Publications

2026

• K-epsilon modelling of turbulent transport in the edge-SOL boundary layer
  
  • Bufferand Hugo
  • Ciraolo Guido
  • Dif-Pradalier Guilhem
  • Garbet Xavier
  • Ghendrih Philippe
  • Grandgirard Virginie
  • Kudashev Ivan
  • Kunimoto Yakumo
  • Medvedeva Anna
  • Panico Olivier
  • Sarazin Yanick
  • Serre Eric
  , 2026. <div><p>In the K-epsilon framework, a predator-prey like model determines the plasma turbulent transport. It depends on the underlying plasma turbulence via the growth rate chosen for the turbulent energy, the prey K, and its predator epsilon. Compared to our previous work [1], a more appropriate expression of the growth rate is proposed by taking into account the fast dynamics of the parallel electron transport. The stabilising terms that are introduced allow for negative values of the growth rate of interchange coupled to drift wave turbulence. Changes to the K-epsilon model are made to adapt it to handle close to marginal states, then allowing one to address a Landau like bifurcation from negative growth rates, without turbulence, to positive growth rates, with turbulence. The closure using the multi-machine SOL width scaling law is revisited to allow the K-epsilon turbulent transport to depend on the growth rate. This is mandatory in the present model to yield increasing turbulent transport towards the edge and enhanced SOL transport governed by the sheath resistivity. Usual predator-prey limit cycles can be achieved whenever the growth rate of the predator is smaller than that of the prey. The growth rates are determined by a simplified 2D turbulence model taking into account magnetic field inhomogeneity and parallel losses, mostly of electrons. These are computed in Fourier space and must be adapted to plasma coarse grained simulations, in particular for edge-SOL-divertor simulations. A growth rate maximisation procedure then determines the wave vector in terms of the plasma parameters. Although the maximisation results are different for drift wave and interchange instabilities, their spectral properties are not discernable and the two instabilities are shown to be difficult to disentangle. Both facets of turbulence are therefore accounted for in the analytical expressions that are obtained for the growth rates, which are to be implemented in K-epsilon simulations of plasma-wall interaction with consistent turbulent transport.</p></div>
• A Combined Computational and Experimental Approach to Investigating Volatile-Surface Interactions on Airless Planetary Bodies
  
  • Ricketts Amanda
  • Mclain Jason
  • Yeo Li Hsia
  • Sarantos Menelaos
  • Verkercke Sébastien
  • Morrissey Liam
  , 2026. The surfaces of airless, planetary bodies like the Moon and Mercury are constantly exposed to several processes that eject atoms into the exosphere1,2. While the composition and densities of these exospheres are partially known based on observational data from exploratory missions3, the source of each component is not well understood. This uncertainty necessitates better constraints for accurately interpreting the observed exospheric data, which requires both experimentally constrained measurement and atomistic-level physical insight.Laboratory studies provide valuable measurements of adsorption and desorption behavior, while molecular dynamics (MD) simulations enable direct investigation of the atomic-scale interactions that cannot be resolved experimentally. By combining these approaches, it becomes possible to better constrain the physical mechanisms controlling surface-exosphere interactions on bodies such as Mercury and the Moon.In this work, MD simulations of Na and K adsorption on silica surfaces are combined with thermal stimulated desorption (TSD) experiments of Na and K adsorbed onto silica. The study focuses on understanding how surface coverage and environmental hydroxylation influence adsorption energetics and desorption behavior4. The combined computational and experimental approach not only provides validation between methods, but also demonstrates how MD simulations can explain experimentally observed trends and identify surface processes relevant to planetary environments. Methodology: MD simulations were performed to investigate Na and K adsorption on silica surfaces under varying surface coverages and surface chemistries. Surface binding energies (SBEs) were calculated for adsorbed Na and K atoms to quantify the strength of adsorbate-surface interactions and to identify how adsorption behavior evolves from isolated adsorbates to high-coverage surfaces5. Additional simulations examined H covered silica surfaces to evaluate the effect of hydroxylation on adsorbed Na SBEs.TSD experiments were conducted by collaborators using Na- and K-dosed Apollo samples6. Following adsorbate deposition, samples were heated to approximately 1000K while monitoring desorption behavior to derive activation energies associated with adsorbate release from the surface. The experimental desorption energetics were compared directly with the MD-derived SBEs to investigate the physical origins of the experimentally observed desorption behavior. Results: The combined MD and experimental results demonstrate strong agreement between stimulated adsorption energetics and experimentally observed desorption behavior. Figure 1 displays the SBE distributions of adsorbed Na on a bare silica surface, Na covered surface, and hydroxylated surface.MD simulations show that isolated Na atoms adsorbed directly onto bare silica surfaces form strongly bound adsorption states with SBEs exceeding 5 eV. These energies are larger than the effective experimental detection range of the TSD studies, which are insensitive to adsorption energies above approximately 3.5 eV at the maximum experimental temperature of 1000K. Consequently, strongly bound adsorbates detected in the MD results are unlikely to desorb during experimental heating cycles.This provides important insight into the physical experiments, suggesting that residual adsorbates likely remain on the silica surface between experimental runs despite minimal dosing conditions. Over time, this accumulated coverage may produce increasingly significant Na-Na or K-K interactions and lower-energy adsorption states, consistent with the experimentally observed desorption energies. In this way, the MD simulations provide a physical explanation for experimental behavior that cannot be directly measured.Further MD simulations demonstrate that hydroxylated silica surface significantly reduce adsorbate SBEs relative to bare silica (by ~2.9 eV). This suggests that exposure of experimental samples to ambient atmospheric water or H during sample transfer may hydroxylate undercoordinated surface oxygens, producing weaker adsorption states and lower desorption temperatures in the TSD measurements. Similar hydroxylation processes are also expected on Mercury and the Moon due to solar wind hydrogen implantation, likely resulting in spatially variable adsorption energetics across the planetary surface.Together, these results demonstrate how combining MD simulations with laboratory experiments enables a more reliable interpretation of both datasets while providing improved insight into the surface processes governing volatile behavior on airless planetary bodies. Conclusion: This study demonstrates the strength of integrating MD simulations with laboratory thermal desorption experiments to investigate surface processes on airless planetary bodies. While experiments provide direct measurements of adsorbate desorption behavior, MD simulations reveal the underlying atomic-scale interactions responsible for the observed trends. The combined approach identifies the important roles of surface coverage and hydroxylation in controlling adsorption energetics and explains how experimentally inaccessible strongly bound adsorption states may influence measured desorption behavior.By coupling computational and experimental methods, this work provides a more physically complete understanding of adsorbate-surface interactions and highlights the importance of considering realistic surface environments when interpreting laboratory measurements and modelling planetary surface-exosphere systems. (10.5194/epsc2026-640)
  DOI : 10.5194/epsc2026-640
• Three-dimensional simulations of thermal and non-thermal hydrogen and deuterium escape from Venus
  
  • Li Dan
  • Martinez Antoine
  • Modolo Ronan
  • Chaufray Jean-Yves
  • Aizawa Sae
  • Xu Qiuyu
  • Montmessin Franck
  • Lefèvre Franck
  • Lebonnois Sébastien
  , 2026. The enrichment of Venusian atmospheric D/H ratio is commonly interpreted as evidence for substantial water loss, but its connection to present-day atmospheric escape remains uncertain. Because hydrogen and deuterium can escape through different thermal and non-thermal pathways, quantifying their relative escape rates is essential for assessing the escape fractionation of Venusian water. We present new developments of the LMDZ Venus Planetary Climate Model for the study of H and D escape. Building on the recent thermospheric and ionospheric extension of the model, we have introduced deuterium-bearing species and reactions, allowing the H- and D-bearing species to be followed from the lower atmosphere to the thermosphere. The model is used to compute the thermal escape of H and D and to provide a self-consistent three-dimensional atmospheric and ionospheric background for non-thermal escape calculations. Photochemical escape is investigated with a Monte Carlo test-particle model, while solar-wind-driven ion escape is studied by coupling the Venus PCM outputs to the LatHyS Venus hybrid model. This work provides a unified framework for comparing the main escape channels of H and D at Venus and for estimating the present-day D/H escape fractionation factor. It offers a step toward linking current upper-atmospheric loss processes to the long-term isotopic evolution history of Venusian water. (10.5194/epsc2026-535)
  DOI : 10.5194/epsc2026-535
• Statistical Noise Removal Method for the Mass Spectrum Analyzer onboard BepiColombo/Mio
  
  • Verkercke Sebastien
  • Hadid Lina
  • Aizawa Sae
  • Delcourt Dominique
  • Raines Jim
  • Fränz Markus
  • Saito Yoshifumi
  • Yokota Shoichiro
  • Rojo Mathias
  • Harada Yuki
  • Fontaine Dominique
  • André Nicolas
  • Katra Bruno
  • Verdeil Christophe
  • Modolo Ronan
  • Krupp Norbert
  • Leblanc François
  • Fiethe Björn
  • Fischer Henning
  , 2026. Mercury is one of the two terrestrial planets in our Solar System possessing an intrinsic magnetic field. Being the closest planet to the Sun and having a weak magnetic field, the Hermean magnetic environment is rapidly changing and forms a tightly coupled system with the planet's core and surface. Its closeness to the Sun causes Mercury's surface to undergo extreme conditions, with continuous space weathering that can eject atoms from the surface to form a tenuous atmosphere called an exosphere (Potter &amp; Morgan 1985). As these atoms become ionized, they drift along the magnetic field lines and populate the magnetosphere of Mercury. Part of these ions can re-impact the surface and eject surface atoms, forming a strong coupling between the magnetosphere, the exosphere, and the surface (Potter &amp; Morgan 1990, Leblanc et al. 2003). More than fifty years after the Mariner 10 mission confirmed the presence of Mercury's magnetic field (Ness et al. 1974), the structure of Mercury's magnetosphere and its ionic composition remain poorly understood. The ESA/JAXA BepiColombo mission is currently cruising towards Mercury to study the Hermean environment, from the planet's surface up to its magnetosphere (Benkhoff et al. 2021). The Mass Spectrum Analyzer (MSA) (Delcourt et al. 2016) on board the ESA/JAXA BepiColombo mission collected some data during its cruise phase and during the different planetary swing-bys. The instrument measures the ions' energy, and the Time-Of-Flight (TOF) of the ions entering MSA TOF chamber. A striking feature observed in the data is a large band of detection counts present at similar energies than protons, when a large number of protons are detected by the instrument. This features was attributed to energy straggling, causing a delay in the ions' detection with respect to their theoretical TOF, and accidental counts generated by true start signals and stop signals caused by random noise. As protons are the most abundant ionic species of the solar wind (SW), this straggler induced noise is nearly always present, and contaminates strongly the rest of the measurements. Using the data acquired by MSA in the SW, we derive a generic statistical fit of the noise induced by the proton stragglers, connecting the proton counts to the noise level. By applying our method to re-analyze some of the data collected by MSA during the Mercury swing-bys (MSB), we demonstrate that : 1) the stragglers play an important role in the determination of the spacecraft outgassing rate and confirm that the outgassing follows an exponential decrease; 2) the MSB3 data collected in Mercury's magnetosphere are heavily affected by the stragglers' noise. Using our noise subtraction method provides a refined constraint on the heavy ion populations during MSB3 and further strengthens the evidence ions detections from the O+, Na+, K+-groups. With our results, we try to infer the spatial distributions of the planetary ions during different Mercury flybys. (10.5194/epsc2026-327)
  DOI : 10.5194/epsc2026-327
• Evidence of a cold and dense plasma in the northern polar cap of Mercury
  
  • Rojo Mathias
  • Dandouras Iannis
  • Aizawa Sae
  • Dewey Ryan
  • Raines Jim
  • Liu Zhi-Yang
  • Le Liboux Thomas
  • Coustillet Camille
  • Gonnet Anderson
  • Hadid Lina
  • Harada Yuki
  • Varsani Ali
  • Williamson Hayley
  • Millilo Anna
  • André Nicolas
  • Saito Yoshifumi
  • Murakami Go
  , 2026. The northern polar cap region of Mercury remains poorly explored, as the MESSENGER orbits were close to the surface. Moreover, this region appears to bepopulated by tenuous plasma. The northern polar cap of Mercury was crossed twice during the 4th and 6th flybys of BepiColombo. The Mercury Electron Ana-lyzer onboard BepiColombo allowed the probing of low-energy electrons for the first time in this region since the third flyby of Mariner 10. We show that thenorthern polar cap is populated with dense and cold electrons. Simultaneously, the four ion sensors did not detect any particles. This lack of detection suggests the presence of very cold ions of exospheric origin. Such a measurement challenges current models of Mercury’s exosphere and could be compatible with a closure of Region 1 field aligned currents above the surface. (10.5194/epsc2026-896)
  DOI : 10.5194/epsc2026-896
• Influence of chemical and morphological properties on the mid-infrared refractive indices of Titan aerosol analogs
  
  • Perrin Zoé
  • Drant Thomas
  • Caurel Enrique Garcia
  • Brubach Jean‐blaise
  • Ruscassier Nathalie
  • Gautier Thomas
  • Sciamma-O’brien Ella
  • Vettier Ludovic
  • Chatain Audrey
  • Guaitella Olivier
  • Carrasco Nathalie
  Astronomy & Astrophysics - A&A, EDP Sciences, 2026, 713, pp.A199. The intrinsic properties of aerosols in Titan's atmosphere are one of the main sources of uncertainty when interpreting and understanding observations of its surface and atmosphere. The optical properties of the solid material have been recovered for both of Titan's aerosols using remote-sensing observations and laboratory analogs. Significant differences are observed in the refractive indices reported in the literature. For laboratory-generated solid analogs, these discrepancies in the refractive indices can originate from the different experimental factors influencing the morphological and chemical properties of solid samples, for example the energy distribution, gas flow rate, and/or gas temperature. In this study, we report new refractive indices, n and k, in the mid-infrared spectral range (2-20 µm) determined on Titan aerosol analogs with different morphological and chemical properties. We compare in detail the differences in optical properties of thin films, commonly used for refractive index measurements, and compressed pellets of quasispherical powders. Using transmission spectroscopy and reflection Mueller ellipsometry, we find that compressed powders are more absorbent than their film equivalent, with increased signature strengths of (hetero-)aromatic and amine features in agreement with a higher nitrogen-to-carbon ratio compared to the film analogs. Finally, we observe that the reflective power of these pellet analogs is not only affected by the refractive index (n) but also significantly by the inter-grain porosity. (10.1051/0004-6361/202554328)
  DOI : 10.1051/0004-6361/202554328
• Dynamics of switchback-like magnetic deflection induced by a propagating coronal jet
  
  • Touresse J.
  • Pariat E.
  • Froment C.
  • Wyper P.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2026. The Parker Solar Probe (PSP) mission revealed the ubiquity of switchbacks (SBs), sharp and localised magnetic deflections, in the nascent solar wind. This finding has sparked significant interest in their origin and formation mechanisms. Among the proposed scenarios, a solar origin associated with solar jets has emerged. Solar jets are collimated, impulsive, and sharp-edged features associated with magnetic reconnection and they generate an Alfvénic torsional wavefront propagating into the heliosphere. In this study, we investigate whether a realistic spacecraft sampling of a propagating solar jet can produce synthetic in situ signatures consistent with PSP-observed SBs. We also characterise the three-dimensional (3D) magnetic topology of the underlying structure and assess how the magnitude of the magnetic deflection evolves with the surrounding environment. We performed a 3D magnetohydrodynamic simulation of a solar jet propagating into the ambient solar wind. A virtual spacecraft trajectory, constructed from the actual PSP orbit during its 22 nd perihelion, was embedded within the simulation to generate synthetic in situ measurements. The simulation reproduces SB-like magnetic signatures with durations and profiles consistent with PSP observations, confirming earlier results obtained using simplified trajectories. For the first time, we directly visualised the fully 3D magnetic topology of a jet-driven SB region. Two distinct families of magnetic field lines are identified: one exhibiting a single magnetic deflection, and another showing two sequential deflections propagating along the same field line. In both configurations, the deflections act as outward-propagating Alfvénic structures. The magnitude of the magnetic deflection is strongly modulated by the background plasma β, with significant amplification in low-β regions and a more moderate evolution where β ∼ 1. These results demonstrate that propagating solar jets can naturally produce Alfvénic, SB-like structures when sampled along realistic in situ trajectories. The magnetic topology of SB regions is inherently 3D and structurally diverse. Their evolution depends on the surrounding plasma β, with complete magnetic reversals requiring longer residence times in low-β environments. This study supports the interpretation that at least a fraction of the SBs observed by PSP may have a solar origin and it provides new constraints for interpreting PSP measurements in terms of their underlying magnetic structure. (10.1051/0004-6361/202659513)
  DOI : 10.1051/0004-6361/202659513
• Automatic Detection of the Earth's Magnetopause Boundary Layer from Multiple Mission Data
  
  • Ghisalberti A
  • Aunai N
  • Lavraud B
  • Michotte de Welle B
  • Jeandet A
  , 2026. The Earth's magnetopause boundary layer (BL) is a dynamic plasma region shaped by the interaction between the solar wind and the magnetosphere. Its properties exhibit strong spatial and temporal variability, making the BL a complex and heterogeneous structure. These characteristics have hindered systematic BL identification and large-scale statistical analysis. In this paper, we present a novel supervised machine learning approach for the automated detection of the magnetopause BL using data from the MMS, THEMIS, and Cluster missions. Our method achieves a BL detection with a precision constrained primarily by the inherent ambiguity in the labeling task. This approach enables, for the first time, the construction of a comprehensive BL dataset comprising over 5 million data points, offering unprecedented spatial coverage compared to previous studies.
• Inferring the Parametric Location of the Earth’s Magnetopause Reconnection X-Line from In Situ Measurements
  
  • Ghisalberti A
  • Aunai N
  • Lavraud B
  • Michotte de Welle B
  • Jeandet A
  , 2026. Magnetic reconnection at the Earth's dayside magnetopause is a fundamental process that governs the transfer of solar wind energy and plasma into the magnetosphere. The location and orientation of the reconnection X-line are critical for understanding this coupling, yet remain debated. This study presents a novel, data-driven approach to infer the average position of the reconnection X-line using in situ measurements from multiple satellite missions (MMS, THEMIS, Cluster). By leveraging a large dataset of boundary layer (BL) ion flows-automatically detected using machine learning-we construct high-resolution maps of the ion bulk velocity difference between the BL and the shocked solar wind. The X-line is identified as the locus of flow reversals, where this velocity difference diverges. Our results reveal that, on average, the X-line is globally continuous and rotates with the interplanetary magnetic field (IMF) clock angle, consistent with local orientation along the magnetic field bisector. We also find a systematic north/south shift of the X-line with the Earth's dipole tilt, with a displacement of approximately 0.12 RE per degree of tilt. These findings are incompatible with the maximum magnetic shear model, and with models that maximize reconnection rate or electric current. The methodology presented does not however allow the study of the dynamic behavior of the X-lines.
• On Phase Transition of ITG Turbulence in the Dimits shift
  
  • Marquant Lucien Noël
  • Morel Pierre
  • Gurcan Ozgur
  Plasma Physics and Controlled Fusion, IOP Publishing, 2026. Abstract The transition between turbulent and zonal flow dominated states is investigated by varying the ion temperature gradient in nonlinear gyrokinetic simulations. Independent gradient scans reveal three distinct regimes: a turbulent regime at high gradients, a zonal flow dominated regime with strongly reduced heat transport at low gradients, and an intermediate regime characterized by intermittent switching between these two states. These different regimes can be classified using an order parameter, defined as the fraction of the zonal to total free energy in the system. To assess the memory effects, the temperature gradient is first lowered gradually from high values that result in fully developed turbulence, to lower values in the Dimits shift region that form strong zonal flows, and then is slowly increased back. Once the zonal flows form, and efficiently suppress turbulence, they can persist at higher gradients, leading to an asymmetric response implying a hysteresis loop. It is observed that, in the zonal flow dominated state, the free energy is mostly condensated in the largest radial scale, with a steep slope of the k x spectrum, while in the turbulent state, it exhibits a wider spectrum with two distinct slopes. (10.1088/1361-6587/ae9ac6)
  DOI : 10.1088/1361-6587/ae9ac6
• Occurrence and controls of ~ 1 Hz waves in Mercury’s magnetosphere: insights from MESSENGER observations
  
  • Persson M.
  • Dimmock A.
  • Wahlund J.-E.
  • Morooka M.
  • Yordanova E.
  • Eriksson A.
  • Hadid L. Z.
  • Aizawa S.
  • Khotyaintsev Yu.
  • Edberg N.
  • André M.
  Earth Planets and Space, Springer / Terra Scientific Publishing Company, 2026, 78 (1), pp.180. (10.1186/s40623-026-02516-6)
  DOI : 10.1186/s40623-026-02516-6
• Thermal Non-equilibrium Cycles in a Non-eruptive Pseudo-Streamer
  
  • Froment Clara
  • Masson Sophie
  Solar Physics, Springer Verlag, 2026, 301 (8), pp.118. Thermal non-equilibrium (TNE) is a well-known thermodynamic mechanism, generally studied in coronal loops. These evaporation and condensation cycles are induced by a quasi-steady and stratified heating. Long-period EUV pulsations and coronal rain are two manifestations of TNE. The quasi-periodicity of the cycles is a strong characteristic of TNE as the system dynamically evolves around a thermal equilibrium position that is not reachable. There are recent reports of coronal rain at open-closed boundaries such as fan-spine topologies and pseudo-streamers. However, no definite conclusions were drawn on the physical mechanisms driving these coronal rain events. In this article, we report the detection of long-period EUV pulsations and co-spatial recurring coronal rain showers in a pseudo-streamer observed with the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO). The magnetic topology and evolution of the pseudo-streamer are studied in detail using a combination of potential field source-surface (PFSS) modeling and EUV dynamics. The 2.5-day event exhibits all the characteristic features of previous TNE events reported in coronal loops: periodic EUV pulses appearing sequentially in the different channels, following the ordering of the peaks in their temperature response, and coronal rain showers appearing toward the end of these cycles. We further show that the TNE cycles in the pseudo-streamer occur not only in the closed field but also in the open field. Our observations support the findings of recent numerical studies showing that TNE can also occur in open field regions and at open-closed boundaries. In parallel, interchange reconnection occurs continuously and non-impulsively all along the open-closed boundary as seen in EUV. The interplay between TNE and interchange reconnection may play a role in the release of condensations below the open-closed boundary and should be studied in detail in future works. This observation opens further perspectives for the understanding of TNE in the solar atmosphere and its potential implications for the solar wind. (10.1007/s11207-026-02671-9)
  DOI : 10.1007/s11207-026-02671-9
• Global plasma modeling of an air-breathing gridded-ion thruster for very low Earth orbit applications
  
  • Carer Charlélie
  • Verdier Solène
  • Flack Léo
  • Scemama Adrien
  • Petronio Federico
  Physics of Plasmas, American Institute of Physics, 2026, 33 (8). A volume-averaged (zero-dimensional) global model of an atmospheric nitrogen–oxygen mixture is proposed. This model is used to predict the performance of an air-breathing electric gridded-ion thruster. Based on particle and energy balance equations, it computes the densities and temperatures of the different species in the discharge chamber and evaluates the thrust generated by ions extracted from the plasma and accelerated between two grids. Simulation results over a range of input radio frequency (RF) powers and altitudes are used to assess the feasible operating regimes and to identify the main limiting mechanisms. Coupling the global model with a simplified drag analysis indicates that satellite operation should be feasible at altitudes between 200 and 250 km, for RF power levels ranging from 1.5 to 3 kW. However, certain limitations associated with the gas compression system and drag estimation deserve further investigation. (10.1063/5.0327675)
  DOI : 10.1063/5.0327675
• Potential Solar Precursors to Magnetic Switchbacks
  
  • Tripathi Durgesh
  • Madjarska Maria S
  • Karpen Judy
  • Velli Marco
  • Froment Clara
  • Pariat Etienne
  • Patsourakos Spiros
  • Raouafi Nour E
  • Rouillard Alexis P
  • Sterling Alphonse C
  • Tziotziou Kostas
  • Wyper Peter F
  Space Science Reviews, Springer Verlag, 2026, 222 (5), pp.60. The origin of magnetic switchbacks-large-amplitude, spherically polarized magnetic-field fluctuations with local polarity inversions shown to be nearly ubiquitous in the inner heliosphere by Parker Solar Probe-is presently one of the most outstanding open questions in solar and heliospheric science. The occurrence of these structures in the young solar wind is a topic of active research, focusing not only on their characteristics and evolution but also on unraveling the puzzle of their origin. We first discuss the potential influence on switchback (SB) formation of large-scale coronal dynamics and restructuring processes that shape and regulate the extended solar corona. Following that, we review the dynamics, physical properties, occurrence rate, and energetics of numerous possible precursor small-scale dynamic events that occur throughout the solar atmosphere, emphasizing their possible roles in creating SBs. Finally, we discuss some recent studies attempting to connect in situ observations of SBs and SB patches with remote-sensing observations, and the related challenges in identifying solar wind source regions precisely and linking in situ observations to transient solar phenomena. We also clarify the terminology used by the solar community to describe small-scale solar phenomena. (10.1007/s11214-026-01312-8)
  DOI : 10.1007/s11214-026-01312-8
• Back reaction of the untwisting solar corona scars sunspots
  
  • Xing Chen
  • Cheng Xin
  • Aulanier Guillaume
  • Ding Mingde
  Science Advances, American Association for the Advancement of Science (AAAS), 2026, 12 (30). The evolution of magnetic fields in the tenuous solar corona is predominantly governed by the motions of the underlying dense photosphere. Despite this, coronal magnetic restructuring driven by magnetic reconnection between interacting coronal fields can sometimes react backward to change photospheric magnetic fields. However, the mechanism of reactions remains undetermined. Here, we report the discovery of a back-reaction phenomenon: The untwisting of coronal loops that become twisted during reconnection in an eruption results in enhanced currents at the boundary of their footpoint away from the eruption, manifesting as the growth of a sunspot scar. It is revealed to arise from the Alfvénic reverse transfer of magnetic twist from the corona to the lower atmosphere, through joint space observations and a magnetohydrodynamic simulation. These findings provide a viable and quantitative interpretation for the majority of puzzling photospheric changes associated with coronal mass ejections and/or flares and warn for unexpected magnetic field evolutions in sunspots and starspots. (10.1126/sciadv.aed5294)
  DOI : 10.1126/sciadv.aed5294
• Atomic Simulations of Volatile Coverage on Silicate Surfaces
  
  • Ricketts Amanda
  • Clouter‐gergen Benjamin A
  • Ebel Denton S
  • Georgiou Anastasis
  • Leblanc Francois
  • Sarantos Menelaos
  • Verkercke Sebastien
  • Morrissey Liam S
  Geophysical Research Letters, American Geophysical Union, 2026, 53 (14), pp.e2026GL122334. <div><p>Understanding how surface processes shape exosphere formation on airless bodies is limited by how surface properties influence the ejection of volatiles such as Na. Recent studies show that retention and release are sensitive to surface binding energy (SBE), motivating the need for SBE values as a function of mineral type and surface coverage. Currently, Na SBE values are available only for silica at 0 or 1 monolayer (ML) coverage. Here, we present the first SBE distributions at intermediate coverages (0.1-0.75 ML) on silica, along with the first SBE distributions for Na adsorbed on albite and anorthite from 0 to 1 ML. Increasing coverage shifts SBE distributions to lower energies, with mean SBE decreasing even at 0.1 ML. Results demonstrate that SBE depends nonlinearly on coverage and surface composition. We incorporate findings into sputtering models to quantify their impact on yield and energy distributions, highlighting the importance of coverage-dependent SBEs in exosphere modeling.</p><p>Plain Language Summary Understanding how atoms escape from the surfaces of airless planetary bodies like the Moon and Mercury help scientists explain how their exospheres form. One important factor is how strongly an atom sticks to the surface, known as the surface binding energy (SBE). This sticking strength changes depending on how many atoms are already covering the surface, although past studies have only focused on empty or fully covered surfaces. In our study, we used computer simulations to test several intermediate coverage levels and also examined different types of minerals found on planetary surfaces. We found that when more sodium atoms are already present, newly added atoms stick less strongly. Even a small amount of prior coverage noticeably lowers the SBE. By visualizing where atoms attach, we also saw that sites near already-occupied spots tend to hold atoms less tight. These results can help improve models that predict how atoms are released into exospheres and support better interpretation of upcoming mission data.</p></div> (10.1029/2026GL122334)
  DOI : 10.1029/2026GL122334
• Unprecedented Fast Winking of Solar Flares Triggered by Bursty Magnetic Reconnection
  
  • Li Ting
  • Duan Xuchun
  • Hou Yijun
  • Aulanier Guillaume
  • Zimovets I.
  • Zhang Jun
  • Lörinčík Juraj
  • Kashapova Larisa
  • Li Zhentong
  • Zhang Yining
  • Wang Yulei
  • Li Leping
  • Ma Suli
  • Huang Jing
  • Yang Shuhong
  • Zhou Guiping
  The Astrophysical Journal, American Astronomical Society, 2026, 1006 (1), pp.47. Abstract Flare ribbons form as a result of energy deposition associated with particles accelerated in low layers of the solar atmosphere. The fine-scale structures of flare ribbons, also called ribbon kernels, offer a potentially powerful diagnostic of the flare reconnection process, however, to date the dynamic evolution of ribbon kernels has not been fully characterized in statistical studies. Here, we checked the state-of-the-art observations (cadence ≤2.5 s) of solar flares in the ultraviolet from space by Interface Region Imaging Spectrograph over the past 12 yr. Our results showed the first statistical study of multiple spatially resolved flare kernel quasiperiodic pulsation events for 31 flares, with the period of 6–24 s. The ribbon kernels have a spatial scale of 480–1200 km and some kernels exhibit an unprecedented fast “winking” process, i.e., quasiperiodic pulsation-like flashing of individual kernels. The shortest heating time reaches about 2–3 s, implying that the energy is deposited only in a small localized region within flare ribbons, persisting for only a few seconds. Meanwhile, some ribbon kernels were observed to slip along the ribbon at speeds of 20–1800 km s −1 . These observations strongly imply a joint picture for the dynamics and the bursty nature of ribbon kernels as being due to coupled effects of plasmoid formation and three-dimensional magnetic reconnection in the overlaying coronal current sheet. We suggest that the observed flare behaviors provide strong observational evidences of 3D bursty reconnection. (10.3847/1538-4357/ae80ae)
  DOI : 10.3847/1538-4357/ae80ae
• Analysis of wave processes using beam-driven Langmuir/Z-mode waveforms generated in particle-in-cell simulations
  
  • Polanco-Rodríguez F J
  • Krafft C.
  • Savoini P.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2026, 711, pp.A139. (10.1051/0004-6361/202659416)
  DOI : 10.1051/0004-6361/202659416
• Benchmark of two-dimensional simulations of Penning-type discharge with Particle-In-Cell algorithms
  
  • Garrigues Laurent
  • Powis Andrew T.
  • Ahedo Eduardo
  • Alvarez Laguna Alejandro
  • Barléon Nicolas
  • Bello-Benítez Enrique
  • Boeuf Jean-Pierre
  • Bogopolsky Guillaume
  • Bourdon Anne
  • Cichocki Filippo
  • Cuenot Bénédicte
  • Denig Andrew
  • Donkó Zoltán
  • Elias Paul-Quentin
  • Encinar Miguel
  • Eremin Denis
  • Fajardo Pablo
  • Faraji Farbod
  • Fubiani Gwenael
  • Hara Kentaro
  • Hartmann Péter
  • Hopkins Matthew J
  • Kaganovich Igor D.
  • Knoll Aaron
  • Lapenta Giovanni
  • Magin Thierry E.
  • Marín-Cebrián Alberto
  • Merino Mario
  • Minelli Pierpaolo
  • Papahn Zadeh Mina
  • Parodi Pietro
  • Petronio Federico
  • Reza Maryam
  • Smolyakov Andrei I.
  • Sydorenko Dmytro
  • Taccogna Francesco
  • Turner Miles M.
  • Vermorel Olivier
  • Villafana Willca
  • Xu L.
  , 2026.
• Investigation of homogeneous dielectric barrier discharges sustained in CO2-containing mixtures
  
  • Naudé Nicolas
  • Wang C
  • Bajon C
  • Dap S
  • Guaitella O
  • Guerra V.
  • Silva T
  , 2026.
• Introduction aux Enjeux Environnementaux : le livre
  
  • Rezeau Laurence
  , 2026. Une partie de l’équipe qui a monté l’enseignement obligatoire TEDS (transition écologique pour un développement soutenable) à Sorbonne Université a décidé d’écrire un livre à partir de cette expérience pluridisciplinaire riche. L’objectif de cet ouvrage est de donner à des lecteurs et des lectrices non spécialistes un socle de connaissances pluridisciplinaires pour comprendre les enjeux environnementaux actuels. Il s’agit d’apporter des éléments de réponse aux questions difficiles auxquelles nous devons toutes et tous faire face de façon urgente pour avoir l’espoir de transmettre une planète habitable pour les générations futures. La première partie de l’ouvrage a pour but de consolider les connaissances liées aux enjeux environnementaux : comprendre le fonctionnement de la planète Terre et son évolution, comprendre comment l’accès à une énergie fossile presqu’illimitée impacte ce fonctionnement, analyser les modèles d'évolution possibles pour la société en tenant compte des limites physiques de la planète et en essayant de construire une société juste et équitable. Cette première partie se base sur les connaissances scientifiques bien établies par les spécialistes. Pour autant il n’y a pas de solution simple aux questions posées. La moindre interrogation en matière de transition environnementale débouche sur des problèmes d’acceptabilité sociale, de contestation des résultats scientifiques, de conflits d’intérêt économiques, de conflit de valeurs, d'enjeux politiques de court terme, etc. L’objet de la seconde partie de l’ouvrage est donc de comprendre comment les connaissances scientifiques se construisent et comment nous pouvons y accéder de manière fiable. Des pistes d'appropriation des compétences informationnelles de base nécessaires sont proposées : confrontation des sources, analyse de la pertinence et de la fiabilité d’une source documentaire. Nous proposons ensuite un cadre méthodologique pour analyser une controverse, c'est-à-dire identifier les acteurs, les enjeux, les points de tension, faire une cartographie de la controverse puis envisager les perspectives possibles. Cette partie sera illustrée par une controverse close dont on peut faire le bilan : le tabac est-il dangereux ?
• Analysis of Geomagnetically Induced Currents (GICs) during the May 2024 Gannon storm
  
  • Amaechi Paul O
  • Grodji Franck O
  • Messanga Honore
  • Despirak Irina
  • Ngwira Chigomezyo M
  • Akala Andrew
  • Oyeyemi Elijah
  • Amory-Mazaudier Christine
  • Nishimura Yukitoshi
  • Weygand James M
  Advances in Space Research, Elsevier, 2026. The May 2024 Gannon storm, one of the most intense geomagnetic disturbances (GMDs) in two decades, provides a valuable opportunity to examine geomagnetically induced currents (GICs), their drivers, and impacts on bulk power system resilience. We analyzed GICs over the United States using direct measurements from three North American Electric Reliability Corporation (NERC) monitoring devices, magnetometer-derived proxy indices, and continuous wavelet transform (CWT). The storm featured multiple substorm onsets, supersubstorms (SSSs), and westward electrojet (WEJ). Results show that during the sudden storm commencement on 10 May, magnetic field variations, |dH/dt| reached 80 nT/min at ~54 o MLAT with GICs of up to 70 A recorded by device 10659 (~54 o MLAT) at about 17:08 UT. During the main phase on 10 May, GICs peaked at 128 A at device 10659 around 21:44 UT due to substorm activity in conjunction with Ps6 pulsations. Furthermore, the substorm onset at ~02:00 UT on 11 May was associated with an enhanced |dH/dt| of 437 nT/min at ~56 o MLAT and the largest GIC response to this GMD with a peak of 176 A (device 10659) at 02:04 UT. CWT analysis further suggests that Ps6 magnetic pulsations contributed as secondary driving mechanisms. The recovery phase was characterized by significant GICs up to 120 A at the same device around 08:41 UT, related to coupled magnetospheric drivers, including Pc5 magnetic pulsations and a SSS under magnetic cloud conditions. This storm phase further featured a GIC of 91 A (at 04:32 UT) associated with substorm activity detected during the high-speed stream on 12 May. The study highlights the role of substorms, SSSs, and associated localized magnetic disturbances driven by distinct ICME features, in generating substantial GICs during the recovery phase of intense storms, emphasizing their critical impact on space-weather hazards. (10.1016/j.asr.2026.06.055)
  DOI : 10.1016/j.asr.2026.06.055
• BGES des activités spatiales du LPP, laboratoire en “transition”
  
  • Rezeau Laurence
  • Sahraoui Fouad
  , 2026.
• STAFF Instrument Calibration, Sensitivity, and Performance Evolutions During the Cluster Mission
  
  • Canu P.
  • Bouzid V.
  • Piberne R.
  • Cornilleau-Wehrlin N.
  • Katra R.
  • Carr C.
  • Alconcel L.
  • Yearby K.
  • Robert P.
  • Lacombe C.
  • de Conchy Y.
  • Grison B.
  • Santolik O.
  • Soucek J.
  • Le Contel O.
  • Baraka M.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2026, 131 (6). The Spatio‐Temporal Analysis of Field Fluctuations (STAFF) instruments onboard the Cluster satellites were designed to measure magnetic fluctuations in the 0.2–12 Hz and 0.2–180 Hz frequency ranges from the Search‐Coil Magnetometer (SCM), as well as electromagnetic spectra from the Spectrum Analyzer (SA) in the 8–4,000 Hz range. They provided a considerable amount of data throughout the 24‐year mission. The production and calibration of these data sets were detailed in Robert et al. (2014, https://doi.org/10.5194/gi‐3‐153‐2014 ), which demonstrated its excellent quality and good agreement with the fluxgate magnetometer (FGM) measurements over their common frequency range. The Cluster's 24 years of operation, which far exceed the nominal 2‐year mission, represent the longest flight of search coil magnetometers and offer a unique opportunity to evaluate their performance over such a long period, as well as to compare the results of four initially identical instruments. The present work, based on data now archived at the Cluster Scientific Archive (CSA), examines the evolution of these products after the first 11 years in space, and until the end of the Cluster operations in September 2024. The quality of the measurements, calibration, sensitivities, and their agreement between spacecraft proved to be excellent and remained stable throughout the mission. Comparison of spectra derived from the calibrated waveforms of STAFF (CWF) and FGM shows a very good agreement until the end of operations, a further proof of the high quality of their respective calibrations. (10.1029/2026JA035072)
  DOI : 10.1029/2026JA035072
• BGES des activités spatiales du LPP, laboratoire en “transition”
  
  • Rezeau Laurence
  • Sahraoui Fouad
  , 2026. L’outil GES 1point5 de Labos1point5 permet d’obtenir de manière simple un bilan des émissions de gaz à effet de serre associées aux activités de recherche effectuées hors du laboratoire, ce qui se résume pour le LPP essentiellement à l’exploitation des données des missions spatiales. Le calcul est fait sur la base des publications mentionnant les différentes missions (méthode de Knödelseder et al 2002, 2024). Les résultats obtenus s’avèrent compliqués à exploiter pour envisager une baisse de nos émissions, en particulier parce qu’ils varient de façon considérable d’une année sur l’autre. Nous discuterons de possibles autres instruments de mesure de notre impact, pour essayer de mieux tenir compte de notre activité réelle. Le but des mesures d’impact est de trouver des moyens de baisser cet impact et de vérifier leur efficacité. Dans le contexte actuel de la recherche il est compliqué, voire irréaliste, d’avoir comme seul levier la baisse des publications. Nous discuterons aussi des potentiels leviers de baisse des émissions elles-mêmes.