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1. Optimizing laser coupling, matter heating, and particle acceleration from solids using multiplexed ultraintense lasers

Author: Weipeng Yao, Motoaki Nakatsutsumi, Sébastien Buffechoux, Patrizio Antici, Marco Borghesi, Andrea Ciardi, Sophia N. Chen, Emmanuel d’Humières, Laurent Gremillet, Robert Heathcote, Vojtěch Horný, Paul McKenna, Mark N. Quinn, Lorenzo Romagnani, Ryan Royle, Gianluca Sarri, Yasuhiko Sentoku, Hans-Peter Schlenvoigt, Toma Toncian, Olivier Tresca, Laura Vassura, Oswald Willi, and Julien Fuchs
Subjects: Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations. Here, we investigate how to optimize their coupling with solid targets. Experimentally, we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside. The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations, revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection, which is one possible mechanism to boost electron energization. In addition, the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation. Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.
Published: 2024
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2. Enhanced Energy, Conversion Efficiency and Collimation of Protons Driven by High-Contrast and Ultrashort Laser Pulses

Author: Weipeng Yao, Ronan Lelièvre, Tessa Waltenspiel, Itamar Cohen, Amokrane Allaoua, Patrizio Antici, Arie Beck, Erez Cohen, Xavier Davoine, Emmanuel d’Humières, Quentin Ducasse, Evgeny Filippov, Cort Gautier, Laurent Gremillet, Pavlos Koseoglou, David Michaeli, Dimitrios Papadopoulos, Sergey Pikuz, Ishay Pomerantz, Francois Trompier, Yuran Yuan, Francois Mathieu, and Julien Fuchs
Subjects: high-power lasers, laser-driven ion acceleration, plasma mirror, particle-in-cell simulation, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract: Progress in laser-driven proton acceleration requires increasing the proton maximum energy and laser-to-proton conversion efficiency while reducing the divergence of the proton beam. However, achieving all these qualities simultaneously has proven challenging experimentally, with the increase in beam energy often coming at the cost of beam quality. Numerical simulations suggest that coupling multi-PW laser pulses with ultrathin foils could offer a route for such simultaneous improvement. Yet, experimental investigations have been limited by the scarcity of such lasers and the need for very stringent temporal contrast conditions to prevent premature target expansion before the pulse maximum. Here, combining the newly commissioned Apollon laser facility that delivers high-power ultrashort (∼24fs) pulses with a double plasma mirror scheme to enhance its temporal contrast, we demonstrate the generation of up to 35 MeV protons with only 5 J of laser energy. This approach also achieves improved laser-to-proton energy conversion efficiency, reduced beam divergence, and optimized spatial beam profile. Therefore, despite the laser energy losses induced by the plasma mirror, the proton beams produced by this method are enhanced on all accounts compared to those obtained under standard conditions. Particle-in-cell simulations reveal that this improvement mainly results from a better space–time synchronization of the maximum of the accelerating charge-separation field with the proton bunch.
Published: 2024
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3. High-flux neutron generation by laser-accelerated ions from single- and double-layer targets

Author: Vojtěch Horný, Sophia N. Chen, Xavier Davoine, Vincent Lelasseux, Laurent Gremillet, and Julien Fuchs
Subjects: Medicine, Science
Abstract: Abstract Contemporary ultraintense, short-pulse laser systems provide extremely compact setups for the production of high-flux neutron beams, such as those required for nondestructive probing of dense matter, research on neutron-induced damage in fusion devices or laboratory astrophysics studies. Here, by coupling particle-in-cell and Monte Carlo numerical simulations, we examine possible strategies to optimise neutron sources from ion-induced nuclear reactions using 1-PW, 20-fs-class laser systems. To improve the ion acceleration, the laser-irradiated targets are chosen to be ultrathin solid foils, either standing alone or preceded by a plasma layer of near-critical density to enhance the laser focusing. We compare the performance of these single- and double-layer targets, and determine their optimum parameters in terms of energy and angular spectra of the accelerated ions. These are then sent into a converter to generate neutrons via nuclear reactions on beryllium and lead nuclei. Overall, we identify configurations that result in neutron yields as high as $$\sim 10^{10}\,{\mathrm{n}}\,{\mathrm{sr}}^{-1}$$ ∼ 10 10 n sr - 1 in $$\sim 1$$ ∼ 1 -cm-thick converters or instantaneous neutron fluxes above $$10^{23}\,{\mathrm{n}}\,{\mathrm{cm}}^{-2}\,{\mathrm{s}}^{-1}$$ 10 23 n cm - 2 s - 1 at the backside of $$\lesssim 100$$ ≲ 100 - $$\upmu$$ μ m-thick converters. Considering a realistic repetition rate of one laser shot per minute, the corresponding time-averaged neutron yields are predicted to reach values ( $$\gtrsim 10^7\,{\mathrm{n}} \,{\mathrm{sr}}^{-1}\,{\mathrm{s}}^{-1}$$ ≳ 10 7 n sr - 1 s - 1 ) well above the current experimental record, and this even with a mere thin foil as a primary target. A further increase in the time-averaged yield up to above $$10^8\,{\mathrm{sr}}^{-1}\,{\mathrm{s}}^{-1}$$ 10 8 sr - 1 s - 1 is foreseen using double-layer targets.
Published: 2022
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4. Laboratory evidence of magnetic reconnection hampered in obliquely interacting flux tubes

Author: Simon Bolaños, Andrey Sladkov, Roch Smets, Sophia N. Chen, Alain Grisollet, Evgeny Filippov, Jose-Luis Henares, Viorel Nastasa, Sergey Pikuz, Raphël Riquier, Maria Safronova, Alexandre Severin, Mikhail Starodubtsev, and Julien Fuchs
Subjects: Science
Abstract: Magnetic reconnection acts as energy transfer process in plasma and induces processes like plasma heating, particle acceleration. Here the authors demonstrate the variation of magnetic reconnection between two flux tubes in the presence of external magnetic field.
Published: 2022
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5. Les Jeux d’hiver de l’Arctique : jeunesse, culture et territoire. La valeur publique d’un évènement

Author: Julien Fuchs
Subjects: Jeux d'hiver de l'arctique, évènement, Jeux régionaux, jeunesse, culture, sport, Arctic Winter Games, event, Regional Games, youth, Juegos de invierno del Ártico, acontecimiento, Juegos regionales, juventud, cultura, deporte, Social Sciences
Abstract: Depuis 1970, les Jeux d’hiver de l’Arctique (JHA) rassemblent des jeunes du monde circumpolaire. Rencontre sportive et culturelle, ils valorisent le partage et l’échange entre jeunes de même que les pratiques culturelles et sportives autochtones (jeux Dene, sports arctiques). Ils entendent ainsi participer à bâtir une communauté arctique. Cet article propose une réflexion sur cet évènement et montre que ce type de rencontre, au-delà de son aspect sportif, peut constituer un levier de développement social, culturel, éducatif pour un territoire. Partant, ce texte consiste en une interrogation du mouvement sportif contemporain. En questionnant la valeur publique des JHA, il discute du paradigme sur lesquels les évènements sportifs internationaux sont aujourd’hui construits.
Published: 2023
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6. Enhanced X-ray emission arising from laser-plasma confinement by a strong transverse magnetic field

Author: Evgeny D. Filippov, Sergey S. Makarov, Konstantin F. Burdonov, Weipeng Yao, Guilhem Revet, Jerome Béard, Simon Bolaños, Sophia N. Chen, Amira Guediche, Jack Hare, Denis Romanovsky, Igor Yu. Skobelev, Mikhail Starodubtsev, Andrea Ciardi, Sergey A. Pikuz, and Julien Fuchs
Subjects: Medicine, Science
Abstract: Abstract We analyze, using experiments and 3D MHD numerical simulations, the dynamic and radiative properties of a plasma ablated by a laser (1 ns, 10 $$^{12}$$ 12 –10 $$^{13}$$ 13 W/cm $$^2$$ 2 ) from a solid target as it expands into a homogeneous, strong magnetic field (up to 30 T) that is transverse to its main expansion axis. We find that as early as 2 ns after the start of the expansion, the plasma becomes constrained by the magnetic field. As the magnetic field strength is increased, more plasma is confined close to the target and is heated by magnetic compression. We also observe that after $$\sim 8$$ ∼ 8 ns, the plasma is being overall shaped in a slab, with the plasma being compressed perpendicularly to the magnetic field, and being extended along the magnetic field direction. This dense slab rapidly expands into vacuum; however, it contains only $$\sim 2\%$$ ∼ 2 % of the total plasma. As a result of the higher density and increased heating of the plasma confined against the laser-irradiated solid target, there is a net enhancement of the total X-ray emissivity induced by the magnetization.
Published: 2021
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7. Characterization of the stability and dynamics of a laser-produced plasma expanding across a strong magnetic field

Author: Weipeng Yao, Julien Capitaine, Benjamin Khiar, Tommaso Vinci, Konstantin Burdonov, Jérôme Béard, Julien Fuchs, and Andrea Ciardi
Subjects: Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Magnetized laser-produced plasmas are central to many studies in laboratory astrophysics, in inertial confinement fusion, and in industrial applications. Here, we present the results of large-scale three-dimensional magnetohydrodynamic simulations of the dynamics of a laser-produced plasma expanding into a transverse magnetic field with a strength of tens of teslas. The simulations show the plasma being confined by the strong magnetic field into a slender slab structured by the magnetized Rayleigh–Taylor instability that develops at the plasma–vacuum interface. We find that when the initial velocity of the plume is perturbed, the slab can develop kink-like motions that disrupt its propagation.
Published: 2022
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8. Alignment of solid targets under extreme tight focus conditions generated by an ellipsoidal plasma mirror

Author: Deepak Kumar, Michal Šmíd, Sushil Singh, Alexander Soloviev, Hannes Bohlin, Konstantin Burdonov, Gashaw Fente, Alexander Kotov, Livia Lancia, Vit Lédl, Sergey Makarov, Michael Morrissey, Sergey Perevalov, Denis Romanovsky, Sergey Pikuz, Ryousuke Kodama, David Neely, Paul McKenna, Tomáš Laštovička, Mikhail Starodubtsev, Stefan Weber, Motoaki Nakatsutsumi, and Julien Fuchs
Subjects: Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The design of ellipsoidal plasma mirrors (EPMs) for the PEARL laser facility is presented. The EPMs achieve a magnification of 0.32 in focal spot size, and the corresponding increase in focused intensity is expected to be about 8. Designing and implementing such focusing optics for short-pulse (
Published: 2019
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9. Se dire 'sportif' dans les pratiques de prédation (chasse, pêche, cueillette) en France. Conditions d’un processus de qualification

Author: Frédérick Guyon and Julien Fuchs
Subjects: Anthropology, GN1-890, Sociology (General), HM401-1281
Abstract: Hunting, fishing and gathering represent a particular part in the total range of variation among physical practices. Although these activities were not originally considered as sports, practitioners now consider them as such. In all cases, sport appears as a standard to – or against which – practitioners refer to. The way they understand their activities has thus expanded. Our purpose is to pinpoint how and why sport is now generally mentioned to qualify these activities either to compare (quite often) or contrast in terms of equipment, places and time. We show that sport characteristics don’t mean the same for those who practice and for the structures in charge of these activities. Referring to sport is both a result and a process aiming at giving value to places, equipment, activities, people, behaviours in order to enhance or denounce their image. We have combined data from written documents, participative observations and interviews with practitioners (n=68) to show that what characterizes hunting, fishing and gathering adapt to today social, cultural and legal conditions. Participants now turn toward a reference to sport in order to show a decent side of their activity.
Published: 2012
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10. Les Vosges comme frontière de l’Alsace (1871-1914)

Author: Sébastien Stumpp and Julien Fuchs
Subjects: Geography. Anthropology. Recreation, Physical geography, GB3-5030
Abstract: Entre 1871 et 1914, la chaîne des Vosges constitue pour les Alsaciens, dont le territoire est alors annexé à l’Allemagne, une limite à la fois distinctive, dans la mesure où elle permet aux populations de revendiquer une singularité culturelle, et intégrative, parce qu’elle est aussi ce qui lie l’Alsace à la France et préserve donc la région d’un point de vue symbolique face aux tentatives d’assimilation au Reich. La manière dont les associations de montagne locales, qui promeuvent la randonnée pédestre et le ski, appréhendent cette frontière à la fois politique et culturelle permet de révéler leur perception singulière d’une limite naturelle fixe par définition, mais mobile dans ses représentations. Nous montrerons notamment que ces structures cultivent singulièrement l’existence d’une zone-frontière culturelle réelle et fantasmée, qui distingue l’Alsace à la fois de l’Allemagne et de la France. Dans ce cadre, l’image de la « ligne bleue des Vosges » est mobilisée, par les pratiquants alsaciens, comme une frontière tantôt unificatrice (perpétuation du mythe des provinces perdues, ritualisation du passage de la frontière franco-allemande, relations suivies avec le Club alpin français), tantôt séparatrice (mise en exergue des spécificités linguistiques et patrimoniales, utilisation du refuge comme lieu d’expression des traditions locales, intégration des Vosges à l’« héritage régional »). En ce sens, la question de la mobilité des frontières politiques (du Rhin vers les Vosges au cours de l’Annexion) s’efface clairement ici derrière une interrogation sur la mobilité du sens de la frontière vosgienne.
Published: 2013
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11. The Vosges, border of Alsace (1871-1914)

Author: Sébastien Stumpp and Julien Fuchs
Subjects: Alsace, mountain associations, hiking, skiing, the Vosges, border, Geography. Anthropology. Recreation, Physical geography, GB3-5030
Abstract: During the annexation of Alsace by Germany between 1871 and 1914, the Vosges mountain range took on particular significance for the inhabitants of the region. It represented a boundary that both allowed the Alsatian people to assert their cultural distinctiveness, while at the same time ‘integrating’ Alsace into France, thereby symbolically preserving the region from attempts to assimilate it into the Reich. The way in which local mountain associations promoting hiking and skiing considered this political and cultural border reveals their unique perception of a natural boundary that was fixed by definition, but mobile in its representations. As we will see, these associations tended to particularly promote the existence of a cultural border area – real and imagined – that effectively set the Alsace region apart from both France and Germany. Within this context, the images of the ‘blue line of the Vosges’ held by the Alsatian members of these clubs differed greatly. Some considered it to be a unifying border that perpetuated the myth of the lost provinces, ritualised the crossing of the Franco-German border, and symbolised their strong ties with the French Alpine Club. Others saw the Vosges more as a dividing border, placing emphasis on language specificities and differences in cultural heritage, the use of mountain huts as centres to celebrate local traditions, and the integration of the mountain range within the ‘regional heritage’. In this sense, the main issue here was not so much the mobility of the political borders (from the Rhine to the Vosges during the German annexation of Alsace), but rather the shifts in the very meaning attributed to this border area.
Published: 2013
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12. Les Jeux de la jeunesse de l’océan Indien : la francophonie au service de la fraternité régionale (1995-2020)

Author: Julien Fuchs
Subjects: Language and Literature
Abstract: Lors de la session 1987 de la Conférence des ministres de la Jeunesse et des Sports de la Francophonie (CONFEJES) au Québec, la création d’une commission des sports de l’océan Indien est actée. Celle-ci s’ouvre, à partir de 1992, au secteur de la jeunesse en devenant la Commission de la Jeunesse et des Sports de l’océan Indien (CJSOI) dont l’objectif est de structurer des actions de coopération régionale (promotion des sports, opérations culturelles, échanges et actions de formation de cadres, etc.) pour encourager les jeunes de cette aire géographique à se rencontrer, à mieux se connaître et à s’exprimer et par le biais du sport et de la culture. Dans ce cadre, elle met sur pied les Jeux de la CJSOI. Si les Jeux des îles de l’océan Indien sont relativement bien connus et ont fait l’objet de divers travaux scientifiques, leurs homologues pour la jeunesse restent plutôt dans leur ombre. Organisés pour la première fois par l’île Maurice en 1995, ils ont lieu tous les deux ans. Ils rassemblent, selon les éditions, entre 500 et 1 000 jeunes de 14 à 18 ans représentant l’union des Comores, la république de Madagascar, la république de Maurice, la république des Seychelles, La Réunion ainsi que, depuis 2003, la république de Djibouti, et, depuis 2005, Mayotte. Bâtis sur le principe d’une complémentarité entre activités sportives et culturelles et de l’échange entre jeunes, ils font de la francophonie un pilier. Cet article se base sur une recherche documentaire et une observation ethnographique réalisée lors des Jeux de 2016 à Madagascar. Il ressort de ce travail sur l’expérience vécue des participants lors de l’évènement ainsi que sur les fondements idéologiques et organisationnels de celui-ci, que la francophonie peut permettre de tisser des liens au sein de cet espace régional traversé de tensions politiques, sociales et économiques. Inévitablement marqués par un contexte géopolitique local problématique, ces Jeux promeuvent pour autant la fraternité par les échanges linguistiques et culturels que permettent les activités socio-éducatives et les sports. Ils constituent aujourd’hui l’une des actions les plus importantes de la CJSOI, du fait de leur potentiel de promotion de l’amitié et de la fraternité entre jeunes de l’océan Indien.
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13. Les classes de découverte : un objet de recherche encore à découvrir

Author: Julien Fuchs and Gilles Brougère
Subjects: Developmental and Educational Psychology, Education
Published: 2023
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14. Le sport juif en Alsace (milieu du XIXe siècle-années 1930) : entre judaïsme en acte et intégration laïque

Author: Sébastien Stumpp and Julien Fuchs
Subjects: Cultural Studies, History, Religious studies
Published: 2023
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15. What future model for international sports events? The case of the arctic winter games

Author: Julien Fuchs
Subjects: Sociology and Political Science, Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine
Published: 2022
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16. La revue STAPS : bilan de la consultation numérique 2015-2020

Author: Julien Fuchs
Subjects: Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine, Social Sciences (miscellaneous)
Published: 2022
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17. Non-thermal electron acceleration from magnetically driven reconnection in a laboratory plasma

Author: Abraham Chien, Lan Gao, Shu Zhang, Hantao Ji, Eric G. Blackman, William Daughton, Adam Stanier, Ari Le, Fan Guo, Russ Follett, Hui Chen, Gennady Fiksel, Gabriel Bleotu, Robert C. Cauble, Sophia N. Chen, Alice Fazzini, Kirk Flippo, Omar French, Dustin H. Froula, Julien Fuchs, Shinsuke Fujioka, Kenneth Hill, Sallee Klein, Carolyn Kuranz, Philip Nilson, Alexander Rasmus, and Ryunosuke Takizawa
Subjects: General Physics and Astronomy
Published: 2023
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18. Une histoire de l’éducation physique dans les instituts médico-éducatifs, 1838-1909. De la gymnastique médicale à l’éducation physique scolaire

Author: Julien Fuchs
Subjects: General Medicine
Abstract: Il y a comme un paradoxe dans l’histoire de l’education physique : si cette pedagogie du corps emerge des le xvie siecle du fait notamment de sa preoccupation hygienique et therapeutique, et que la sphere medicale encadre son developpement jusqu’au xxe siecle, l’education physique dediee aux enfants malades, deficients ou en situation de handicap demeure peu connue, les travaux des historiens s’etant surtout penches sur le processus de scolarisation de cette discipline depuis la fin du xixe s...
Published: 2020
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19. On the growth of the thermally modified non-resonant streaming instability

Author: Andrea Ciardi, A. Marret, Julien Fuchs, Roch Smets, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), and ANR-17-CE30-0026,PiNNaCLE,Développement d'une ligne de neutrons pulsés compacte et de haute brillance(2017)
Subjects: FOS: Physical sciences, Cosmic ray, magnetic fields, Kinetic energy, 01 natural sciences, 7. Clean energy, Instability, 010305 fluids & plasmas, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, 010303 astronomy & astrophysics, acceleration of particles, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Range (particle radiation), Magnetic energy, Astronomy and Astrophysics, Plasma, plasmas, Magnetic field, Computational physics, instabilities, Space and Planetary Science, Streaming instability, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: The cosmic rays non-resonant streaming instability is believed to be the source of substantial magnetic field amplification. In this work we investigate the effects of the ambient plasma temperature on the instability and derive analytical expressions of its growth rate in the hot, demagnetized regime of interaction. To study its non-linear evolution we perform hybrid-PIC simulations for a wide range of temperatures. We find that in the cold limit about two-thirds of the cosmic rays drift kinetic energy is converted into magnetic energy. Increasing the temperature of the ambient plasma can substantially reduce the growth rate and the magnitude of the saturated magnetic field., Under review in MNRAS
Published: 2020
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20. Promoting a positive image of France. Holiday camps at the service of French foreign and Algerian policy (from 1945 to the mid-1950s)

Author: Julien Fuchs, Université de Bretagne Occidentale - Faculté des sciences du sport et de l'éducation (UBO UFR SSE), and Université de Brest (UBO)
Subjects: Cultural Studies, Service (business), History, Sociology and Political Science, Political science, 05 social sciences, 0507 social and economic geography, Public administration, [SHS.HIST]Humanities and Social Sciences/History, 050701 cultural studies, ComputingMilieux_MISCELLANEOUS
Abstract: Since their creation in the 1880s, holiday camps (‘colonies de vacances’) in France have experienced continued and increasing success. Organised for the most part by local associations or municipal...
Published: 2020
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21. In memoriam

Author: Laurent Besse, Julien Fuchs, Jean-Claude Richez, Yaëlle Amsellem-Mainguy, and Marianne Autain
Subjects: Ocean Engineering
Published: 2022
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22. Generic method to assess transmutation feasibility for nuclear waste treatment and application to irradiated graphite

Author: Mathieu Rasson, Julien Fuchs, Grégoire Augé, Jean-Louis Quéri, Gérard Laurent, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and École polytechnique (X)
Subjects: Accelerator Physics (physics.acc-ph), Nuclear Energy and Engineering, [PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], FOS: Physical sciences, Physics - Accelerator Physics
Abstract: Graphite-moderated nuclear reactors have already produced more than 250000 tons of irradiated nuclear graphite, or i-graphite, world-wide. The sustainability of this technology relies on the end-of-life management of its moderator, which is activated into a long-lived nuclear waste, by neutron fluxes, during operating time. In particular, C14 is created. Nuclear transmutation, enabled by laser-driven particle acceleration, has been envisioned as a potential novel treatment scheme for long-lived nuclear waste. By triggering controlled nuclear reactions with energetic particles, long-lived radionuclides could be transformed into stable isotopes. Such a system could treat the C14 nuclei trapped within the i-graphite matrix, which is difficult to isolate by other means. This work performs a quantitative preliminary study of this transmutation scheme, in order to assess its feasibility at an industrial scale. The method used can be transposed to assess any transmutation scheme using a beam of particles directly sent on the material to be treated. First, a nuclear interaction channel which transmutes C14 nuclei without creating new long-lived radionuclides is identified. It consists in the choice of a type of particle, among which protons, gamma photons and neutrons can all be accelerated by laser-matter interaction; and it is completed by the adequate energy at which this particle must be sent on i-graphite. To that end, the nuclear cross-sections of C12, C13 and C14 are reviewed, neglecting other impurities in i-graphite. Then, based on the interaction channel identification, the energy cost of this scheme is estimated. Protons between 1 and 5 MeV make it possible to transmute C14 without creating any new long-lived activity. However, our result show that, even in this favorable reaction channel, the transmutation energy cost is too high for an i-graphite transmutation scheme to be feasible., Discussion clarified, results unchanged
Published: 2022

23. Laboratory modelling of equatorial ‘tongue’ accretion channels in young stellar objects caused by the Rayleigh-Taylor instability

Author: Alexander Soloviev, Andrea Ciardi, R. Bonito, A. Korzhimanov, K. F. Burdonov, M. Romanova, M. V. Starodubtsev, W. P. Yao, A. Sladkov, Julien Fuchs, S. N. Chen, R. Zemskov, Salvatore Orlando, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), IAP, Russian Academy of Sciences, 603155, Nizhny Novgorod, Russia, INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE), IFIN-HH, Cornell University [New York], European Project: ERC787539,GENESIS, Institute of Applied Physics (IAP, Nizhny Novgorod), and Alma Mater Studiorum University of Bologna (UNIBO)
Subjects: Physics, Young stellar object, accretion disks, Astronomy and Astrophysics, Astrophysics, stars: pre-main sequence, magnetohydrodynamics (MHD), Accretion (astrophysics), accretion, Space and Planetary Science, instabilities, Physics::Space Physics, Astrophysics::Solar and Stellar Astrophysics, Rayleigh–Taylor instability, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics::Galaxy Astrophysics
Abstract: This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project EquipMeso (reference ANR-10-EQPX29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche.; International audience; Context. The equatorial accretion scenario, caused by the development of the Rayleigh-Taylor (RT) instability at the disk edge, was suggested by accurate three-dimensional magnetohydrodynamic (MHD) modelling, but no observational or experimental confirmation of such phenomena has been evidenced yet.Aims. We studied the propagation of a laterally extended laser-generated plasma stream across a magnetic field and investigated if this kind of structure can be scaled to the case of equatorial ‘tongue’ accretion channels in young stellar objects (YSOs); if so, this would support the possibility of equatorial accretion in young accreting stars.Methods. We conducted a scaled laboratory experiment at the PEARL laser facility. The experiment consists in an optical laser pulse that is focused onto the surface of a Teflon target. The irradiation of the target leads to the expansion of a hot plasma stream into the vacuum, perpendicularly to an externally applied magnetic field. We used a Mach-Zehnder interferometer to diagnose the plasma stream propagation along two axes, to obtain the three-dimensional distribution of the plasma stream.Results. The laboratory experiment shows the propagation of a laterally extended laser-generated plasma stream across a magnetic field. We demonstrate that: (i) such a stream is subject to the development of the RT instability, and (ii) the stream, decomposed into tongues, is able to efficiently propagate perpendicular to the magnetic field. Based on numerical simulations, we show that the origin of the development of the instability in the laboratory is similar to that observed in MHD models of equatorial tongue accretion in YSOs.Conclusions. As we verify that the laboratory plasma scales favourably to accretion inflows of YSOs, our laboratory results support the argument in favour of the possibility of the RT-instability-caused equatorial tongue accretion scenario in the astrophysical case.
Published: 2022
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24. In Memoriam

Author: Rémi Richard, Julien Fuchs, and Jacques Gleyse
Subjects: Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine, Social Sciences (miscellaneous)
Published: 2023
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25. Enhancement of the non-resonant streaming instability by particle collisions

Author: Loïc Nicolas, Alexis Marret, Julien Fuchs, Andrea Ciardi, Roch Smets, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), and Observatoire de Paris
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Plasma Physics (physics.plasm-ph), Physics - Space Physics, FOS: Physical sciences, General Physics and Astronomy, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Space Physics (physics.space-ph), Physics - Plasma Physics, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph]
Abstract: Streaming cosmic rays can power the exponential growth of a seed magnetic field by exciting a non-resonant instability that feeds on their bulk kinetic energy. By generating the necessary turbulent magnetic field, it is thought to play a key role in the confinement and acceleration of cosmic rays at shocks. In this work we present hybrid-Particle-In-Cell simulations of the non-resonant mode including Monte Carlo collisions, and investigate the interplay between the pressure anisotropies produced by the instability and particle collisions in the background plasma. Simulations of poorly ionized plasmas confirm the rapid damping of the instability by proton-neutral collisions predicted by linear fluid theory calculations. In contrast we find that Coulomb collisions in fully ionized plasmas do not oppose the growth of the magnetic field, but under certain conditions suppress the pressure anisotropies and actually enhance the magnetic field amplification., Accepted to be published in Physical Review Letters
Published: 2021
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26. Design and commissioning of a neutron counter adapted to high-intensity laser matter interactions

Author: Mirela Cerchez, M. Gugiu, S. Dorard, Julien Fuchs, V. Lelasseux, S. Aogaki, K. Burdonov, P.-A. Söderström, Oswald Willi, A. Fazzini, Sophia Chen, F. Rotaru, S. A. Pikuz, F. Negoita, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and ANR-17-CE30-0026,PiNNaCLE,Développement d'une ligne de neutrons pulsés compacte et de haute brillance(2017)
Subjects: Physics, 010308 nuclear & particles physics, business.industry, High intensity, Nuclear engineering, Detector, Scintillator, Modular design, Laser, 7. Clean energy, 01 natural sciences, law.invention, law, [SDU]Sciences of the Universe [physics], 0103 physical sciences, Calibration, Neutron source, Neutron, 010306 general physics, business, Instrumentation
Abstract: International audience; The advent of multi-PW laser facilities world-wide opens new opportunities for nuclear physics. With this perspective, we developed a neutron counter taking into account the specifics of a high-intensity laser environment. Using GEANT4 simulations and prototype testings, we report on the design of a modular neutron counter based on boron-10 enriched scintillators and a high-density polyethylene moderator. This detector has been calibrated using a plutonium-beryllium neutron source and commissioned during an actual neutron-producing laser experiment at the LULI2000 facility (France). An overall efficiency of 4.37(59)% has been demonstrated during calibration with a recovery time of a few hundred microseconds after laser-plasma interaction.
Published: 2021
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27. Experimental Study of the Interaction of a Laser Plasma Flow With a Transverse Magnetic Field

Author: R. Zemskov, A. A. Shaikin, A. A. Kochetkov, A. A. Soloviev, A. G. Luchinin, M. Yu. Glyavin, M. V. Starodubtsev, Ivan V. Yakovlev, S. E. Perevalov, K. F. Burdonov, A. V. Kotov, A. A. Kuzmin, Vladislav Ginzburg, Mikhail V. Morozkin, Efim A. Khazanov, Julien Fuchs, M. D. Proyavin, and I. A. Shaikin
Subjects: Physics, Quantum optics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Plasma sheet, Astronomy and Astrophysics, Statistical and Nonlinear Physics, Plasma, Radius, Laser, Molecular physics, Electronic, Optical and Magnetic Materials, Magnetic field, law.invention, Plasma flow, Physics::Plasma Physics, law, Transverse magnetic field, Physics::Space Physics, Electrical and Electronic Engineering, human activities
Abstract: We present the results of studying experimentally the expansion of laser plasma in a strong external magnetic field (with a magnetic flux density of 13.5 T) at various sizes of the region of plasma formation on the surface of a solid-state target. It is shown that when the size of the plasma formation region is smaller than the classical plasma braking radius, a nearly identical topology of plasma flows is observed, which is characterized by the formation of a thin plasma sheet directed along the external magnetic field. If the width of the plasma formation region is comparable with the classical plasma braking radius, an additional plasma sheet starts to be formed.
Published: 2020
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28. Characterization of Neutron Beams Generated in High-Intensity Interactions for Nuclear Physics Experiments

Author: Julien Fuchs, Par-Anders Soderstrom, Florin Rotaru, Sandra Dorard, Mirela Cerchez, Oswald Willi, Vincent Lelasseux, Soichiro Aogaki, Sophia Chen, S. A. Pikuz, Alice Fazzini, Florin Negoita, K. F. Burdonov, and Marius Gugiu
Subjects: Physics, Proton, Physics::Instrumentation and Detectors, business.industry, Detector, Modular design, Scintillator, Laser, law.invention, Nuclear physics, law, Calibration, Physics::Accelerator Physics, Neutron source, Neutron, Nuclear Experiment, business
Abstract: The advent of multi-PW laser facilities world-wide opens new opportunities for nuclear physics. With this perspective, we developed a high efficiency neutron counter taking into account the specifics of a high intensity laser environment. Using GEANT4 simulations and prototype testings, we report on the design of a modular neutron-counter based on boron-10 enriched scintillators and high-density polyethylene moderator. This detector has been calibrated using a plutonium-beryllium neutron source and commissioned during an actual neutrons producing laser experiment at theLULI2000 facility (France). An overall efficiency of 4.37(59)% has been demonstrated during calibration with a recovery time of a few hundreds microseconds after laser-plasma interaction. We also tested using units of this detector in neutron time-of-flight configuration during the commissioning of the 1PW arm of the Apollon laser facility. Neutrons produced by the conversion of proton accelerated by the 1PW arm of the Apollon facility have been detected, of which we will present preliminary results.
Published: 2021
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29. Apollon Facility Short Focal Length Area Commissioning

Author: L. Lancia, K. F. Burdonov, T. Ceccotti, V. Lelasseaux, Fabien Quéré, F. Perez, Julien Fuchs, A. Leblanc, P. Forestier-Colleoni, A. Fazzini, and S. A. Pikuz
Subjects: Physics, Optics, law, business.industry, Focal length, Laser, business, Nominal power (radio broadcasting), Beam (structure), Laser beams, law.invention, Pulse (physics)
Abstract: We present here the results of the commissioning of the "short focal length" area, which was performed with the first available laser beam of the Apollon laser facility (Saclay, France), i.e. using the presently available F2 beam at a nominal power of one petawatt. This beam delivered laser pulses of 10 J average on-target energy with pulse durations of 25 fs.
Published: 2021
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30. Finisterian sea classes and their spatial diffusion. The challenges of an educational model rooted in local activism

Author: Malo Camus-Le Pape, Emmanuelle Peyvel, Julien Fuchs, Nicolas Bernard, and Université de Bretagne Occidentale
Subjects: 4. Education, 05 social sciences, 0211 other engineering and technologies, 0507 social and economic geography, General Earth and Planetary Sciences, 021107 urban & regional planning, 02 engineering and technology, 14. Life underwater, [SHS.HIST]Humanities and Social Sciences/History, 050703 geography, ComputingMilieux_MISCELLANEOUS, General Environmental Science
Abstract: L’article analyse les consequences de la diffusion des classes de mer qui, en pres de soixante ans d’existence, ont evolue d’une experience finisterienne vers un dispositif educatif plebiscite par nombre d’enseignants. Cette recherche montre que ce sont d’abord les initiatives locales qui ont permis le developpement d’un modele de classe de mer, en lien avec les services de l’Education nationale. La diffusion de ce phenomene s’accompagne d’evolutions a l’echelle de la France, mais les reseaux locaux restent predominants dans l’organisation des classes de mer, notamment grâce aux appuis de pouvoirs publics qui les considerent comme une initiative pedagogique a valoriser autant qu’une opportunite de developpement social et economique pour le territoire. L’article cherche enfin a eclairer les difficultes actuelles du modele initial, mis a l’epreuve des mutations societales contemporaines.
Published: 2021
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31. Characterization of the stability and dynamics of a laser-produced plasma expanding across strong magnetic field

Author: Weipeng Yao, Julien Capitaine, Benjamin Khiar, Tommaso Vinci, Konstantin Burdonov, Jérôme Béard, Julien Fuchs, Andrea Ciardi, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), DPHY, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, A.M.Obukhov Institute of Atmospheric Physics (IAP), Russian Academy of Sciences [Moscow] (RAS), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), ANR-10-EQPX-0029,EQUIP@MESO,Equipement d'excellence de calcul intensif de Mesocentres coordonnés - Tremplin vers le calcul petaflopique et l'exascale(2010), and European Project: 787539,GENESIS - 10.3030/787539
Subjects: [PHYS]Physics [physics], Plasma Physics (physics.plasm-ph), Physics::Fluid Dynamics, Nuclear and High Energy Physics, Nuclear Energy and Engineering, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Physics::Plasma Physics, Physics::Space Physics, FOS: Physical sciences, Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Physics - Plasma Physics
Abstract: International audience; Magnetized laser-produced plasmas are central to many new studies in laboratory astrophysics, inertial confinement fusion, and in industrial applications. Here we present the results of large-scale, three-dimensional magneto-hydrodynamic simulations of the dynamics of a laser-produced plasma expanding into a transverse magnetic field with strength of tens of Tesla. The simulations show the plasma being confined by the strong magnetic field into a slender slab structured by the magnetized Rayleigh-Taylor instability that develops at the plasma-vacuum interface. We find that by perturbing the initial velocity of the plume the slab can develops kink-like motion which disrupt its propagation, as observed in recent experiments.
Published: 2021
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32. Inferring possible magnetic field strength of accreting inflows in EXor-type objects from scaled laboratory experiments

Author: Mikhail Gushchin, Rosaria Bonito, K. Gubskiy, Efim A. Khazanov, Julien Fuchs, A. V. Strikovskiy, V. I. Gundorin, A. Kuznetsov, S. N. Ryazantsev, S. A. Pikuz, Salvatore Orlando, Alexander Soloviev, W. P. Yao, I. Shaykin, Teresa Giannini, R. Zemskov, Ivan V. Yakovlev, Shihua Chen, N. A. Aidakina, I. Zudin, Andrey Shaykin, M. V. Starodubtsev, Vladislav Ginzburg, K. Burdonov, A. A. Kuzmin, J. Béard, G. Revet, A. A. Kochetkov, Andrea Ciardi, S. V. Korobkov, Costanza Argiroffi, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institute of Applied Physics of RAS, Russian Academy of Sciences [Moscow] (RAS), INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astronomico di Roma (OAR), Università degli studi di Palermo - University of Palermo, Horia Hulubei National Institute for Physics and Nuclear Engineering, Moscow State Engineering Physics Institute (MEPhI), Joint Institute for High Temperatures of the RAS (JIHT), The National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) [Moscow, Russia], This work was partly done within the LABEX Plas@Par, the DIM ACAV funded by the Region Ile-de-France, and supported by Grant No. 11-IDEX- 0004-02 from ANR, The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics (ELINP) Phase II, a project co-financed by the Romanian Government and European Union through the European Regional Development Fund, and by the project ELI-RO-2020-23 funded by IFA (Romania)., European Project: ERC787539,GENESIS, Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), HEP, INSPIRE, Burdonov K., Bonito R., Giannini T., Aidakina N., Argiroffi C., Beard J., Chen S.N., Ciardi A., Ginzburg V., Gubskiy K., Gundorin V., Gushchin M., Kochetkov A., Korobkov S., Kuzmin A., Kuznetsov A., Pikuz S., Revet G., Ryazantsev S., Shaykin A., Shaykin I., Soloviev A., Starodubtsev M., Strikovskiy A., Yao W., Yakovlev I., Zemskov R., Zudin I., Khazanov E., Orlando S., and Fuchs J.
Subjects: Shock wave, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Field strength, Astrophysics, stars: pre-main sequence, 01 natural sciences, magnetohydrodynamics (MHD), Settore FIS/05 - Astronomia E Astrofisica, accretion, 0103 physical sciences, Protostar, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, [PHYS]Physics [physics], accretion disks, Astronomy and Astrophysics, Radius, Plasma, shock waves, Accretion, accretion disks, Accretion (astrophysics), Magnetic field, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, instabilities, stars: individual: V1118 Ori, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims. EXor-type objects are protostars that display powerful UV-optical outbursts caused by intermittent and powerful events of magnetospheric accretion. These objects are not yet well investigated and are quite difficult to characterize. Several parameters, such as plasma stream velocities, characteristic densities, and temperatures, can be retrieved from present observations. As of yet, however, there is no information about the magnetic field values and the exact underlying accretion scenario is also under discussion. Methods. We use laboratory plasmas, created by a high power laser impacting a solid target or by a plasma gun injector, and make these plasmas propagate perpendicularly to a strong external magnetic field. The propagating plasmas are found to be well scaled to the presently inferred parameters of EXor-type accretion event, thus allowing us to study the behaviour of such episodic accretion processes in scaled conditions. Results. We propose a scenario of additional matter accretion in the equatorial plane, which claims to explain the increased accretion rates of the EXor objects, supported by the experimental demonstration of effective plasma propagation across the magnetic field. In particular, our laboratory investigation allows us to determine that the field strength in the accretion stream of EXor objects, in a position intermediate between the truncation radius and the stellar surface, should be of the order of 100 G. This, in turn, suggests a field strength of a few kilogausses on the stellar surface, which is similar to values inferred from observations of classical T Tauri stars.
Published: 2021
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33. Laboratory evidence for proton energization by collisionless shock surfing

Author: G. Revet, K. Burdonov, J. Béard, A. Fazzini, E. D. Filippov, S. Bolaños, Julien Fuchs, V. Lelasseux, S. A. Pikuz, D. C. Popescu, Salvatore Orlando, W. P. Yao, V. Nastasa, Patrizio Antici, Andrea Ciardi, S. Kisyov, Quentin Moreno, Marco Miceli, Xavier Ribeyre, Emmanuel d'Humières, R. Diab, Sophia Chen, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Centre d'Etudes Lasers Intenses et Applications (CELIA), Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), ITA, FRA, CAN, CZE, ROU, RUS, Yao W., Fazzini A., Chen S.N., Burdonov K., Antici P., Beard J., Bolanos S., Ciardi A., Diab R., Filippov E.D., Kisyov S., Lelasseux V., Miceli M., Moreno Q., Nastasa V., Orlando S., Pikuz S., Popescu D.C., Revet G., Ribeyre X., d'Humieres E., Fuchs J., Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Bordeaux (UB)
Subjects: Shock wave, Proton, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, FOS: Physical sciences, 01 natural sciences, Acceleration, Settore FIS/05 - Astronomia E Astrofisica, 0103 physical sciences, Bow shock (aerodynamics), 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Mechanics, plasmas, Physics - Plasma Physics, Charged particle, Computer Science::Computers and Society, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Magnetic field, Shock (mechanics), Plasma Physics (physics.plasm-ph), Supernova, 13. Climate action, Physics::Space Physics, Physics::Accelerator Physics
Abstract: Charged particles can be accelerated to high energies by collisionless shock waves in astrophysical environments, such as supernova remnants. By interacting with the magnetized ambient medium, these shocks can transfer energy to particles. Despite increasing efforts in the characterization of these shocks from satellite measurements at Earth’s bow shock as well as powerful numerical simulations, the underlying acceleration mechanism or a combination thereof is still widely debated. Here we show that astrophysically relevant super-critical quasi-perpendicular magnetized collisionless shocks can be produced and characterized in the laboratory. We observe the characteristics of super-criticality in the shock profile as well as the energization of protons picked up from the ambient gas to hundreds of kiloelectronvolts. Kinetic simulations modelling the laboratory experiment identified shock surfing as the proton acceleration mechanism. Our observations not only provide direct evidence of early-stage ion energization by collisionless shocks but also highlight the role played by this particular mechanism in energizing ambient ions to feed further stages of acceleration. Furthermore, our results open the door to future laboratory experiments investigating the possible transition to other mechanisms, when increasing the magnetic field strength, or the effect that induced shock front ripples could have on acceleration processes. Proton acceleration by a super-critical collisionless shock is observed in laboratory experiments, and numerical simulations suggest shock surfing as the underlying acceleration mechanism.
Published: 2021
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34. Laboratory disruption of scaled astrophysical outflows by a misaligned magnetic field

Author: Mirela Cerchez, Drew Higginson, E. D. Filippov, T. Gangolf, S. A. Pikuz, I. Yu. Skobelev, B. Khiar, G. Revet, Tommaso Vinci, B. Olmi, Salvatore Orlando, J. Béard, O. Willi, Rosaria Bonito, M. V. Starodubtsev, Costanza Argiroffi, M. Safronova, M. Ouillé, S. N. Ryazantsev, Julien Fuchs, Andrea Ciardi, Andrea Mignone, Sophia Chen, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Lasers Intenses et Applications (CELIA), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Bordeaux (UB), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institute of Applied Physics (IAP, Nizhny Novgorod), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Flash Center for Computational Science (FCCS), University of Chicago, Joint Institute for High Temperatures of the RAS (JIHT), Russian Academy of Sciences [Moscow] (RAS), Dipartimento di Fisica e Chimica [Palermo] (DiFC), Università degli studi di Palermo - University of Palermo, INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut für Laser und Plasmaphysik, Heinrich Heine Universität Düsseldorf = Heinrich Heine University [Düsseldorf], Horia Hulubei Natl Inst Phys & Nucl Engn IFIN HH, ELI NP Dept, Reactorului Str 30, Magurele 077125, Romania, Lawrence Livermore National Laboratory (LLNL), Dipartimento di Fisica Generale, Università di Torino, INAF - Osservatorio Astrofisico di Arcetri (OAA), The National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) [Moscow, Russia], Revet G., Khiar B., Filippov E., Argiroffi C., Beard J., Bonito R., Cerchez M., Chen S.N., Gangolf T., Higginson D.P., Mignone A., Olmi B., Ouille M., Ryazantsev S.N., Skobelev I.Y., Safronova M.I., Starodubtsev M., Vinci T., Willi O., Pikuz S., Orlando S., Ciardi A., and Fuchs J.
Subjects: Science, Astrophysics::High Energy Astrophysical Phenomena, Nozzle, outflows, magnetohydrodynamics(MHD), shockwaves, astrophysical jets, General Physics and Astronomy, FOS: Physical sciences, Astrophysics, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, Collimated light, Settore FIS/05 - Astronomia E Astrofisica, Ambient field, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Magnetic pressure, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Laboratory astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Jet (fluid), Multidisciplinary, Laser-produced plasmas, General Chemistry, Physics - Plasma Physics, Magnetic field, Plasma Physics (physics.plasm-ph), Astrophysics - Solar and Stellar Astrophysics, Physics::Accelerator Physics, Outflow, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: The shaping of astrophysical outflows into bright, dense, and collimated jets due to magnetic pressure is here investigated using laboratory experiments. Here we look at the impact on jet collimation of a misalignment between the outflow, as it stems from the source, and the magnetic field. For small misalignments, a magnetic nozzle forms and redirects the outflow in a collimated jet. For growing misalignments, this nozzle becomes increasingly asymmetric, disrupting jet formation. Our results thus suggest outflow/magnetic field misalignment to be a plausible key process regulating jet collimation in a variety of objects from our Sun’s outflows to extragalatic jets. Furthermore, they provide a possible interpretation for the observed structuring of astrophysical jets. Jet modulation could be interpreted as the signature of changes over time in the outflow/ambient field angle, and the change in the direction of the jet could be the signature of changes in the direction of the ambient field., Mass outflow is a common process in astrophysical objects. Here the authors investigate in which conditions an astrophysically-scaled laser-produced plasma flow can be collimated and evolves in the presence of a misaligned external magnetic field.
Published: 2021
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35. Enhanced x-ray emission arising from laser-plasma confinement by a strong transverse magnetic field

Author: Amira Guediche, Julien Fuchs, S. A. Pikuz, J. Béard, K. F. Burdonov, S. Bolaños, W. P. Yao, M. V. Starodubtsev, Jack Hare, E. D. Filippov, G. Revet, Igor Yu. Skobelev, Denis Romanovsky, Sophia Chen, S. S. Makarov, Andrea Ciardi, University of Nizhny Novgorod, Joint Institute for High Temperatures of the RAS (JIHT), Russian Academy of Sciences [Moscow] (RAS), Lomonosov Moscow State University (MSU), Institute of Applied Physics of RAS, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Horia Hulubei National Institute for Physics and Nuclear Engineering, Imperial College London, The National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) [Moscow, Russia], Lobachevsky State University [Nizhni Novgorod], Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)
Subjects: Materials science, Science, FOS: Physical sciences, Magnetically confined plasmas, 01 natural sciences, Article, 010305 fluids & plasmas, law.invention, Magnetization, law, Physics::Plasma Physics, 0103 physical sciences, Emissivity, Radiative transfer, 010306 general physics, [PHYS]Physics [physics], Multidisciplinary, Laser-produced plasmas, Plasma, Laser, Physics - Plasma Physics, Magnetic field, Plasma Physics (physics.plasm-ph), Transverse plane, Physics::Space Physics, Medicine, Atomic physics, Magnetohydrodynamics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We analyze, using experiments and 3D MHD numerical simulations, the dynamics and radiative properties of a plasma ablated by a laser (1 ns, 10$^{12}$-10$^{13}$ W/cm$^2$) from a solid target, as it expands into a homogeneous, strong magnetic field (up to 30 T) transverse to its main expansion axis. We find that as soon as 2 ns after the start of the expansion, the plasma becomes constrained by the magnetic field. As the magnetic field strength is increased, more plasma is confined close to the target and is heated by magnetic compression. We also observe a dense slab that rapidly expands into vacuum after ~ 8 ns; however, this slab contains only ~ 2 % of the total plasma. As a result of the higher density and increased heating of the confined plasma, there is a net enhancement of the total x-ray emissivity induced by the magnetization., 15 pages, 4 figures, Supplementary Information, submitted to PRL
Published: 2020
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36. Laboratory evidence for asymmetric accretion structure upon slanted matter impact in young stars

Author: Rosaria Bonito, Salvatore Orlando, O. Willi, Julien Fuchs, S. N. Chen, K. F. Burdonov, Mirela Cerchez, J. Béard, G. Revet, S. A. Pikuz, M. V. Starodubtsev, Rafael L. Rodríguez, E. D. Filippov, Costanza Argiroffi, Andrea Ciardi, G. Espinosa, S. Bolanos, Michal Smid, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Burdonov K., Revet G., Bonito R., Argiroffi C., Beard J., Bolanos S., Cerchez M., Chen S.N., Ciardi A., Espinosa G., Filippov E., Pikuz S., Rodriguez R., Smid M., Starodubtsev M., Willi O., Orlando S., Fuchs J., Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), Università degli studi di Palermo - University of Palermo, Heinrich Heine Universität Düsseldorf = Heinrich Heine University [Düsseldorf], Horia Hulubei National Institute for Physics and Nuclear Engineering, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Universidad de las Palmas de Gran Canaria (ULPGC), Joint Institute for High Temperatures of the RAS (JIHT), Russian Academy of Sciences [Moscow] (RAS), Institute of Applied Physics (IAP, Nizhny Novgorod), Moscow State Engineering Physics Institute (MEPhI), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), This work was partly done within the LABEX Plas@Par, the DIM ACAV funded by the Region Ilede-France, This work was supported by Grant No. 11-IDEX- 0004-02 from ANR (France), ANR-12-BS09-0025,SILAMPA,Simuler en laboratoire des écoulements de plasmas magnétisés pour l'astrophysique(2012), European Project: ERC787539,GENESIS, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Shock wave, stars, Accretion, Magnetohydrodynamics (MHD), Young stellar object, FOS: Physical sciences, X-rays: stars, Astrophysics, 01 natural sciences, Shock waves, Settore FIS/05 - Astronomia E Astrofisica, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, Ejecta, 010303 astronomy & astrophysics, Chromosphere, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, pre-main sequence -X-rays, Astronomy and Astrophysics, Plasma, Planetary system, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], accretion disks -instabilities -magnetohydrodynamics (MHD) -shock waves -stars, Accretion (astrophysics), Stars, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Instabilities, Accretion disks, Stars: pre-main sequence, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims. Investigating the process of matter accretion onto forming stars through scaled experiments in the laboratory is important in order to better understand star and planetary system formation and evolution. Such experiments can indeed complement observations by providing access to the processes with spatial and temporal resolution. A previous investigation revealed the existence of a two-component stream: a hot shell surrounding a cooler inner stream. The shell was formed by matter laterally ejected upon impact and refocused by the local magnetic field. That laboratory investigation was limited to normal incidence impacts. However, in young stellar objects, the complex structure of magnetic fields causes variability of the incident angles of the accretion columns. This led us to undertake an investigation, using laboratory plasmas, of the consequence of having a slanted accretion impacting a young star. Methods. Here, we used high power laser interactions and strong magnetic field generation in the laboratory, complemented by numerical simulations, to study the asymmetry induced upon accretion structures when columns of matter impact the surface of young stars with an oblique angle. Results. Compared to the scenario where matter accretes perpendicularly to the star surface, we observe a strongly asymmetric plasma structure, strong lateral ejecta of matter, poor confinement of the accreted material, and reduced heating compared to the normal incidence case. Thus, slanted accretion is a configuration that seems to be capable of inducing perturbations of the chromosphere and hence possibly influencing the level of activity of the corona.
Published: 2020
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37. Frankophilie, Germanophilie und 'Elsässertum' in den Jugendbewegungen Straßburgs zwischen 1918 und 1925. Patriotismus – Körpererziehung – Naturbegeisterung

Author: Jean Saint-Martin, Julien Fuchs, Denis Jallat, Centre de recherche bretonne et celtique (CRBC), Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Sport et sciences sociales (E3S), and Université de Strasbourg (UNISTRA)
Subjects: Government, [SHS.EDU]Humanities and Social Sciences/Education, Identity (social science), Gender studies, General Medicine, Alsace, language.human_language, [SHS]Humanities and Social Sciences, Physical education, German, Political science, Religious education, National identity, language, francophilie, sport, [SHS.HIST]Humanities and Social Sciences/History, mouvements de jeunesse
Abstract: International audience; In 1918, youth organizations were formed in Alsace, particularly in Strasbourg, between France and Germany. This article aims first of all to understand the modalities of their development in the post-war period, by showing, in particular, their diversity (there are indeed Scout movements, religious associations, etc., both of which propose to supervise the youth). This article also attempts to understand the position about issues of national identity of these groups, that educate and train youth, and promote an original form of body education. The youth movements, heirs of the associations of the Reichsland period on which they are based – although this heritage must often be nuanced – differ in their relationship with France. This rapprochement cannot be understood without the reference to a true regional ethos or, in other words, an “Alsatian identity”.
Published: 2019
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38. Modelling energy deposition in TR image plate detectors for various ion types

Author: Julien Fuchs, V. Lelasseux, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE30-0026,PiNNaCLE,Développement d'une ligne de neutrons pulsés compacte et de haute brillance(2017), and European Project: ERC787539,GENESIS
Subjects: 010302 applied physics, Imagination, Chemical substance, Materials science, business.industry, media_common.quotation_subject, Detector, Linear energy transfer, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 010305 fluids & plasmas, Ion, Optics, 0103 physical sciences, Deposition (phase transition), business, Instrumentation, Mathematical Physics, Ip address, Energy (signal processing), media_common
Abstract: International audience; Ion species discrimination method by linear energy transfer measurement in Fujifilm BAS-SR imaging plate M. Nishiuchi et al-This content was downloaded from IP address 92.184.117.159 on 12/11/2020 at 15:45
Published: 2020
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39. 'Playing with the Border:' Alsatian Sports Societies and Alsace’s Problematic Return to France after the First World War

Author: Sébastien Stumpp, Denis Jallat, Julien Fuchs, Centre de recherche bretonne et celtique (CRBC Brest), Université de Brest (UBO)-Institut Brestois des Sciences de l'Homme et de la Société (IBSHS), Université de Brest (UBO)-Centre de recherche bretonne et celtique (CRBC), Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Rennes 2 (UR2), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Subjects: German annexation, First World War, History, Sociology and Political Science, 05 social sciences, Geography, Planning and Development, 0211 other engineering and technologies, 0507 social and economic geography, Rowing, 021107 urban & regional planning, 02 engineering and technology, Ancient history, 16. Peace & justice, Alsace, [SHS]Humanities and Social Sciences, First world war, Political Science and International Relations, Nationality, Return to France, [SHS.HIST]Humanities and Social Sciences/History, 10. No inequality, 050703 geography, Law
Abstract: International audience; Annexed by Germans in 1870, the region Alsace became French again, in 1918. After a triumphal welcom for the French troops, the Alsatians, influenced by 47 years of German presence, showcase very timidly their new nationality. In a France that cultivates anti-Germanism, the political and professional scenes do not, however, allow to claim the German heritage. It is different in the field of sport, which cultivates contradictions by playing its neutral and apolitical image. The local associations of sport maintains a special relationship with the borders and with those who live over the border. At the same time, the relationships are made of porosities and exchanges with Germany and of looking at the French territory or even at the Alsatian aera. This ambiguous positioning leads them to hesitate in two ways : on the one hand, They adopt a public posture advocating their attachment to the Republic; on the other hand, they undertake an "infrapolytic" posture of fiddling with the new borders. We will illustrate this phenomenon through the monograph of a rowing club, the “Cercle Nautique de Strasbourg”.
Published: 2018
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40. Self-modulation and anomalous collective scattering of laser produced intense ion beam in plasmas

Author: Sophia Chen, Julien Fuchs, Kunioki Mima, J.-R. Marquès, Toshihiro Taguchi, José Manuel Perlado, Jesus Pelaez Alvarez, and Toshiki Tajima
Subjects: Physics, Nuclear and High Energy Physics, Ion beam, Scattering, Plasma, Laser, 7. Clean energy, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, law.invention, Ion, Nuclear Energy and Engineering, law, Physics::Plasma Physics, 0103 physical sciences, Stopping power (particle radiation), Physics::Accelerator Physics, lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Electrical and Electronic Engineering, Atomic physics, 010306 general physics, Inertial confinement fusion, Beam (structure)
Abstract: The collective interaction between intense ion beams and plasmas is studied by simulations and experiments, where an intense proton beam produced by a short pulse laser is injected into a pre-ionized gas. It is found that, depending on its current density, collective effects can significantly alter the propagated ion beam and the stopping power. The quantitative agreement that is found between theories and experiments constitutes the first validation of the collective interaction theory. The effects in the interaction between intense ion beams and background gas plasmas are of importance for the design of laser fusion reactors as well as for beam physics. Keywords: Two stream instabilities, Ultra intense short pulse laser, Proton beam, Wake field, Electron plasma wave, Laser plasma interaction, PACS codes: 52.38.Kd, 29.27.Fh, 52.40.Kh, 52.70.Nc
Published: 2018

41. « On n’a pas tous les jours 40 ans… »

Author: Julien Fuchs
Subjects: Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine, Social Sciences (miscellaneous)
Published: 2022
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42. Introduction

Author: Sébastien Laffage-Cosnier, Christian Vivier, and Julien Fuchs
Subjects: Ocean Engineering
Published: 2018
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43. Two-Silicon Cycle for Carbonyl Hydrosilylation with Nikonov’s Cationic Ruthenium(II) Catalyst

Author: Hendrik F. T. Klare, Julien Fuchs, and Martin Oestreich
Subjects: Silylation, 010405 organic chemistry, Chemistry, Hydrosilylation, Hydride, chemistry.chemical_element, General Chemistry, Silyl enol ether, 010402 general chemistry, Photochemistry, 01 natural sciences, Oxidative addition, Catalysis, 0104 chemical sciences, Ruthenium, Lewis acid catalysis, Silyl ether, chemistry.chemical_compound, Polymer chemistry
Abstract: An experimental analysis proves that Nikonov’s carbonyl hydrosilylation proceeds through a two-silicon cycle rather than the originally proposed one-silicon cycle. The intermediate ruthenium(II) monohydride is not sufficiently hydridic to transfer its hydride onto the silylcarboxonium ion. However, that hydricity is enhanced by oxidative addition of another hydrosilane molecule to afford the corresponding ruthenium(IV) silyl dihydride as the actual hydride donor. The present study also demonstrates that the acetonitrile ligands in Nikonov’s ruthenium(II) catalyst are not innocent. That complex is able to hydrosilylate its own ligand(s), and the resulting N,N-disilylated amine base accounts for competing dehydrogenative silylation of enolizable carbonyl compounds, explaining the formation of a silyl enol ether in substantial quantities next to the expected silyl ether. Both findings lead to a revised mechanistic picture that provides the basis for the development of more efficient and chemoselective catalysts.
Published: 2017
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44. La jeunesse alsacienne et la France: mouvements de jeunes et nation, 1918–50

Author: Julien Fuchs
Subjects: History, media_common.quotation_subject, 0211 other engineering and technologies, 021107 urban & regional planning, Gender studies, 06 humanities and the arts, 02 engineering and technology, 16. Peace & justice, First world war, 060104 history, Youth groups, Political science, Civic engagement, 0601 history and archaeology, Ideology, Autonomy, media_common
Abstract: This paper deals with youth organizations in Alsace, a region standing at the crossroads between France and Germany. It focuses on how the issue of nationhood was constructed within these youth groups during the first half of the twentieth century. Our hypothesis is that these socio-educational organizations, training grounds for autonomy and responsibility, are based on a principle of civic engagement from their young members. To this effect, in post-First World War Alsace, these organizations served as vehicles for the reintegration of this region into France, a process that cannot, however, be considered without respect for local social and cultural specificities. In other words, with regard to the activist direction of these movements, a local socio-political configuration seems to far outweigh the ideology of each group.
Published: 2017
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