sein de CNRS INSU (Institut National des Sciences de l'Univers, également appelé CNRS Terre &amp; Univers) sur la période 2022-2024. Il présente un résumé thématique et méthodologique de nos activités, un panorama de la structuration actuelle de notre communauté, ainsi qu'un bilan des recrutements et des promotions. Il est fondé sur le travail de la section 17, lequel comprend les concours de recrutement, les recrutements contractuels RQTH, la carrière (évaluation, promotion, éméritat, demande de rattachement à la section ou de détachement de celle-ci, changement d'affectation et RIPEC C3) des personnels de recherche rattachés à la section 17 ; l'évaluation des structures rattachées à la section 17 ; les propositions pour les médailles d'argent et de bronze du CNRS ; les demandes d'accueil en délégation au CNRS ; les écoles thématiques.
• Quantitative estimates of the magnetic flux variations in the inner magnetosphere during an intense storm.
  
  • Alqeeq Soboh
  • Fontaine Dominique
  • Le Contel Olivier
  • Akhavan-Tafti Mojtaba
  • Cazzola Emanuele
  • Atilaw Tsige
  , 2025. In the present study, we analyzed the Earth's magnetospheric dynamics in response to the intense geomagnetic storm of 19th December 2015, marked by a substantial decrease in the SYM-H index to -188 nT. We focushere on the variations of the magnetic flux content (MFC) within closed magnetic shells in the inner magnetosphe up to a distance roughly corresponding to the magnetopause. During this event, we had the chance to have observations on the dayside and on the nightside and at different distances in the magnetosphere (OMNI, Van Allen Probes, GOES, THEMIS, MMS, Cluster). Using these various observations together with the Tsyganenko T96 model, we estimated the MFC in the inner magnetosphere. It is found that in comparison to pre-storm conditions, MCF decreased during SSC by 17% and in the main phase by 27% but it gradually rebounded (swelled) during 3 following days of the recovery phase reducing the decrease to 22%, 14% and 8% respectively. The importance of storm-time magnetospheric dynamics in the field of space weather forecasting is emphasized by these findings and calls for further studies. (10.5194/egusphere-egu25-8724)
  DOI : 10.5194/egusphere-egu25-8724
• The SCM instrument for the ESA Plasma Observatory mission
  
  • Le Contel Olivier
  • Kretzschmar Matthieu
  • Retino Alessandro
  • Mehrez Fatima
  • Jannet Guillaume
  • Alison Dominique
  • Revillet Claire
  • Mirioni Laurent
  • Agrapart Clémence
  • Sou Gérard
  • Geyskens Nicolas
  • Berthod Christophe
  • Chust Thomas
  • Berthomier Matthieu
  • Fiachetti Cécile
  • Khotyaintsev Yuri
  • Cripps Vicki
  • Marcucci Maria Federica
  , 2025. The proposal of the Plasma Observatory mission was selected for a competitive phase A with two other missions in the framework of the seventh call for medium mission (M7) organized by ESA. The mission selection is planned in 2026 for a launch in 2037. Its main objectives are to unveil how are particles energized in space plasma and which processes dominate energy transport and drive coupling between the different regions of the terrestrial magnetospheric system? The mission consists of seven satellites, a main platform (mothercraft, MSC) and six smaller identical satellites (daughtercraft) evolving along an equatorial elliptical orbit with an apogee ~17 and a perigee ~8 Earth radii. The seven satellites will fly forming two tetraedra and allowing simultaneous measurements at both fluid and ion scales. The mission will include three key science regions: dayside (solar wind, bow shock, magnetosheath, magnetopause), nightside transition region (quasidipolar region, transient near-Earth current sheet, field-aligned currents, braking flow region) and the medium magnetotail (near-Earth reconnection region, fast flow formation region). Plasma Observatory mission is the next logical step after the four satellite magnetospheric missions Cluster and MMS. The search-coil magnetometer (SCM), strongly inherited of the SCM designed for the ESA JUICE mission, is only included in the Fields instrument suite of the MSC. SCM will be delivered by LPP and LPC2E and will provide the three components of the magnetic field fluctuations in the [0.1Hz-8kHz] frequency range, after digitization by the Low frequency Receiver (LFR) within the Field and Wave Processor (FWP), relevant for the three Key science regions. It will be mounted on a 6m boom and will allow to reach the following sensitivities [10-3, 1.5x10-6, 5x10-9, 10-10, 5x10-10] nT2/Hz at [1, 10, 100, 1000, 8000] Hz. Associated with the electric field instrument (EFI), SCM will allow to fully characterize the wave polarization and estimate the direction of propagation of the wave energy. These measurements are crucial to understand the role of electromagnetic waves in the energy conversion processes, the plasma and energy transport, the acceleration and the heating of the plasma. (10.5194/egusphere-egu25-16777)
  DOI : 10.5194/egusphere-egu25-16777
• Particle-In-Cell simulations of an electron beam: stability and wave emissions
  
  • Dargent Jeremy
  • Ripoll Jean-François
  • Beck Arnaud
  • Le Contel Olivier
  • Retinó Alessandro
  , 2025. During peaks of magnetospheric activity, energetic electrons trapped in the inner magnetosphere can precipitate in the lower ionosphere due to electromagnetic wave activity. Such waves can be generated naturally or artificially, for instance, through the emission of plasma beams. In this work, we study waves generated by electron beams emitted parallel to the magnetic field using fully kinetic Particle-In-Cell simulations. To this end, we use the heavily parallelized SMILEI code. To reduce the weight of the simulation, we take advantage of the rotational symmetry of the problem and use a cylindrical frame, which reduces the simulation to a 2D problem with cylindrical symmetry. We investigate the impact of the beam characteristics (such as beam density, frequency, length, etc.) on the wave generation, and the structural evolution of the beam as it exchanges energy with the electromagnetic fields and interacts with the background plasma. (10.5194/egusphere-egu25-10538)
  DOI : 10.5194/egusphere-egu25-10538
• 2D fully kinetic simulations of dayside magnetic reconnection in the presence of cold ions and a moderate guide field.
  
  • Baraka Mohammed
  • Le Contel Olivier
  • Retino Alessandro
  • Dargent Jérémy
  • Beck Arnaud
  • Toledo-Redondo Sergio
  • Cozzani Giulia
  • Fuselier Stephen
  • Chust Thomas
  • Alqeeq Soboh
  , 2025. The standard conditions considered for magnetic reconnection to occur are usually antiparallel magnetic field configurations with a shear angle of 180◦. Reconnection is often observed with an additional out-of-plane component of the magnetic field (guide field). We performed two sets of 2D fully kinetic simulations using SMILEI code of asymmetric reconnection. The first set was performed initially by Dargent et al., 2017 with and without cold ions. While the second set with and without cold ions each conducted in the presence of a moderate guide field. The simulation domain size is set to (xmax , ymax) = (320, 128) di, enabling us to study these effects in the electron diffusion region (EDR) as well as the coupling across different scales, including ion diffusion region (IDR), outflow jets, and extended separatrices far from diffusion region. When the density gradient is combined with a guide field component at the magnetopause, it was suggested by Swisdak et al., 2003 that the electron diamagnetic drift governs the motion of the X-line.Our simulations reveal the development of an asymmetry in the reconnection plane as expected and a motion of the X-line in the opposite direction of the electron diamagnetic drift. This finding challenges the previously proposed explanation. We also report our progress in investigating the impact of cold ions in reinforcing the electron dynamics and further investigate the impact of adding a moderate guide field in their presence. These effects are expected to influence the energization, energy partitioning across scales, and potentially the suppression of reconnection. Fluid scales coupling with smaller ion scales aligns with the primary objective of the Plasma Observatory (PO) mission which aims to study plasma energization and energy transport. Our findings will contribute to the preparation of the PO mission and aim at improving its science return. (10.5194/egusphere-egu25-18438)
  DOI : 10.5194/egusphere-egu25-18438
• An Electron Plasma Camera for the Plasma Observatory ESA mission
  
  • Berthomier Matthieu
  • Forsyth Colin
  • Leblanc Frédéric
  • Techer Jean-Denis
  • Alata Yvon
  • Poggia Gabriel
  • Seneret Evan
  • Brockley-Blatt Chris
  • Retino Alessandro
  • Le Contel Olivier
  , 2025. Measuring both the energy spectrum and the 3D distribution of charged particles at high temporal resolution is one of the main challenges in space plasma instrumentation. The conventional solution to date has been to use multiple sensors that couple the native quasi-2D instantaneous field of view of the electrostatic top-hat analyser with a scanning electrostatic deflection system.For the Plasma Observatory ESA mission, we proposed an alternate strategy that reduces the level of resources required for rapid plasma measurements at sub-ion scale in the magnetospheric environment. The Electron Plasma Camera (EPC) is based on the donut-shaped electrostatic analyser topology that do not require any electrostatic scanning to provide a hemispheric field-of-view of the surrounding plasma.This optics is manufactured through the selective metallization of a high-resolution 3D printed polymer. It is coupled to a 256-pixel imaging detection system that uses the detection technology that was demonstrated on the Solar Orbiter mission. EPC’s fully integrated front-end electronics takes advantage of the high-geometric factor of its electrostatic optics to enable the capture of high temporal resolution images of electron phase space. We present the expected capability of the instrument in the key science regions the Plasma Observatory mission will encounter, and some of the major science questions related to multi-scale phenomena the Plasma Observatory mission will address with its unique data set. (10.5194/egusphere-egu25-17978)
  DOI : 10.5194/egusphere-egu25-17978
• The Search-Coil Magnetometer (SCM) of the Radio and Plasma Waves Investigation (RPWI) onboard the ESA JUICE mission: in-flight performance and first observations.
  
  • Retino Alessandro
  • Mansour Malik
  • Le Contel Olivier
  • Chust Thomas
  • Stassen Theo
  • Mirioni Laurent
  • Piberne Rodrigue
  • Santolik Ondrej
  • Soucek Jan
  • Pisa David
  • Wahlund Jan-Erik
  • Khotyaintsev Yuri
  • Bergman Jan
  , 2025. The JUpiter ICy moons Explorer (JUICE) mission is the first large-class (L1) mission of ESA Cosmic Vision. JUICE has been launched in April 2023 with an arrival at Jupiter in 2031 and at least four years making detailed plasma 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. The Search Coil Magnetometer (SCM) of RPWI, combined with the RPWI Low-Frequency receiver (LF), will provide for the first time three-dimensional measurements of magnetic field fluctuations within Jupiter's magnetosphere, with high sensitivity (~10 fT / √Hz at 1 kHz) in the frequency range 0.1 Hz - 20 kHz. Here we present SCM in-flight performance and first observations obtained during its cruise phase, including those from the Lunar-Earth Gravity Assist (LEGA) in 2024. These observations show a nominal functioning and performance of SCM, in agreement with ground calibrations, together with a rather good magnetic cleanliness of the JUICE spacecraft. Observations during LEGA have also allowed to properly identify a number of plasma boundaries in the Earth’s magnetosphere, such as the magnetopause and the magnetotail current sheet, successfully testing the SCM capability to study such boundaries at Jupiter’s and of Ganymede's magnetosphere. (10.5194/egusphere-egu25-20614)
  DOI : 10.5194/egusphere-egu25-20614
• MMS Analysis of a Dayside Compressed Magnetospheric Separatrix in the Presence of Cold Ions and a Moderate Guide Field
  
  • Baraka M.
  • Le Contel O.
  • Canu P.
  • Alqeeq S W
  • Dargent J.
  • Beck A.
  • Cozzani G.
  • Retinò A.
  • Chust T.
  • Mirioni L.
  • Toledo‐redondo S
  • Akhavan‐tafti M
  • Bandyopadhyay R.
  • Chasapis A.
  • Norgren C.
  • Khotyaintsev Y.
  • Ahmadi N.
  • Wei H Y
  • Fischer D.
  • Gershman D J
  • Burch J L
  • Torbert R B
  • Giles B L
  • Fuselier S A
  • Ergun R E
  • Lindqvist P.-A ‐a
  • Russell C T
  • Strangeway R J
  • Bromund K R
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2025, 130 (4). This study reports on a dayside magnetic reconnection event detected by the Magnetospheric Multiscale mission in the presence of a moderate guide field (times the reconnecting magnetic field on the magnetosphere side) and assumed to be present in the whole reconnection region. The spacecraft traversed the compressed magnetospheric separatrix region, observing cold ions with densities up to 10 cm-3 and a large magnetosheath density of up to 150 cm-3. We provide a detailed analysis of current densities, generalized Ohm's law, and energy conversion processes in both the spacecraft and the fluid frames during the separatrix crossing. The normal electric field is directed away from the separatrix due to the cold ion drift on the magnetosphere side and to the magnetosheath ion drift in the presence of a guide field in the exhaust region. In the spacecraft frame, energy transfers from the plasma to the fields due to the convective field associated with the earthward motion of the magnetopause and the ion diamagnetic current associated with the large density gradient. In the fluid frame, energy conversion reverses due to the magnetic field-aligned current density and electric field produced by the divergence of the electron pressure tensor. Additionally, we give insights into the local changes in electromagnetic, bulk flow, and thermal energies. We show that flow and thermal energy variations of the plasma are mostly driven by the compressible term of the electron pressure strain at the separatrix. (10.1029/2024JA033234)
  DOI : 10.1029/2024JA033234
• Transferred plasma catheter for endotherapeutic applications: a parametric study of guided streamers dynamics
  
  • Soulier Manon
  • Vacek Thibaut
  • Géraud Korentin
  • Dufour Thierry
  Physics of Plasmas, American Institute of Physics, 2025, 32 (4). Non-thermal atmospheric pressure plasma jets (APPJs) are increasingly used in biomedical applications due to their low temperatures and ability to generate reactive oxygen and nitrogen species (RONS), making them suitable for sensitive environments like medical therapies. The transferred plasma catheter (TPC), a variant of APPJ, shows promise for endoscopic applications but requires precise control of plasma dynamics in confined spaces to ensure safety and efficacy. Despite extensive studies on guided streamers in traditional APPJs, there is limited understanding of streamer behavior in TPC configurations, particularly in challenging scenarios involving grounded metallic surfaces. This study examines the spatiotemporal dynamics of guided streamers generated by TPCs under varying gap distances to establish a robust framework for safe and effective plasma delivery in endoscopic settings. Combining electrical and optical diagnostics, the study characterizes streamer propagation, electric field profiles, and plasma-induced currents in a helium-driven TPC delivering cold plasma to a grounded metal target across gaps of 2 to 18 mm. Results show that streamers maintain charge stability and effectively interact with the target for gap distances below 12 mm, producing significant therapeutic currents. Beyond this threshold, propagation deteriorates due to recombination and reduced electric field intensity. For shorter gaps, counterpropagating waves and secondary streamer interactions are observed, while larger gaps lead to charge dissipation and reduced efficacy. These findings highlight the importance of optimizing gap distances for plasma-assisted endoscopic procedures and demonstrate the TPC's robustness in adverse conditions. (10.1063/5.0254402)
  DOI : 10.1063/5.0254402
• MESSENGER Observations of a Possible Alfvén Wing at Mercury Driven by a Low Alfvénic Mach Number Interplanetary Coronal Mass Ejection
  
  • Bowers Charles
  • Jackman Caitríona
  • Jia Xianzhe
  • Slavin James
  • Saur Joachim
  • Holmberg Mika
  • Dewey Ryan
  • Heyner Daniel
  • Elekes Filip
  • Hadid Lina
  • Lavraud Benoit
  • Wang Yang
  • Huybrighs Hans
  • Rutala Matthew
  • Fogg Alexandra
  • Lee Stephenie Brophy
  • Hollman Daragh
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2025, 130 (3). Abstract We investigate Mercury's response to rare, low Alfvénic Mach number solar wind conditions using observations from the Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission. This study provides compelling evidence of Mercury's altered magnetospheric state under these extreme conditions, including the first observational confirmation of Alfvén wing formation at the planet. Our analysis estimates that the upstream conditions during the interplanetary coronal mass ejection (ICME) were sub‐to trans‐Alfvénic ( 1.5). These unusually low solar wind conditions were driven by large interplanetary magnetic fields (IMF) associated with an ICME impact observed by MESSENGER on 30 December 2011. During this 17 hr event, MESSENGER completed one orbital pass through Mercury's magnetosphere, capturing magnetic field and plasma observations of its altered state. We compare these observations to a three‐dimensional magnetohydrodynamic simulation of the event and to MESSENGER observations under typical conditions ( 5.0). Compared with its nominal state, the dayside magnetosphere during the ICME exhibited a weaker, more expanded bow shock and significantly lower plasma density within the magnetosheath. On the nightside, MESSENGER observed a highly inclined magnetic field relative to the typical magnetospheric magnetic field, populated with high‐density plasma consistent with the formation of an Alfvén wing– a characteristic feature of sub‐Alfvénic magnetospheric interactions. This investigation of Mercury under extreme conditions provides insights into the nominal, sub‐Alfvénic interactions between many outer planet moons and their host planet's magnetosphere and also informs our understanding of the many exoplanetary‐stellar wind interactions occurring in low‐ environments. (10.1029/2024JA033619)
  DOI : 10.1029/2024JA033619
• Parametric Study of the Performance of an Electrostatic Analyzer With an Hemispheric Field‐of‐View Based on the Donut Topology
  
  • Hénaff Gwendal
  • Berthomier Matthieu
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2025, 130 (3). We carried out a parametric study of the optical performance of an electrostatic analyzer based on the donut topology. The instantaneous hemispheric field‐of‐view of the optics eliminates the need of electrostatic deflectors, which are usually added to the energy analyzer in other designs to cover such a wide field‐of‐view. Parametrization of the donut topology and the use of parallel computing have enabled a wide parametric study of the instrument's performance as a function of the angle resolution of the instrument. We have identified a limited number of geometric parameters, including the outer radius of the detection system, which determine the geometric factor and energy resolution of the instrument for a given angular resolution. The average geometric factor per pixel of this 3D plasma camera varies in the range with an energy resolution between 9% and 14% for an energy limit of 20 keV. Our results suggest that a wide range of space missions could benefit from this new instrument concept. A low‐angular‐resolution version of the instrument could be installed on a nano‐satellite platform, for example, for space weather monitoring on low‐Earth orbit. For space missions requiring high‐angular‐resolution measurements, a high‐temporal‐resolution plasma camera would be able to provide the detailed distribution function of charged particles on larger platforms. (10.1029/2024JA033367)
  DOI : 10.1029/2024JA033367
• Decay of Turbulent Upper-hybrid Waves in Weakly Magnetized Solar Wind Plasmas
  
  • Polanco-Rodríguez F.
  • Krafft C.
  • Savoini P.
  The Astrophysical Journal Letters, Bristol : IOP Publishing, 2025, 982 (1), pp.L24. Large-scale and long-term two-dimensional particle-in-cell simulations of high resolution are performed for the first time to study the dynamics of electrostatic decay of upper-hybrid wave turbulence generated by electron beams into Langmuir/$\mathcal{Z}$-mode ($\mathcal{LZ}$) waves in weakly to moderately magnetized plasmas, in conditions relevant to type III solar radio bursts. Simulations use parameters characteristic of beam–plasma interactions between ∼0.1 and 1 au. The impact of plasma magnetic field on decay is shown, and magnetic properties of $\mathcal{LZ}$ waves are determined. During their energy transport through k wavevector scales, waves undergo several decay cascades, acquiring increasing magnetic energy until they reach electromagnetic $\mathcal{Z}$-mode dispersion below the plasma frequency. Whereas the impact of magnetic field on decaying waves of large k = ∣ k ∣ is weak, important differences with respect to the unmagnetized plasma case manifest at small k -scales, where a boundary layer delimiting a spectral domain free of $\mathcal{LZ}$ energy is revealed. It prevents decayed waves from reaching the $\mathcal{Z}$-mode cutoff frequency and a high level of left-handed polarization, and it modifies the conditions for the appearance of modulational instabilities and strong turbulence phenomena at k ∼ 0. Ordinary $\mathcal{O}$-mode waves are generated jointly with $\mathcal{Z}$-mode waves at comparable energy levels, via electromagnetic decay, whereas $\mathcal{X}$-mode emissions are much weaker in most cases. These results provide support for the interpretation of observations by satellites such as Parker Solar Probe and Solar Orbiter, and they supply a solid basis for tackling the more complex problem of dynamics of upper-hybrid wave turbulence in magnetized plasmas where random density fluctuations cannot be neglected. (10.3847/2041-8213/adba64)
  DOI : 10.3847/2041-8213/adba64
• Milestone in predicting core plasma turbulence: successful multi-channel validation of the gyrokinetic code GENE
  
  • Höfler Klara
  • Görler Tobias
  • Happel Tim
  • Lechte Carsten
  • Molina Pedro
  • Bergmann Michael
  • Bielajew Rachel
  • Conway Garrard
  • David Pierre
  • Denk Severin
  • Fischer Rainer
  • Hennequin Pascale
  • Jenko Frank
  • Mcdermott Rachael
  • White Anne
  • Stroth Ulrich
  Nature Communications, Nature Publishing Group, 2025, 16 (1), pp.2558. Abstract On the basis of several recent breakthroughs in fusion research, many activities have been launched around the world to develop fusion power plants on the fastest possible time scale. In this context, high-fidelity simulations of the plasma behavior on large supercomputers provide one of the main pathways to accelerating progress by guiding crucial design decisions. When it comes to determining the energy confinement time of a magnetic confinement fusion device, which is a key quantity of interest, gyrokinetic turbulence simulations are considered the approach of choice – but the question, whether they are really able to reliably predict the plasma behavior is still open. The present study addresses this important issue by means of careful comparisons between state-of-the-art gyrokinetic turbulence simulations with the GENE code and experimental observations in the ASDEX Upgrade tokamak for an unprecedented number of simultaneous plasma observables. (10.1038/s41467-025-56997-2)
  DOI : 10.1038/s41467-025-56997-2
• Magnetosphere and Plasma Science with the Jupiter Icy Moons Explorer
  
  • Masters Adam
  • Modolo Ronan
  • Roussos Elias
  • Krupp Norbert
  • Witasse Olivier
  • Vallat Claire
  • Cecconi Baptiste
  • Edberg Niklas J T
  • Futaana Yoshifumi
  • Galand Marina
  • Heyner Daniel
  • Holmberg Mika
  • Huybrighs Hans
  • Jia Xianzhe
  • Khurana Krishan
  • Lamy Laurent
  • Roth Lorenz
  • Sulaiman Ali
  • Tortora Paolo
  • Barabash Stas
  • Bruzzone Lorenzo
  • Dougherty Michele K
  • Gladstone Randall
  • Gurvits Leonid I
  • Hartogh Paul
  • Hussmann Hauke
  • Iess Luciano
  • Poulet François
  • Wahlund Jan-Erik
  • Andrews David J
  • Arridge Chris S
  • Bagenal Fran
  • Baskevitch Claire
  • Bergman Jan
  • Bocanegra Tatiana M
  • Brandt Pontus
  • Bunce Emma J
  • Clark George
  • Coates Andrew J
  • Galanti Eli
  • Galli André
  • Grodent Denis
  • Jones Geraint
  • Kasaba Yasumasa
  • Kaspi Yohai
  • Katoh Yuto
  • Kaweeyanun Nawapat
  • Khotyaintsev Yuri
  • Kimura Tomoki
  • Kollmann Peter
  • Mitchell Don
  • Moirano Alessandro
  • Molera Calvés Guifré
  • Morooka Michiko
  • Müller-Wodarg Ingo C F
  • Muñoz Claudio
  • Mura Alessandro
  • Pätzold Martin
  • Pinto Marco
  • Plainaki Christina
  • Retherford Kurt D
  • Retinò Alessandro
  • Rothkaehl Hanna
  • Santolík Ondřej
  • Saur Joachim
  • Stenberg Wieser Gabriella
  • Tsuchiya Fuminori
  • Volwerk Martin
  • Vorburger Audrey
  • Wurz Peter
  • Zannoni Marco
  Space Science Reviews, Springer Verlag, 2025, 221, pp.art. 24. The Jupiter Icy Moons Explorer ( JUICE ) is a European Space Agency mission to explore Jupiter and its three icy Galilean moons: Europa, Ganymede, and Callisto. Numerous JUICE investigations concern the magnetised space environments containing low-density populations of charged particles that surround each of these bodies. In the case of both Jupiter and Ganymede, the magnetic field generated internally produces a surrounding volume of space known as a magnetosphere. All these regions are natural laboratories where we can test and further our understanding of how such systems work, and improved knowledge of the environments around the moons of interest is important for probing sub-surface oceans that may be habitable. Here we review the magnetosphere and plasma science that will be enabled by JUICE from arrival at Jupiter in July 2031. We focus on the specific topics where the mission will push forward the boundaries of our understanding through a combination of the spacecraft trajectory through the system and the measurements that will be made by its suite of scientific instruments. Advances during the initial orbits around Jupiter will include construction of a comprehensive picture of the poorly understood region of Jupiter’s magnetosphere where rigid plasma rotation with the planet breaks down, and new perspectives on how Jupiter’s magnetosphere interacts with both Europa and Callisto. The later orbits around Ganymede will dramatically improve knowledge of this moon’s smaller magnetosphere embedded within the larger magnetosphere of Jupiter. We conclude by outlining the high-level operational strategy that will support this broad science return. (10.1007/s11214-025-01148-8)
  DOI : 10.1007/s11214-025-01148-8