| 09:00 |
welcome coffee |
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| 09:30 |
News about the Federation |
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Andrea Ciardi |
| 09:45 |
Tutorial talk - Solar flare energetic particles |
ⓘ Solar flares, bright manifestations of magnetic reconnection in our solar system, are efficient in acceleration of large numbers of energetic particles up to a few hundred MeV. The solar energetic electrons propagating in solar magnetic fields produce bright X-ray and radio emissions. These emissions provide important diagnostics of the acceleration and propagation of energetic electrons in the solar atmosphere, while in-situ observations by near Earth satellites diagnose escaping energetic particles. I will discuss the recent progress in understanding acceleration and propagation of the energetic particles using X-ray and radio emissions highlighting the challenges and open questions. |
Eduard Kontar, University of Glasgow |
| 10:30 |
Space weather forecast of Solar Wind fluctuations |
ⓘ Solar wind fluctuations are the source and the consequences of various processes from reconnections to instabilities and more broadly turbulence. These fluctuations could affect locally the energy transport in the magnetosphere and then, its impact on our society. So, it is necessary to forecast them. However, forecasting solar wind fluctuations of less than 1-hour scale is one of the current challenges of Space Weather. We will explore the potential of a forecasting method based on analogue ensembles. |
Pauline Simon, LPP |
| 10:50 |
Efficient ion re-acceleration in laboratory-produced interpenetrating collisionless shocks |
ⓘ The origin of cosmic rays (CRs) remains a major open problem in astrophysics. Magnetized collisionless shocks are recognized as efficient particle accelerators, yet their ability to account for the highest observed CR energies is still debated. Recent theoretical work proposes that collisions between shocks, such as those occurring in stellar clusters, could provide the required additional acceleration. We present a laser-driven experiment that reproduces such magnetized shock interactions under laboratory conditions relevant to astrophysical plasmas. Our measurements show that when two collisionless shocks interpenetrate, ambient protons previously energized by single shocks are further accelerated, leading to a clear enhancement in energy and acceleration efficiency. Kinetic simulations support this interpretation, showing proton reacceleration through multiple reflections in the convective electric fields of the colliding flows. This new experimental platform provides a controlled path toward testing multi-shock acceleration and potentially diffusive shock acceleration mechanisms in the laboratory. |
Weipeng Yao, LULI |
| 11:10 |
The Interplay Between the Bell and Firehose Instabilities |
ⓘ In astrophysical shocks, instabilities driven by the streaming of energetic particles into the upstream medium amplify magnetic fields and generate turbulence, enabling efficient cosmic-ray acceleration. The growth and saturation of these instabilities determine the maximum particle energy and regulate how effectively shocks accelerate cosmic rays. Capturing their nonlinear behavior requires kinetic simulations that can resolve both microphysical and large-scale processes. We present a series of 1D kinetic simulations performed with the SMILEI PIC code to study the nonlinear evolution of the Bell and firehose instabilities in counter-streaming monoenergetic proton beams, used here as a minimal model for cosmic-ray–driven turbulence. By varying the beam density ratio, we probe regimes where either the Bell or the firehose instability dominates. Our results reveal nonlinear self-coupling among the dominant modes, leading to an inverse transfer of energy toward larger spatial scales. This process provides a potential mechanism for generating large-scale magnetic fluctuations in space and astrophysical plasmas, with implications for the confinement and acceleration of cosmic rays. |
Maxence Tabary, LUX |
| 11:30 |
PHARE: Towards adaptive mesh and model refinement for space plasmas |
ⓘ Understanding energy transport and regional coupling in the magnetosphere is challenging due to the multi-scale nature of magnetic reconnection. Kinetic models are computationally expensive, while fluid models lack realism. We present progress on a next-generation simulation framework using the open-source PHARE code, with validated Adaptive Mesh Refinement (AMR) solvers for Hall-MHD and Hybrid-PIC models. These solvers have been applied to large-scale simulations of magnetic reconnection in symmetric and asymmetric current sheets, and the results are currently under analysis. The next steps are to implement Adaptive Mesh and Model Refinement (AM2R), enabling the Hall- MHD and Hybrid-PIC solvers to operate together within a single simulation, as well as including a planetary dipole configuration. Together, these developments will allow global magnetospheric simulations that capture kinetic effects where they matter most. |
Ulysse Caromel, LPP |
| 11:50 |
Laser guided streamers in air |
ⓘ A powerful femtosecond laser pulse propagating through a transparent medium such as air naturally self-organizes into stable, high-intensity light structures due to the optical Kerr effect. In the wake of the laser pulse, weakly ionized plasma channels, known as filaments, are generated [1]. These filaments can extend over hundreds of meters, making them a unique tool for various atmospheric applications, including remote sensing [2], the guiding of electromagnetic waves but also electrical discharges [3]. The most remarkable achievement concerning guided discharges was the demonstration of laser-guided lightning over a distance of 60 meters in Switzerland in 2021 [4]. We present several experiments and diagnostics aimed at studying the dynamics of laser-guided discharges produced on a Tesla coil developed at LOA. Particular attention is given to the ignition process, which deal with the propagation of a so-called streamer discharge. To understand this phase, we have started to perform fluid numerical simulations of the streamer propagation assisted by filamentation. Preliminary results and future development will be presented. [1] A. Couairon et al, Femtosecond filamentation in transparent media, Phys. Rep. 441 47 ⟨hal-00454778⟩ (2007). [2] J. Kasparian, et al., White-light filaments for atmospheric analysis, Science 301 61-64 ⟨hal-00463648⟩ (2003). [3] B. Forestier et al., Triggering, guiding and deviation of long air spark discharges with femtosecond laser filament, AIP Advances 2 012151 ⟨hal-00852030⟩ (2012). [4] A. Houard et al., Laser-guided lightning, Nat. Photon. 17 231–235 ⟨hal-03947576⟩ (2023). [5] Robert Marskar, 3D fluid modeling of positive streamer discharges in air with stochastic photoionization, Plasma Sources Sci. Technol. 29 055007 (2020) |
Thomas Clark, LOA |
| 12:10 |
Lunch provided by Plas@par and poster session |
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| 14:15 |
Tutorial talk - Electric Propulsion in Space |
ⓘ Electric propulsion in space uses plasmas to convert electrical energy (from solar arrays, batteries, etc) to mechanical energy. The electromagnetic force can accelerate charged particles to exhaust velocities in the tens of km/s range. This idea was explored since the beginning of space exploration. Initially supported by govermnent agencies, its use was initially met with caution, but has exploded over the last decade, particularly due to the NewSpace movement. This talk will seek to provide an overview of the concepts of Electric Propulsion, providing some context and discussing the key metrics relevant to these propulsion systems. It will also provide a discussion of the current scientific challenges and perspectives that might interest researchers new to this field. In particular, we will argue that the EP field would benefit from the expertise developed for fusion research. |
Paul-Quentin Elias, ONERA |
| 15:00 |
Electron-iodine (I₂) collisions for plasma-propelled thrusters |
ⓘ The development of low power electric thrusters is a crucial step to respond to the growing demand for small satellite technology. In this context, iodine is a promising candidate to replace the currently used propellants (e.g. xenon), for both technological and economical reasons. However, the physics and the chemistry of iodine low-temperature plasma are not well understood, due to the lack of data on the elementary electronic processes occurring. In this context, we have studied the electronic processes in electron-iodine molecule collisions up to 100 eV using the R-matrix method. |
Alejandro Garcia, LCPMR |
| 15:20 |
Machine learning for emission spectroscopy of Hall thrusters |
ⓘ Tsanko V. Tsankov [ Laboratoire de Physique des Plasmas (LPP), CNRS, École polytechnique, Institut polytechnique de Paris, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris ] Tarek Ben Slimane [ Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa ] Clarence Deltel [ Safran Spacecraft Propulsion, Vernon, France ] Federico Petronio [ Laboratoire de Physique des Plasmas (LPP), Ecole Polytechnique, CNRS, Palaiseau, France ] Optical emission spectroscopy is one of the most commonly applied methods for non-invasive characterization and diagnostics of plasmas. In order to extract from the recorded spectra the plasma parameters, such as electron density and temperature, collisional-radiative models (CRM) are employed. With the advancement of machine-learning (ML) techniques, new ways of analysing the emission spectra are becoming available [1,2]. These methods allow to train models that act as an inverse of a CRM. This provides fast estimation of the plasma parameters from the emission intensities and opens the possibility for the development of fast-response systems that can act as feed-back controllers for improved control of the plasma system [3]. In this work, we focus on the application of ML methods to Xe and Kr spectra at conditions relevant for Hall effect thrusters. Both analytical distribution functions and plasma parameters from particle in cell simulations are used to generate spectra for analysis by the ML approach. Unsupervised learning methods reveal the importance of data preparation - an aspect that is often omitted in the discussions. In the talk, the machine learning methods used will be briefly described and their results will be discussed. [1] Arellano, F. J., etal, J. Vac. Sci. Technol. A, 42, 053001 (2024). [2] Ben Slimane, T., Investigation of the Optical Emission of Hall Effect Thrusters using Collisional Radiative Model, Particle-In-Cell Simulations, and Machine Learning, PhD thesis (2023, IP Paris). [3] Ben Slimane, T., etal, J. Appl. Phys., 136, 153302 (2024). |
Tsanko Vaskov Tsankov, LPP |
| 15:40 |
Simulating pulsars' oblique electrospheres with realistic neutron star parameters |
ⓘ Fabrice Mottez, Guillaume Voisin, Théo Francez, LUX, CNRS, Observatoire de Paris-psl Electrospheres are environments with the same origin as pulsars: a highly magnetized rotating neutron star. In pulsars, a cascade of electron-positron pair creation by gamma ray photons enriches the plasma. The plasma surrounding an electrosphere consists solely of particles that have escaped from the surface of the neutron star. Most of the 300 million presumed neutron stars in the Galaxy are not pulsars, but electrospheres. They are therefore fairly common objects, despite their low luminosity, which has so far prevented direct observation. Electrospheres whose magnetic axis is aligned with the rotation axis have been well described for decades. The case of a magnetic axis oblique to the axis of rotation has resisted much theoretical research. We aimed at studying the physics of aligned and oblique electrospheres using a dedicated numerical simulation code which would enable ab initio simulations with realistic neutron star parameters. This code has recently been completed. Several numerical simulations have been carried out. I will show you a few of them. |
Fabrice Mottez, LUX |
| 16:00 |
Heat Transport in Laser-Produced Magnetized Plasmas |
ⓘ A. Triantafyllidis 1 , J. -R. Marquès 1 , P. Loiseau 2,3 , L. Lancia 1 , J. J. Santos 4 , C. Vlachos 4 , N. Ozaki 5,6 , J. Beard 7 , M. Koenig 1 , B. Albertazzi 1 1 LULI - CNRS, CEA, Sorbonne Universités, École Polytechnique, Institut Polytechnique de Paris, France 2 CEA, DAM, DIF, F-91297 Arpajon, France 3 Université Paris-Saclay, CEA, Laboratoire Matière en Conditions Extrêmes, France 4 Université de Bordeaux, CNRS, CEA, Centre Lasers Intenses et Applications, France 5 Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka, 565-0871 Japan 6 Graduate School of Engineering, Osaka University, Osaka, 565-0871, Japan 7 LNCMI, UPR 3228, CNRS-UJF-UPS-Institut National des Sciences Appliquées (INSA), France Heat transport in high-energy-density environments is a fundamental process that is strongly influenced by magnetic fields. Indeed, magnetic fields are expected to play a crucial role in Inertial Confinement Fusion (ICF), where they may help achieve optimal ignition conditions by magneto-thermally insulating and confining electrons [1], and in numerous astrophysical systems, where plasma permeated by magnetic fields is ubiquitous. However, laser-driven heating and the subsequent steep temperature gradients inevitably introduce nonlocal transport effects that lead to the preheating of the fuel, a process that significantly degrades fusion yield [2]. Accurately modelling the interplay between thermal transport, magnetic fields, and hydrodynamics remains challenging, further hindered by a critical lack of experimental data. To address this, an experimental campaign was undertaken at LULI2000 to investigate the impact of magnetic fields on heat transport. High-power lasers heated up gas jets of various compositions and pressures, while a pulsed-power-driven coil generated external magnetic fields up to 20 T [3]. The plasma conditions were characterized using multiple temporally and spatially resolved diagnostics, including Thomson scattering (TS), interferometry, and streaked optical pyrometry (SOP). Our results provide direct evidence of heat flux inhibition and preheat suppression due to the applied magnetic field. Notably, TS spectra reveal a significant temperature increase in magnetized plasmas, and that electrons have a non-Maxwellian distribution function, strongly associated with inverse bremsstrahlung heating. This was obtained by extracting the electron distribution function from experimental data using a TS form factor fitting algorithm. References [1] Slutz, S. A. & Vesey, R. A. PRL (2012). [2] Brodrick, J. P. et al. PoP 24 (2017). [3] Albertazzi, B. et al. Rev. Sci. Instrum. (2013). [4] Forte, A. et al. Comm. Phys. 7, 266 (2024). |
Angelos Triantafyllidis, LULI |
| 16:20 |
Observation of a mixed close-packed structure in superionic water |
ⓘ Under extreme pressure–temperature conditions, molecular systems exhibit complex physical behavior and chemically rich phenomena. In water, these conditions give rise to an exotic superionic phase, where oxygen atoms remain fixed in a crystalline lattice while hydrogen ions move freely within it. This unique state lies between a solid and a liquid, exhibiting remarkable ionic conductivity. Since its theoretical prediction, superionic (SI) water has been intensively studied, yet key questions persist regarding its melting curve and the stability of different oxygen lattices. Experimental results at moderate pressures often disagree, while data at higher pressures remain scarce due to the formidable challenges of such measurements. In this work, we presents pioneering ultrafast X-ray diffraction experiments on water dynamically compressed by multiple shocks using advanced x-ray sources from XFEL facilities. These studies establish new constraints on the stability domains of SI phases and reveal subtle structural features, including stacking desorder. Together, these findings provide fresh insight into the complex behavior of water under extreme conditions, with implications for planetary interiors and high-energy-density physics. |
Léon Andriambariarijaona, LULI |
| 16:40 |
Poster and photo prizes announcement |
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