Publications

2025

• Investigation of Filamentary and Diffuse DBD in CO₂ by Means of InSitu FTIR Absorption Spectroscopy
  
  • Bajon Corentin
  • Baratte Edmond
  • Sadi Dihya
  • Guaitella O.
  • Belinger A.
  • Dap Simon
  • Hoder T.
  • Naudé N.
  Journal of Physical Chemistry C, American Chemical Society, 2025, 129 (38), pp.16967-16976. This work investigates CO₂ dielectric barrier discharges (DBDs) at atmospheric pressure in the filamentary and diffuse regimes for the first time using in situ FTIR absorption measurements. The conversion factor of CO₂ is determined and is consistent with the results obtained for DBDs in the literature, following a power law with respect to the specific energy input in both regimes. Vibrational temperatures for CO₂ and CO molecules as well as rotational temperature are also determined within the discharge. A noticeably high vibrational temperature of CO is observed for low specific energy input (SEI). It drops abruptly when increasing the SEI which is attributed to strong vibrationalto-translational energy transfers by O atoms coming from CO₂ dissociation. Except that, the ordering of the different temperatures is similar to the results reported for other CO₂ discharges generated at lower pressures: the vibrational temperature of CO is higher than those of the different vibrational modes of CO₂. The latter are slightly higher than the rotational temperature of the gas for the diffuse mode, whereas they are almost the same for the filamentary mode. The evolution of the measured parameters as a function of the specific energy input is then discussed and a detailed comparison of the two different regimes is carried out. These data together with the knowledge of the reduced electric field in the diffuse regime, which is included in the range 120-140 Td for all conditions, can be of significant importance for further studies exploring the fundamentals of CO₂ plasma chemistry at atmospheric pressure, serving as reference for kinetic models. (10.1021/acs.jpcc.5c02224)
  DOI : 10.1021/acs.jpcc.5c02224
• Breaking seed dormancy in Mediterranean Brassica rapa wild populations: is cold plasma treatment efficient?
  
  • Wagner Marie-Hélène
  • Dufour Thierry
  • Geraci Anna
  • Oddo Elisabetta
  • Tarantino G.R.
  • Scafidi F.
  • Bailly C.
  • Hadj Arab H.
  • Boucenna B.
  • Tiret Mathieu
  • Falentin Cyril
  • Dupont A.
  • Ducournau S.
  • Chèvre Anne-Marie
  Seed Science and Technology, International Seed Testing Association Ista, 2025, 53 (3), pp.369-389. Turnip (Brassica rapa) is a native species of the Mediterranean area, spread from northwest France to south Algeria. In this study, dormancy and germination traits were assessed for 61 wild Brassica rapa populations collected across the Mediterranean region. Seed dormancy is a key factor influencing germination and seedling establishment. Three dormancy-breaking methods were compared: gibberellic acid, scarification and cold plasma. The efficiency and selectivity were evaluated through germination ability, time to 10% germination (T10), mean germination time and greenhouse emergence. Five days after imbibition, germination was only 18% for the untreated seeds but 60% for the plasma-treated seeds. Germination also began 24 hours earlier and mean germination time was reduced across most populations. However, there was a limited effect on seedling emergence, which remained around 55% for both untreated and treated samples. Comparative analysis indicates that cold plasma was more effective in alleviating embryo dormancy. In addition, histological and scanning electron microscopy showed that the seed coat differed according to the geographical origin of the populations, with a deeper dormancy in seeds from Sicilian populations. (10.15258/sst.2025.53.3.03)
  DOI : 10.15258/sst.2025.53.3.03
• Hybrid simulations of Mercury’s global dynamics and the interplanetary ions’ precipitation fluxes under different interplanetary conditions
  
  • Cazzola E.
  • Fontaine D.
  • Modolo Ronan
  Astronomy & Astrophysics - A&A, EDP Sciences, 2025, 701, pp.A209. Aims. We aim to quantify the impact of different interplanetary conditions met by Mercury along its orbit between its aphelion (~0.47 AU) and perihelion (~0.31 AU) on the Hermean environment, including the rate of solar-wind ion precipitation onto the surface.Methods. We performed a set of 3D global hybrid simulations (kinetic ions and fluid electrons) with interplanetary conditions taken from recent statistics from observations on board the Parker Solar Probe and MESSENGER missions in such a way as to represent an average scenario at both the aphelion and perihelion positions, and in the cases of a slow (250 km/s) and fast (450 km/s) solar wind.Results. The results are in general agreement with empirical models. However, we have found that the subsolar stand-off distances of magnetopause and bow shock, respectively, in the range of 1.0–1.4 RM and 1.3–2.0 RM, are relatively shorter than global statistical averages of, respectively, 1.45 and 1.96 RM. We also observe a local time (LT) asymmetry in the cusp’s location, with the northern cusp located in the post-noon sector centred around 13–14.3 LT and the southern cusp located in the pre-noon sector centred around 9–10.7 LT. Noticeably, the southern cusp region takes the shape of a parallelogram extended from southern middle latitudes in the pre-noon sector to equatorial latitudes in the post-noon sector. We suggest that these effects could result from the orientation of the interplanetary magnetic field along the Parker spiral, which is characterised by an almost radial orientation with a small duskward component. (10.1051/0004-6361/202553953)
  DOI : 10.1051/0004-6361/202553953
• Refining the modeling strategy for anomalous electron transport in fluid simulations of Hall thrusters via insights from PIC simulations
  
  • Petronio Federico
  • Alvarez Laguna Alejandro
  • Guillon Martin Jacques
  • Bourdon Anne
  • Chabert Pascal
  Physics of Plasmas, American Institute of Physics, 2025, 32 (7), pp.073513. Modeling anomalous transport in fluid simulations is a fundamental challenge for developing efficient and robust fluid simulation tools for Hall thrusters. This paper investigates optimal strategies for modeling anomalous transport in such simulations. Using the particle-in-cell (PIC) benchmark (BM) setup of Charoy et al., we demonstrate that various terms in the electron momentum equation can be readily identified. In particular, we show that the assumption of expressing the rate of change of the electron momentum due to instability as proportional to the momentum itself does not hold under these simulation conditions. Subsequently, we present two fluid simulations that replicate the conditions of the PIC BM setup. The first employs the conventional empirical anomalous collision frequency approach. While this model provides generally satisfactory results, it fails to capture specific plasma characteristics. The second fluid model adopts a data-driven approach to represent the anomalous force terms in the momentum equation. This approach furnishes significantly improved results, suggesting that although the anomalous collisionality framework provides meaningful outcomes, it can be effectively replaced by more advanced techniques. (10.1063/5.0274535)
  DOI : 10.1063/5.0274535
• Fast gas heating and peculiarities of temperature measurements by optical emission spectroscopy in nanosecond surface dielectric barrier discharge
  
  • Zhang Bin
  • Kreyder Geoffrey
  • Popov Nikolay
  • Shcherbanev Sergey
  • Starikovskaia Svetlana
  Plasma Sources Science and Technology, IOP Publishing, 2025, 34 (9), pp.095010. The aim of this work is the experimental and theoretical study of nanosecond Surface dielectric barrier discharge (SDBD) parameters in atmospheric pressure air. Measurements of electric current and delivered energy, ICCD images of the discharge at all stages of its evolution, and gas heating in the discharge and near afterglow are performed. The paper presents the results of 2D numerical modeling of the nanosecond SDBD. The results of the calculations are compared with measured data on the dynamics of current, energy input and gas heating. Special attention is paid to the study of the spatial structure of the discharge, in particular, to the distribution of gas temperature and the second positive system emission intensity in the direction perpendicular to the surface of the dielectric. It is shown that the results of temperature measurements in SDBD using optical emission spectroscopy technique are severely influenced by this spatial structure. The parameters of a probe discharge of smaller amplitude, which is formed by a reflected pulse 500 ns after the main discharge, are also calculated. The possibility of using the second diagnostic pulse to measure the gas temperature in the afterglow discharge is discussed. (10.1088/1361-6595/ae00ef)
  DOI : 10.1088/1361-6595/ae00ef
• Survey of the edge radial electric field in L-mode TCV plasmas using Doppler backscattering
  
  • Rienäcker S
  • Hennequin P
  • Vermare L
  • Honoré C
  • Coda S
  • Labit B
  • Vincent Benjamin
  • Wang Y
  • Frassinetti L
  • Panico O
  Plasma Physics and Controlled Fusion, IOP Publishing, 2025, 67 (6), pp.065003. A Doppler backscattering (DBS) diagnostic has recently been installed on the Tokamak à Configuration Variable (TCV) to facilitate the study of edge turbulence and flow shear in a versatile experimental environment. The dual channel V-band DBS system is coupled to TCV’s quasi-optical diagnostic launcher, providing access to the upper low-field side region of the plasma cross-section. Verifications of the DBS measurements are presented. The DBS equilibrium v ⊥ profiles are found to compare favorably with gas puff imaging (GPI) measurements and to the E r inferred from the radial force balance of the carbon impurity. The radial structure of the edge E r × B equilibrium flow and its dependencies are investigated across a representative set of L-mode TCV discharges, by varying density, auxiliary heating and magnetic configuration. (10.1088/1361-6587/add0e0)
  DOI : 10.1088/1361-6587/add0e0
• Phase transition from turbulence to zonal flows in the Hasegawa–Wakatani system
  
  • Guillon P L
  • Gürcan Ö D
  Physics of Plasmas, American Institute of Physics, 2025, 32 (1). The transition between two-dimensional hydrodynamic turbulence and quasi-one-dimensional zonostrophic turbulence is examined in the modified Hasegawa–Wakatani system, which is considered as a minimal model of β-plane-like drift-wave turbulence with an intrinsic instability. Extensive parameter scans were performed across a wide range of values for the adiabaticity parameter C describing the strength of coupling between the two equations. A sharp transition from 2D isotropic turbulence to a quasi-1D system, dominated by zonal flows, is observed using the fraction of the kinetic energy of the zonal modes as the order parameter, at C≈0.1. It is shown that this transition exhibits a hysteresis loop around the transition point, where the adiabaticity parameter plays the role of the control parameter of its nonlinear self-organization. It was also observed that the radial particle flux scales with the adiabaticity parameter following two different power law dependencies in the two regimes. A simple quasi-linear saturation rule which accounts for the presence of zonal flows is proposed, and is shown to agree very well with the observed nonlinear fluxes. Motivated by the phenomenon of quasi-one dimensionalisation of the system at high C, a number of reduction schemes based on a limited number of modes were investigated and the results were compared to direct numerical simulations. In particular, it was observed that a minimal reduced model consisting of 2 poloidal and 2 radial modes was able to replicate the phase transition behavior, while any further reduction failed to capture it. (10.1063/5.0242282)
  DOI : 10.1063/5.0242282