Scientific publications

2026

• Future trajectories of the BepiColombo MPO and Mio spacecraft: a quantitative tool for magnetospheric region prediction
  
  • Hollman Daragh M
  • Jackman Caitríona M
  • Domijan Katarina
  • Bowers Charles F
  • Hadid Lina Z
  • Heyner Daniel
  Earth Planets and Space, Springer / Terra Scientific Publishing Company, 2026, 78 (1), pp.188. Mercury possesses one of the most dynamic magnetospheres in our solar system, with strong driving by the solar wind, and significant motion of the magnetospheric boundaries in response. The BepiColombo mission will provide the first dual-spacecraft view of this system. In order to maximise the scientific output from BepiColombo, we need quantitative predictions of which magnetospheric region each spacecraft will be sampling at any given time. This is important for the planning of spacecraft operations, where the coordination and collaboration of many instruments across two spacecraft is vitally important, not only for science, but also due to telemetry and power limitations. In this work, we outline a new method using MESSENGER observations to make quantified predictions, with uncertainties, of the probability of observing solar wind, magnetosheath, and magnetosphere for a given position in Mercury’s magnetospheric environment. We apply this technique to five of the six completed BepiColombo Mercury flybys, and additionally forecast magnetospheric region sampling during a representative 10-hour interval of the nominal science mission. We aim to make this approach as accessible as possible, and include in a software repository simple worked examples to aid users in applying these predictions in their own research. (10.1186/s40623-026-02515-7)
  DOI : 10.1186/s40623-026-02515-7
• Self-consistent stabilization of large-scale linear magnetic holes via ion trapping
  
  • Ballerini Giulio
  • Arrò Giuseppe
  • Califano Francesco
  • Henri P.
  • Pucci Francesco
  • Simon Wedlund Cyril
  • Preisser Luis
  Physics of Plasmas, American Institute of Physics, 2026, 33. Magnetic holes (MHs) are localized depressions in the magnetic field commonly observed in space plasmas such as the solar wind, planetary magnetosheaths, and cometary environments. Despite the abundance of spacecraft observations, the mechanisms governing the generation of these structures are not fully understood. In this study, we investigate the stability of magnetic depressions in a controlled plasma environment via two-dimensional hybrid particle-in-cell simulations using the Menura code. Initializing the system with preexisting magnetic field depressions embedded in a mirror-stable plasma allows us to isolate the fundamental physical mechanisms responsible for stabilization and equilibrium. We analyze the roles of the initial depth, characteristic width, and magnetic field geometry of the depression. Our results demonstrate that narrow depressions (of the order of ion kinetic scales) are unstable, whereas broader structures can reach stable equilibria through ion trapping, resulting in localized density enhancements and temperature anisotropy consistent with in situ observations of large-scale MHs. The findings highlight the importance of ion trapping for stabilization and provide a controlled framework to investigate MH dynamics. (10.1063/5.0327618)
  DOI : 10.1063/5.0327618
• Disturbed and quiet days ∑O/N₂ variations at low and mid-latitudes during solar cycles 23 and 24
  
  • Khan Jahan Zeb
  • Younas Waqar
  • Amory-Mazaudier Christine
  • Khan Majid
  Advances in Space Research, Elsevier, 2026, 77 (5), pp.6295-6314. We analyzed the column density ratio of thermospheric compositions (∑O/N₂) using data from the Global Ultraviolet Imager (GUVI) onboard the TIMED satellite from 2002 to 2020. Daily ∑O/N 2 values for the three most geomagnetically disturbed and quietest days each month were used to compute monthly means at low and mid-latitudes across both hemispheres. These variations were also examined across various longitudinal sectors, including Asia, Africa, and the Americas. The fluctuations in ∑O/N₂ were more pronounced at mid-latitudes than at low latitudes, with low latitude values in both hemispheres peaking near the equinoxes. At midlatitudes, the highest values occurred during local winter, with stronger peaks in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH). The winter and equinoctial maxima are also observed in all longitudinal sectors. Besides this, the distinct longitudinal asymmetries over Asian, African, and American regions at mid-latitudes, influenced by geomagnetic field geometry, are also observed. The downwelling of ∑O/N₂ in local winter is stronger, while upwelling in local summer is weaker in the longitudinal sectors containing the magnetic pole. Annual (AV) and semiannual variations (SAV) were extracted using a bandpass filter. AV was stronger at mid-latitudes, peaking in local winter and highlighting the winter anomaly in both hemispheres. SAV were dominant at low latitudes, with positive peaks at equinoxes and negative dips at solstices, generally in phase across hemispheres and longitude sectors. The amplitudes of AV and SAV are stronger during solar maximum periods, justifying the solar cycle trend. Analysis also revealed that during geomagnetically disturbed periods, ∑O/N₂ typically decreased (≤ -10%) at mid-latitudes and increased (≥10%) at low latitudes compared to quiet periods. Although opposite trends-enhancement at mid-latitudes and depletion at low latitudes -were occasionally observed, they were less significant. This study aims to provide valuable insights into the dynamics of thermospheric composition, thereby contributing to the improved modeling of ionospheric behavior and space weather forecasting. (10.1016/j.asr.2025.12.115)
  DOI : 10.1016/j.asr.2025.12.115
• Nonlinear phase synchronization and the role of spacing in shell models
  
  • Manfredini L.
  • Gürcan Ö D
  Physical Review E, American Physical Society (APS), 2026, 113 (1), pp.015101. A shell model can be considered as a self-similar chain of interacting triads, where each triad can be interpreted as a nonlinear oscillator that can be mapped to a spinning top. Investigating the relation between phase dynamics and intermittency in such a chain of nonlinear oscillators, it is found that synchronization is linked to increased energy transfer. In particular, our results indicate that the observed systematic increase of intermittency, as the shell spacing is decreased, is associated with strong phase alignment among consecutive triadic phases, facilitating the energy cascade. It is shown that while the overall level of synchronization can be quantied using a Kuramoto order parameter for the global phase coherence in the inertial range, a local, weighted Kuramoto parameter can be used for the detection of burst-like events propagating across shells in the inertial range. This novel analysis reveals how locally phase-locked states are associated with the passage of extreme events of energy ux. Applying this method to helical shell models ( i.e. for a class of helical interactions that couple the two helicities in a non separable topology) reveals that a reduction in phase coherence correlates with suppression of intermittency. When inverse cascade scenarios are considered using two dierent shell models including a non local helical shell model, and a local standard shell model with a modied conservation law, it was shown that a particular phase organization is needed in order to sustain the inverse energy cascade. It was also observed that the PDFs of the triadic phases were peaked in accordance with the basic considerations of the form of the ux, which suggests that a triadic phase of π/2 and -π/2 maximizes the forward and the inverse energy cascades respectively. (10.1103/2vxp-1k2t)
  DOI : 10.1103/2vxp-1k2t
• First in Situ Detection of the Magnetic Component of a Solar Type III Radio Wave
  
  • Kretzschmar Matthieu
  • Vecchio Antonio
  • Krasnoselskikh Vladimir
  • Maksimovic Milan
  • Soucek Jan
  • Pisa David
  • Gasque Claire
  • Bale Stuart D.
  • Dudok de Wit Thierry
  • Pulupa Marc
  • Khotyaintsev Yuri V.
  • Chust Thomas
  • Jannet Guillaume
  • Brochot Jean-Yves
  • Revillet Claire
  • Fergeau Patrice
  • Bonnin Xavier
  • Goetz Keith
  The Astrophysical Journal Letters, Bristol : IOP Publishing, 2026, 1001. Solar radio bursts, and astrophysical radio emissions in general, are observed either in space or on the ground by measuring their fluctuating electric field. Here, we report the first measurement of the magnetic component of a solar radio wave, observed simultaneously by the Solar Orbiter and Parker Solar Probe missions. The observations were made during the type III radio burst on 2021 October 28. The analysis of the wave polarization and magnetic and electric field amplitudes allows us to estimate the refractive index and put constraints on the direction of the wave. The wave is found to be consistent with an ordinary-mode wave and with a source near the southeast limb of the Sun. These results pave the way for future observations and analyses of the magnetic field of radio waves, in particular, for solar radio bursts. (10.3847/2041-8213/ae5893)
  DOI : 10.3847/2041-8213/ae5893
• Determination of the accuracy of actinometry and line ratio techniques in an O2 glow discharge: II. Electric field measurements with Ar and Xe admixtures
  
  • Kuijpers L
  • Baratte E
  • Guaitella O
  • Booth Jean-Paul
  • Guerra V
  • van de Sanden M C M
  • Silva T
  Plasma Sources Science and Technology, IOP Publishing, 2026, 35 (1), pp.015010. A line-ratio method for determining the reduced electric field is benchmarked against independent measurements from electrostatic probes and cavity ring-down spectroscopy. The method is applied to oxygen DC glow discharges with trace admixtures of argon and xenon. A corona model incorporating fluorescence quenching by heavy species is used to simulate the emission, with electron-impact excitation rates calculated using the LisbOn KInetics Boltzmann solver. The excitation cross sections and quenching coefficients are those proposed and validated for actinometry in part one of this combined study (Baratte et al 2025 Plasma Sources Sci. Technol.). The reduced electric field is determined over a pressure range of 0.55 to 5 Torr (at 40 mA) and a current range of 15 to 50 mA (at 5 Torr). Consistent agreement with measured emission line intensities is achieved when applying a correction factor of κ c,Ar = 3 ± 0.5 to the excitation cross sections for the argon lines at 750 nm and 811 nm. With this correction, the reduced electric field values obtained from the line-ratio method are in good agreement with direct measurements. A comparison of different line ratios is presented, showing that the best performance is achieved using the ratio of the Ar 750 nm and Xe 828 nm lines. This ratio is particularly sensitive to changes in the electron energy distribution function, due to the large difference in excitation thresholds, while remaining independent of the knowledge of species densities. (10.1088/1361-6595/ae24aa)
  DOI : 10.1088/1361-6595/ae24aa
• Cold Atmospheric Plasma Decontaminates Arabidopsis thaliana Seeds and Remodels Seedling Fungal Microbiota
  
  • Taras Léna
  • Chaumont Nicole
  • Kunz Caroline
  • Dufour Thierry
  • Bailly Christophe
  Plants, MDPI, 2026, 15 (17), pp.2719. Seed-associated microorganisms influence seed quality, seedling establishment, and plant health and also constitute a major source of seed-borne pathogens. Cold atmospheric plasma (CAP) has emerged as a promising alternative to chemical seed treatments because of its antimicrobial activity, although its effects on fungal communities associated with developing seedlings remain poorly understood. Here, Arabidopsis thaliana seeds from two ecotypes (Columbia and Landsberg erecta) were exposed to CAP for 5 or 15 min. Seed decontamination efficiency was assessed by culturing on malt extract agar and nephelometric analyses, while fungal communities associated with seedlings derived from treated and untreated seeds were characterized by ITS1 amplicon sequencing. CAP efficiently reduced fungal contamination without affecting seed germination. CAP altered the composition of fungal communities associated with developing seedlings, but the magnitude of these changes depended on seed batch and ecotype. Dominant taxa markedly declined after treatment, whereas several low-abundance taxa increased in relative abundance. These findings demonstrate that CAP is an effective pesticide-free technology for seed decontamination and can also reshape fungal communities associated with developing seedlings, highlighting broader ecological consequences of plasma-based seed treatments. (10.3390/plants15172719)
  DOI : 10.3390/plants15172719
• Diffusion of atoms produced by photodissociation in an I 2 vapour: pressure dependence of surface recombination and a correction of the decay time of the fundamental mode
  
  • Raimbault Jean-Luc
  • Blondel Christophe
  • Esteves Benjamin
  • Drag Cyril
  Physica Scripta, IOP Publishing, 2026, 101 (32), pp.325401. This work investigates, theoretically and experimentally, the spatio-temporal evolution of the density of iodine atoms produced in a cylindrical fused silica cell containing iodine molecular gas. The atoms are generated along the axis of the cell by laser photodissociation at the wavelength 488 nm and their density is monitored using the two-photon absorption laser-induced fluorescence technique. The diffusion coefficient D and the wall-recombination probability γ are determined by fitting a multimode model of atomic diffusion to experimental time variations of the atomic density recorded under various pressures. An improved formula is established for the fundamental-mode decay time, beyond the usual addition of a diffusion time and a recombination time. The diffusion coefficient D of I in I2 vapour is found equal to 0.048 ± 0.009 m 2 s−1 at 10 Pa, while the wall-recombination coefficient γ decreases from 0.25 to 0.05 when the pressure increases from 2.7 to 31.1 Pa. (10.1088/1402-4896/ae89f3)
  DOI : 10.1088/1402-4896/ae89f3
• Weibel-mediated filamentary structures observed in the ICF context
  
  • Ruyer C
  • Bolaños S
  • Laborde P.E. Masson
  • Gremillet L
  • Blanchot N
  • Boutoux G
  • Cayzac W
  • Courtois C
  • Dannhoff S.G
  • Denis V
  • Le Deroff L
  • Li C.K
  • Fuchs J
  • Grisollet A
  • Lantuéjoul I
  • Riquier R
  • Smets R
  • Sutcliffe G.D
  • Vauzour B
  Phys.Plasmas, 2026, 33 (5), pp.052113. In light of novel and past experimental results, we demonstrate how Weibel-mediated filamentary structures can develop in the expanding plasma plume of a laser-irradiated foil. The transverse ballistic cooling that occurs during the quasi-spherical plasma expansion naturally drives an electron pressure anisotropy, resulting in the growth of electron current filaments. This effect competes with electron-ion Coulomb collisions which tend to isotropize the electron distribution function. Based on theoretical and particle-in-cell modeling, we provide estimates of the dominant wavelength and amplitude of the self-generated magnetic fluctuations, which are found to explain experimental data obtained at the OMEGA and Laser Megajoule facilities. (10.1063/5.0321057)
  DOI : 10.1063/5.0321057
• Properties of Magnetic Switchbacks in the Near-Sun Solar Wind
  
  • Badman Samuel T.
  • Fargette Naïs
  • Matteini Lorenzo
  • Agapitov Oleksiy V.
  • Akhavan-Tafti Mojtaba
  • Bale Stuart D.
  • Bharati Das Srijan
  • Bizien Nina
  • Bowen Trevor A.
  • Dudok de Wit Thierry
  • Froment Clara
  • Horbury Timothy
  • Huang Jia
  • Jagarlamudi Vamsee Krishna
  • Larosa Andrea
  • Madjarska Maria S.
  • Panasenco Olga
  • Pariat Etienne
  • Raouafi Nour E.
  • Rouillard Alexis P.
  • Ruffolo David
  • Sioulas Nikos
  • Soni Shirsh Lata
  • Sorriso-Valvo Luca
  • Suen Gabriel Ho Hin
  • Velli Marco
  • Verniero Jaye
  Space Science Reviews, Springer Verlag, 2026, 222. Magnetic switchbacks are fluctuations in the solar wind in which the interplanetary magnetic field sharply deflects away from its background direction so as to create folds in magnetic field lines while remaining of roughly constant magnitude. The magnetic field and velocity fluctuations are extremely well correlated in a way corresponding to Alfvénic fluctuations propagating away from the Sun. For a background field which is nearly radial this causes an outwardly propagating jet to form. Switchbacks and their characteristic velocity jets have recently been observed to be nearly ubiquitous by Parker Solar Probe with in situ measurements in the inner heliosphere within 0.3 AU. Their prevalence, substantial energy content, and potentially fundamental role in the dynamics of the outer corona and solar wind motivate the significant research efforts into their understanding. Here we review the in situ measurements of these structures (primarily by Parker Solar Probe). We discuss how they are identified and measured, and present an overview of the primary observational properties of these structures, both in terms of individual switchbacks and their collective arrangement into "patches". We identify both properties for which there is a strong consensus and those that have limited or qualified support and require further investigation. We identify and collate several open questions and recommendations for future studies. (10.1007/s11214-026-01267-w)
  DOI : 10.1007/s11214-026-01267-w
• Effect of Solar Wind Turbulence on Temperature-Anisotropy-Driven Modes in Mercury's Magnetosheath
  
  • Ballerini G.
  • Califano F.
  • Henri P.
  • Simon Wedlund C.
  • Preisser L.
  • Pucci F.
  • Sporhykin F.
  • Passot T.
  • Sulem P. L.
  Journal of Geophysical Research: Space Physics, 2026, 131. Planetary magnetosheaths are plasma regions between the solar wind and planetary magnetospheres where temperature anisotropies act as a source of free energy driving plasma instabilities. While these instabilities have been extensively studied at Earth, their properties at Mercury remain poorly investigated. To support the science goals of the ongoing BepiColombo mission, we investigate the development of ion temperature anisotropy throughout Mercury's magnetosheath using the first global hybrid particle-in-cell simulations of the Hermean plasma environment under turbulent solar wind conditions. We employ the 3D hybrid PIC code Menura to model Mercury's magnetosphere for both laminar and turbulent upstream states and classify magnetosheath regions by local bow-shock geometry (quasi-parallel, quasi-perpendicular, and intermediate). The simulations reveal strong spatial variations in plasma stability, with quasi-perpendicular sectors showing enhanced occurrence of mirror-mode and ion-cyclotron unstable plasma. Turbulent solar wind produces a dayside magnetosheath that is, on average, more unstable than in laminar case, while the nightside becomes comparatively more stable. These results demonstrate that upstream solar wind turbulence plays a role in regulating anisotropy-driven instabilities in Mercury's magnetosheath and should be accounted for in the interpretation of in situ BepiColombo observations. (10.1029/2025JA034897)
  DOI : 10.1029/2025JA034897