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19 results on '"Galassi, Davide"'

1. X-point and divertor filament dynamics from Gas Puff Imaging on TCV

Author

Wüthrich, Curdin, Theiler, Christian, Offeddu, Nicola, Galassi, Davide, de Oliveira, Diego Sales, Duval, Basil, Février, Olivier, Golfinopoulos, Theodore, Han, Woonghee, Marmar, Earl, Terry, Jim, and Tsui, Cedric

Subjects
Physics - Plasma Physics
Abstract

A new Gas Puff Imaging (GPI) diagnostic has been installed on the TCV tokamak, providing two-dimensional insights into Scrape-Off-Layer (SOL) turbulence dynamics above, at and below the magnetic X-point. A detailed study in L-mode, attached, lower single-null discharges shows that statistical properties have little poloidal variations, while vast differences are present in the 2D behaviour of intermittent filaments. Strongly elongated filaments, just above the X-point and in the divertor far-SOL, show a good consistency in shape and dynamics with field-line tracing from filaments at the outboard midplane, highlighting their connection. In the near-SOL of the outer divertor leg, shortlived, high frequency and more circular (diameter $\sim$15 sound Larmour radii) filaments are observed. These divertor-localised filaments appear born radially at the position of maximum density and display a radially outward motion with velocity $\approx$400\,m/s that is comparable to radial velocities of upstream-connected filaments. Conversely, in these discharges ($B\times\nabla B$ pointing away from the divertor), these divertor filaments' poloidal velocities differ strongly from those of upstream-connected filaments. The importance of divertor-localised filaments upon radial transport and profile broadening is explored using filament statistics and in-situ kinetic profile measurements along the divertor leg. This provides evidence that these filaments contribute significantly to electron density profile broadening in the divertor., Comment: This is the version of the article before peer review or editing, as submitted by an author to IOPScience Nuclear Fusion. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. 15 pages, 15 figures

Published
2022
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3. Parallel flows as a key component to interpret Super-X divertor experiments

Author

Carpita, Massimo, primary, Février, Olivier, additional, Reimerdes, Holger, additional, Theiler, Christian, additional, Duval, Basil P, additional, Colandrea, Claudia, additional, Durr-Legoupil-Nicoud, Garance Hélène Salomé, additional, Galassi, Davide, additional, Gorno, Sophie, additional, Huett, Emanuel, additional, Loizu, Joaquim, additional, Martinelli, Lorenzo, additional, Perek, Artur, additional, Simons, Luke, additional, Sun, Guang-Yu, additional, Tonello, Elena, additional, and Wüthrich, Curdin Tobias, additional

Published
2024
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4. Models Implemented in the Methodological Approach to Design the Initial Step First Wall Contour

Author

Vaccaro, Dario, primary, Cook, James, additional, Kahn, Sebastien, additional, Barrett, Tom, additional, Bluteau, Matthew, additional, Coleman, Matti, additional, Federici, Fabio, additional, Galassi, Davide, additional, Henderson, Stuart, additional, Horsley, David, additional, Hudoba, Agnieszka, additional, Kovari, Michael, additional, Osawa, Ryoko, additional, Pearce, Alexander, additional, Richiusa, Maria Lorena, additional, Short, Dan, additional, Subramani, Manoj, additional, Verhaegh, Kevin, additional, and Vizvary, Zsolt, additional

Published
2024
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5. Edge turbulence in ISTTOK: a multi-code fluid validation

Author

Dudson, Benjamin Daniel, Gracias, W A, Jorge, Rogerio, Nielsen, A.H., Olsen, M B, Ricci, Paolo, Silva, Carlos, Tamain, P., Ciraolo, G., Fedorczak, N., Galassi, Davide, Madsen, Jens, Militello, Fulvio, Nace, N, Rasmussen, J J, Riva, Fabio, Serre, Eric, CEA, IRFM, F-13108, Saint Paul lez Durance, France, Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), University of Copenhagen = Københavns Universitet (KU), EURATOM/UKAEA, Culham Science Centre [Abingdon], Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), University of Copenhagen = Københavns Universitet (UCPH), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
validation, [PHYS]Physics [physics], [SPI]Engineering Sciences [physics], [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, [SPI.PLASMA]Engineering Sciences [physics]/Plasmas, simulation, tokamak, [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, ComputingMilieux_MISCELLANEOUS
Abstract

Fluid models used to study the edge plasma region need to be benchmarked against similar conditions given that models can strongly differ in complexity and therefore the results they produce. Via this validation study undertaken through the framework of EUROfusion Enabling Research, four state-of-the art models-GBS, Hermes/BOUT++, hot-edge-sol-electrostatic and TOKAM3X-are compared to experimental plasma turbulence measurements on the ISTTOK tokamak. Statistical comparisons of simulation and experiment data show that fluid models used here can replicate most of the experiment in terms of IsatVfloat< fluctuations despite their differences. Furthermore, it is shown that without including more complex information (like core turbulence information and domain geometry details and magnetic topological aspects) in fluid models, the results recovered vary from their experimental counterparts. Via the simulations using these codes, it is demonstrated that fluid models continue to be a good cost-effective tool in recovering many global aspects of edge plasma behaviour.

Published
2021

6. Impact of self-consistent neutrals dynamics and particle sources on edge plasma transport and turbulence in 3D first principle simulations

Author

Tamain, Patrick, Baudoin, Camille, Bufferand, Hugo, Ciraolo, Guido, Fan, Dongmei, Fedorczak, Nicolas, Galassi, Davide, Ghendrih, Philippe, Luce, Benjamin, Marandet, Yannick, Nace, Nicolas, Serre, Eric, Schwander, Frédéric, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Boutin, Olivier, and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

8. Drift-driven cross-field transport and Scrape-Off Layer width in the limit of low anomalous transport

Author

Baudoin, Camille, Tamain, Patrick, Bufferand, Hugo, Ciraolo, Guido, Fedorczak, Nicolas, Galassi, Davide, Gallo, Alberto, Ghendrih, Philippe, Nace, Nicolas, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Modélisation et Simulation Numérique (en mécanique des fluides) (M2P2), Centre National de la Recherche Scientifique (CNRS)-Université de Provence - Aix-Marseille 1-Université Paul Cézanne - Aix-Marseille 3-Université de la Méditerranée - Aix-Marseille 2, Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée - Aix-Marseille 2-Université Paul Cézanne - Aix-Marseille 3-Université de Provence - Aix-Marseille 1-Centre National de la Recherche Scientifique (CNRS), and Baudoin, Camille

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph]
Abstract

The impact of the ∇B-drift in the cross-field transport and its effect on the density and power scrape-off layer (SOL) width in the limit of low anomalous transport is studied with the fluid code SolEdge2D. In a first part of the work, the simulations are run with an isothermal reduced fluid model. It is found that a ∇B-drift dominated regime is reached in all geometries studied (JET-like, ASDEX-like and circular analytic geometries), and that the transition toward this regime comes along with the apparition of supersonic shocks, and a complex parallel equilibrium. The parametric dependencies of the SOL width in this regime are investigated, and the temperature and the poloidal magnetic field are found to be the principal parameters governing the evolution of the SOL width. In the second part of this paper, the impact of additional physics is studied (inclusion of the centrifugal drift, self-consistent variation of temperature and the treatment of the neutral species). The addition of centrifugal drift and neutral species are shown to play a role in the establishment of the parallel equilibrium, impacting the SOL's width. Finally, the numerical results are compared with the estimate of the Goldston's heuristic drift based model (HD-model), which has showed good agreement with experimental scaling laws. We find that the particles SOL's widths in the ∇B-drift dominated regime are, at least, two times smaller than the estimate of the HD-model. Moreover, in the parametric dependencies proposed by the HD-model, only the dependency with B pol is retrieved but not the one on T .

Published
2017

9. Impact of X-point and divertor topology on global turbulent transport in tokamak edge plasma

Author

Galassi, Davide, Tamain, Patrick, Bufferand, Hugo, Baudoin, C., Ciraolo, Guido, Fedorczak, N., Ghendrih, Philippe, Nace, Nicolas, Serre, Eric, Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), and conf, M2P2

Subjects
[SPI.MECA.MEFL] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], ComputingMilieux_MISCELLANEOUS, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

International audience

Published
2017

10. Impact of diverted geometry on turbulence and transport barrier formation in 3D global simulations of tokamak edge plasma

Author

Galassi, Davide, Tamain, Patrick, Boudoin, C., Bufferand, Hugo, Ciraolo, Guido, N., Fedorzack, Ghendrih, Philippe, Nace, Nicolas, Serre, Eric, conf, M2P2, Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.MECA.MEFL] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], ComputingMilieux_MISCELLANEOUS, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

International audience

Published
2017

13. Interchange Turbulence Model for the Edge Plasma in SOLEDGE2D-EIRENE

Author

Bufferand, Hugo, Ciraolo, Guido, Ghendrih, Philippe, Marandet, Yannick, Bucalossi, J., Colin, C., Fedorczak, Nicolas, Galassi, Davide, Gunn, J., Leybros, R., Serre, E., Tamain, Patrick, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), 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 Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU)

Subjects
[PHYS]Physics [physics], [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

15th International Workshop on Plasma Edge Theory in Fusion Devices (PET), Nara Kasugano Int Forum IRAKA, Nara, JAPAN, SEP 09-11, 2015; International audience; Cross-field transport in edge tokamak plasmas is known to be dominated by turbulent transport. A dedicated effort has been made to simulate this turbulent transport from first principle models but the numerical cost to run these simulations on the ITER scale remains prohibitive. Edge plasma transport study relies mostly nowadays on so-called transport codes where the turbulent transport is taken into account using effective ad-hoc diffusion coeffecients. In this contribution, we propose to introduce a transport equation for the turbulence intensity in SOLEDGE2D-EIRENE to describe the interchange turbulence properties. Going beyond the empirical diffusive model, this system automatically generates profiles for the turbulent transport and hence reduces the number of degrees of freedom for edge plasma transport codes. We draw inspiration from the k-epsilon model widely used in the neutral fluid community. ((c) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Published
2016
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14. Impact of drift velocities on divertor flows and steadiness with the transport code SOLEDGE2D-EIRENE

Author

Bufferand, Hugo, Galassi, Davide, Ciraolo, Guido, Marandet, Yannick, Boudoin, C., Bucalossi, Jérôme, Denis, J., Fedorczak, N., Gallo, A., Ghendrih, Philippe, Leybros, R., Schwander, Frédéric, Serre, Eric, Tamain, Patrick, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU)

Subjects
ComputingMilieux_MISCELLANEOUS, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

International audience

Published
2016

15. Analysis of SOL flows in diverted plasmas

Author

Galassi, Davide, Bufferand, Hugo, Ciraolo, Guido, Colin, Clothilde, Ghendrih, Philippe, Serre, Eric, Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), conf, M2P2, and Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU)

Subjects
[SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, [SPI.MECA.MEFL] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], [SPI.FLUID] Engineering Sciences [physics]/Reactive fluid environment, ComputingMilieux_MISCELLANEOUS, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

International audience

Published
2016

16. Interplay between Plasma Turbulence and Particle Injection in 3D Global Simulations

Author

Tamain, Patrick, Bufferand, Hugo, Carbajal, L., Marandet, Yannick, Baudoin, C., Ciraolo, G., Colin, C., Futtersack, R., Galassi, Davide, Ghendrih, Philippe, Nace, N., Schwander, Frédéric, Serre, Eric, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph]
Abstract

15th International Workshop on Plasma Edge Theory in Fusion Devices (PET), Nara Kasugano Int Forum IRAKA, Nara, JAPAN, SEP 09-11, 2015; International audience; The impact of a 3D localized particle source on the edge plasma in 3D global turbulence simulations is investigated using the TOKAM3X fluid code. Results apply to advanced fueling methods such as Supersonic Molecular Beam Injection (SMBI) or pellets injection. The fueling source is imposed as a volumetric particle source in the simulations so that the physics leading to the ionization of particles and its localization are not taken into account. As already observed in experiments, the localized particle source strongly perturbs both turbulence and the large scale organization of the edge plasma. The localized increase of the pressure generated by the source drives sonic parallel flows in the plasma, leading to a poloidal redistribution of the particles on the time scale of the source duration. However, the particle deposition also drives localized transverse pressure gradients which impacts the stability of the plasma with respect to interchange processes. The resulting radial transport occurs on a sufficiently fast time scale to compete with the parallel redistribution of particles, leading to immediate radial losses of a significant proportion of the injected particles. Low Field Side (LFS) and High Field Side (HFS) injections exhibit different dynamics due to their interaction with curvature. In particular, HFS particle deposition drives an inward flux leading to differences in the particle deposition efficiency (higher for HFS than LFS). These results demonstrate the importance of taking into account plasma transport in a self-consistent manner when investigating fueling methods. ((c) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Published
2016
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17. Drift effects in SOLPS-ITER simulations for the TCV divertor upgrade

Author

Wensing, Mirko, De Oliveira, Hugo, Duval, Basil, Fevrier, Olivier, Fil, Alexandre, Galassi, Davide, Loizu, Joaquim, Martinelli, Loreno, Maurizio, Roberto, Reimerdes, Holger, Theiler, Christian, Thornton, Andrew, Verhaegh, Kevin, and Wischmeier, Marco

Abstract

This contribution reports on the progress towards including drift effects in SOLPS-ITER simulations to assess power distribution and detachment onset in the light of the 2019 TCV divertor upgrade [1]. The installation of in-vessel gas baffles (Figure 1a) is predicted to increase the divertor neutral density by a factor ∼ 5 and therefore facilitates the access to detachment [2]. The conditions for the onset of detachment at each strike point depend on the power entering each divertor leg and thus simulations must correctly include the power distribution between the inner and outer divertor that is greatly affected by scrape-off layer drifts. Surprisingly, the sharing of particles and heat between the targets in reversed field conditions is found to be shifted towards the outer target. This counter-intuitive flowpattern is due to an electric potential well below the X-point that occurs in high density reversed field simulations.

18. Flux expansion effect on turbulent transport in 3D global simulations

Author

Eric Serre, D. Galassi, Patrick Tamain, Hugo Bufferand, N. Nace, G Ciraolo, Nicolas Fedorczak, Philippe Ghendrih, C. Baudoin, Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Thales Alenia Space (TAS), THALES, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Thales Alenia Space [Toulouse] (TAS), THALES [France], and Galassi, Davide

Subjects
Nuclear and High Energy Physics, Materials Science (miscellaneous), 01 natural sciences, Instability, Ballooning, 010305 fluids & plasmas, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Flux (metallurgy), [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Limiter, [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 010306 general physics, Physics, Turbulence, Mechanics, lcsh:TK9001-9401, Magnetic field, [SPI.MECA.GEME]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanical engineering [physics.class-ph], Shear (sheet metal), Amplitude, Classical mechanics, Nuclear Energy and Engineering, [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], lcsh:Nuclear engineering. Atomic power
Abstract

International audience; The flux expansion effect on the Scrape-Off Layer equilibrium is inspected through TOKAM3X 3D turbulence simulations. Three magnetic equilibria with analytically controlled flux expansion are built, representing respectively a positive, a null and a negative Shafranov shift. Turbulent E × B fluxes across flux surfaces show similar amplitudes and poloidal distributions in all cases. The ballooning nature of the interchange instability is recovered, with an enhancement of turbulence in the vicinity of the limiter, probably due to a Kelvin–Helmoltz instability. Interestingly, the poloidally averaged density decay length is found to be shorter almost by a factor 2 in the case of flux surfaces compressed at the low-field side midplane, with respect to the opposite case, indicating the presence of unfavorable conditions for the turbulent transport. The difference in the magnetic field line shape is pointed out as a mechanism which affects the turbulent transport across the flux surfaces. Indeed the unstable region has a larger parallel extension when flux expansion in the low-field side is larger. Moreover, the configuration with a lower magnetic shear at the low-field side midplane shows a more unstable behavior. The role of this parameter in turbulence stabilization is qualitatively evaluated. The difference in the distribution of transport along the parallel direction is shown to affect also the parallel flows, which are analyzed for the three proposed cases.

Published
2017
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19. Drive of parallel flows by turbulence and large-scale E × B transverse transport in divertor geometry

Author

Philippe Ghendrih, D. Galassi, Patrick Tamain, Hugo Bufferand, N. Nace, G. Ciraolo, C. Baudoin, Nicolas Fedorczak, Eric Serre, C. Colin, Galassi, Davide, Equipements d'excellence - Equipement d'excellence de calcul intensif de Mesocentres coordonnés - Tremplin vers le calcul petaflopique et l'exascale - - EQUIP@MESO2010 - ANR-10-EQPX-0029 - EQPX - VALID, INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE - - Amidex2011 - ANR-11-IDEX-0001 - IDEX - VALID, Dipartimento di Scienze Ambientali, Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Thales Alenia Space [Toulouse] (TAS), THALES [France], Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), AMIDEX project KFC, ANR-10-EQPX-0029,EQUIP@MESO,Equipement d'excellence de calcul intensif de Mesocentres coordonnés - Tremplin vers le calcul petaflopique et l'exascale(2010), ANR-11-IDEX-0001,Amidex,INITIATIVE D'EXCELLENCE AIX MARSEILLE UNIVERSITE(2011), Università degli Studi dell'Aquila (UNIVAQ), Thales Alenia Space (TAS), and THALES

Subjects
Nuclear and High Energy Physics, Divertor geometry, Field (physics), K-epsilon turbulence model, Large-scale flows, media_common.quotation_subject, 01 natural sciences, Asymmetry, 010305 fluids & plasmas, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Momentum, Physics::Fluid Dynamics, symbols.namesake, [SPI]Engineering Sciences [physics], [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Statistical physics, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 010306 general physics, media_common, Physics, Turbulence, Divertor, Plasma, Mechanics, Poloidal asymmetries, Condensed Matter Physics, Mach number, [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], symbols
Abstract

International audience; The poloidal asymmetries of parallel flows in edge plasmas are investigated by the 3D fluid turbulence code TOKAM3X. A diverted COMPASS-like magnetic equilibrium is used for the simulations. The measurements and simulations of parallel Mach numbers are compared, and exhibit good qualitative agreement. Small-scale turbulent transport is observed to dominate near the low field side midplane, even though it co-exists with significant large-scale cross-field fluxes. Despite the turbulent nature of the plasma in the divertor region, simulations show the low effectiveness of turbulence for the cross-field transport towards the private flux region. Nevertheless, a complex pattern of fluxes associated with the average field components are found to cross the separatrix in the divertor region. Large-scale and small-scale turbulent E x B transport, along with the del B drift, drive the asymmetries in parallel flows. A semian-alytical model based on mass and parallel momentum balances allows the poloidal drift effects on the asymmetry pattern to be evaluated. As in the experiments, a reversed B-T simulation provides a way of self-consistently separating the effects of turbulent transport and large-scale flows, which must be reversed for a reversed field. The large-scale contribution is found to be responsible for typically 50% of the effect on the Mach number, evaluated at the top of the machine. The presented picture shows the complex interplay between drifts and turbulence, underlining the necessity of a global approach to edge plasma modelling, including a self-consistent description of the turbulence.

Published
2016
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