Publications

2023

• Analysis of the Breathing Mode dynamics in Hall thrusters using a hybrid simulation
  
  • Petronio Federico
  • Bourdon Anne
  • Chabert Pascal
  • Alvarez Laguna Alejandro
  , 2023. The Breathing Mode (BM) is a macroscopic oscillation of the plasma in Hall Thrusters (HTs). In recent years, several studies have tried to explain theoretically and numerically the origin and development of this instability. Yet, some efforts are still required to fully characterize it. In the current work, we use a hybrid code, in which the neutral dynamics is treated with 1D Euler equations, while the dynamics of the charged species (electrons and single-charged positive ions) is reproduced by a 2.5D Particle-in-Cell (PIC) module. The ionization is self-consistently calculated within the Monte-Carlo collision (MCC) module. Thus, the consequent coupling of the neutral species dynamics with the charged species allows for replicating the BM mechanism. The data provided by the hybrid simulation allows us to analyze the microscopic processes that originate the BM and the relation between the variation of the various parameters. In particular, we analyze which is the relationship of the ionization with the charge and neutral densities and electron temperature variation at different stages of the BM cycle. From our results, it emerges that the temperature increment alone is not capable of sustaining the ionization. The particle creation appears to be dependent on the variation of both the gas and the plasma densities, along with the ionization rate coefficient. The hybrid code results allow us also to study the evolution of some quantities at different times of the BM cycle. For example, by analyzing the parameters fluctuations during a BM, we show that the diamagnetic drift is always lower than the ExB one and that the isothermal approximation is not valid in HT conditions. Moreover, we show that the effect of the anomalous transport is particularly strong during the BM growing phase, while it is much less marked when the current is low.
• Probing surface reactivity in plasmas- is it valid to use a constant reaction probability model?
  
  • Booth Jean-Paul
  , 2023. Surface-catalyzed recombination of atoms and free radicals play a key role in the plasma equilibrium for molecular plasmas in enclosed reactors. For simplicity, surface recombination is generally characterized by a constant surface reaction probability. This parameter is nearly always very poorly characterized, or taken as the adjustable variable to fit models to experimental data. Ab-initio theories are not currently able to reliably predict the rates of these processes, so they must be determined by in-situ measurements (either through the measurement of spatial mole-fraction gradients adjacent to the surface, or (more commonly) by time-resolved measurements in modulated plasmas). The surface recombination of oxygen atoms on borosilicate glass tube walls was studied by time-resolved optical emission actinometry of partially modulated DC positive column discharges. The observed reaction probabilities (10-3) were not constant, but can be explained by Eley-Rideal reaction of incident atoms with chemisorbed atoms with an activation energy provided by the kinetic energy of the incident atom. For full modulation, the atom decay in the afterglow (measured by Cavity Ringdown spectroscopy, CRDS) is non-exponential, starting fast then slowing down. This suggests a second, quadratic, term in the recombination probability which can be attributed to reaction with weakly-bound physisorbed atoms. The presence of small quantities (10-3) of air from vacuum leaks was found to strongly reduce surface recombination, explaining the large variability in oxygen atom density. CRDS measurements in RF capacitively-coupled plasmas in an aluminium showed surprisingly small surface recombination coefficients (10-4) at pressures above 2 Torr. At lower pressures the surface reaction probability increases dramatically with RF power, indicating a transition from an oxidized (unreactive) surface to a metallic surface when the ion flux and energy is higher.
• Two Classes of Equatorial Magnetotail Dipolarization Fronts Observed by Magnetospheric Multiscale Mission: A Statistical Overview
  
  • Alqeeq Soboh
  • Le Contel O.
  • Canu P.
  • Retinò A.
  • Chust T.
  • Mirioni L.
  • Chuvatin A.
  • Nakamura R.
  • Ahmadi N.
  • Wilder F.
  • Gershman D.
  • Khotyaintsev Yu.
  • Lindqvist P.‐a.
  • Ergun R.
  • Burch J.
  • Torbert R.
  • Fuselier S.
  • Russell C.
  • Wei H.
  • Strangeway R.
  • Bromund K.
  • Fischer D.
  • Giles B.
  • Saito Y.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2023, 128 (10). Magnetotail earthward fast plasma flows (Baumjohann et al., 1990) or bursty bulk flows (BBF, Angelopoulos et al., 1992) play a major role in the energy, plasma and magnetic flux transport from the magnetotail to the inner magnetosphere (e.g., Angelopoulos et al., 1994). They are often, although not always (Richard et al., 2022), accompanied by a sharp and transient increase of the northward component of the magnetic field called dipolarization fronts (DFs). DFs are considered as tangential discontinuities (velocity and magnetic field variations are tangential to the front so with no normal component of the magnetic field and no plasma flux flowing through it) separating a relatively cold dense plasma at rest from a hot tenuous plasma in rapid motion (e.g., H. S. Fu et al., 2012a; Sergeev et al., 2009). The origin of the fast flows and their related DFs is still a matter of debate. The main formation mechanisms currently studied are magnetic reconnection (e.g., (10.1029/2023JA031738)
  DOI : 10.1029/2023JA031738
• Properties of Whistler Waves’ Ducting in Plasmas With Systems of Small‐Scale Density Depletions
  
  • Zudin I. Yu.
  • Zaboronkova T.
  • Gushchin M.
  • Korobkov S.
  • Krafft C.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2023, 128 (10). Abstract The ducting of whistler waves by systems of small‐scale field‐aligned plasma density depletions is studied. Similarly to our previous paper (Zudin et al., 2019, https://doi.org/10.1029/2019ja026637 ), we carry out analytical calculations and numerical simulations for the parameters of an active experiment in which very low frequency whistler waves emitted by a ground‐based transmitter at a frequency of 18 kHz were received onboard the DEMETER satellite at 700 km above the SURA heating facility. Random‐sized density depletions with a level around 10%–20% and perpendicular sizes ranging from 10 m up to about 300 m are considered. The properties of ducted waves are determined by the perpendicular size of individual depletions. Particularly, depletions with a width of more then d 0 ∼ 100 m form separate ducting structures, that is, coupled waveguides capable of exchanging energy by means of mode overlap. Depletions with a width of less than d 0 ∼ 100 m form a common waveguide structure, whose properties are equivalent to those of a wider irregularity with a smoothed density profile. Two important differences are revealed in ducting properties of density depletions compared to density enhancements considered in Zudin et al. (2019, https://doi.org/10.1029/2019ja026637 ). First, depletions support highly oblique Gendrin mode waves, rather than quasi‐longitudinal whistlers as in the case of density enhancements. Second, the characteristic perpendicular size d 0 ∼ 100 m of density depletions separating the regimes of “coupled waveguides” and of “equivalent ducting structure” with smoothed density profile is by an order of magnitude smaller than for density enhancements of the same 10–20% relative level. (10.1029/2023JA031616)
  DOI : 10.1029/2023JA031616
• D’une pression isotrope à l’anisotropie de pression dans les plasmas spatiaux turbulents : investigation analytique, numérique et observationnelle
  
  • Simon Pauline
  , 2023. Le vent solaire est un plasma hautement turbulent où les quantités fluides (vitesse, densité et pression) ainsi que les champs électrique et magnétique varient beaucoup. Ces fluctuations se traduisent entre autres par des spectres turbulents couvrant plusieurs décades en fréquences. Les spectres des fluctuations de vitesse et de champ magnétique suivent des lois de puissances dont les exposants dépendent de l’échelle considérée. Aux basses fréquences, des exposants proches de -5/3 sont observés. Ils sont interprétés comme une signature de la dynamique turbulente magnétohydrodynamique (MHD) du plasma. Cette dynamique prendrait la forme d’une cascade transférant non-linéairement l’énergie présente à grande échelle, vers les petites échelles où sa dissipation est possible. Cette cascade turbulente peut être étudiée au moyen de lois exactes dérivées à partir des équations des différentes quantités fluides. Ces lois lient le taux de cascade aux fluctuations turbulentes. Le taux de cascade est associé au taux de dissipation d’après la théorie de Kolmogorov et correspondrait donc à l’estimation d’un taux de chauffage du plasma. Ce taux est une clef de compréhension du problème du chauffage du vent solaire, la température de ce dernier décroissant plus lentement avec la distance héliocentrique que ne le prédit la théorie de l’expansion radiale adiabatique. Ces dernières années, la théorie des lois exactes a été étendue avec succès aux modèles MHD et MHD-Hall, l’effet Hall étendant le domaine de validité de la MHD à des échelles comparables ou plus petites que l’échelle caractéristique des ions. Ces lois ont été dérivées dans le cadre d’approximations (fermetures) de type incompressible (densité constante) ou isotherme (pression proportionnelle à la densité). Ces fermetures permettent de simplifier les équations décrivant le plasma. Cependant, leur validité est sujette à caution dans le cadre des plasmas spatiaux tels que le vent solaire. Une hypothèse un peu plus réaliste consisterait à prendre en compte une fermeture du type polytrope (pression proportionnelle à une puissance de la densité). En étendant la théorie des lois exactes dans cette direction, une loi plus versatile a été obtenue : elle dépend d’une pression isotrope (scalaire) quelconque. L’apport de cette loi a ensuite été analysé à travers une application à des données relevées dans le vent solaire par la sonde Parker Solar Probe lancée par la NASA en 2018 en direction du Soleil. Dans les plasmas spatiaux, il s’avère que le champ magnétique et le manque de collisions induisent une anisotropie de pression. La pression est alors tensorielle et prend en compte, a minima, une différence de pression parallèlement et perpendiculairement au champ magnétique ambiant (hypothèse gyrotrope). Une nouvelle étape d’extension de la théorie des lois exactes a donc été entreprise en relaxant l’isotropie de la pression. La loi obtenue est applicable à des écoulements régis par une pression tensorielle décrits par exemple par une fermeture CGL (Chew, Goldberger, Low, 1956), dite aussi bi-adiabatique, car dépendant de la gyrotropie de pression. Cette loi apporte un cadre d’étude rigoureux de l’impact de l’anisotropie sur la cascade turbulente et le taux de chauffage. Afin de valider son apport et d’affiner son interprétation, la loi CGL est enfin appliquée dans des simulations tridimensionnelles turbulentes du modèle CGL-MHD-Hall.
• Multiscale solar wind turbulence : from theory to observations
  
  • David Vincent
  , 2023. The solar wind is a turbulent plasma that can be measured in situ by spacecraft such as Voyager/NASA, THEMIS/ESA, or PSP/NASA. Measurements reveal magnetic field fluctuations over a wide range of frequencies, with a change in slope around 1 Hz, indicating a transition from the single-fluid MHD behavior of the plasma to a state where ions and electrons have distinct dynamics. A second transition is observed around 50 Hz, beyond which the magnetic spectrum becomes steeper, marking a change in physics where the inertia effects of electrons become significant. The study of this turbulence is closely linked to understanding the origin of local heating, characterized by a slow decrease in ion temperature with increasing heliospheric distance. This decrease is interpreted as a signature of heating resulting from the transfer of energy from large to small scales by turbulence. The objective of this thesis is to study solar wind turbulence from MHD scales to electron inertial scales. In the first part, we use the Zeroth law of turbulence to measure energy dissipation at MHD scales. This law states that energy dissipation per unit mass approaches a non-zero limit, known as anomalous dissipation, as viscosity/resistivity decreases. A local form of Kolmogorov’s exact law is used with THEMIS and PSP data to show that heating calculated using anomalous dissipation can be significantly higher than the average heating predicted by the exact MHD law. Furthermore, the application of anomalous dissipation proves the Zeroth law in a simplified MHD model. Its application to Voyager 2 data reveals that heating generated by shocks near Jupiter is dominant compared to that from turbulent fluctuations. In the second part, we focus on sub-MHD scales (frequencies between 1 and 50 Hz). In situ measurements show a monofractal behavior of magnetic fluctuations, whereas at MHD scales a (standard) multifractal behavior is observed. To study this difference, high-resolution 3D direct numerical simulations of the electron reduced MHD equations are conducted in weak and strong wave turbulence regimes. These simulations reveal that only weak turbulence can reproduce the monofractality. Combined with recent work, this result suggests that at electron scales, the solar wind is in a regime of weak kinetic Alfv´en wave turbulence without collisions. Finally, a theory of (weak) wave turbulence for inertial electron MHD in the presence of a strong external magnetic field is developed. Exact solutions (Kolmogorov-Zakharov spectrum) are provided, and it is shown that the cascade is direct. The importance of considering electron mass in this regime is highlighted. Remarkably, these equations are identical (up to a constant) to those describing inertial wave turbulence in rapidly rotating non-ionized fluids. This connection underscores the importance of laboratory investigations to study turbulence at these scales, which are currently challenging to access by satellites. These studies provide a comprehensive understanding of the turbulent behavior of the solar wind from observational, numerical, and theoretical perspectives.
• Whistler-mode waves in Mercury’s magnetosphere observed by BepiColombo/Mio
  
  • Ozaki Mitsunori
  • Yagitani Satoshi
  • Kasaba Yasumasa
  • Kasahara Yoshiya
  • Matsuda Shoya
  • Omura Yoshiharu
  • Hikishima Mitsuru
  • Sahraoui Fouad
  • Mirioni Laurent
  • Chanteur Gérard
  • Kurita Satoshi
  • Nakazawa Satoru
  • Murakami Go
  Nature Astronomy, Nature Publishing Group, 2023, 7 (11), pp.1309-1316. (10.1038/s41550-023-02055-0)
  DOI : 10.1038/s41550-023-02055-0
• Gaining insight into E × B flow control in tokamaks
  
  • Rienäcker S
  • Hennequin P.
  • Varennes R
  • Honoré C
  • Gunn J P
  , 2023.
• Deciphering the Slow-rise Precursor of a Major Coronal Mass Ejection
  
  • Cheng X.
  • Xing C.
  • Aulanier Guillaume
  • Solanki S.
  • Peter H.
  • Ding M.
  The Astrophysical Journal Letters, Bristol : IOP Publishing, 2023, 954 (2), pp.L47. Abstract Coronal mass ejections are explosive plasma phenomena prevalently occurring on the Sun and probably on other magnetically active stars. However, how their pre-eruptive configuration evolves toward the main explosion remains elusive. Here, based on comprehensive observations of a long-duration precursor in an event on 2012 March 13, we determine that the heating and slow rise of the pre-eruptive hot magnetic flux rope (MFR) are achieved through a precursor reconnection located above cusp-shaped high-temperature precursor loops. It is observed that the hot MFR threads are built up continually, with their middle initially showing an “M” shape and then being separated from the cusp of precursor loops, causing the slow rise of the entire MFR. The slow rise, in combination with the thermal-dominated hard X-ray source concentrated at the top of the precursor loops, shows that the precursor reconnection is much weaker than the flare reconnection of the main eruption. We also perform a 3D magnetohydrodynamics simulation that reproduces the early evolution of the MFR transiting from the slow to fast rise. It is revealed that the magnetic tension force pertinent to “M”-shaped threads drives the slow rise, which, however, evolves into a magnetic pressure gradient-dominated regime responsible for the rapid acceleration eruption. (10.3847/2041-8213/acf3e4)
  DOI : 10.3847/2041-8213/acf3e4
• Transport and zonal flows dynamics in flux-driven interchange and drift waves turbulence
  
  • Panico O
  • Sarazin Y
  • Hennequin P
  • Gürcan Ö
  • Bigué R
  • Dif-Pradalier G
  • Garbet X
  • Varennes R
  • Munschy Y
  , 2023. The saturation of heat and particle turbulent transport in tokamak plasmas is efficiently controlled by large scale sheared flows. While collisions govern the linear damping of these flows, nonlinear couplings of turbulent fluctuations provide source terms via Reynolds' forces [1]. Numerical simulations [2] later confirmed by experimental measurements [3] have shown that self-generated zonal flows (ZF) can structure in so-called staircases. The mechanisms of their generation, their impact on turbulent transport and their robustness with respect to the various types of turbulence remain active research topics. In the present work, these issues are addressed by means of the reduced nonlinear model Tokam1D that features interchange and drift-wave turbulences, both suspected to be active at the edge of tokamak plasmas [4]. The model derives from the continuity and charge balance equations, where single poloidal and parallel wave numbers are retained and constant ion and electron temperatures are assumed. A generalized Ohm's law closes the system, linking the parallel current to the electric field and the electron pressure gradient. One of the strengths of this 1-dimensional model is to be flux driven: it evolves self-consistently the equilibrium and fluctuations of density and electric potential. It allows one to study the generation and structuration of large scale flows as well as their impact on turbulent transport. The linear properties of both instabilities are controlled by two plasma parameters, the mean curvature g of the magnetic field and the adiabaticity parameter C that scales like the square of the parallel wave vector divided by the electron-ion collision frequency. They exhibit rich characteristics in the parameter space. Consistently with previous findings, all the three control plasma parameters – g, C and the ion to electron temperature ratio =Ti/Te – are found to have a dual role, either stabilizing or destabilizing depending on the parameter regime. Also, they govern the phase shift between the density and electric potential fluctuations, hence the efficiency of the quasi-linear transport at prescribed fluctuation magnitude. The generation and structuration of ZFs and their interplay with turbulence and transport are analyzed in nonlinear simulations on confinement timescales. Whatever the values of the scanned parameters g, C and , ZFs are always active. They are driven by both components of the Reynolds stress, electric and diamagnetic [5], the contribution of the former being dominant when interchange dominates (large g). Two regimes are observed: ZFs are either structured in staircases or not. Staircases are found to emerge as a result of an anti-diffusive process. While maxima of the density gradient and of the shear of ZFs coincide, the ZF curvature governs the cross phase between density and electric potential fluctuations. These results help to characterize the large scale flow dynamics and their efficiency in regulating turbulent transport, and to discriminate plasma regimes where staircases are likely to be observed experimentally.
• At the frontier of physics and biology: cold plasma, a new therapeutic approach in lung cancer?
  
  • Marmier Solenne
  • Decauchy Henri
  • Geraud Korentin
  • Soulier Manon
  • Sibéril Sophie
  • Dufour Thierry
  • Cremer Isabelle
  , 2023.
• Experimental and numerical investigations of electron transport enhancement by electron-cyclotron plasma-wave interaction in tokamaks
  
  • Cazabonne J
  • Donnel P
  • Coda S
  • Decker J
  • Di Giannatale G
  • Iantchenko A
  • Kumar U
  • Peysson Y
  • Porte L
  • Rienäcker S
  • Tema-Biwole A
  • Villard L
  Plasma Physics and Controlled Fusion, IOP Publishing, 2023, 65 (10), pp.104001. Abstract Energy transfer from electron-cyclotron (EC) waves to the plasma is being routinely used in tokamaks to heat and drive current through the electron channel. Technical applications such as magnetohydrodynamic mode mitigation require power deposition with a high degree of localization. However, observations made in tokamaks show a broader distribution of suprathermal electrons than predicted by standard drift-kinetic codes. The present paper explores a possible wave-induced increase of electron turbulent transport that may explain the experimental data, using power-modulated EC waves in the Tokamak à Configuration Variable (TCV). In particular, an indirect measurement of the suprathermal electron population via hard x-rays exhibits an enhanced radial transport with increased wave power. This correlates well with the measured increase of the density fluctuation level during the power pulses, associated with the destabilization of ion temperature gradient modes and trapped electron modes and with stiff electron profiles. Forward bounce-averaged drift-kinetic simulations show that a radial diffusion model directly proportional to the wave power deposition is required to match the experimental data. The power dependency is confirmed by global flux-driven gyro-kinetic simulations using a realistic EC power source, computing turbulent transport from first principles and showing a radial increase of electron transport with increased wave power. (10.1088/1361-6587/acf39c)
  DOI : 10.1088/1361-6587/acf39c
• Unravelling the multifaceted antitumor effects of cold atmospheric pasma on cholangiocarcinoma
  
  • Pavy Allan
  • Decauchy Henri
  • Lekbaby Bouchra
  • Soulier Manon
  • Minini Mirko
  • Geraud Korentin
  • Aoudjehane Lynda
  • El Mourabit Haquima
  • Augustin Jérémy
  • Renault Gilles
  • Camus Marine
  • Pol Jonathan
  • Dufour Thierry
  • Fouassier Laura
  , 2023.
• Delayed response of low latitudes TEC during thirty-six geomagnetic storms from 2014 to 2017
  
  • Mohamed Heba Salah
  • Amory-Mazaudier Christine
  • Panda Sampad Kumar
  • Shalabiea O.M.
  • Mahrous A.
  Journal of Atmospheric and Solar-Terrestrial Physics, Elsevier, 2023, 250, pp.106109. Ionospheric response to the onset of geomagnetic storms is an important aspect for developing models towards better understanding and prediction of ionospheric parameters, particularly over the equatorial and low latitude sectors that are associated with several complexities. Our paper discusses the time response of the ionosphere (∆t iono), where ∆t iono is the time elapsed from the onset of sudden storm commencement (SSC) of a magnetic storm to the absolute maximum value of DVTEC (TEC: total electron content). Over the period 2014 to 2017, thirty-six storms are reviewed, and their ∆t iono are analyzed along with the magnetic and solar parameters. We defined a threshold value of TEC to be 8 TECU. Three storms are studied in detail as a reference for the entire range of storms (March 2015, June 2015, and September 2015). The stations used are Kourou (KOUR; 5.25°N/52.80°W (10.1016/j.jastp.2023.106109)
  DOI : 10.1016/j.jastp.2023.106109
• From Basics to Frontiers: A Comprehensive Review of Plasma-Modified and Plasma-Synthesized Polymer Films
  
  • Dufour Thierry
  Polymers, MDPI, 2023, 15 (17), pp.3607. This comprehensive review begins by tracing the historical development and progress of cold plasma technology as an innovative approach to polymer engineering. The study emphasizes the versatility of cold plasma derived from a variety of sources including low-pressure glow discharges (e.g., radiofrequency capacitively coupled plasmas) and atmospheric pressure plasmas (e.g., dielectric barrier devices, piezoelectric plasmas). It critically examines key operational parameters such as reduced electric field, pressure, discharge type, gas type and flow rate, substrate temperature, gap, and how these variables affect the properties of the synthesized or modified polymers. This review also discusses the application of cold plasma in polymer surface modification, underscoring how changes in surface properties (e.g., wettability, adhesion, biocompatibility) can be achieved by controlling various surface processes (etching, roughening, crosslinking, functionalization, crystallinity). A detailed examination of Plasma-Enhanced Chemical Vapor Deposition (PECVD) reveals its efficacy in producing thin polymeric films from an array of precursors. Yasuda’s models, Rapid Step-Growth Polymerization (RSGP) and Competitive Ablation Polymerization (CAP), are explained as fundamental mechanisms underpinning plasma-assisted deposition and polymerization processes. Then, the wide array of applications of cold plasma technology is explored, from the biomedical field, where it is used in creating smart drug delivery systems and biodegradable polymer implants, to its role in enhancing the performance of membrane-based filtration systems crucial for water purification, gas separation, and energy production. It investigates the potential for improving the properties of bioplastics and the exciting prospects for developing self-healing materials using this technology. (10.3390/polym15173607)
  DOI : 10.3390/polym15173607
• Magnetospheric Time History in Storm‐Time Magnetic Flux Dynamics
  
  • Akhavan-Tafti M.
  • Atilaw T.
  • Fontaine D.
  • Le Contel O.
  • Slavin J.
  • Pulkkinen T.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2023, 128 (9). Abstract Magnetospheric magnetic flux dynamics is quantified in 29 geomagnetic storms between 2015 and 2019, using near‐equatorial Van Allen Probe, GOES, and Magnetospheric Multiscale satellites. For the first time, concurrent, multi‐probe observations are utilized to preserve magnetospheric time history, defined as the state of the magnetosphere leading up to an observation. It is revealed that, relative to pre‐storm conditions, (a) during the storm sudden commencement (SSC), magnetic flux uniformly increases Δ Ψ = +15% throughout the magnetosphere, except in the nightside inner magnetosphere where Δ Ψ = −30%, and (b) during storm main and recovery phases, Δ Ψ = −30% and −15%, respectively, in the nightside magnetosphere, at radial distances 5 ≤ r [ R E ] < 8. It is found that a symmetric ring current is likely formed in the nightside, early in the storm process (localized during SSC), which then broadens during the main phase, before weakening during the recovery phase. The current system on the dayside shows a distinct dawn‐dusk asymmetry. (10.1029/2023JA031832)
  DOI : 10.1029/2023JA031832
• Formation of an observed eruptive flux rope above the torus instability threshold through tether-cutting magnetic reconnection
  
  • Prasad Avijeet
  • Kumar Sanjay
  • Sterling Alphonse
  • Moore Ronald L.
  • Aulanier Guillaume
  • Bhattacharyya Ramit
  • Hu Qiang
  Astronomy & Astrophysics - A&A, EDP Sciences, 2023, 677, pp.A43. Context. Erupting magnetic flux ropes (MFRs) are believed to play a crucial role in producing solar flares. However, the formation of erupting MFRs in complex coronal magnetic configurations and the role of their subsequent evolution in the flaring events are not fully understood. Aims. We perform a magnetohydrodynamic (MHD) simulation of active region NOAA 12241 to understand the formation of a rising magnetic flux rope during the onset of an M6.9 flare on 2014 December 18 around 21:41 UT (SOL2014-12- 18T21:41M6.9), which was followed by the appearance of parallel flare ribbons. Methods. The MHD simulation was initialised with an extrapolated non-force-free magnetic field generated from the photospheric vector magnetogram of the active region taken a few minutes before the flare. Results. The initial magnetic field topology displays a pre-existing sheared arcade enveloping the polarity inversion line. The simulated dynamics exhibit the movement of the oppositely directed legs of the sheared arcade field lines towards each other due to the converging Lorentz force, resulting in the onset of tether-cutting magnetic reconnection that produces an underlying flare arcade and flare ribbons. Concurrently, a magnetic flux rope above the flare arcade develops inside the sheared arcade and shows a rising motion. The flux rope is found to be formed in a torus-unstable region, thereby explaining its eruptive nature. Interestingly, the location and rise of the rope are in good agreement with the corresponding observations seen in extreme-ultraviolet channels of the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO). Furthermore, the foot points of the simulation’s flare arcade match well with the location of the observed parallel ribbons of the flare. Conclusions. The presented simulation supports the development of the MFR by the tether-cutting magnetic reconnection inside the sheared coronal arcade during flare onset. The MFR is then found to extend along the polarity inversion line (PIL) through slip-running reconnection. The MFR’s eruptive nature is ascribed both to its formation in the torus-unstable region and also to the runaway tether-cutting reconnection. (10.1051/0004-6361/202346267)
  DOI : 10.1051/0004-6361/202346267
• Multi-point Assessment of the Kinematics of Shocks (MAKOS): A Heliophysics Mission Concept Study. (Whitepaper #135 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033.)
  
  • Goodrich Katherine
  • Iii Lynn
  • Schwartz Steven
  • Cohen Ian
  • Turner Drew
  • Whittlesey Phyllis
  • Caspi Amir
  • Rose Randy
  • Smith Keith
  • Allen Robert
  • Burgess David
  • Caprioli Damiano
  • Cassak Paul
  • Eastwood Jonathan
  • Giacalone Joe
  • Gingell Imogen
  • Haggerty Colby
  • Halekas Jasper
  • Hospodarsky George
  • Howes Gregory
  • Juno James
  • Khotyaintsev Yuri
  • Klein Kris
  • Kucharek Harald
  • Lembège Bertrand
  • Lichko Emily
  • Liu Terry
  • Malaspina David
  • Marcucci Maria Federica
  • Mazelle Christian
  • Meziane Karim
  • Plaschke Ferdinand
  • Retino A.
  • Russell Chris
  • Scime Earl
  • Sibeck David
  • Stevens Michael
  • Tenbarge Jason
  • Vasko Ivan
  • Wang Shan
  • Wang Linghua
  • Zhang Hui
  Bulletin of the American Astronomical Society, American Astronomical Society, 2023, 55 (3). (10.3847/25c2cfeb.431a46a0)
  DOI : 10.3847/25c2cfeb.431a46a0
• Magnetic Energy Powers the Corona: How We Can Understand its 3D Storage & Release
  
  • Caspi Amir
  • Seaton Daniel
  • Casini Roberto
  • Downs Cooper
  • Gibson Sarah
  • Gilbert Holly
  • Glesener Lindsay
  • Guidoni Silvina
  • Hughes J. Marcus
  • Mckenzie David
  • Plowman Joseph
  • Reeves Katharine
  • Saint-Hilaire Pascal
  • Shih Albert
  • West Matthew
  • Alaoui Meriem
  • Alexander David
  • Allred Joel
  • Antiochos Spiro
  • Ashfield William
  • Ballai Istvan
  • Barata Teresa
  • Barta Miroslav
  • Benz Arnold
  • Berlicki Arkadiusz
  • Bradshaw Stephen
  • Bröse Malte
  • Buitrago-Casas Juan Camilo
  • Cassak Paul
  • Chamberlin Phillip
  • Che Haihong
  • Chen Thomas
  • Chen Bin
  • Cheng Xin
  • Christe Steven
  • Comisso Luca
  • Dahlin Joel
  • Nolfo Georgia De
  • Dennis Brian
  • Dickson Ewan
  • Drake James
  • Dudík Jaroslav
  • Dzifcakova Elena
  • Emslie Gordon
  • Erdelyi Robertus
  • Farid Samaiyah
  • Fleishman Gregory
  • French Ryan
  • Gallagher Peter
  • Gan Weiqun
  • Gary Dale
  • Guo Fan
  • Hayes Laura
  • Hudson Hugh
  • Ji Hantao
  • Jones Andrew
  • Kansabanik Devojyoti
  • Kawate Tomoko
  • Kerr Graham
  • Keshav Aggarwal
  • Knuth Trevor
  • Kobelski Adam
  • Kooi Jason
  • Kumari Anshu
  • Lee Jeongwoo
  • Li Ying
  • Longo Francesco
  • Maharana Anwesha
  • Mandrini Cristina
  • Oliveros Juan Carlos Martinez
  • Mason James Paul
  • Mason E.
  • Massone Anna Maria
  • Mcateer R.
  • Mcconnell Mark
  • Mctiernan James
  • Mitchell J. Grant
  • Mohan Atul
  • Motorina Galina
  • Mrozek Tomasz
  • Musset Sophie
  • Narukage Noriyuki
  • Nayak Sushree
  • Nitta Nariaki
  • Panesar Navdeep
  • Pariat Etienne
  • Piana Michele
  • Pohjolainen Silja
  • Qiu Jiong
  • Reale Fabio
  • Rivera Yeimy
  • Rozelot Jean Pierre
  • Sarkar Ranadeep
  • Setterberg William
  • Shaik Shaheda Begum
  • Shaikh Zubair
  • Sharma Rohit
  • Skokic Ivica
  • Stores Morgan
  • Struminsky Alexei
  • Sylwester Janusz
  • Takahashi Tadayuki
  • Tiwari Sanjiv
  • Tsiklauri David
  • Vievering Juliana
  • Warmuth Alexander
  • White Stephen
  • Zimovets Ivan
  Bulletin of the American Astronomical Society, American Astronomical Society, 2023, 55. Synopsis The coronal magnetic field is the prime driver behind many as-yet unsolved mysteries: solar eruptions, coronal heating, and the solar wind, to name a few. It is, however, still poorly observed and understood. We highlight key questions related to magnetic energy storage, release, and transport in the solar corona, and their relationship to these important problems. We advocate for new and multi-point co-optimized measurements, sensitive to magnetic field and other plasma parameters, spanning from optical to γ-ray wavelengths, to bring closure to these long-standing and fundamental questions. We discuss how our approach can fully describe the 3D magnetic field, embedded plasma, particle energization, and their joint evolution to achieve these objectives. Magnetic Energy Powers the Corona: How We Can Understand its 3D Storage & Release (10.3847/25c2cfeb.1dbfea1f)
  DOI : 10.3847/25c2cfeb.1dbfea1f
• Observations of Kolmogorov Turbulence in Saturn's Magnetosphere
  
  • Xu S.
  • Huang S.
  • Sahraoui F.
  • Yuan Z.
  • Wu H.
  • Jiang K.
  • Zhang J.
  • Lin R.
  Geophysical Research Letters, American Geophysical Union, 2023, 50 (16). Abstract The Kolmogorov scaling in the inertial range of scales is a distinct characteristic of fully developed turbulence, and studying it offers valuable insights into the evolution of turbulence. In this work, we perform a statistical survey of the power spectra with the Kolmogorov scaling in Saturn's magnetosphere using Cassini measurements. Two cases study show that both magnetic‐field and electron density spectra exhibit f −5/3 at the MHD scales. The statistical analysis reveals a wide‐ranging and abundant presence of Kolmogorov spectra throughout magnetosphere, observed across all local times. Interestingly, the occurrence rate of these Kolmogorov‐like events within Saturn's magnetosphere surpasses that observed in the planetary magnetosheath. The measurements of magnetic compressibility for the Kolmogorov‐like events show the dominance of incompressible Alfvénic turbulence (44.64%) with respect to magnetosonic‐like one (6.94%). In addition, the source and evolution of the turbulent fluctuations are further discussed. (10.1029/2023GL105463)
  DOI : 10.1029/2023GL105463
• COMPLETE: a flagship mission for complete understanding of 3D coronal magnetic energy release
  
  • Caspi Amir
  • Casini Roberto
  • Downs Cooper
  • Gibson Sarah
  • Gilbert Holly
  • Glesener Lindsay
  • Guidoni Silvina
  • Hughes J. Marcus
  • Mckenzie David
  • Plowman Joseph
  • Seaton Daniel
  • Reeves Katharine
  • Saint-Hilaire Pascal
  • Shih Albert
  • West Matthew
  • Alaoui Meriem
  • Alexander David
  • Allred Joel
  • Ashfield William
  • Bradshaw Stephen
  • Bröse Malte
  • Buitrago-Casas Juan Camilo
  • Chamberlin Phillip
  • Chandra Ramesh
  • Che Haihong
  • Chen Thomas
  • Chen Bin
  • Cheng Xin
  • Christe Steven
  • Dahlin Joel
  • Nolfo Georgia De
  • Dickson Ewan
  • Dudík Jaroslav
  • Emslie Gordon
  • Erdelyi Robertus
  • Gallagher Peter
  • Gan Weiqun
  • Gary Dale
  • Guo Fan
  • Hayes Laura
  • Hudson Hugh
  • Ji Hantao
  • Jones Andrew
  • Kerr Graham
  • Keshav Aggarwal
  • Knuth Trevor
  • Kooi Jason
  • Kumari Anshu
  • Li Ying
  • Limousin Olivier
  • Longo Francesco
  • Maharana Anwesha
  • Mandrini Cristina
  • Oliveros Juan Carlos Martinez
  • Massone Anna Maria
  • Mcateer R.
  • Mcconnell Mark
  • Mctiernan James
  • Meuris Aline
  • Mitchell J. Grant
  • Motorina Galina
  • Mrozek Tomasz
  • Musset Sophie
  • Narukage Noriyuki
  • Nayak Sushree
  • Newmark Jeffrey
  • Nitta Nariaki
  • Panesar Navdeep
  • Pariat Etienne
  • Piana Michele
  • Qiu Jiong
  • Raouafi Nour
  • Reale Fabio
  • Rozelot Jean Pierre
  • Samaiyah Farid
  • Sarkar Ranadeep
  • Shaik Shaheda Begum
  • Skokic Ivica
  • Stores Morgan
  • Struminsky Alexei
  • Su Yang
  • Takahashi Tadayuki
  • Tiwari Sanjiv
  • Tsiklauri David
  • Vievering Juliana
  • Warmuth Alexander
  • White Stephen
  • Zhang Jie
  • Zimovets Ivan
  Bulletin of the American Astronomical Society, American Astronomical Society, 2023, 55. COMPLETE is a flagship mission concept combining broadband spectroscopic imaging and comprehensive magnetography from multiple viewpoints around the Sun to enable tomographic reconstruction of 3D coronal magnetic fields and associated dynamic plasma properties, which provide direct diagnostics of energy release. COMPLETE re-imagines the paradigm for solar remote-sensing observations through purposefully cooptimized detectors distributed on multiple spacecraft that operate as a single observatory, linked by a comprehensive data/model assimilation strategy to unify individual observations into a single physical framework. We describe COMPLETE's science goals, instruments, and mission implementation. With targeted investment by NASA, COMPLETE is feasible for launch in 2032 to observe around the maximum of Solar Cycle 26. (10.3847/25c2cfeb.b95dd671)
  DOI : 10.3847/25c2cfeb.b95dd671
• Improving Multi-Dimensional Data Formats, Access, and Assimilation Tools for the Twenty-First Century
  
  • Seaton Daniel
  • Caspi Amir
  • Casini Roberto
  • Downs Cooper
  • Gibson Sarah
  • Gilbert Holly
  • Glesener Lindsay
  • Guidoni Silvina
  • Hughes J. Marcus
  • Mckenzie David
  • Plowman Joseph
  • Reeves Katharine
  • Saint-Hilaire Pascal
  • Shih Albert
  • West Matthew
  • Alaoui Meriem
  • Alzate Nathalia
  • Ashfield William
  • Bradshaw Stephen
  • Buitrago-Casas Juan Camilo
  • Che Haiong
  • Chen Thomas
  • Christe Steven
  • Erdelyi Robertus
  • Farid Samaiyah
  • Gallagher Peter
  • Gary Dale
  • Gilly Chris
  • Guo Fan
  • Hayes Laura
  • Hudson Hugh
  • Ji Hantao
  • Jones Andrew
  • Keshav Aggarwal
  • Kirk Michael
  • Knuth Trevor
  • Kobelski Adam
  • Kooi Jason
  • Kumari Anshu
  • Li Ying
  • Li Jing
  • Lowder Chris
  • Mandrini Cristina
  • Oliveros Juan Carlos Martinez
  • Mason James Paul
  • Mason E.
  • Massone Anna Maria
  • Mcateer R.
  • Mctiernan James
  • Motorina Galina
  • Nayak Sushree
  • Nitta Nariaki
  • Panesar Navdeep
  • Pariat Etienne
  • Piana Michele
  • Reale Fabio
  • Reardon Kevin
  • Rivera Yeimy
  • Sarkar Ranadeep
  • Shaikh Zubair
  • Stores Morgan
  • Tiwari Sanjiv
  • Warmuth Alexander
  • White Stephen
  Bulletin of the American Astronomical Society, American Astronomical Society, 2023. (10.3847/25c2cfeb.6d8ecdc1)
  DOI : 10.3847/25c2cfeb.6d8ecdc1
• Random Bullets Versus Self-Triggered Short Discharges in a Helium Atmospheric Pressure Plasma Jet
  
  • Yang Hang
  • van Zwol Annemarie
  • Burdonov Konstantin
  • Fuchs Julien
  • Rousseau Antoine
  Plasma Chemistry and Plasma Processing, Springer Verlag, 2023, 43 (6), pp.1491-1507. Atmospheric pressure plasma jets driven by AC voltage are reported to exhibit randomness or periodicity under certain operating conditions. In the present article, discharges in a helium plasma jet driven by 16 kHz sinusoidal voltage are studied. In the positive half cycle, several short and slow periodic discharges (3–6 km/s) are observed before the ignition of random longer and faster bullets (20–60 km/s). The characteristics of the random discharges are studied using statistical methods. The propagation of slow plasma bullets and fast bullets is analysed using an ICCD camera and a streak camera. Glowing like plasma that lasts for 2–6 μs is observed near the gap region and possibly provides a high seed electron density for a following microdischarge. The results are compared with a previous study with a similar APPJ which exhibits multi-periodicity under certain conditions. It is proposed that volumetric residual charges may play an important role for APPJs with short gap distances. (10.1007/s11090-023-10358-3)
  DOI : 10.1007/s11090-023-10358-3
• Quantifying the Energy Budget in the Solar Wind from 13.3-100 Solar Radii
  
  • Halekas J.
  • Bale S.
  • Berthomier M.
  • Chandran B.
  • Drake J.
  • Kasper J.
  • Klein K.
  • Larson D.
  • Livi R.
  • Pulupa M.
  • Stevens M.
  • Verniero J.
  • Whittlesey P.
  The Astrophysical Journal, American Astronomical Society, 2023, 952 (1), pp.26. A variety of energy sources, ranging from dynamic processes like magnetic reconnection and waves to quasi-steady terms like the plasma pressure, may contribute to the acceleration of the solar wind. We utilize a combination of charged particle and magnetic field observations from the Parker Solar Probe (PSP) to attempt to quantify the steady-state contribution of the proton pressure, the electric potential, and the wave energy to the solar wind proton acceleration observed by PSP between 13.3 and ~100 solar radii (RS). The proton pressure provides a natural kinematic driver of the outflow. The ambipolar electric potential acts to couple the electron pressure to the protons, providing another definite proton acceleration term. Fluctuations and waves, while inherently dynamic, can act as an additional effective steady-state pressure term. To analyze the contributions of these terms, we utilize radial binning of single-point PSP measurements, as well as repeated crossings of the same stream at different distances on individual PSP orbits (i.e. "fast radial scans"). In agreement with previous work, we find that the electric potential contains sufficient energy to fully explain the acceleration of the slower wind streams. On the other hand, we find that the wave pressure plays an increasingly important role in the faster wind streams. The combination of these terms can explain the continuing acceleration of both slow and fast wind streams beyond 13.3 RS. (10.3847/1538-4357/acd769)
  DOI : 10.3847/1538-4357/acd769
• Increasing signal-to-noise ratio in over-determined Mueller matrices
  
  • Philpott H.
  • Garcia-Caurel E.
  • Guaitella O.
  • Sobota A.
  Optics Express, Optical Society of America - OSA Publishing, 2023, 31 (16), pp.25585. This work investigates how the signal-to-noise ratio (SNR) of an over-determined Mueller matrix can be improved by changing the method of calculation. Specifically, our investigation focused on comparing SNRs achieved using the vector methodology from the field of partial Mueller polarimetry, and the matrix methodology. We use experimentally derived measurements from an investigation into the time-varying signal produced by the Mueller matrix of an electro-optic Bismuth Silicon Oxide (BSO) crystal undergoing cyclical impact of a Helium plasma ionisation wave. Our findings show that the vector methodology is superior to the matrix methodology, with a maximum SNR of 7.54 versus 4.97. We put forth that the superiority of the vector methodology is due to its greater flexibility, which results in the Mueller matrix being calculated with better condition matrices, and higher levels of SNR in the intensity measurements used for calculation. (10.1364/OE.493464)
  DOI : 10.1364/OE.493464