Publications

2022

• Fast gas heating and kinetics of electronically excited states in a nanosecond capillary discharge in CO2
  
  • Pokrovskiy G V
  • Popov N A
  • Starikovskaia S M
  Plasma Sources Science and Technology, IOP Publishing, 2022, 31 (3), pp.035010. Fast gas heating in a pulsed nanosecond capillary discharge in pure CO_2 under the conditions of high specific deposited energy (around 1.2 eV/molecule) and high reduced electric fields (150–250 Td) has been studied experimentally and numerically. Specific deposited energy, reduced electric field and gas temperature have been measured as functions of time. The radial distribution of the electron density has been analyzed experimentally. The role of quenching of O( ^1D), O(^1S) and CO(a^3Π) excited atoms and molecules leading to heat release at sub-microsecond time scale have been analyzed by numerical modeling in the framework of 1D axial approximation. (10.1088/1361-6595/ac5102)
  DOI : 10.1088/1361-6595/ac5102
• Science goals and new mission concepts for futureexploration of Titan’s atmosphere, geologyand habitability: titan POlar scout/orbitEr and in situ lakelander and DrONe explorer (POSEIDON)
  
  • Rodriguez Sébastien
  • Vinatier Sandrine
  • Cordier Daniel
  • Tobie G.
  • Achterberg Richard K.
  • Anderson Carrie M.
  • Badman Sarah V.
  • Barnes Jason W.
  • Barth Erika L.
  • Bézard Bruno
  • Carrasco Nathalie
  • Charnay Benjamin
  • Clark Roger N.
  • Coll Patrice
  • Cornet Thomas
  • Coustenis Athena
  • Couturier-Tamburelli Isabelle
  • Dobrijevic Michel
  • Flasar F. Michael
  • de Kok Remco
  • Freissinet Caroline
  • Galand Marina
  • Gautier Thomas
  • Geppert Wolf D.
  • Griffith Caitlin A.
  • Gudipati Murthy S.
  • Hadid Lina Z.
  • Hayes Alexander G.
  • Hendrix Amanda R.
  • Jauman Ralf
  • Jennings Donald E.
  • Jolly Antoine
  • Kalousova Klara
  • Koskinen Tommi T.
  • Lavvas Panayotis
  • Lebonnois Sébastien
  • Lebreton Jean-Pierre
  • Le Gall Alice
  • Lellouch Emmanuel
  • Le Mouélic Stéphane
  • Lopes Rosaly M. C.
  • Lora Juan M.
  • Lorenz Ralph D.
  • Lucas Antoine
  • Mackenzie Shannon
  • Malaska Michael J.
  • Mandt Kathleen
  • Mastrogiuseppe Marco
  • Newman Claire E.
  • Nixon Conor A.
  • Radebaugh Jani
  • Rafkin Scot C.
  • Rannou Pascal
  • Sciamma-O-Brien Ella M.
  • Soderblom Jason M.
  • Solomonidou Anezina
  • Sotin Christophe
  • Stephan Katrin
  • Strobel Darrell
  • Szopa Cyril
  • Teanby Nicholas A.
  • Turtle Elizabeth P.
  • Vuitton Véronique
  • West Robert A.
  Experimental Astronomy, Springer Link, 2022, 54, pp.911-973. In response to ESA Voyage 2050 announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn largest moon Titan. Titan, a "world with two oceans", is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a "heavy" drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan northern latitudes with an orbiter and in situ element(s) would be highly complementary with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan equatorial regions in the mid-2030s. (10.1007/s10686-021-09815-8)
  DOI : 10.1007/s10686-021-09815-8
• Assisted combustion through radical input within the low-temperature regime
  
  • Panaget T.
  • Fenard Y.
  • Pillier L.
  • Starikovskaia S.
  • Vanhove Guillaume
  , 2022.
• Disambiguation of Vector Magnetograms by Stereoscopic Observations from the Solar Orbiter (SO)/Polarimetric and Helioseismic Imager (PHI) and the Solar Dynamic Observatory (SDO)/Helioseismic and Magnetic Imager (HMI)
  
  • Valori Gherardo
  • Löschl Philipp
  • Stansby David
  • Pariat Etienne
  • Hirzberger Johann
  • Chen Feng
  Solar Physics, Springer Verlag, 2022, 297 (1), pp.12. Spectropolarimetric reconstructions of the photospheric vector magnetic field are intrinsically limited by the $180^{\circ}$ 180 ∘ ambiguity in the orientation of the transverse component. The successful launch and operation of Solar Orbiter have made the removal of the 180 ∘ ambiguity possible using solely observations obtained from two different vantage points. While the exploitation of such a possibility is straightforward in principle, it is less so in practice, and it is therefore important to assess the accuracy and limitations as a function of both the spacecrafts’ orbits and measurement principles. In this work, we present a stereoscopic disambiguation method (SDM) and discuss thorough testing of its accuracy in applications to modeled active regions and quiet-Sun observations. In the first series of tests, we employ magnetograms extracted from three different numerical simulations as test fields and model observations of the magnetograms from different angles and distances. In these more idealized tests, SDM is proven to reach a 100% disambiguation accuracy when applied to moderately-to-well resolved fields. In such favorable conditions, the accuracy is almost independent of the relative position of the spacecraft with the obvious exceptions of configurations where the spacecraft are within a few degrees of co-alignment or quadrature. Even in the case of disambiguation of quiet-Sun magnetograms with significant under-resolved spatial scales, SDM provides an accuracy between 82% and 98%, depending on the field strength. The accuracy of SDM is found to be mostly sensitive to the variable spatial resolution of Solar Orbiter in its highly elliptic orbit, as well as to the intrinsic spatial scale of the observed field. Additionally, we provide an example of the expected accuracy as a function of time that can be used to optimally place remote-sensing observing windows during Solar Orbiter observation planning. Finally, as a more realistic test, we consider magnetograms that are obtained using a radiative-transfer inversion code and the SO/PHI Software siMulator (SOPHISM) applied to a 3D-simulation of a pore, and we present a preliminary discussion of the effect of the viewing angle on the observed field. In this more realistic test of the application of SDM, the method is able to successfully remove the ambiguity in strong-field areas. (10.1007/s11207-021-01942-x)
  DOI : 10.1007/s11207-021-01942-x
• Global three-dimensional draping of magnetic field lines in Earth's magnetosheath from in-situ spacecraft measurements
  
  • Michotte de Welle Bayane
  • Aunai Nicolas
  • Nguyen Gautier
  • Lavraud Benoit
  • Génot Vincent
  • Jeandet Alexis
  • Smets Roch
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2022, 127 (12), pp.e2022JA030996. Magnetic field draping occurs when the magnetic field lines frozen in a plasma flow wrap around a body or plasma environment. The draping of the interplanetary magnetic field (IMF) around the Earth’s magnetosphere has been confirmed in the early days of space exploration. However, its global and three‐dimensional structure is known from modeling only, mostly numerical. Here, this structure in the dayside of the Earth’s magnetosheath is determined as a function of the upstream IMF orientation purely from in‐situ spacecraft observations. We show the draping structure can be organized in three regimes depending on how radial the upstream IMF is. Quantitative analysis demonstrates how the draping pattern results from the magnetic field being frozen in the magnetosheath flow, deflected around the magnetopause. The role of the flow is emphasized by a comparison of the draping structure to that predicted to a magnetostatic draping. (10.1029/2022JA030996)
  DOI : 10.1029/2022JA030996
• ICARUS: in-situ studies of the solar corona beyond Parker Solar Probe and Solar Orbiter
  
  • Krasnoselskikh Vladimir
  • Tsurutani Bruce T.
  • Dudok de Wit Thierry
  • Walker Simon
  • Balikhin Michael
  • Balat-Pichelin Marianne
  • Velli Marco
  • Bale Stuart D.
  • Maksimovic Milan
  • Agapitov Oleksiy
  • Baumjohann Wolfgang
  • Berthomier Matthieu
  • Bruno Roberto
  • Cranmer Steven R.
  • de Pontieu Bart
  • Meneses Domingos de Sousa
  • Eastwood Jonathan
  • Erdelyi Robertus
  • Ergun Robert
  • Fedun Viktor
  • Ganushkina Natalia
  • Greco Antonella
  • Harra Louise
  • Henri P.
  • Horbury Timothy
  • Hudson Hugh
  • Kasper Justin
  • Khotyaintsev Yuri
  • Kretzschmar Matthieu
  • Krucker Säm
  • Kucharek Harald
  • Langevin Yves
  • Lavraud Benoît
  • Lebreton Jean-Pierre
  • Lepri Susan
  • Liemohn Michael
  • Louarn Philippe
  • Moebius Eberhard
  • Mozer Forrest
  • Nemecek Zdenek
  • Panasenco Olga
  • Retino Alessandro
  • Safrankova Jana
  • Scudder Jack
  • Servidio Sergio
  • Sorriso-Valvo Luca
  • Souček Jan
  • Szabo Adam
  • Vaivads Andris
  • Vekstein Grigory
  • Vörös Zoltan
  • Zaqarashvili Teimuraz
  • Zimbardo Gaetano
  • Fedorov Andrei
  Experimental Astronomy, Springer Link, 2022, 54, pp.277-315. The primary scientific goal of ICARUS (Investigation of Coronal AcceleRation and heating of solar wind Up to the Sun), a mother-daughter satellite mission, proposed in response to the ESA "Voyage 2050" Call, will be to determine how the magnetic field and plasma dynamics in the outer solar atmosphere give rise to the corona, the solar wind, and the entire heliosphere. Reaching this goal will be a Rosetta Stone step, with results that are broadly applicable within the fields of space plasma physics and astrophysics. Within ESA's Cosmic Vision roadmap, these science goals address Theme 2: "How does the Solar System work?" by investigating basic processes occurring "From the Sun to the edge of the Solar System". ICARUS will not only advance our understanding of the plasma environment around our Sun, but also of the numerous magnetically active stars with hot plasma coronae. ICARUS I will perform the first direct in situ measurements of electromagnetic fields, particle acceleration, wave activity, energy distribution, and flows directly in the regions in which the solar wind emerges from the coronal plasma. ICARUS I will have a perihelion altitude of 1 solar radius and will cross the region where the major energy deposition occurs. The polar orbit of ICARUS I will enable crossing the regions where both the fast and slow winds are generated. It will probe the local characteristics of the plasma and provide unique information about the physical processes involved in the creation of the solar wind. ICARUS II will observe this region using remote-sensing instruments, providing simultaneous, contextual information about regions crossed by ICARUS I and the solar atmosphere below as observed by solar telescopes. It will thus provide bridges for understanding the magnetic links between the heliosphere and the solar atmosphere. Such information is crucial to our understanding of the plasma physics and electrodynamics of the solar atmosphere. ICARUS II will also play a very important relay role, enabling the radio-link with ICARUS I. It will receive, collect, and store information transmitted from ICARUS I during its closest approach to the Sun. It will also perform preliminary data processing before transmitting it to Earth. Performing such unique in situ observations in the area where presumably hazardous solar energetic particles are energized, ICARUS will provide fundamental advances in our capabilities to monitor and forecast the space radiation environment. Therefore, the results from the ICARUS mission will be extremely crucial for future space explorations, especially for long-term crewed space missions. (10.1007/s10686-022-09878-1)
  DOI : 10.1007/s10686-022-09878-1
• Low-Latitude Ionospheric Responses and Coupling to the February 2014 Multiphase Geomagnetic Storm from GNSS, Magnetometers, and Space Weather Data
  
  • Calabia Andres
  • Anoruo Chukwuma
  • Shah Munawar
  • Amory-Mazaudier Christine
  • Yasyukevich Yury
  • Owolabi Charles
  • Jin Shuanggen
  Atmosphere, MDPI, 2022, 13 (4), pp.518. The ionospheric response and the associated mechanisms to geomagnetic storms are very complex, particularly during the February 2014 multiphase geomagnetic storm. In this paper, the low-latitude ionosphere responses and their coupling mechanisms, during the February 2014 multiphase geomagnetic storm, are investigated from ground-based magnetometers and global navigation satellite system (GNSS), and space weather data. The residual disturbances between the total electron content (TEC) of the International GNSS Service (IGS) global ionospheric maps (GIMs) and empirical models are used to investigate the storm-time ionospheric responses. Three clear sudden storm commencements (SSCs) on 15, 20, and 23 February are detected, and one high speed solar wind (HSSW) event on 19 February is found with the absence of classical SSC features due to a prevalent magnetospheric convection. The IRI-2012 shows insufficient performance, with no distinction between the events and overestimating approximately 20 TEC units (TECU) with respect to the actual quiet-time TEC. Furthermore, the median average of the IGS GIMs TEC during February 2014 shows enhanced values in the southern hemisphere, whereas the IRI-2012 lacks this asymmetry. Three low-latitude profiles extracted from the IGS GIM data revealed up to 20 TECU enhancements in the differential TEC. From these profiles, longer-lasting TEC enhancements are observed at the dip equator profiles than in the profiles of the equatorial ionospheric anomaly (EIA) crests. Moreover, a gradual increase in the global electron content (GEC) shows approximately 1 GEC unit of differential intensification starting from the HSSW event, while the IGS GIM profiles lack this increasing gradient, probably located at higher latitudes. The prompt penetration electric field (PPEF) and equatorial electrojet (EEJ) indices estimated from magnetometer data show strong variability after all four events, except the EEJ’s Asian sector. The low-latitude ionosphere coupling is mainly driven by the variable PPEF, DDEF (disturbance dynamo electric fields), and Joule heating. The auroral electrojet causing eastward PPEF may control the EIA expansion in the Asian sector through the dynamo mechanism, which is also reflected in the solar-quiet current intensity variability. (10.3390/atmos13040518)
  DOI : 10.3390/atmos13040518
• Tracking of magnetic helicity evolution in the inner heliosphere
  
  • Alberti T.
  • Narita Y.
  • Hadid L. Z.
  • Heyner D.
  • Milillo A.
  • Plainaki C.
  • Auster H.-U.
  • Richter I.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2022, 664, pp.L8. Context. Magnetic helicity is one of the invariants in ideal magnetohydrodynamics, and its spectral evolution has a substantial amount of information to reveal the mechanism that are behind turbulence in space and astrophysical plasmas. Aims. The goal of our study is to observationally characterize the magnetic helicity evolution in the inner heliosphere by resolving the helicity transport in a scale-wise fashion in the spectral domain. Methods. The evolution of the magnetic helicity spectrum in the inner heliosphere was tracked using a radial alignment event achieved by Parker Solar Probe at a distance of 0.17 astronomical units (AU) from the Sun and BepiColombo at 0.58 AU with a delay of about 3.5 days. Results. The reduced magnetic helicity resolved in the frequency domain shows three main features: (1) a coherent major peak of a highly helical component at the lowest frequency at about 5 × 10 −4 Hz, (2) a damping of helicity oscillation at the intermediate frequencies from 10 −3 to 10 −2 Hz when observed at 0.58 AU, and (3) a coherent nonhelical component in the ion-kinetic range at frequencies of about 0.1 − 1 Hz. Conclusions. Though limited in the frequency range, the main message from this work is that the solar wind develops into turbulence by convecting large-scale helicity components on the one hand and creating and annihilating helical wave components on the other hand. Excitation of waves can overwrite the helicity profile in the inner heliosphere. By comparing this with the typical helicity spectra at a distance of 1 AU (that is, a randomly oscillating helicity sign in the intermediate frequency range up to about 1 Hz), the helicity evolution reaches a nearly asymptotic state at the Venus orbit (about 0.7 AU) and beyond. (10.1051/0004-6361/202244314)
  DOI : 10.1051/0004-6361/202244314
• Analysis of multiscale structures at the quasi-perpendicular Venus bow shock
  
  • Dimmock A.
  • Khotyaintsev Yu.
  • Lalti A.
  • Yordanova E.
  • Edberg N.
  • Steinvall K.
  • Graham D.
  • Hadid L. Z.
  • Allen R.
  • Vaivads A.
  • Maksimovic M.
  • Bale S.
  • Chust T.
  • Krasnoselskikh V.
  • Kretzschmar M.
  • Lorfèvre E.
  • Plettemeier D.
  • Souček J.
  • Steller M.
  • Štverák Š.
  • Trávníček P.
  • Vecchio A.
  • Horbury T.
  • O’brien H.
  • Evans V.
  • Angelini V.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2022, 660, pp.A64. Context. Solar Orbiter is a European Space Agency mission with a suite of in situ and remote sensing instruments to investigate the physical processes across the inner heliosphere. During the mission, the spacecraft is expected to perform multiple Venus gravity assist maneuvers while providing measurements of the Venusian plasma environment. The first of these occurred on 27 December 2020, in which the spacecraft measured the regions such as the distant and near Venus magnetotail, magnetosheath, and bow shock. Aims. This study aims to investigate the outbound Venus bow shock crossing measured by Solar Orbiter during the first flyby. We study the complex features of the bow shock traversal in which multiple large amplitude magnetic field and density structures were observed as well as higher frequency waves. Our aim is to understand the physical mechanisms responsible for these high amplitude structures, characterize the higher frequency waves, determine the source of the waves, and put these results into context with terrestrial bow shock observations. Methods. High cadence magnetic field, electric field, and electron density measurements were employed to characterize the properties of the large amplitude structures and identify the relevant physical process. Minimum variance analysis, theoretical shock descriptions, coherency analysis, and singular value decomposition were used to study the properties of the higher frequency waves to compare and identify the wave mode. Results. The non-planar features of the bow shock are consistent with shock rippling and/or large amplitude whistler waves. Higher frequency waves are identified as whistler-mode waves, but their properties across the shock imply they may be generated by electron beams and temperature anisotropies. Conclusions. The Venus bow shock at a moderately high Mach number (∼5) in the quasi-perpendicular regime exhibits complex features similar to the Earth’s bow shock at comparable Mach numbers. The study highlights the need to be able to distinguish between large amplitude waves and spatial structures such as shock rippling. The simultaneous high frequency observations also demonstrate the complex nature of energy dissipation at the shock and the important question of understanding cross-scale coupling in these complex regions. These observations will be important to interpreting future planetary missions and additional gravity assist maneuvers. (10.1051/0004-6361/202140954)
  DOI : 10.1051/0004-6361/202140954
• Modeling the impact of a strong X‐class solar flare on the planetary ion composition in Mercury’s magnetosphere
  
  • Werner Elisabeth
  • Leblanc François
  • Chaufray Jean-Yves
  • Modolo Ronan
  • Aizawa Sae
  • Hadid L. Z.
  • Baskevitch Claire
  Geophysical Research Letters, American Geophysical Union, 2022, 49 (3), pp.e2021JA029914. We model the impact of an extreme solar flare on the Mg+, Na+, O+ and He+ ion density distribution in Mercury’s magnetosphere. The Flare Irradiance Spectral Model of the solar irradiance during the X9.3-class flare on 6 September 2017 is used as input to the time-dependent Latmos Ionized Exosphere ion density model. We find that the time-evolution of the planetary ion distribution differs with respect to energy, location and species. There exist two ion energy populations on the dayside that experience different dynamical evolution. The peak ion density in the nightside plasma sheet is delayed by ∼7 − 8 minutes compared to the dayside. The maximum Mg+ density occurs ∼ 4 minutes before He+ and O+ in the whole magnetosphere. The time delay between different species does not necessarily occur for solar flares that erupt near the apparent solar limb, where the optical depth is large. (10.1029/2021GL096614)
  DOI : 10.1029/2021GL096614
• Electron acceleration observed by Mercury Electron Analyzer onboard Mio/BepiColombo during its second Mercury flyby
  
  • Aizawa Sae
  • André Nicolas
  • Saito Yoshifumi
  • Persson Moa
  • Savaud Jean-André
  • Fedorov Andrei
  • Yokota Shoichiro
  • Barthe Alain
  • Penou Emmanuel
  • Rojo Mathias
  • Harada Yuki
  • Hadid L. Z.
  • Delcourt Dominique
  • Matsuda Shoya
  • Murakami Go
  , 2022, 2022. BepiColombo was launched in October 2018 and is currently en route to Mercury. Although its orbit insertion is planned for December 2025, BepiColombo will acquire new measurements during planetary flybys. During the cruise phase, the two spacecraft are docked together with Mio being protected behind the MOSIF sun shield. Thus, only partial observations of plasma distribution functions can be obtained by the Mercury Plasma Particle Experiment (MPPE) onboard Mio. However, since electrons have small Larmor radii and more isotropic distributions even in the solar wind, the two Mercury Electron Analyzer (MEA) of MPPE will provide us with new and unique measurements in the range of 5 eV to 3 keV when in solar wind mode and 3 eV to ~ 26 keV when in magnetospheric mode. We will present the interesting observations obtained by MEA onboard Mio/BepiColombo during its second Mercury flyby that happened on the 23rd of June, 2022. In particular we will focus on the properties of the low-energy electron populations and inverted-V structures observed during its crossing of Mercury's magnetosphere.
• Charged-particles measurements in low-pressure iodine plasmas used for electric propulsion
  
  • Esteves B
  • Marmuse F
  • Drag C
  • Bourdon A
  • Laguna A Alvarez
  • Chabert P
  Plasma Sources Science and Technology, IOP Publishing, 2022, 31 (8), pp.085007. This paper investigates iodine as an alternative propellant for space plasma propulsion. Measurements are taken in a low-pressure inductively-coupled plasma chamber used as the ionisation stage of a gridded ion-engine. Langmuir probes are used to measure the electron density and the electron energy distribution functions spatial variations between the inductive coil and the extraction grids for several radiofrequency (RF) powers and mass flow rates. Measurements in iodine are compared to xenon, krypton and argon in order to evaluate performances of these various propellants for ionization (and therefore power) efficiency. At low mass flow rates, iodine is found to be the most efficient propellant, however, as the mass flow rate increases, the ionization cost in iodine increases rapidly due to both its molecular and electronegative nature. The ratio of negative ion to electron density is measured using laser-induced photodetachment in order to quantify the effect of iodine electronegativity. Finally, all measurements are compared to a previously published global (volume-averaged) model. The agreement between model and experiments is acceptable, however several modelling improvements are proposed. (10.1088/1361-6595/ac8288)
  DOI : 10.1088/1361-6595/ac8288
• BibHelioTech internship report
  
  • Dablanc Axel
  • Génot Vincent
  • de Salabert Camille
  • Barreaux Sabine
  • Cuxac Pascal
  • Dufourg Nicolas
  • Aunai Nicolas
  • Exbrayat Williams
  , 2022. <p>renaming version with correct semantic versioning conventions (<a href="https://semver.org/">https://semver.org/</a>).</p> (10.5281/zenodo.6867940)
  DOI : 10.5281/zenodo.6867940
• Quenching of O2(b1Σg+) by O(3P) atoms. Effect of gas temperature
  
  • Booth Jean-Paul
  • Chatterjee A
  • Guaitella O
  • Lopaev D
  • Zyryanov S
  • Volynets A
  • Rakhimova T
  • Voloshin D
  • Chukalovsky A
  • Mankelevich Yu.
  • Guerra V
  Plasma Sources Science and Technology, IOP Publishing, 2022, 31 (6), pp.065012. We present a detailed study of the density and kinetics of O2(b1Σg+) in steady-state and partially-modulated DC positive column discharges in pure O2 for gas pressures of 0.3–10 Torr and 10–40 mA current. The time-resolved density of O2(b1Σg+) was determined by absolutely-calibrated optical emission spectroscopy (OES) of the A-band emission at 762 nm. Additionally, the O2(b1Σg+) density was determined by VUV absorption spectroscopy using the Fourier-transform spectrometer at the DESIRS beamline at Synchrotron Soleil, allowing the absolute calibration of OES to be confirmed. The O(3P) atoms were detected by time-resolved sub-Doppler cavity ringdown spectroscopy (CRDS) using the O(3P2) → O(1D2) transition at 630 nm. The CRDS measurements were synchronized to the discharge modulation allowing the O(3P) dynamics to be observed. As a function of gas pressure the O2(b1Σg+) density passes through a maximum at about 2 Torr. Below this maximum, the O2(b1Σg+) density increases with discharge current, whereas above this maximum it decreases with current. The gas temperature increases with pressure and current, from 300 to 800 K. These observations can only be explained by the existence of fast quenching process of O2(b1Σg+) by O(3P), with a rate that increases strongly with gas temperature, i.e. with a significant energy barrier. The data are interpreted using a 1D self-consistent model of the O2 discharge. The best fit of this model to all experimental data (including the O2(b1Σg+) average density as a function of pressure and current, the radial profiles, and the temporal response to current modulation) is achieved using a rate constant of kQ = 10−10 exp(−3700/T) cm3 s−1. (10.1088/1361-6595/ac7749)
  DOI : 10.1088/1361-6595/ac7749
• Magnetic Helicity Evolution and Eruptive Activity in NOAA Active Region 11158
  
  • Green L.
  • Thalmann J.
  • Valori G.
  • Pariat Etienne
  • Linan L.
  • Moraitis K.
  The Astrophysical Journal, American Astronomical Society, 2022, 937 (2), pp.59. Coronal mass ejections are among the Sun’s most energetic activity events yet the physical mechanisms that lead to their occurrence are not yet fully understood. They can drive major space weather impacts at Earth, so knowing why and when these ejections will occur is required for accurate space weather forecasts. In this study we use a 4 day time series of a quantity known as the helicity ratio, ∣ H J ∣/∣ H V ∣ (helicity of the current-carrying part of the active region field to the total relative magnetic helicity within the volume), which has been computed from nonlinear force-free field extrapolations of NOAA active region 11158. We compare the evolution of ∣ H J ∣/∣ H V ∣ with the activity produced in the corona of the active region and show this ratio can be used to indicate when the active region is prone to eruption. This occurs when ∣ H J ∣/∣ H V ∣ exceeds a value of 0.1, as suggested by previous studies. We find the helicity ratio variations to be more pronounced during times of strong flux emergence, collision and reconnection between fields of different bipoles, shearing motions, and reconfiguration of the corona through failed and successful eruptions. When flux emergence, collision, and shearing motions have lessened, the changes in helicity ratio are somewhat subtle despite the occurrence of significant eruptive activity during this time. (10.3847/1538-4357/ac88cb)
  DOI : 10.3847/1538-4357/ac88cb
• Laboratory evidence of magnetic reconnection hampered in obliquely interacting flux tubes
  
  • Bolaños Simon
  • Sladkov Andrey
  • Riquier Raphël
  • Smets Roch
  • Chen Sophia
  • Grisollet Alain
  • Filippov Evgeny
  • Henares Jose-Luis
  • Nastasa Viorel
  • Pikuz Sergey
  • Safronova Maria
  • Severin Alexandre
  • Starodubtsev Mikhail
  • Fuchs Julien
  Nature Communications, Nature Publishing Group, 2022, 13 (1), pp.6426. Magnetic reconnection can occur when two plasmas, having anti-parallel components of the magnetic field, encounter each other. In the reconnection plane, the anti-parallel component of the field is annihilated and its energy released in the plasma. Here, we investigate through laboratory experiments the reconnection between two flux tubes that are not strictly anti-parallel. Compression of the anti-parallel component of the magnetic field is observed, as well as a decrease of the reconnection efficiency. Concomitantly, we observe delayed plasma heating and enhanced particle acceleration. Three-dimensional hybrid simulations support these observations and highlight the plasma heating inhibition and reconnection efficiency reduction for these obliquely oriented flux tubes. (10.1038/s41467-022-33813-9)
  DOI : 10.1038/s41467-022-33813-9
• The European Solar Telescope
  
  • Quintero Noda C.
  • Schlichenmaier R.
  • Bellot Rubio L. R.
  • Löfdahl M. G.
  • Khomenko E.
  • Jurčák J.
  • Leenaarts J.
  • Kuckein C.
  • González Manrique S. J.
  • Gunár S.
  • Nelson C. J.
  • de la Cruz Rodríguez J.
  • Tziotziou K.
  • Tsiropoula G.
  • Aulanier G.
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  • Solanki S. K.
  • Soler Trujillo M.
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  • Sordini A.
  • Sosa Méndez A.
  • Stangalini M.
  • Steiner O.
  • Stenflo J. O.
  • Štěpán J.
  • Strassmeier K. G.
  • Sudar D.
  • Suematsu Y.
  • Sütterlin P.
  • Tallon M.
  • Temmer M.
  • Tenegi F.
  • Tritschler A.
  • Trujillo Bueno J.
  • Turchi A.
  • Utz D.
  • van Harten G.
  • van Noort M.
  • van Werkhoven T.
  • Vansintjan R.
  • Vaz Cedillo J. J.
  • Vega Reyes N.
  • Verma M.
  • Veronig A. M.
  • Viavattene G.
  • Vitas N.
  • Vögler A.
  • von der Lühe O.
  • Volkmer R.
  • Waldmann T. A.
  • Walton D.
  • Wisniewska A.
  • Zeman J.
  • Zeuner F.
  • Zhang L. Q.
  • Zuccarello F.
  • Collados M.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2022, 666. The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems. (10.1051/0004-6361/202243867)
  DOI : 10.1051/0004-6361/202243867
• BepiColombo mission confirms stagnation region of Venus and reveals its large extent
  
  • Persson Moa
  • Aizawa Sae
  • André Nicolas
  • Barabash Stanislav V.
  • Saito Y.
  • Harada Y.
  • Heyner Daniel
  • Orsini Stefano
  • Fedorov Andréi
  • Mazelle Christian
  • Futaana Yoshifumi
  • Hadid Lina Z.
  • Volwerk Martin
  • Collinson Glyn A.
  • Sanchez-Cano Beatriz
  • Barthe Alain
  • Penou Emmanuel
  • Yokota S.
  • Génot Vincent N.
  • Sauvaud Jean-André
  • Delcourt Dominique C.
  • Fraenz Markus
  • Modolo Ronan
  • Milillo Anna
  • Auster Hans-Ulrich
  • Richter Ingo
  • Mieth Johannes Z. D.
  • Louarn Phillippe H.
  • Owen Christopher J.
  • Horbury Timothy S.
  • Asamura Kazushi
  • Matsuda S.
  • Nilsson Hans
  • Wieser Martin
  • Alberti Tommaso
  • Varsani Ali
  • Mangano V.
  • Mura Alessandro
  • Lichtenegger Herbert Iwo Maria
  • Laky Gunther
  • Jeszenszky Harald
  • Masunaga Kei
  • Signoles Claire
  • Rojo Mathias
  • Murakami Go
  Nature Communications, Nature Publishing Group, 2022, 13, pp.7743. The second Venus flyby of the BepiColombo mission offer a unique opportunity to make a complete tour of one of the few gas-dynamics dominated interaction regions between the supersonic solar wind and a Solar System object. The spacecraft pass through the full Venusian magnetosheath following the plasma streamlines, and cross the subsolar stagnation region during very stable solar wind conditions as observed upstream by the neighboring Solar Orbiter mission. These rare multipoint synergistic observations and stable conditions experimentally confirm what was previously predicted for the barely-explored stagnation region close to solar minimum. Here, we show that this region has a large extend, up to an altitude of 1900 km, and the estimated low energy transfer near the subsolar point confirm that the atmosphere of Venus, despite being non-magnetized and less conductive due to lower ultraviolet flux at solar minimum, is capable of withstanding the solar wind under low dynamic pressure. (10.1038/s41467-022-35061-3)
  DOI : 10.1038/s41467-022-35061-3
• An In-depth Numerical Study of Exact Laws for Compressible Hall Magnetohydrodynamic Turbulence
  
  • Ferrand R.
  • Sahraoui Fouad
  • Galtier S.
  • Andrés N.
  • Mininni P.
  • Dmitruk P.
  The Astrophysical Journal, American Astronomical Society, 2022, 927 (2), pp.205. Abstract Various exact laws governing compressible magnetohydrodynamic (MHD) and compressible Hall-MHD (CHMHD) turbulence have been derived in recent years. Other than their fundamental theoretical interest, these laws are generally used to estimate the energy dissipation rate from spacecraft observations in order to address diverse problems related, e.g., to heating of the solar wind and magnetospheric plasmas. Here we use various 1024 3 direct numerical simulation data of free-decay isothermal CHMHD turbulence obtained with the GHOST code (Geophysical High-Order Suite for Turbulence) to analyze two of the recently derived exact laws. The simulations reflect different intensities of the initial Mach number and the background magnetic field. The analysis demonstrates the equivalence of the two laws in the inertial range and relates the strength of the Hall effect to the amplitude of the cascade rate at sub-ion scales. When taken in their general form (i.e., not limited to the inertial range), some subtleties regarding the validity of the stationarity assumption or the absence of the forcing in the simulations are discussed. We show that the free-decay nature of the turbulence induces a shift from a large-scale forcing toward the presence of a scale-dependent reservoir of energy fueling the cascade or dissipation. The reduced form of the exact laws (valid in the inertial range) ultimately holds even if the stationarity assumption is not fully verified. (10.3847/1538-4357/ac517a)
  DOI : 10.3847/1538-4357/ac517a
• Inner southern magnetosphere observation of Mercury via SERENA ion sensors in BepiColombo mission
  
  • Orsini Stefano
  • Milillo A.
  • Lichtenegger H.
  • Varsani A.
  • Barabash S.
  • Livi S.
  • de Angelis E.
  • Alberti T.
  • Laky G.
  • Nilsson H.
  • Phillips M.
  • Aronica A.
  • Kallio E.
  • Wurz P.
  • Olivieri A.
  • Plainaki C.
  • Slavin J. A.
  • Dandouras I
  • Raines J. M.
  • Benkhoff J.
  • Zender J.
  • Berthelier Jean-Jacques
  • Dosa M.
  • Ho G. C.
  • Killen R. M.
  • Mckenna-Lawlor S.
  • Torkar K.
  • Vaisberg O.
  • Allegrini F.
  • Daglis I. A.
  • Dong C.
  • Escoubet C. P.
  • Fatemi S.
  • Fränz M.
  • Ivanovski S.
  • Krupp N.
  • Lammer H.
  • Leblanc François
  • Mangano V.
  • Mura A.
  • Rispoli R.
  • Sarantos M.
  • Smith H. T.
  • Wieser M
  • Camozzi F.
  • Di Lellis A. M.
  • Fremuth G.
  • Giner F.
  • Gurnee R.
  • Hayes J.
  • Jeszenszky H.
  • Trantham B.
  • Balaz J.
  • Baumjohann W.
  • Cantatore M.
  • Delcourt Dominique C.
  • Delva M.
  • Desai M.
  • Fischer H.
  • Galli A.
  • Grande M.
  • Holmström M.
  • Horvath I.
  • Hsieh K. C.
  • Jarvinen R.
  • Johnson R. E.
  • Kazakov A.
  • Kecskemety K.
  • Krüger H.
  • Kürbisch C.
  • Leblanc Frédéric
  • Leichtfried M.
  • Mangraviti E.
  • Massetti S.
  • Moissenko D.
  • Moroni M.
  • Noschese R.
  • Nuccilli F.
  • Paschalidis N.
  • Ryno J.
  • Seki K.
  • Shestakov A.
  • Shuvalov S.
  • Sordini R.
  • Stenbeck F.
  • Svensson J.
  • Szalai S.
  • Szego K.
  • Toublanc Dominique
  • Vertolli N.
  • Wallner R.
  • Vorburger A.
  Nature Communications, Nature Publishing Group, 2022, 13, pp.7390. In this study we present the observation of Mercury's inner southern magnetosphere and surrounding regions, never previously explored, as detected by the two ion sensors of the instrument package: 'Search for Exospheric Refilling and Emitted Natural Abundances' (SERENA), named 'Planetary Ion CAMera' (PICAM) and 'Miniaturized Ion Precipitation Analyzer' (MIPA), on board BepiColombo mission during the first Mercury flyby, on 1 st October 2021. Here we show the analysis of the data acquired during this flyby, a glimpse of what we will get from the nominal mission: in particular we observe and describe specific ion features nearby and inside the Hermean environment, like: intermittent high energy signal due to an interplanetary magnetic flux rope; magnetospheric ions with different energy drifting at low altitudes above the planet and determining specific plasma regimes; ion signals detected outside the magnetosphere at low energy. (10.1038/s41467-022-34988-x)
  DOI : 10.1038/s41467-022-34988-x
• The first simultaneous observation of low energy ions and electrons at Mercury during the first BepiColombo flyby
  
  • Aizawa S.
  • Harada Y.
  • Saito Y.
  • André N.
  • Persson M.
  • Delcourt D.
  • Hadid L. Z.
  • Katra B.
  • Fraenz M.
  • Fedorov A.
  • Penou E.
  • Barthe A.
  • Sauvaud J. -A.
  • Matsuda S.
  • Murakami G.
  , 2022, pp.23-23. The first Mercury flyby by BepiColombo was successfully conducted on the 1st of October 2021 and this is the first time to have the simultaneous observation of low energy ions and electrons at Mercury. The data from Mercury Plasma Particle Experiment (MPPE) onboard Mio/BepiColombo shows (1) the compressed Mercury's magnetosphere compared to the average of MESSENGER observations, (2) boundary motions around magnetopause crossings, (3) periodic signatures in ion and electron spectra in both dawn- and dusk- night sides, which is most likely the ULF waves, and (4) high energy ions and electrons after the closest approach, which indicates the substorm related injection. Detailed analysis of these features will be addressed in the presentation, and compare them with previous MESSENGER and Mariner-10 observations.
• Observations of the Time Domain Sampler receiver from the Radio and Plasma Wave instrument during the Solar Orbiter Earth flyby
  
  • Pisa David
  • Soucek Jan
  • Santolik Ondrej
  • Hanzelka Miroslav
  • Maksimovic Milan
  • Vecchio Antonio
  • Khotyaintsev Yuri
  • Chust Thomas
  • Kretzschmar Matthieu
  • Matteini Lorenzo
  • Horbury Timothy
  , 2022. On November 27, 2021, Solar Orbiter completed its only flyby of Earth on its way to the following Sun's encounter in March 2022. Although this fast flyby was performed primarily to decrease the spacecraft's velocity and change orbit to get closer to the Sun, the Radio and Plasma Wave (RPW) instrument had the opportunity to perform high cadence measurements in the Earth's magnetosphere. We review the main observation of the Time Domain Sampler (TDS) receiver, a part of the RPW instrument, made during this flyby at frequencies below 200 kHz. The TDS receiver operated in a high cadence mode providing us with the regular waveform snapshot with 62 ms length every ten seconds for two electric components. Besides the regular captures, we have got more than five hundred onboard classified snapshots and the statistical products with a sixteen-second cadence. Before entering the terrestrial magnetosphere around 02:30UT, the spacecraft wandered through the foreshock region, registering intense bursts of Langmuir waves. After the bowshock crossing, Solar Orbiter was for more than two hours in the morning sector of the magnetosphere, recording various plasma wave modes. The closest approach was reached at 04:30UT above North Africa at an altitude of 460 km. Then the spacecraft continued into the Earth's tail and entered the magnetosheath around 13:00UT. After 15:00UT, the Solar Orbiter crossed the bowshock, and bursts of Langmuir waves were detected again pointing out to the deep downstream foreshock region. Further from the Earth, intense Auroral Kilometric Radiation (AKR) at frequencies above 100 kHz was also detected. (10.5194/egusphere-egu22-4130)
  DOI : 10.5194/egusphere-egu22-4130
• Turbulence-driven magnetic reconnection and the magnetic correlation length: Observations from Magnetospheric Multiscale in Earth's magnetosheath
  
  • Stawarz J.
  • Eastwood J.
  • Phan T.
  • Gingell I.
  • Pyakurel P.
  • Shay M.
  • Robertson S.
  • Russell C.
  • Le Contel O.
  Physics of Plasmas, American Institute of Physics, 2022, 29 (1), pp.012302. (10.1063/5.0071106)
  DOI : 10.1063/5.0071106
• CFD for turbulence: from fundamentals to geophysics and astrophysics
  
  • Cambon Claude
  • Alvarez Laguna Alejandro
  • Zhou Ye
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2022, 350 (S1), pp.1-20. Over the years, the combination of computational fluid dynamics (CFD) and theoretical models have critically contributed to improving our understanding of the nature of turbulent flows. In this paper, we review the role of CFD in the study of turbulence through both direct numerical simulations and the resolution of statistical multi-scale theories. With a historical perspective, we will discuss the evolution of the numerical modeling of turbulence from the first numerical experiments as proposed by Orszag and Patterson [1] to complex geophysical and plasma simulations where body forces such as Coriolis, the buoyancy force, or the Lorentz force can introduce strong anisotropies. Looking beyond the horizon, we address the future challenges for CFD and turbulence theorists with the prospect of exascale supercomputing. (10.5802/crmeca.135)
  DOI : 10.5802/crmeca.135
• Fan-shaped jet close to a light bridge
  
  • Liu Y.
  • Ruan G. P.
  • Schmieder B.
  • Masson S.
  • Chen Y.
  • Su J. T.
  • Wang B.
  • Bai X. Y.
  • Su Y.
  • Cao W.
  Astronomy & Astrophysics - A&A, EDP Sciences, 2022, 667. Aims: On the Sun, jets in light bridges (LBs) are frequently observed with high-resolution instruments. The respective roles played by convection and the magnetic field in triggering such jets are not yet clear. Methods: We report a small fan-shaped jet along a LB observed by the 1.6m Goode Solar Telescope (GST) with the TiO Broadband Filter Imager (BFI), the Visible Imaging Spectrometer (VIS) in H<SUB>α</SUB>, and the Near-InfraRed Imaging Spectropolarimeter (NIRIS), along with the Stokes parameters. The high spatial and temporal resolution of those instruments allowed us to analyze the features identified during the jet event. By constructing the Hα Dopplergrams, we found that the plasma is first moving upward, whereas during the second phase of the jet, the plasma is flowing back. Working with time slice diagrams, we investigated the propagation-projected speed of the fan and its bright base. Results: The fan-shaped jet developed within a few minutes, with diverging beams. At its base, a bright point was slipping along the LB and ultimately invaded the umbra of the sunspot. The Hα profiles of the bright points enhanced the intensity in the wings, similarly to the case of Ellerman bombs. Co-temporally, the extreme ultraviolet (EUV) brightenings developed at the front of the dark material jet and moved at the same speed as the fan, leading us to propose that the fan-shaped jet material compressed and heated the ambient plasma at its extremities in the corona. Conclusions: Our multi-wavelength analysis indicates that the fan-shaped jet could result from magnetic reconnection across the highly diverging field low in the chromosphere, leading to an apparent slipping motion of the jet material along the LB. However, we did not find any opposite magnetic polarity at the jet base, as would typically be expected in such a configuration. We therefore discuss other plausible physical mechanisms, based on waves and convection, that may have triggered the event. <P />Movie associated to Fig. 1 is available at <A href="https://www.aanda.org/10.1051/0004-6361/202243292/olm">https://www.aanda.org</A> (10.1051/0004-6361/202243292)
  DOI : 10.1051/0004-6361/202243292