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32 results on '"Cartier-Michaud, T"'

1. Radial density and heat fluxes description in the velocity space: Nonlinear simulations and quasi-linear calculations

Author

Médina, J, Lesur, M, Gravier, E, Réveillé, T, Idouakass, M, Drouot, T, Bertrand, P, Cartier-Michaud, T, Garbet, X, and Diamond, PH

Subjects
Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Classical Physics, Fluids & Plasmas
Abstract

In the context of temperature gradient-driven, collisionless trapped-ion modes in magnetic confinement fusion, we perform and analyse numerical simulations to explore the turbulent transport of density and heat, with a focus on the velocity dimension (without compromising the details in the real space). We adopt the bounce-averaged gyrokinetic code TERESA, which focuses on trapped particles dynamics and allows one to study low frequency phenomena at a reduced computational cost. We focus on a time in the simulation where the trapped-ion modes have just saturated in amplitude. We present the structure in velocity space of the fluxes. Both density and heat fluxes present a narrow (temperature-normalized energy width ΔE/T ≈ 0.15) resonance peak with an amplitude high enough for resonant particles to contribute for 90% of the heat flux. We then compare these results obtained from a nonlinear simulation to the prediction from the quasi-linear theory and we find a qualitative agreement throughout the whole energy dimension: from thermal particles to high-energy particles. Quasi-linear theory over-predicts the fluxes by about 15%; however, this reasonable agreement is the result of a compensation between two larger errors of about 50%, both at the resonant energy and at the thermal energy.

Published
2018

2. Optilization of the gyroaverage operator based on hermite interpolation

Author

Rozar, F, Steiner, C, Latu, G, Mehrenberger, M, Grandgirard, V, Bigot, Julien, Cartier-Michaud, T, and Roman, Jean

Subjects
Physics - Computational Physics, Computer Science - Distributed, Parallel, and Cluster Computing, Computer Science - Numerical Analysis
Abstract

Gyrokinetic modeling is appropriate for describing Tokamak plasma turbulence, and the gyroaverage operator is a cornerstone of this approach. In a gyrokinetic code, the gyroaveraging scheme needs to be accurate enough to avoid spoiling the data but also requires a low computation cost because it is applied often on the main unknown, the 5D guiding-center distribution function, and on the 3D electric potentials. In the present paper, we improve a gyroaverage scheme based on Hermite interpolation used in the Gysela code. This initial implementation represents a too large fraction of the total execution time. The gyroaverage operator has been reformulated and is now expressed as a matrix-vector product and a cache-friendly algorithm has been setup. Different techniques have been investigated to quicken the computations by more than a factor two. Description of the algorithms is given, together with an analysis of the achieved performance.

Published
2016

3. PoPe (Projection on Proper elements) for code control: verification, numerical convergence and reduced models. Application to plasma turbulence simulations

Author

Cartier-Michaud, T, Ghendrih, P, Sarazin, Y, Abiteboul, J, Bufferand, H, Dif-Pradalier, G, Garbet, X, Grandgirard, V, Latu, G, Norscini, C, Passeron, C, and Tamain, P

Subjects
Physics - Plasma Physics
Abstract

The Projection on Proper elements (PoPe) is a novel method of code control dedicated to 1) checking the correct implementation of models, 2) determining the convergence of numerical methods and 3) characterizing the residual errors of any given solution at very low cost. The basic idea is to establish a bijection between a simulation and a set of equations that generate it. Recovering equations is direct and relies on a statistical measure of the weight of the various operators. This method can be used in any dimensions and any regime, including chaotic ones. This method also provides a procedure to design reduced models and quantify the ratio costs to benefits. PoPe is applied to a kinetic and a fluid code of plasma turbulence.

Published
2015
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4. A simple model for electron dissipation in trapped ion turbulence

Author

Lesur, M, Cartier-Michaud, T, Drouot, T, Diamond, PH, Kosuga, Y, Réveillé, T, Gravier, E, Garbet, X, Itoh, S-I, and Itoh, K

Subjects
Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Classical Physics, Fluids & Plasmas
Abstract

Trapped ion resonance-driven turbulence is investigated in the presence of electron dissipation in a simplified tokamak geometry. A reduced gyrokinetic bounce-averaged model for trapped ions is adopted. Electron dissipation is modeled by a simple phase-shift δ between density and electric potential perturbations. The linear eigenfunction features a peak at the resonant energy, which becomes stronger with increasing electron dissipation. Accurately resolving this narrow peak in numerical simulation of the initial-value problem yields a stringent lower bound on the number of grid points in the energy space. Further, the radial particle flux is investigated in the presence of electron dissipation, including kinetic effects. When the density gradient is higher than the temperature gradient, and the phase-shift is finite but moderate (δ≈0.02), the particle flux peaks at an order-of-magnitude above the gyro-Bohm estimate. Slight particle pinch is observed for δ

Published
2017

5. Transport Barrier generation at the interface of regions with different zonal flows dynamics

Author

Norscini, C., Ghendrih, Ph., Cartier-Michaud, T., Dif-Pradalier, G., Garbet, X., Nace, N., Sarazin, Y., and Tamain, P.

Subjects
Physics - Plasma Physics
Abstract

A novel and generic understanding of spontaneous generation of transport barriers and zonation regimes in turbulent self-organization is presented. It associates the barrier onset to the development of a spectral gap between large scale flows and turbulence modes leading to a zonation regime. A robust barrier builds-up at the interface of such a region and a neighboring one with reduced zonal flow generation. This more complex and generic transition paradigm could fit the numerous and sometimes conflicting observations as in fusion plasma experiments. Barrier relaxation by bursts of turbulence regenerate the zonal flows that are eroded by viscous (collisional-like) damping. The duration of the quiescent phase between the quasi-periodic relaxation events is governed by this damping process, hence the barrier collision frequency for fusion plasmas.

Published
2015

6. Evaluating kernels on Xeon Phi to accelerate Gysela application

Author

Latu, G., Haefele, M., Bigot, J., Grandgirard, V., Cartier-Michaud, T., and Rozar, F.

Subjects
Physics - Computational Physics, Computer Science - Distributed, Parallel, and Cluster Computing, Computer Science - Performance
Abstract

This work describes the challenges presented by porting parts ofthe Gysela code to the Intel Xeon Phi coprocessor, as well as techniques used for optimization, vectorization and tuning that can be applied to other applications. We evaluate the performance of somegeneric micro-benchmark on Phi versus Intel Sandy Bridge. Several interpolation kernels useful for the Gysela application are analyzed and the performance are shown. Some memory-bound and compute-bound kernels are accelerated by a factor 2 on the Phi device compared to Sandy architecture. Nevertheless, it is hard, if not impossible, to reach a large fraction of the peek performance on the Phi device,especially for real-life applications as Gysela. A collateral benefit of this optimization and tuning work is that the execution time of Gysela (using 4D advections) has decreased on a standard architecture such as Intel Sandy Bridge., Comment: submitted to ESAIM proceedings for CEMRACS 2014 summer school version reviewed

Published
2015

7. Finding the Elusive E×B Staircase in Magnetized Plasmas

Author

Dif-Pradalier, G, Hornung, G, Ghendrih, Ph, Sarazin, Y, Clairet, F, Vermare, L, Diamond, PH, Abiteboul, J, Cartier-Michaud, T, Ehrlacher, C, Estève, D, Garbet, X, Grandgirard, V, Gürcan, ÖD, Hennequin, P, Kosuga, Y, Latu, G, Maget, P, Morel, P, Norscini, C, Sabot, R, and Storelli, A

Subjects
Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract

Turbulence in hot magnetized plasmas is shown to generate permeable localized transport barriers that globally organize into the so-called "ExB staircase" [G. Dif-Pradalier et al., Phys. Rev. E, 82, 025401(R) (2010)]. Its domain of existence and dependence with key plasma parameters is discussed theoretically. Based on these predictions, staircases are observed experimentally in the Tore Supra tokamak by means of high-resolution fast-sweeping X-mode reflectometry. This observation strongly emphasizes the critical role of mesoscale self-organization in plasma turbulence and may have far-reaching consequences for turbulent transport models and their validation.

Published
2015

13. Generation and dynamics of SOL corrugated profiles

Author

Ghendrih, P., primary, Asahi, Y., additional, Caschera, E., additional, Dif-Pradalier, G., additional, Donnel, P., additional, Garbet, X., additional, Gillot, C., additional, Grandgirard, V., additional, Latu, G., additional, Sarazin, Y., additional, Baschetti, S., additional, Bufferand, H., additional, Cartier-Michaud, T., additional, Ciraolo, G., additional, Tamain, P., additional, Tatali, R., additional, and Serre, E., additional

Published
2018
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14. A 5D gyrokinetic full-f global semi-Lagrangian code for flux-driven ion turbulence simulations

Author

Grandgirard, V., primary, Abiteboul, J., additional, Bigot, J., additional, Cartier-Michaud, T., additional, Crouseilles, N., additional, Dif-Pradalier, G., additional, Ehrlacher, Ch., additional, Esteve, D., additional, Garbet, X., additional, Ghendrih, Ph., additional, Latu, G., additional, Mehrenberger, M., additional, Norscini, C., additional, Passeron, Ch., additional, Rozar, F., additional, Sarazin, Y., additional, Sonnendrücker, E., additional, Strugarek, A., additional, and Zarzoso, D., additional

Published
2016
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16. Further details on the plasma E × B staircase

Author

Guilhem Dif-Pradalier, Hornung, G., Philippe Ghendrih, Yanick Sarazin, Clairet, F., laure vermare, Diamond, P., Abiteboul, J., Cartier-Michaud, T., Ehrlacher, C., Esteve, D., Xavier Garbet, Virginie Grandgirard, Özgür Gürcan, Hennequin, P., Kosuga, A., Guillaume Latu, Pierre Morel, Norscini, C., Sabot, R., Storelli, A., Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Computations were run on the Helios supercomputer., ANR-10-BLAN-0941,GYPSI,Simulation GYrocinétique haute Performance Pour ITER(2010), ANR-09-BLAN-0035,ESPOIR(2009), European Project: 633053,H2020,EURATOM-Adhoc-2014-20,EUROfusion(2014), and 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)

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

International audience; Turbulence in hot magnetised plasmas spontaneously has been shown to spontaneously organise on global scales into the so-called " E × B staircase ". Further characterisation of this structure is detailed below.

Published
2015

17. Projection on Proper elements for code control: Verification, numerical convergence, and reduced models. Application to plasma turbulence simulations

Author

Cartier-Michaud, T., primary, Ghendrih, P., additional, Sarazin, Y., additional, Abiteboul, J., additional, Bufferand, H., additional, Dif-Pradalier, G., additional, Garbet, X., additional, Grandgirard, V., additional, Latu, G., additional, Norscini, C., additional, Passeron, C., additional, and Tamain, P., additional

Published
2016
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22. Finding the ElusiveE×BStaircase in Magnetized Plasmas

Author

Dif-Pradalier, G., primary, Hornung, G., additional, Ghendrih, Ph., additional, Sarazin, Y., additional, Clairet, F., additional, Vermare, L., additional, Diamond, P. H., additional, Abiteboul, J., additional, Cartier-Michaud, T., additional, Ehrlacher, C., additional, Estève, D., additional, Garbet, X., additional, Grandgirard, V., additional, Gürcan, Ö. D., additional, Hennequin, P., additional, Kosuga, Y., additional, Latu, G., additional, Maget, P., additional, Morel, P., additional, Norscini, C., additional, Sabot, R., additional, and Storelli, A., additional

Published
2015
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25. Interplay between fast ions and turbulence in magnetic fusion plasmas

Author

Dumont, R J, primary, Zarzoso, D, additional, Sarazin, Y, additional, Garbet, X, additional, Strugarek, A, additional, Abiteboul, J, additional, Cartier-Michaud, T, additional, Dif-Pradalier, G, additional, Ghendrih, Ph, additional, Girardo, J-B, additional, Grandgirard, V, additional, Latu, G, additional, Passeron, C, additional, and Thomine, O, additional

Published
2013
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26. Unraveling Quasiperiodic Relaxations of Transport Barriers with Gyrokinetic Simulations of Tokamak Plasmas

Author

Strugarek, A., primary, Sarazin, Y., additional, Zarzoso, D., additional, Abiteboul, J., additional, Brun, A. S., additional, Cartier-Michaud, T., additional, Dif-Pradalier, G., additional, Garbet, X., additional, Ghendrih, Ph., additional, Grandgirard, V., additional, Latu, G., additional, Passeron, C., additional, and Thomine, O., additional

Published
2013
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27. Science and technology research and development in support to ITER and the Broader Approach at CEA

Author

Bécoulet, A., primary, Hoang, G.T., additional, Abiteboul, J., additional, Achard, J., additional, Alarcon, T., additional, Alba-Duran, J., additional, Allegretti, L., additional, Allfrey, S., additional, Amiel, S., additional, Ané, J.M., additional, Aniel, T., additional, Antar, G., additional, Argouarch, A., additional, Armitano, A., additional, Arnaud, J., additional, Arranger, D., additional, Artaud, J.F., additional, Audisio, D., additional, Aumeunier, M., additional, Autissier, E., additional, Azcona, L., additional, Back, A., additional, Bahat, A., additional, Bai, X., additional, Baiocchi, B., additional, Balaguer, D., additional, Balme, S., additional, Balorin, C., additional, Barana, O., additional, Barbier, D., additional, Barbuti, A., additional, Basiuk, V., additional, Baulaigue, O., additional, Bayetti, P., additional, Baylard, C., additional, Beaufils, S., additional, Beaute, A., additional, Bécoulet, M., additional, Bej, Z., additional, Benkadda, S., additional, Benoit, F., additional, Berger-By, G., additional, Bernard, J.M., additional, Berne, A., additional, Bertrand, B., additional, Bertrand, E., additional, Beyer, P., additional, Bigand, A., additional, Bonhomme, G., additional, Borel, G., additional, Boron, A., additional, Bottereau, C., additional, Bottollier-Curtet, H., additional, Bouchand, C., additional, Bouquey, F., additional, Bourdelle, C., additional, Bourg, J., additional, Bourmaud, S., additional, Brémond, S., additional, Bribiesca Argomedo, F., additional, Brieu, M., additional, Brun, C., additional, Bruno, V., additional, Bucalossi, J., additional, Bufferand, H., additional, Buravand, Y., additional, Cai, L., additional, Cantone, V., additional, Cantone, B., additional, Caprin, E., additional, Cartier-Michaud, T., additional, Castagliolo, A., additional, Belo, J., additional, Catherine-Dumont, V., additional, Caulier, G., additional, Chaix, J., additional, Chantant, M., additional, Chatelier, M., additional, Chauvin, D., additional, Chenevois, J., additional, Chouli, B., additional, Christin, L., additional, Ciazynski, D., additional, Ciraolo, G., additional, Clairet, F., additional, Clapier, R., additional, Cloez, H., additional, Coatanea-Gouachet, M., additional, Colas, L., additional, Colledani, G., additional, Commin, L., additional, Coquillat, P., additional, Corbel, E., additional, Corre, Y., additional, Cottet, J., additional, Cottier, P., additional, Courtois, X., additional, Crest, I., additional, Dachicourt, R., additional, Dapena Febrer, M., additional, Daumas, C., additional, de Esch, H.P.L., additional, De Gentile, B., additional, Dechelle, C., additional, Decker, J., additional, Decool, P., additional, Deghaye, V., additional, Delaplanche, J., additional, Delchambre-Demoncheaux, E., additional, Delpech, L., additional, Desgranges, C., additional, Devynck, P., additional, Dias Pereira Bernardo, J., additional, Dif-Pradalier, G., additional, Doceul, L., additional, Dong, Y., additional, Douai, D., additional, Dougnac, H., additional, Dubuit, N., additional, Duchateau, J.-L., additional, Ducobu, L., additional, Dugue, B., additional, Dumas, N., additional, Dumont, R., additional, Durocher, A., additional, Duthoit, F., additional, Ekedahl, A., additional, Elbeze, D., additional, Escarguel, A., additional, Escop, J., additional, Faïsse, F., additional, Falchetto, G., additional, Farjon, J., additional, Faury, M., additional, Fedorzack, N., additional, Féjoz, P., additional, Fenzi, C., additional, Ferlay, F., additional, Fiet, P., additional, Firdaouss, M., additional, Francisquez, M., additional, Franel, B., additional, Frauche, J., additional, Frauel, Y., additional, Futtersack, R., additional, Garbet, X., additional, Garcia, J., additional, Gardarein, J., additional, Gargiulo, L., additional, Garibaldi, P., additional, Garin, P., additional, Garnier, D., additional, Gauthier, E., additional, Gaye, O., additional, Geraud, A., additional, Gerome, M., additional, Gervaise, V., additional, Geynet, M., additional, Ghendrih, P., additional, Giacalone, I., additional, Gibert, S., additional, Gil, C., additional, Ginoux, S., additional, Giovannangelo, L., additional, Girard, S., additional, Giruzzi, G., additional, Goletto, C., additional, Goncalves, R., additional, Gonde, R., additional, Goniche, M., additional, Goswami, R., additional, Grand, C., additional, Grandgirard, V., additional, Gravil, B., additional, Grisolia, C., additional, Gros, G., additional, Grosman, A., additional, Guigue, J., additional, Guilhem, D., additional, Guillemaut, C., additional, Guillerminet, B., additional, Guimaraes Filho, Z., additional, Guirlet, R., additional, Gunn, J. P., additional, Gurcan, O., additional, Guzman, F., additional, Hacquin, S., additional, Hariri, F., additional, Hasenbeck, F., additional, Hatchressian, J.C., additional, Hennequin, P., additional, Hernandez, C., additional, Hertout, P., additional, Heuraux, S., additional, Hillairet, J., additional, Honore, C., additional, Hornung, G., additional, Houry, M., additional, Hunstad, I., additional, Hutter, T., additional, Huynh, P., additional, Icard, V., additional, Imbeaux, F., additional, Irishkin, M., additional, Isoardi, L., additional, Jacquinot, J., additional, Jacquot, J., additional, Jiolat, G., additional, Joanny, M., additional, Joffrin, E., additional, Johner, J., additional, Joubert, P., additional, Jourd'Heuil, L., additional, Jouve, M., additional, Junique, C., additional, Keller, D., additional, Klepper, C., additional, Kogut, D., additional, Kubič, M., additional, Labassé, F., additional, Lacroix, B., additional, Lallier, Y., additional, Lamaison, V., additional, Lambert, R., additional, Larroque, S., additional, Latu, G., additional, Lausenaz, Y., additional, Laviron, C., additional, Le, R., additional, Le Luyer, A., additional, Le Niliot, C., additional, Le Tonqueze, Y., additional, Lebourg, P., additional, Lefevre, T., additional, Leroux, F., additional, Letellier, L., additional, Li, Y., additional, Lipa, M., additional, Lister, J., additional, Litaudon, X., additional, Liu, F., additional, Loarer, T., additional, Lombard, G., additional, Lotte, P., additional, Lozano, M., additional, Lucas, J., additional, Lütjens, H., additional, Magaud, P., additional, Maget, P., additional, Magne, R., additional, Mahieu, J.-F., additional, Maini, P., additional, Malard, P., additional, Manenc, L., additional, Marandet, Y., additional, Marbach, G., additional, Marechal, J.-L., additional, Marfisi, L., additional, Marle, M., additional, Martin, C., additional, Martin, V., additional, Martin, G., additional, Martinez, A., additional, Martino, P., additional, Masset, R., additional, Mazon, D., additional, Mellet, N., additional, Mercadier, L., additional, Merle, A., additional, Meshcheriakov, D., additional, Messina, P., additional, Meyer, O., additional, Millon, L., additional, Missirlian, M., additional, Moerel, J., additional, Molina, D., additional, Mollard, P., additional, Moncada, V., additional, Monier-Garbet, P., additional, Moreau, D., additional, Moreau, M., additional, Moreau, P., additional, Morel, P., additional, Moriyama, T., additional, Motassim, Y., additional, Mougeolle, G., additional, Moulton, D., additional, Moureau, G., additional, Mouyon, D., additional, Naim Habib, M., additional, Nardon, E., additional, Négrier, V., additional, Nemeth, J., additional, Nguyen, C., additional, Nguyen, M., additional, Nicolas, L., additional, Nicolas, T., additional, Nicollet, S., additional, Nilsson, E., additional, N'Konga, B., additional, Noel, F., additional, Nooman, A., additional, Norscini, C., additional, Nouailletas, R., additional, Oddon, P., additional, Ohsako, T., additional, Orain, F., additional, Ottaviani, M., additional, Pagano, M., additional, Palermo, F., additional, Panayotis, S., additional, Parrat, H., additional, Pascal, J.-Y., additional, Passeron, C., additional, Pastor, P., additional, Patterlini, J., additional, Pavy, K., additional, Pecquet, A.-L., additional, Pégourié, B., additional, Peinturier, C., additional, Pelletier, T., additional, Peluso, B., additional, Petrzilka, V., additional, Peysson, Y., additional, Pignoly, E., additional, Pirola, R., additional, Pocheau, C., additional, Poitevin, E., additional, Poli, V., additional, Poli, S., additional, Pompon, F., additional, Porchy, I., additional, Portafaix, C., additional, Preynas, M., additional, Prochet, P., additional, Prou, M., additional, Ratnani, A., additional, Raulin, D., additional, Ravenel, N., additional, Renard, S., additional, Ricaud, B., additional, Richou, M., additional, Ritz, G., additional, Roche, H., additional, Roubin, P., additional, Roux, C., additional, Ruiz, K., additional, Sabathier, F., additional, Sabot, R., additional, Saille, A., additional, Saint-Laurent, F., additional, Sakamoto, R., additional, Salasca, S., additional, Salmon, T., additional, Samaille, F., additional, Sanchez, S., additional, Santagiustina, A., additional, Saoutic, B., additional, Sarazin, Y., additional, Sardain, P., additional, Schlosser, J., additional, Schneider, M., additional, Schwob, J., additional, Segui, J., additional, Seguin, N., additional, Selig, G., additional, Serret, D., additional, Signoret, J., additional, Simonin, A., additional, Soldaini, M., additional, Soler, B., additional, Soltane, C., additional, Song, S., additional, Sourbier, F., additional, Sparagna, J., additional, Spitz, P., additional, Spuig, P., additional, Storelli, A., additional, Strugarek, A., additional, Tamain, P., additional, Tena, M., additional, Theis, J., additional, Thomine, O., additional, Thouvenin, D., additional, Torre, A., additional, Toulouse, L., additional, Travère, J., additional, Tsitrone, E., additional, Turck, B., additional, Urban, J., additional, Vallet, J.-C., additional, Vallory, J., additional, Valognes, A., additional, Van Helvoirt, J., additional, Vartanian, S., additional, Verger, J.-M., additional, Vermare, L., additional, Vermare, C., additional, Vezinet, D., additional, Vicente, K., additional, Vidal, J., additional, Vignal, N., additional, Vigne, T., additional, Villecroze, F., additional, Villedieu, E., additional, Vincent, B., additional, Volpe, B., additional, Volpe, D., additional, Volpe, R., additional, Wagrez, J., additional, Wang, H., additional, Wauters, T., additional, Wintersdorff, O., additional, Wittebol, E., additional, Zago, B., additional, Zani, L., additional, Zarzoso, D., additional, Zhang, Y., additional, Zhong, W., additional, and Zou, X.L., additional

Published
2013
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30. Impact of Energetic-Particle-Driven Geodesic Acoustic Modes on Turbulence

Author

Zarzoso, D., primary, Sarazin, Y., additional, Garbet, X., additional, Dumont, R., additional, Strugarek, A., additional, Abiteboul, J., additional, Cartier-Michaud, T., additional, Dif-Pradalier, G., additional, Ghendrih, Ph., additional, Grandgirard, V., additional, Latu, G., additional, Passeron, C., additional, and Thomine, O., additional

Published
2013
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32. Fusion plasma turbulence described by modified sandpile dynamics.

Author

Ghendrih P, Ciraolo G, Dif-Pradalier G, Norscini C, Sarazin Y, Abiteboul J, Cartier-Michaud T, Garbet X, Grandgirard V, and Strugarek A

Abstract

Transport in fusion plasmas is investigated with modified sandpile models. Based on results from more complete simulations, the sandpile model is modified in steps. Models with a constant source are obtained by coupling two sandpiles. Decoupling the mean field from the bursts allows one to develop a reduced model which captures some of the key features of flux-driven simulations. In the latter sandpile model, turbulent transport is mediated by the burst field while the mean-field gradient governs the transfer to the bursts. This allows one to investigate spreading, namely turbulent transport into stable regions, and transport barriers, regions where the transfer from the mean field to turbulence is reduced. Both cases are found to exhibit intermittent behaviors when the system undergoes spontaneous transitions between different transport regimes. Finally, one couples to the sandpile algorithm a species evolution algorithm that assigns a quality factor to each site. The latter appears to self-generate corrugations, or micro-barriers. These are found to naturally cluster radially in structures that are large enough to impact confinement. The mechanisms introduced to alleviate the clustering, destabilization of the corrugation by overloading and by secondary instabilities at critical radial extents, are shown to generate long-range relaxation events in space and in time with quasiperiodic reorganization of the corrugation pattern.

Published
2014
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