Publications

2023

• Safety factor influence on the edge E × B velocity establishment in tokamak plasmas.
  
  • Varennes Robin
  • Vermare Laure
  • Garbet Xavier
  • Hennequin P
  • Dif-Pradalier G.
  • Sarazin Yanick
  • Grandgirard Virginie
  • Panico Olivier
  • Donnel Peter
  • Obrejan K.
  Plasma Physics and Controlled Fusion, IOP Publishing, 2023, 66 (2), pp.025003. This study is motivated by experiments on Tore Supra and WEST tokamaks where a deepening of the radial electric field near the edge is observed when the safety factor decreases. Flux-driven global simulations of Ion Temperature Gradient (ITG) turbulence recover qualitatively the trend observed in the experiments, i.e. the E × B velocity increases when decreasing the safety factor. From these simulations, multiple clues point out the role of turbulence in the establishment of the radial electric field even though the linear growth rate increases with the safety factor. The proposed mechanism to elucidate this phenomenon, backed up by a reduced model, is that the neoclassical friction - particularly sensitive to the safety factor - effectively damps the effect of the turbulent drive. (10.1088/1361-6587/ad1653)
  DOI : 10.1088/1361-6587/ad1653
• Étude de structures électroniques non-linéaires dans la magnétosphère et le vent-solaire : théorie et simulations
  
  • Gauthier Gaëtan
  , 2023. Au cours de cette thèse, nous avons fait une étude en deux parties distinctes avec un point commun : l’instabilité de faisceau-plasma (ou « bump-on-tail » en anglais). Dans un premier temps, nous avons étudié les émissions d’ondes électromagnétiques à la fréquence plasma et sa première harmonique dans le contexte héliosphérique. Notre étude a été essentiellement numérique et basée sur des simulations (Smilei) massivement parallèles « Particle-In-Cell » (PIC) 2D3V générant des ondes électrostatiques puis électromagnétiques par relaxation d’un faisceau d’électrons à l’origine des sursauts radio de type III qui se propagent dans le plasma du vent solaire. En généralisant les études précédentes, les caractéristiques physiques et numériques de nos simulations nous ont permis d’étudier les modes principaux des ondes associées à ces émissions générées par un couplage non-linéaire. Par un choix de paramètres, nous avons montré que le bruit numérique (inhérent aux codes PIC) pouvait être suffisamment réduit pour nous permettre de modéliser les fluctuations de densité observées dans le vent solaire. Ce qui est une condition permettant de montrer que ces fluctuations, bien que très faibles, peuvent modifier les caractéristiques des émissions. Dans un second temps, nous nous sommes intéressés à des structures cinétiques non-linéaires appelées « trou d’électron dans l’espace des phases » (ou EH en abrégé) observées dans de nombreuses régions de la magnétosphère. Notre étude a été menée suivant deux approches : (i) Une étude théorique basée sur la méthode intégrale BGK (pour Bernstein-Greene-Kruskal) permettant de déterminer les distributions des particules (électrons et ions) associées à ces EHs, ainsi que leurs conditions d’existence. Nous avons ainsi développé un modèle 3D de symétrie de révolution autour du champ magnétique ambiant, qui tient compte à la fois de la dérive de polarisation des électrons et d’une description plus réaliste des conditions aux limites du plasma avec l’introduction de la vitesse de l’EH par rapport au plasma ambiant. Ce modèle nous a permis de caractériser le rapport entre échelles parallèle et perpendiculaire des EHs dans les différentes régions de la magnétosphère ainsi que certaines restrictions sur leurs conditions d’existence. (ii) La seconde approche est une étude numérique PIC permettant de générer ces EHs avec des conditions initiales réalistes et de les comparer aux observations spatiales in situ. Grâce à une étude paramétrique, nous avons montré que les conditions du milieu (champ magnétique ambiant, densité du faisceau) impactent leur génération et leur nature (quasi-électrostatique ou avec une composante de champ magnétique interne). Cette étude numérique qualitative et quantitative a notamment permis de préciser certains paramètres comme la densité du faisceau encore difficilement accessible aux mesures des missions spatiales, ainsi que d’autres caractéristiques fondamentales des EHs telles que leur vitesse de propagation ou encore la conservation et la conversion d’énergie en leur sein.
• Investigation of the Optical Emission of Hall Effect Thrusters using a Collisional Radiative Model, Particle-In-Cell Simulations, and Machine Learning
  
  • Ben Slimane Tarek
  , 2023. This thesis provides an analysis of the optical emission of Hall Effect thrusters. The study is grounded in the context of the dynamic field of micro reusable launchers and ride-share satellite programs, which have substantially reduced space operation costs. This shift has intensified the demand for standardized and miniaturized satellite equipment, with a particular focus on Hall thrusters due to their advantageous thrust-to-power ratio, specific impulse, and efficiency.This thesis builds upon the development of the LPPic Particle-In-Cell code, and explores the plasma dynamics and interactions within the thruster by coupling the simulation results with virtual diagnostics. First is the collective Thomson scattering, which explores the electron density fluctuations in the thruster. Second is the optical emission spectroscopy coupled with a collisional radiative model, which characrerizes the electron energy distribution function. Both are instrumental in validating LPPic simulations, with the latter also serving as a promising tool for assessing the performance in orbit and characterizing ground facility effects.The methodology consists of a blend of simulations and experiments, relying on virtual diagnostics to assess simulations and guide experimental practices. The thesis is structured into eight chapters. These include the exploration of virtual collective Thomson scattering diagnostics, the development and validation of HET0D, a collisional-radiative model for neutral xenon, and the establishment of a framework for performing virtual optical emission spectroscopy from Particle-In-Cell simulations. This established the importance of considering spatial gradients in the plume of the thruster when extracting plasma parameters from optical emission. It also highlighted the validity of the transport and Maxwellian assumptions in the collisional radiative models of neutral species and highlighted line-specific bandwidth limitations for the implementation of optical emission spectroscopy to study high frequency instabilities (>MHz). These insights were confronted with experiments where actual spectra were used to extract plasma parameters using the collisional radiative model under various thruster conditions, thereby demonstrating the validity of the virtual diagnostic analysis and the adequacy of optical emission and collisional radiative models to monitor Hall Effect thrusters. Finally, an innovative enhancement to optical emission and collisional radiative model through the integration of artificial neural networks is also presented, which significantly improves the efficiency and scope of the diagnostic, by speeding up the processing, reducing the needed hardware in-orbit, and allowing the optical control of the operating parameters.This research makes an initial contribution to the field of electric propulsion by offering a unique perspective that combines numerical simulations, virtual diagnostics with experimental data, and neural networks, thereby enhancing the understanding of diagnostics, simulations, and the behavior of Hall Effect thrusters.
• Experimental evidence of the role of non-gyrotropy in the magnetopause equilibrium
  
  • Ballerini Giulio
  • Rezeau Laurence
  • Belmont Gérard
  • Califano Francesco
  , 2023.
• The Status of Space Weather Infrastructure and Research in Africa
  
  • Baki Paul
  • Rabiu Babatunde
  • Amory-Mazaudier Christine
  • Fleury Rolland
  • Cilliers Pierre J
  • Adechinan Joseph
  • Emran Anas
  • Bounhir Aziza
  • Cesaroni Claudio
  • Dinga J. Bienvenue
  • Doherty Patricia
  • Gaye Idrissa
  • Ghalila Hassen
  • Grodji Franck
  • Habarulema John-Bosco
  • Kahindo Bruno
  • Mahrous Ayman
  • Messanga Honoré
  • Mungufeni Patrick
  • Nava Bruno
  • Nigussie Melessew
  • Olwendo Joseph
  • Sibanda Patrick
  • Loua René Tato
  • Uwamahoro Jean
  • Zaourar Naima
  • Zerbo Jean-Louis
  Atmosphere, MDPI, 2023, 14 (12), pp.1791. Space weather science has been a growing field in Africa since 2007. This growth in infrastructure and human capital development has been accompanied by the deployment of ground-based observing infrastructure, most of which was donated by foreign institutions or installed and operated by foreign establishments. However, some of this equipment is no longer operational due to several factors, which are examined in this paper. It was observed that there are considerable gaps in ground-based space-weather-observing infrastructure in many African countries, a situation that hampers the data acquisition necessary for space weather research, hence limiting possible development of space weather products and services that could help address socio-economic challenges. This paper presents the current status of space weather science in Africa from the point of view of some key leaders in this field, focusing on infrastructure, situation, human capital development, and the research landscape. (10.3390/atmos14121791)
  DOI : 10.3390/atmos14121791
• Progress in the in situ Raman spectroscopy of plasma interactions with liquids and solids
  
  • Pai David Z
  • Polprasarn Kasidapa
  • Bellet Romain
  • Khereddine Hanane
  • Orrière Thomas
  • Kurniawan Darwin
  • Fang Chih-Yi
  • Lin Kai-Sheng
  • Chiang Wei-Hung
  • Sadi Dihya
  • Guaitella Olivier
  • Pareek Pankaj
  • Janda Mario
  , 2023.
• Mercury’s magnetosphere: BepiColombo’s flybys observations of the ion composition from the Mass Spectrum Analyzer
  
  • Hadid L. Z.
  • Delcourt Dominique
  • Saitou Yoshifumi
  • Fraenz Markus
  • Yokota Shoichiro
  • Fiethe Björn
  • Verdeil Christophe
  • Katra Bruno
  • Harada Yuki
  • Glass Austin N.
  • Aizawa Sae
  • Raines Jim
  • Leblanc François
  • Modolo Ronan
  • Leblanc Frédéric
  • Fischer Henning
  • Fontaine D.
  • Krupp Norbert
  • Krüger Harald
  • Murakami Go
  • Matsuda Shoya
  , 2023. On June 23rd 2022 and 19th 2023, BepiColombo performed its second (MFB2) and third (MFB3) gravity assist maneuvers at Mercury. The two flybys had similar trajectories, the spacecraft approaching the planet from dusk-nightside toward dawn-dayside and traveling down to extremely close distances (down to ~198 km and ~ 235 km altitudes above the planet’s surface for MFB2 and MFB3, respectively). Even though BepiColombo is in a so-called “stacked configuration” during cruise (meaning that most of the instruments cannot be fully operated yet), a number of instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the plasma composition and dynamics along a unique path across the magnetosphere and very close to the planet. In this presentation, we will show the first ion composition observations of the Mass Spectrum Analyzer (MSA) at Mercury during the two flybys. MSA is part of the Mercury Plasma Particle Experiment (MPPE, PI: Y. Saito) consortium that is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements onboard Mio (Saito et al. 2021). MSA is a time-of-flight spectrometer that provides information on the plasma composition and the three-dimensional ion distribution functions in the ~ 10 eV/q-38 keV/q energy range and in the ~ 1-60 amu mass range (Delcourt et al. 2016). We will focus on the third Mercury flyby during which MSA revealed the presence of energetic (> 10 keV) and cold (< 100 eV) heavy ions inside the magnetosphere around closest approach. Moreover, we will show major features of the Mercury magnetosphere highlighting different regions: 1) plasma sheet, 2) nightside bounday-layer and 3) magnetosheath [Hadid et al., in prep].
• Ground-based infrastructure for improved space weather specification at low latitudes
  
  • Makela Jonathan J
  • Wu Qian
  • Monstein Christian
  • Habarulema John Bosco
  • Groves Keith
  • Jakowski Norbert
  • Amory Cristine
  , 2023. Much of what is known about equatorial ionospheric physics is based on observations of the incoherent scatter and the MST/coherent radar (JULIA) at Jicamarca, Peru [e.g., Chau et al., 2012]. Jicamarca is located in the American sector, where there is a fairly large excursion between the geomagnetic and geodetic equator due to the dip of the geomagnetic equator. However, equatorial ionospheric phenomena, such as equatorial spread F/equatorial plasma bubbles (EPBs), the equatorial electrojet, the strength of the prereversal enhancement (PRE), the dynamo efficiency, and the behavior of thermospheric winds and tides, are all in some way influenced by the regional geomagnetic field, its declination, and the proximity of the magnetic to the geographic equator, all of which vary as a function of longitude. (10.3847/25c2cfeb.eb22a102)
  DOI : 10.3847/25c2cfeb.eb22a102
• The role of magnetic reconnection in the evolution of solar eruptive Flux ropes
  
  • Xing Chen
  , 2023. Coronal mass ejections (CMEs) are impulsive eruptions of plasmas in the solar corona. Their interaction with the Earth's magnetosphere can induce extreme space weather conditions, with a major impact on human activities related to advanced technologies. A thorough understanding of the evolution of CMEs and their progenitors is extremely important for predicting CME eruptions and their related space weather. In this thesis, using numerical simulations and space observations, we study the kinematics, thermal properties and magnetic field evolution of flux ropes in CME progenitors and CMEs, and especially, the specific role of magnetic reconnection. We have discovered that the initiation of CMEs before their impulsive rise is a multiple-physics coupled-process. We have shown that the initiation of CMEs is first triggered and driven by the reconnection in hyperbolic flux tubes, and then driven by the coupling of torus instability and reconnection. We have also shown that the hot channel before the impulsive ejection is built up by hot flux rope field lines, the latter of which are progressively formed and heated by slipping reconnection in thin current sheets surrounding the flux rope. We also studied the evolution of magnetic flux in CMEs, and found that the pre-eruptive flux rope, rather than the magnetic reconnection during the eruption, is most likely the main contributor to the toroidal flux of the CME. More specifically, the magnetic reconnection first increases and then decreases the toroidal flux of the CME flux rope during the eruption. In addition, we studied two new observational phenomena related to CMEs and flares in the solar lower atmosphere, which are manifestations of the growth and deformation of flux ropes in CME progenitors and CMEs induced by magnetic reconnection. Finally, we have proposed two methods for identifying the footpoints of flux ropes associated with CMEs, which will be very useful for future work aimed at studying their evolution in the solar corona and interplanetary space.
• Investigating the effects of cold piezoelectric plasma on cholangiocarcinoma in vitro
  
  • Soulier Manon
  • Lekbaby Bouchra
  • Decauchy Henri
  • Houari Imane
  • Pavy Allan
  • Coumes Alexia
  • Fouassier Laura
  • Dufour Thierry
  , 2023.
• Cold plasma technology in cholangiocarcinoma: a catheter-based approach
  
  • Geraud Korentin
  • Soulier Manon
  • Pavy Allan
  • Camus Marine
  • Fouassier Laura
  • Dufour Thierry
  , 2023.
• Improving our understanding of plasma-surface interactions through in-situ measurements
  
  • Booth Jean-Paul
  , 2023.
• Unveiling plasma energization and energy transport in the Earth's Magnetospheric System: the need for future coordinated multiscale observations
  
  • Retino A.
  • Kepko L.
  • Kucharek H.
  • Marcucci M.
  • Nakamura R.
  • Amano T.
  • Angelopoulos V.
  • Bale S.
  • Caprioli D.
  • Cassak P.
  • Chasapis A.
  • Chen L. -J.
  • Dai L.
  • Dunlop M.
  • Forsyth C.
  • Fu H.
  • Galvin A.
  • Le Contel O.
  • Yamauchi M.
  • Kistler L.
  • Khotyaintsev Y.
  • Klein K.
  • Mann I.
  • Matthaeus W.
  • Mouikis K.
  • Nykyri K.
  • Palmroth M.
  • Plaschke F.
  • Saito Y.
  • Soucek J.
  • Spence H.
  • Turner D.
  • Vaivads A.
  • Valentini F.
  , 2023. Energetic plasma is everywhere in the Universe. The terrestrial Magnetospheric System is a key case where direct measures of plasma energization and energy transport can be made in situ at high resolution. Despite the large amount of available observations, we still do not fully understand how plasma energization and energy transport work. Key physical processes driving much plasma energization and energy transport occur where plasma on fluid scales couple to the smaller ion kinetic scales. These scales (1 RE) are strongly related to the larger mesoscales (several RE) at which large-scale plasma energization and energy transport structures form. All these scales and processes need to be resolved experimentally, however existing multi-point in situ observations do not have a sufficient number of measurement points. New multiscale observations simultaneously covering scales from mesoscales to ion kinetic scales are needed. The implementation of these observations requires a strong international collaboration in the coming years between the major space agencies. The Plasma Observatory is a mission concept tailored to resolve scale coupling in plasma energization and energy transport at fluid and ion scales. It targets the two ESA-led Medium Mission themes Magnetospheric Systems and Plasma Cross-scale Coupling of the ESA Voyage 2050 report and is currently under evaluation as a candidate for the ESA M7 mission. MagCon (Magnetospheric Constellation) is a mission concept being studied by NASA aiming at studying the flow of mass, momentum, and energy through the Earth magnetosphere at mesoscales. Coordination between Plasma Observatory and MagCon missions would allow us for the first time to simultaneously cover from mesoscales to ion kinetic scales leading to a paradigm shift in the understanding of the Earth Magnetospheric System. (10.48550/arXiv.2311.09920)
  DOI : 10.48550/arXiv.2311.09920
• The French contribution for the NASA HelioSwarm mission
  
  • Le Contel Olivier
  • Lavraud B.
  • Retinò A.
  • Kretzschmar M.
  • Génot V.
  • Alexandrova O.
  • Mansour M.
  • Amoros C.
  • Janet G.
  • Baruah R.
  • Mehrez F.
  • Camus T.
  • Alison D.
  • Grigoriev A.
  • Revillet C.
  • Studniarek M.
  • Pledel S.
  • Mirioni L.
  • Agrapart C.
  • Sou Gérard
  • Geyskens N.
  • Pinçon J.-L.
  • Spence H.
  • Klein K. G.
  , 2023. The HelioSwarm mission was selected as a MIDEX mission by NASA in February 2022 for launch in 2029 with a nominal duration of 15 months. Its main objectives are to reveal the 3D spatial structure and dynamics of turbulence in a weakly collisional plasma and to investigate the mutual impact of turbulence near boundaries (e. g., Earth’s bow shock and magnetopause) and large-scale structures evolving in the solar wind (e. g., coronal mass ejection, corotating interaction region). The HelioSwarm mission will also contribute to the space weather science and to a better understanding of the Sun-Earth relationship. It consists of a platform (Hub) and eight smaller satellites (nodes) evolving along an elliptical orbit with an apogee ~ 60 and a perigee ~15 Earth radii. These 9 satellites, three-axis stabilised, will provide 36 pair combinations and 126 tetrahedral configurations covering the scales from 50~km (subion scale) to 3000 km (MHD scale). It will be the first mission able to investigate the physical processes related to cross-scale couplings between ion and MHD scales by measuring, simultaneously at these two scales, the magnetic field, ion density and velocity variations. Thus each satellite is equipped with the same instrument suite. A fluxgate magnetometer (MAG from Imperial College, UK) and a search-coil magnetometer (SCM) provide the 3D measurements of the magnetic field fluctuations whereas a Faraday cup (FC, SAO, USA) performs the ion density and velocity measurements. In addition, the ion distribution function is measured at a single point onboard the Hub by the iESA instrument, allowing to investigate the ion heating in particular. The SCM for HelioSwarm provided by LPP and LPC2E is strongly inherited of the SCM designed for the ESA JUICE mission. It will be mounted at the tip of a 3m boom and will cover the frequency range associated with the ion and subion scales in the near-Earth environment [0.1-16Hz] with the following sensitivities [15pT/√Hz at 1 Hz and 1.5 pT/√Hz at 10 Hz]. The iESA, developped by IRAP and LAB, is inherited from the PAS instrument operating on the ESA Solar Orbiter mission. It will provide the ion distribution function at high time and angular resolutions, respectively 0.150 s and 3°. Furthermore the energy range will be ~200 eV to 20 keV with 8% energy resolution. Status of the development of SCM and iESA prototypes will be presented.
• Adapting object detection techniques to time series: application to the multi-class detection of ICMEs and CIRs
  
  • Nguyen Gautier
  • Bernoux Guillerme
  • Aunai Nicolas
  , 2023.
• BibHelioTech
  
  • Génot Vincent
  • Dablanc Axel
  • Hitier Richard
  • de Salabert Camille
  • Barreaux Sabine
  • Cuxac Pascal
  • Cabanac Guillaume
  • Leung Dominica
  • Aunai Nicolas
  , 2023. From a corpus of heliophysics articles using data from space missions, BibHelioTech carries out automated textual detections on the observed events, the satellites/instruments used, the spatial regions and the physical processes concerned, in order to link these entities with the publications from which they are extracted, in catalogs usable by the discipline's data analysis tools. This strong and systematized link between data and publications, non-existent to date, 1/ will increase the data analysis experience by immersing the researcher in the bibliographic context of their case study, 2/ will significantly improve the reproducibility of published results, and 3/ will facilitate the reuse of these catalogs in new statistical and comparative studies.
• On the need for International Solar Terrestrial Program Next (ISTPNext)
  
  • Kepko Larry
  • Vourlidas Angelos
  • Blum Lauren
  • Baker Daniel
  • Lavraud Benoit
  • Angelopoulos Vassilis
  • Ho George
  • Sibeck David Gary
  • Sorathia Kareem
  • Berthomier Matthieu
  • Walsh Brian
  • Chakrabarty Dibyendu
  • Liemohn Michael
  • Goldstein Jerry
  • Claudepierre Seth
  • Daglis Ioannis
  • Reeves Geoffrey
  • Dunlop Malcolm
  • Palmroth Minna
  • Nakamura Rumi
  • Retino Alessandro
  • Marcucci Maria Federica
  • Vilmer Nicole
  • Blanco-Cano Xochitl
  • Kretzschmar Matthieu
  • Génot Vincent
  • Opgenoorth Hermann
  • Rae Jonathan
  • Worms Jean-Claude
  • Petrukovich Anatoli
  • Mann Ian
  • Burch Jim
  • Cairns Iver
  • Deforest Craig
  • Donovan Eric
  • Lj Sarah
  • Klimchuk Jim
  • Manuel John
  • Denardin Clezio
  • Mcwilliams Kathryn
  • Saito Yoshifumi
  • Wang Chi
  • Waters Colin
  • Hwang Junga
  • Karpen Judy
  • Spiro Antiochos
  , 2023. (10.3847/25c2cfeb.d1ebc3b9)
  DOI : 10.3847/25c2cfeb.d1ebc3b9
• Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 White Paper Plasma turbulence: Challenges and next transformative steps from the perspective of multi-spacecraft measurements
  
  • Chen Li-Jen
  • Spence Harlan
  • Klein Kristopher
  • Matthaeus William
  • Lavraud Benoit
  • Szabo Adam
  • Roberts Owen Wyn
  • Génot Vincent
  • Verscharen Daniel
  • Horbury Tim
  • Retino Alessandro
  • Alexandrova Olga
  • Reynolds Chris
  • Halekas Jasper
  • Dors Ivan
  • Arzamasskiy Lev
  • Contel Olivier Le
  • Tenbarge Jason
  • Forsyth Colin
  • Jian Lan
  • Galvin Antoinette
  • Schekochihin Alexander
  • Maruca Bennett
  , 2023. Synopsis We recommend to bring into reality the following within the next decade: 1. Measurements from multiple spacecraft covering a 3D volume and simultaneously spanning the MHD to kinetic scales (such as HelioSwarm). 2. Coordination of the new multi-scale mission(s) with existing multi-spacecraft missions such as MMS to maximize the power of cross-scale ion and electron measurements. (10.3847/25c2cfeb.136be7e4)
  DOI : 10.3847/25c2cfeb.136be7e4
• The essential role of multi-point measurements in investigations of heliospheric turbulence, three-dimensional structure, and dynamics
  
  • Matthaeus W. H.
  • Adhikari S.
  • Bandyopadhyay R.
  • Brown M. R.
  • Bruno R.
  • Borovsky J.
  • Carbone V.
  • Caprioli D.
  • Dasso S.
  • Dmitruk P.
  • del Zanna L.
  • Dmitruk P.
  • Franci Luca
  • Gary S. P.
  • Goldstein M. L.
  • Greco A.
  • Horbury T. S.
  • Ji Hantao
  • Kasper J. C.
  • Klein K. G.
  • Landi S.
  • Li Hui
  • Malara F.
  • Maruca B. A.
  • Mininni P.
  • Oughton Sean
  • Papini E.
  • Parashar T. N.
  • Pecora F.
  • Petrosyan Arakel
  • Pouquet Annick
  • Retinò Alessandro
  • Roberts Owen
  • Ruffolo David
  • Servidio Sergio
  • Spence Harlan
  • Smith C. W.
  • Stawarz J. E.
  • Tenbarge Jason
  • Vasquez B. J.
  • Vaivads Andris
  • Valentini F.
  • Velli Marco
  • Verdini A.
  • Verscharen Daniel
  • Whittlesey Phyllis
  • Wicks Robert
  • Yang Y.
  • Zimbardo G.
  , 2022. Space plasmas are three-dimensional dynamic entities. Except under very special circumstances, their structure in space and their behavior in time are not related in any simple way. Therefore, single spacecraft in situ measurements cannot unambiguously unravel the full space-time structure of the heliospheric plasmas of interest in the inner heliosphere, in the Geospace environment, or the outer heliosphere. This shortcoming leaves numerous central questions incompletely answered. Deficiencies remain in at least two important subjects, Space Weather and fundamental plasma turbulence theory, due to a lack of a more complete understanding of the space-time structure of dynamic plasmas. Only with multispacecraft measurements over suitable spans of spatial separation and temporal duration can these ambiguities be resolved. We note that these characterizations apply to turbulence across a wide range of scales, and also equally well to shocks, flux ropes, magnetic clouds, current sheets, stream interactions, etc. In the following, we will describe the basic requirements for resolving space-time structure in general, using turbulence' as both an example and a principal target or study. Several types of missions are suggested to resolve space-time structure throughout the Heliosphere. (10.48550/arXiv.2211.12676)
  DOI : 10.48550/arXiv.2211.12676
• Disentangling the Spatiotemporal Structure of Turbulence Using Multi-Spacecraft Data
  
  • Tenbarge Jason
  • Arzamasskiy Lev
  • Boldyrev Stanislav
  • Califano Francesco
  • Caprioli Damiano
  • Cerri Silvio Sergio
  • Chen Christopher
  • Dors Ivan
  • Dorland William
  • Eastwood Jonathan
  • Génot Vincent
  • Halekas Jasper
  • Haggerty Colby
  • Howes Gregory
  • Ji Hantao
  • Jian Lan
  • Juno James
  • Klein Kristopher
  • Kunz Matthew
  • Lavraud Benoit
  • Contel Olivier Le
  • Loureiro Nuno
  • Mallet Alfred
  • Maruca Bennett
  • Matthaeus William
  • Perez Jean
  • Retino Alessandro
  • Roberts Owen Wyn
  • Sahraoui Fouad
  • Schekochihin Alexander
  • Smith Charles
  • Spence Harlan
  • Stevens Michael
  • Squire Jonathan
  • Verscharen Daniel
  • Wicks Robert
  , 2023. This white paper prepared for the 2024 Decadal Survey for Solar and Space Physics concerns the importance of research related to multi-spacecraft missions to address fundamental questions concerning plasma turbulence. In this white paper, some of the important questions facing the turbulence community that can only be addressed by funding research related to multipoint measurements are presented. (10.3847/25c2cfeb.9f70da28)
  DOI : 10.3847/25c2cfeb.9f70da28
• Meta-analysis of CO2 conversion, energy efficiency, and other performance data of plasma-catalysis reactors with the open access PIONEER database
  
  • Salden Antoine
  • Budde Maik
  • Garcia-Soto Carolina
  • Biondo Omar
  • Barauna Jairo
  • Faedda Marzia
  • Musig Beatrice
  • Fromentin Chloé
  • Nguyen-Quang Minh
  • Philpott Harry
  • Hasrack Golshid
  • Aceto Domenico
  • Cai Yuxiang
  • Jury Federico Azzolina
  • Bogaerts Annemie
  • da Costa Patrick
  • Engeln Richard
  • Gálvez María Elena
  • Gans Timo
  • Garcia Tomas
  • Guerra Vasco
  • Henriques Carlos
  • Motak Monika
  • Navarro Maria Victoria
  • Parvulescu Vasile
  • van Rooij Gerard
  • Samojeden Bogdan
  • Sobota Ana
  • Tosi Paolo
  • Tu Xin
  • Guaitella Olivier
  Journal of Energy Chemistry, Elsevier, 2023, 86, pp.318-342. (10.1016/j.jechem.2023.07.022)
  DOI : 10.1016/j.jechem.2023.07.022
• A multiple time scale approach for anisotropic inertial wave turbulence
  
  • Galtier Sébastien
  Journal of Fluid Mechanics, Cambridge University Press (CUP), 2023, 974, pp.A24. Wave turbulence is the study of the long-time statistical behaviour of equations describing a set of weakly nonlinear interacting waves. Such a theory, which has a natural asymptotic closure, allows us to probe the nature of turbulence more deeply than the exact Kolmogorov laws by rigorously proving the direction of the cascade and the existence of an inertial range, predicting stationary spectra for conserved quantities, or evaluating the Kolmogorov constant. An emblematic example is given by fast rotating fluids for which a wave turbulence theory has been derived by Galtier ( Phys. Rev. E, vol. 68, issue 1, 2003, p. 015301). This work involves non-trivial analytical developments for a problem that is anisotropic by nature. We propose here a new path for the derivation of the kinetic equation by using the anisotropy at the beginning of the analysis. We show that the helicity basis is not necessary to obtain the wave amplitude equation for the canonical variables that involve a combination of poloidal and toroidal fields. The multiple time scale method adapted to this anisotropic problem is then used to derive the kinetic equation that is the same as the original work when anisotropy is eventually taken into account. This result proves the commutativity between asymptotic closure and anisotropy. In addition, the multiple time scale method informs us that the kinetic equation can be derived without imposing restrictions on the probability distribution of the wave amplitude such as quasi-Gaussianity, or on the phase such as random phase approximation that naturally occurs dynamically. (10.1017/jfm.2023.825)
  DOI : 10.1017/jfm.2023.825
• Three-dimensional modelling of the shock–turbulence interaction
  
  • Trotta D
  • Pezzi O
  • Burgess D
  • Preisser L
  • Blanco-Cano X
  • Kajdic P
  • Hietala H
  • Horbury T
  • Vainio R
  • Dresing N
  • Retinò A
  • Marcucci M
  • Sorriso-Valvo L
  • Servidio S
  • Valentini F
  Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2023, 525 (2), pp.1856-1866. ABSTRACT The complex interaction between shocks and plasma turbulence is extremely important to address crucial features of energy conversion in a broad range of astrophysical systems. We study the interaction between a supercritical, perpendicular shock and pre-existing, fully developed plasma turbulence, employing a novel combination of magnetohydrodynamic and small-scale, hybrid-kinetic simulations where a shock is propagating through a turbulent medium. The variability of the shock front in the unperturbed case and for two levels of upstream fluctuations is addressed. We find that the behaviour of shock ripples, i.e. shock surface fluctuations with short (a few ion skin depths, di) wavelengths, is modified by the presence of pre-existing turbulence, which also induces strong corrugations of the shock front at larger scales. We link this complex behaviour of the shock front and the shock downstream structuring with the proton temperature anisotropies produced in the shock–turbulence system. Finally, we put our modelling effort in the context of spacecraft observations, elucidating the role of novel cross-scale, multispacecraft measurements in resolving shock front irregularities at different scales. These results are relevant for a broad range of astrophysical systems characterized by the presence of shock waves interacting with plasma turbulence. (10.1093/mnras/stad2384)
  DOI : 10.1093/mnras/stad2384
• Non-universality of the Turbulent Spectra at Sub-ion Scales in the Solar Wind: Dispersive Effects versus the Doppler Shift
  
  • Sahraoui Fouad
  • Huang Shiyong
  The Astrophysical Journal, American Astronomical Society, 2023, 956 (2), pp.89. Abstract Large surveys of the power spectral density of the magnetic fluctuations in the solar wind have reported different slope distributions at MHD, sub-ion and sub-electron scales: the smaller the scale, the broader the distribution. Here, we review briefly some of the most relevant explanations of the broadening of the slopes at sub-ion scales. Then, we present a new one that has been overlooked in the literature, which is based on the relative importance of the dispersive effects with respect to the Doppler shift due to the mean flow speed. We build a toy model based on a dispersion relation of a linear mode that matches at high frequency ( ω ≳ ω ci ) the Alfvén (respectively whistler) mode at high oblique (respectively quasi-parallel) propagation angles θ kB . Starting with a double power-law spectrum of turbulence k ⊥ − 1.66 in the inertial range and k ⊥ − 2.8 at the sub-ion scales, the transformed spectrum (in frequency f ) as it would be measured in the spacecraft reference frame shows a broad range of slopes at the sub-ion scales that depend both on the angle θ kB and the flow speed V . Varying θ kB in the range 4°–106° and V in the range 400−800 km s −1 the resulting distribution of slopes at the sub-ion scales reproduces quite well the observed one in the solar wind. Fluctuations in the solar wind speed and the wavevector anisotropy of the turbulence may explain (or at least contribute to) the variability of the spectral slopes reported from spacecraft observations in the solar wind. (10.3847/1538-4357/acf45b)
  DOI : 10.3847/1538-4357/acf45b
• Non-universality of the Turbulent Spectra at Sub-ion Scales in the Solar Wind: Dispersive Effects versus the Doppler Shift
  
  • Sahraoui Fouad
  • Huang Shiyong
  The Astrophysical Journal, American Astronomical Society, 2023, 956 (2), pp.89. Large surveys of the power spectral density of the magnetic fluctuations in the solar wind have reported different slope distributions at MHD, sub-ion and sub-electron scales: the smaller the scale, the broader the distribution. Here, we review briefly some of the most relevant explanations of the broadening of the slopes at sub-ion scales. Then, we present a new one that has been overlooked in the literature, which is based on the relative importance of the dispersive effects with respect to the Doppler shift due to the mean flow speed. We build a toy model based on a dispersion relation of a linear mode that matches at high frequency ( ω ≳ ω ci ) the Alfvén (respectively whistler) mode at high oblique (respectively quasi-parallel) propagation angles θ kB . Starting with a double power-law spectrum of turbulence k ⊥ − 1.66 in the inertial range and k ⊥ − 2.8 at the sub-ion scales, the transformed spectrum (in frequency f ) as it would be measured in the spacecraft reference frame shows a broad range of slopes at the sub-ion scales that depend both on the angle θ kB and the flow speed V . Varying θ kB in the range 4°–106° and V in the range 400−800 km s −1 the resulting distribution of slopes at the sub-ion scales reproduces quite well the observed one in the solar wind. Fluctuations in the solar wind speed and the wavevector anisotropy of the turbulence may explain (or at least contribute to) the variability of the spectral slopes reported from spacecraft observations in the solar wind. (10.3847/1538-4357/acf45b)
  DOI : 10.3847/1538-4357/acf45b