Publications HAL du labo/EPI 89902;541926;1043006

2021

Journal articles

titre
Approaching detachment in I-mode—response of core confinement and the edge pedestal in the ASDEX Upgrade tokamak
auteur
T. Happel, M.L. Reinke, D. Silvagni, M. Bernert, O. Grover, Pascale Hennequin, A.E. Hubbard, U. Plank, E. Trier, D. Brida, P. David, R. Fischer, L. Gil, K. Höfler, P. Manz, R.M. Mcdermott, A. Merle, U. Stroth, E. Viezzer, M. Willensdorfer, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
Nuclear Fusion, IOP Publishing, 2021, 61 (3), pp.036026. ⟨10.1088/1741-4326/abd7b7⟩
DOI
DOI : 10.1088/1741-4326/abd7b7
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titre
Overview of the isotope effects in the ASDEX Upgrade tokamak
auteur
P Schneider, Pascale Hennequin, N Bonanomi, M Dunne, G Conway, U Plank
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2021, 63 (6), pp.064006. ⟨10.1088/1361-6587/abf540⟩
resume
In recent years, measurements on the ASDEX Upgrade tokamak and modelling performed for plasmas with hydrogen (H) and deuterium (D) as the main gas have improved our understanding of the ion mass dependencies in fusion plasmas. The observed isotope effects can be explained with established physics processes which highlight the importance of treating heat transport with coupled electron and ion heat channels. In the core of electron heated L-mode plasmas, the mass dependence of the electron–ion equipartition results in a reduction of $q_\textrm{i}/q_\textrm{e}$ with increasing ion mass. Combined with higher profile stiffness in the ions compared to the electrons, this results in improved core confinement for higher ion masses. At the edge of L-mode plasmas where a higher collisionality is observed, parallel electron dynamics is fundamental for turbulence. The parallel electron dynamics term in the gyrokinetic equations directly depends on $m_\textrm{i}/m_\textrm{e}$, resulting in a different kinetic response with different ion mass. Higher turbulent fluxes are expected with lower ion mass. This is consistent with the difference in $L_{n\textrm{e}}$ observed in the experiment. The mass dependence of turbulent transport in the L-mode edge has direct consequences for the L–H transition. More heating power is required to enter the H-mode at lower mass ($P_\textrm{L-H}^\textrm{H}\sim 2 P_\textrm{L-H}^\textrm{D}$). This is expected if the critical E × B shearing rate $\gamma_{E\times B}$ is important for the transition from L to H mode. In the H-mode pedestal, $\gamma_{E\times B}$ remains important to regulate the turbulent transport. The electrons do not contribute to $\gamma_{E\times B}$ and the enhanced equipartition for lower ion masses causes a shift from the ion channel to the electron channel in the absolute heat fluxes. Consequently, the inter edge localised mode (ELM) transport is found to be higher with lower isotope mass. This enhanced transport in H can prevent the pedestal from reaching the peeling–ballooning stability boundary with engineering parameters where D plasmas are peeling–ballooning unstable. Increasing the triangularity reduces the inter ELM transport in H stronger than in comparable D plasmas. For matched pedestal top and matched heat sources, the core heat transport is found to be similar for H and D when the fast-ion content is low. When ion temperature gradient turbulence stabilisation by fast ions becomes relevant, the mass dependent fast-ion slowing down results in higher fast-ion content in D and therefore in a reduction of ion heat transport in the core. Then, even for matched pedestals $\tau_\textrm{E}^\textrm{D}\gt\tau_\textrm{E}^\textrm{H}$.
DOI
DOI : 10.1088/1361-6587/abf540
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https://hal.sorbonne-universite.fr/hal-03231161/file/Schneider_2021_Plasma_Phys._Control._Fusion_63_064006.pdf BibTex
titre
Fast-ion pressure dominating the mass dependence of the core heat transport in ASDEX Upgrade H-modes
auteur
P.A. Schneider, N. Bonanomi, C. Angioni, M. Weiland, M. Cavedon, P. David, R. Fischer, Pascale Hennequin, J. Hobirk, A. Kappatou, B. Kurzan, R.M. Mcdermott, U. Plank, T. Pütterich, F. Ryter, M. Willensdorfer
article
Nuclear Fusion, IOP Publishing, 2021, 61 (3), pp.036033. ⟨10.1088/1741-4326/abd95e⟩
resume
H-mode plasmas in ASDEX Upgrade (AUG) using different hydrogen isotopes are analysed with respect to their core transport properties. The experimental results are discussed and we present gyrokinetic simulations which are able to reproduce the experimental observations. A novel strategy allows us to disentangle core and pedestal physics by mitigating the isotopic dependence of pedestal properties while keeping the heat and particle sources the same. Matched pedestal profiles are obtained between hydrogen (H) and deuterium (D) plasmas when increasing the triangularity in H plasmas with respect to D plasmas. In the core of these plasmas little isotopic dependence is observed when the fast-ion content is low Wfast/Wth < 1/3. Quasi-linear modelling with TGLF reproduces the experimental trends under these conditions. For larger fast-ion fractions an isotope dependence is observed in the core heat transport. This is related to a difference in fast-ion stabilization of turbulent transport. The fast-ion pressure in H and D plasmas is different due to the mass dependence in the fast-ion slowing down time as well as to operational restrictions when heating with H neutral beam injection (H-NBI) or D-NBI. Typically, Wfast,H < 1/2Wfast,D for comparable NBI heating powers in AUG. The gyrokinetic analysis shows that linear growth rates of ITG modes do not show a pure gyro-Bohm mass dependence, but follow the experimentally observed mass dependence when taking collisions, EM-effects and fast ions into account. Non-linear gyrokinetic simulations reproduce the experimental heat fluxes for different isotopes when fast ions are included. This highlights the role of the fast-ion pressure as a key element to explain the observed differences in the core of H and D plasmas.
DOI
DOI : 10.1088/1741-4326/abd95e
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https://hal.archives-ouvertes.fr/hal-03242646/file/88618_paschneider_isotopes-hmode_revised.pdf BibTex
titre
Poloidally resolved measurements of the perpendicular propagation velocity of density fluctuations in ASDEX Upgrade L-mode plasmas
auteur
K Höfler, T Happel, Pascale Hennequin, U Stroth, M Cavedon, R Dux, R Fischer, R Mcdermott, E Poli, C Schuster, E Wolfrum
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2021, 63 (3), pp.035020. ⟨10.1088/1361-6587/abd896⟩
resume
Poloidal asymmetries of the propagation velocity of density fluctuations perpendicular to the magnetic field measured with Doppler reflectometry have been reported in several magnetic confinement plasma devices. Careful analysis of a large variety of different low confinement mode plasma scenarios performed at the ASDEX Upgrade tokamak does not reveal such an asymmetry outside the uncertainties of the evaluation process of the measurement data. The perpendicular velocity is investigated between mid-radius and the plasma edge and follows the poloidal dependence of the E × B drift velocity regardless of the probed turbulence structure size. Compared to measurements of a charge exchange recombination spectroscopy diagnostic this points towards a significantly smaller phase velocity than the E × B drift velocity. The analysis technique is presented in a representative discharge together with a sensitivity study of the impact of density, magneto hydrodynamic equilibrium and diagnostic alignment on the interpretation of the measured Doppler shift using ray tracing and thus on poloidal asymmetries. Three more highly different plasma scenarios with poloidally symmetric velocity profiles are shown.
DOI
DOI : 10.1088/1361-6587/abd896
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https://hal.archives-ouvertes.fr/hal-03242658/file/Ho%CC%88fler_2021_Plasma_Phys._Control._Fusion_63_035020.pdf BibTex

2020

Journal articles

titre
Connecting the global H-mode power threshold to the local radial electric field at ASDEX Upgrade
auteur
M. Cavedon, G. Birkenmeier, T. Pütterich, F. Ryter, E. Viezzer, E. Wolfrum, R. Dux, T. Happel, Pascale Hennequin, U. Plank, U. Stroth, M. Willensdorfer
article
Nuclear Fusion, IOP Publishing, 2020, 60 (6), pp.066026. ⟨10.1088/1741-4326/ab8777⟩
DOI
DOI : 10.1088/1741-4326/ab8777
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https://hal.archives-ouvertes.fr/hal-02889083/file/CavedonNF20accepted.pdf BibTex
titre
Turbulence driven widening of the near-SOL power width in ASDEX Upgrade H-Mode discharges
auteur
T. Eich, P. Manz, R.J. Goldston, Pascale Hennequin, P. David, M. Faitsch, B. Kurzan, B. Sieglin, E. Wolfrum
article
Nuclear Fusion, IOP Publishing, 2020, 60 (5), pp.056016. ⟨10.1088/1741-4326/ab7a66⟩
DOI
DOI : 10.1088/1741-4326/ab7a66
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https://hal.archives-ouvertes.fr/hal-02565895/file/NF-103613_Proof_hi.pdf BibTex
titre
Design of a variable frequency comb reflectometer system for the ASDEX Upgrade tokamak
auteur
T. Happel, W. Kasparek, Pascale Hennequin, K. Höfler, Cyrille Honoré, Asdex Upgrade Team
article
Plasma Science and Technology, 2020, 22 (6), pp.064002. ⟨10.1088/2058-6272/ab618c⟩
resume
Comb reflectometers offer the advantage of measuring several radial positions in plasma simultaneously. This allows for the investigation of fast timescales during L-H transitions, I-phases, I-mode bursts, transients during heat wave propagation, etc. A drawback of many present-day systems is that they use a fixed frequency difference between the probing frequencies. Hence, although the central probing frequency can be varied, the probing frequency difference is usually fixed. The new design presented in this work uses an advanced microwave generation and detection scheme, which allows for arbitrary probing frequencies and probing frequency separations.
DOI
DOI : 10.1088/2058-6272/ab618c
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https://hal.archives-ouvertes.fr/hal-02571938/file/paper.pdf BibTex

2019

Journal articles

titre
Stationarity of I-mode operation and I-mode divertor heat fluxes on the ASDEX Upgrade tokamak
auteur
T. Happel, M. Griener, D. Silvagni, S. J. Freethy, Pascale Hennequin, F. Janky, P. Manz, D. Prisiazhniuk, F. Ryter, M. Bernert, D. Brida, T. Eich, M. Faitsch, L. Gil, L. Guimarais, A. Merle, D. Nille, J R Pinzón, B. Sieglin, U. Stroth, E. Viezzer
article
NUCLEAR MATERIALS AND ENERGY, 2019, 18, pp.159 - 165. ⟨10.1016/j.nme.2018.12.022⟩
resume
Recent I-mode investigations from the ASDEX Upgrade tokamak are reported. It is shown that neutral-beam-injection heated I-modes can be stationary, which is important in terms of extrapolability towards future fusion devices. Furthermore, detailed studies on the weakly coherent mode are reported. In particular, experimental observations point towards its existence in L-mode, before I-mode starts. Moreover, its impact on density and temperature fluctuations is evaluated. Studies of stationary divertor heat fluxes show that in I-mode, the upstream power fall-off length is between those observed in L-mode and H-mode, and it is connected to the scrape-off layer temperature fall-off length. Moreover, analysis of transient divertor heat loads shows that intermittent turbulent events, observed in the confinement region and linked to the weakly coherent mode, are responsible for a significant part of divertor heat loads.
DOI
DOI : 10.1016/j.nme.2018.12.022
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titre
Physics research on the TCV tokamak facility: from conventional to alternative scenarios and beyond
auteur
S. Coda, M. Agostini, R. Albanese, S. Alberti, E. Alessi, S. Allan, J. Allcock, R. Ambrosino, H. Anand, Y. Andrèbe, H. Arnichand, F. Auriemma, J.M. Ayllon-Guerola, F. Bagnato, J. Ball, M. Baquero-Ruiz, A.A. Beletskii, M. Bernert, W. Bin, P. Blanchard, T.C. Blanken, J.A. Boedo, O. Bogar, T. Bolzonella, F. Bombarda, N. Bonanomi, F. Bouquey, C. Bowman, D. Brida, J. Bucalossi, J. Buermans, H. Bufferand, P. Buratti, G. Calabró, L. Calacci, Y. Camenen, D. Carnevale, F. Carpanese, M. Carr, L. Carraro, A. Casolari, F. Causa, J. Čeřovský, O. Chellaï, P. Chmielewski, D. Choi, N. Christen, G. Ciraolo, L. Cordaro, S. Costea, N. Cruz, A. Czarnecka, A. Dal Molin, P. David, J. Decker, H. De Oliveira, D. Douai, M.B. Dreval, B. Dudson, M. Dunne, B.P. Duval, T. Eich, S. Elmore, O. Embréus, B. Esposito, M. Faitsch, M. Farník, A. Fasoli, N. Fedorczak, F. Felici, S. Feng, X. Feng, G. Ferro, O. Février, O. Ficker, Alexandre Fil, M. Fontana, L. Frassinetti, I. Furno, D.S. Gahle, D. Galassi, K. Ga\lązka, A. Gallo, C. Galperti, S. Garavaglia, J. Garcia, M. Garcia-Muñoz, A.J. Garrido, I. Garrido, J. Gath, B. Geiger, G. Giruzzi, M. Gobbin, T.P. Goodman, G. Gorini, M. Gospodarczyk, G. Granucci, J.P. Graves, M. Gruca, T. Gyergyek, A. Hakola, T. Happel, G.F. Harrer, J. Harrison, E. Havlíčková, J. Hawke, S. Henderson, P. Hennequin, L. Hesslow, D. Hogeweij, J.-Ph. Hogge, C. Hopf, M. Hoppe, J. Horáček, Z. Huang, A. Hubbard, A. Iantchenko, V. Igochine, P. Innocente, C. Ionita Schrittwieser, H. Isliker, R. Jacquier, A. Jardin, A. Kappatou, A. Karpushov, P.-V. Kazantzidis, D. Keeling, N. Kirneva, M. Komm, M. Kong, J. Kovacic, N. Krawczyk, O. Kudlacek, T. Kurki-Suonio, R. Kwiatkowski, B. Labit, E. Lazzaro, B. Linehan, B. Lipschultz, X. Llobet, R. Lombroni, V.P. Loschiavo, T. Lunt, E. Macusova, J. Madsen, E. Maljaars, P. Mantica, M. Maraschek, C. Marchetto, A. Marco, A. Mariani, C. Marini, Y. Martin, F. Matos, R. Maurizio, B. Mavkov, D. Mazon, P. Mccarthy, R. Mcdermott, V. Menkovski, A. Merle, H. Meyer, D. Micheletti, F. Militello, K. Mitosinkova, J. Mlynář, V. Moiseenko, P.A. Molina Cabrera, J. Morales, J.-M. Moret, A. Moro, R.T. Mumgaard, V. Naulin, R.D. Nem, F. Nespoli, A.H. Nielsen, S.K. Nielsen, M. Nocente, S. Nowak, N. Offeddu, F.P. Orsitto, R. Paccagnella, A. Palha, G. Papp, A. Pau, R.O. Pavlichenko, A. Perek, V. Pericoli Ridolfini, F. Pesamosca, V. Piergotti, L. Pigatto, P. Piovesan, C. Piron, V. Plyusnin, E. Poli, L. Porte, G. Pucella, M.E. Puiatti, T. Pütterich, M. Rabinski, J. Juul Rasmussen, T. Ravensbergen, M. Reich, H. Reimerdes, F. Reimold, C. Reux, D. Ricci, P. Ricci, N. Rispoli, J. Rosato, S. Saarelma, M. Salewski, A. Salmi, O. Sauter, M. Scheffer, Ch. Schlatter, B.S. Schneider, R. Schrittwieser, S. Sharapov, R.R. Sheeba, U. Sheikh, R. Shousha, M. Silva, J. Sinha, C. Sozzi, M. Spolaore, L. Stipani, P. Strand, T. Tala, A.S. Tema Biwole, A.A. Teplukhina, D. Testa, C. Theiler, A. Thornton, G. Tomaž, M. Tomes, M.Q. Tran, C. Tsironis, C.K. Tsui, Joanna Urban, M. Valisa, M. Valla, D. Van Vugt, S. Vartanian, O. Vasilovici, K. Verhaegh, L. Vermare, N. Vianello, E. Viezzer, W.A.J. Vijvers, F. Villone, I. Voitsekhovitch, N.M.T. Vu, N. Walkden, T. Wauters, M. Weiland, H. Weisen, M. Wensing, M. Wiesenberger, G. Wilkie, M. Wischmeier, K. Wu, M. Yoshida, R. Zagorski, P. Zanca, J. Zebrowski, A. Zisis, M. Zuin, The Eurofusion Mst1 Team
article
Nuclear Fusion, 2019, 59 (11), pp.112023. ⟨10.1088/1741-4326/ab25cb⟩
resume
The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the device’s unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly non-inductive H-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power ‘starvation’ reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached L-mode phase, increasing the outer connection length reduces the in–out heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variable-configuration baffles and possibly divertor pumping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECRH and 1 MW neutral beam injection heating will be added.
DOI
DOI : 10.1088/1741-4326/ab25cb
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titre
Experimental investigation of the tilt angle of turbulent structures in the core of fusion plasmas
auteur
Javier Pinzon, T. Happel, Pascale Hennequin, Clemente Angioni, Teresa Estrada, Alexander Lebschy, Ulrich Stroth, The Asdex Upgrade Team
article
Nuclear Fusion, 2019, 59, pp.074002. ⟨10.1088/1741-4326/ab227e⟩
resume
The tilt angle of turbulent structures stands for the anisotropy of turbulence which is essential for understanding the dynamics of magnetized plasmas. It is a quantity predicted by theory and simulations, that provides information on the interplay between turbulence, micro-instabilities and plasma flows. A new method for measuring the tilt angle of turbulent structures in the core region of fusion plasmas using Doppler reflectometry is presented. First measurements of this type on the ASDEX Upgrade tokamak have shown a significant difference of tilt angle for different plasma conditions. The dominance of sheared flows in determining the structure tilt is experimentally demonstrated for different turbulence regimes.
DOI
DOI : 10.1088/1741-4326/ab227e
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titre
Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
auteur
B. Labit, T. Eich, G.F. Harrer, E. Wolfrum, M. Bernert, M.G. Dunne, L. Frassinetti, Pascale Hennequin, R. Maurizio, A. Merle, H. Meyer, S. Saarelma, U. Sheikh, The Eurofusion Mst1 Team
article
Nuclear Fusion, 2019, 59 (8), pp.086020. ⟨10.1088/1741-4326/ab2211⟩
resume
Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.
DOI
DOI : 10.1088/1741-4326/ab2211
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titre
Measurement of the tilt angle of turbulent structures in magnetically confined plasmas using Doppler reflectometry
auteur
Javier Pinzon, Teresa Estrada, T. Happel, Pascale Hennequin, E. Blanco, Ulrich Stroth
article
Plasma Physics and Controlled Fusion, 2019, ⟨10.1088/1361-6587/ab394d⟩
resume
The mean tilt angle of turbulent structures is a key element for describing the turbulence and its interplay with plasma flows in magnetically confined plasmas. It is a quantity predicted by theories and gyrokinetic simulations, which can provide information on the type of the dominant micro-instability, and also on the turbulence anisotropy induced by sheared flows. A new method for measuring the tilt angle of turbulent structures using Doppler reflectometry has been recently introduced [J R Pinzón et al 2019 Nucl. Fusion 59 074002]. It is based on the time delay of the cross-correlation between microwaves backscattered at radially displaced positions. In this paper, the method is presented in detail and is successfully applied on the ASDEX Upgrade tokamak and the TJ-II stellarator. Measurements of the tilt angle in the core of both machines are reported, in the TJ-II case, for the first time.
DOI
DOI : 10.1088/1361-6587/ab394d
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titre
ELM-induced cold pulse propagation in ASDEX Upgrade
auteur
Elisée Trier, E. Wolfrum, M. Willensdorfer, Q. Yu, M. Hoelzl, F. Orain, F. Ryter, C. Angioni, M. Bernert, M. G Dunne, S. S Denk, J. C Fuchs, R. Fischer, Pascale Hennequin, B. Kurzan, F. Mink, A. Mlynek, T. Odstrcil, P. a Schneider, U. Stroth, G. Tardini, B. Vanovac, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
Plasma Physics and Controlled Fusion, 2019, 61 (4), pp.045003. ⟨10.1088/1361-6587/aaf9c3⟩
resume
In ASDEX Upgrade, the propagation of cold pulses induced by type-I edge localized modes (ELMs) is studied using electron cyclotron emission measurements, in a dataset of plasmas with moderate triangularity. It is found that the edge safety factor or the plasma current are the main determining parameters for the inward penetration of the T e perturbations. With increasing plasma current the ELM penetration is more shallow in spite of the stronger ELMs. Estimates of the heat pulse diffusivity show that the corresponding transport is too large to be representative of the inter-ELM phase. Ergodization of the plasma edge during ELMs is a possible explanation for the observed properties of the cold pulse propagation, which is qualitatively consistent with non-linear magneto-hydro-dynamic simulations.
DOI
DOI : 10.1088/1361-6587/aaf9c3
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Conference papers

titre
Inner versus outer ExB shear layer: an attempt to radially localize the L-H transition
auteur
M. Cavedon, R. Dux, T. Happel, Pascale Hennequin, U. Plank, T. Pütterich, F. Ryter, U. Stroth, E. Viezzer, E. Wolfrum, The Asdex Upgrade Team
article
46th European Physical Society Conference on Plasma Physics, Jul 2019, Milan, Italy
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titre
Ramping up RF power and increasing pulse length in the full tungsten environment of WEST
auteur
C. Bourdelle, J. Bucalossi, N. Fedorczak, T. Loarer, E. Moreau, J.-F Tsitrone, V Artaud, S. Brezinsek, H. Bufferand, L. Colas, Y. Corre, X. Courtois, L. Delpech, C. Desgranges, P. Devynck, T Dittmar, A Drenik, D Douai, R. Dumont, F Durodié, A. Ekedahl, J. Garcia, J Gaspar, C. Gil, M. Goniche, J. Gunn, W Helou, J. Hillairet, P Hennequin, C Klepper, E Lerche, P. Maget, Y Marandet, D. Mazon, O Meyer, G. Lombard, P. Manas, P. Mollard, J. Morales, E. Nardon, R. Nouailletas, M Peret, Y. Peysson, C. Reux, F. Saint-Laurent, J.-L Schwob, P. Tamain, G. Urbanczyk, S Vartanian, L Vermare, D Vézinet, X Yang
article
46th EPS Conference on Plasma Physics, Jul 2019, Milan, Italy
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https://hal.archives-ouvertes.fr/hal-02395304/file/Bourdelle_EPS19_O5.101.pdf BibTex
titre
Turbulence driven widening of the near-SOL power width for H-mode operation in ASDEX Upgrade
auteur
T. Eich, R.J. Goldston, P. Manz, Pascale Hennequin, P. David, M. Faitsch, B. Kurzan, B. Sieglin, E. Wolfrum, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
46th European Physical Society Conference on Plasma Physics, Jul 2019, Milan, Italy
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titre
Observations on edge GAM-turbulence interactions in ASDEX Upgrade
auteur
G.C Conway, F. Palermo, I. Novikau, P. Manz, P. Simon, Pascale Hennequin, The Asdex Upgrade Team
article
46th European Physical Society Conference on Plasma Physics, Jul 2019, Milan, Italy
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2018

Journal articles

titre
Observations of core ion cyclotron emission on ASDEX Upgrade tokamak
auteur
R. Ochoukov, V. Bobkov, B. Chapman, R. Dendy, M. Dunne, H. Faugel, M. García Muñoz, B. Geiger, Pascale Hennequin, K. G. Mcclements, D. Moseev, S. Nielsen, J. Rasmussen, P. Schneider, M. Weiland, J.-M. Noterdaeme
article
Review of Scientific Instruments, American Institute of Physics, 2018, 89 (10), pp.10J101. ⟨10.1063/1.5035180⟩
DOI
DOI : 10.1063/1.5035180
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titre
Validation of gyrokinetic simulations with measurements of electron temperature fluctuations and density-temperature phase angles on ASDEX Upgrade
auteur
S. J. Freethy, T. Görler, A. J. Creely, G. D. Conway, S. S. Denk, T. Happel, C. Koenen, Pascale Hennequin, A. E. White
article
Physics of Plasmas, American Institute of Physics, 2018, 25 (5), pp.055903. ⟨10.1063/1.5018930⟩
resume
Measurements of turbulent electron temperature fluctuation amplitudes, δTe⊥/Te, frequency spectra, and radial correlation lengths, Lr(Te⊥), have been performed at ASDEX Upgrade using a newly upgraded Correlation ECE diagnostic in the range of scales k⊥<1.4 cm−1, kr<3.5 cm−1 (k⊥ρs<0.28 and krρs<0.7). The phase angle between turbulent temperature and density fluctuations, αnT, has also been measured by using an ECE radiometer coupled to a reflectometer along the same line of sight. These quantities are used simultaneously to constrain a set of ion-scale non-linear gyrokinetic turbulence simulations of the outer core (ρtor = 0.75) of a low density, electron heated L-mode plasma, performed using the gyrokinetic simulation code, GENE. The ion and electron temperature gradients were scanned within uncertainties. It is found that gyrokinetic simulations are able to match simultaneously the electron and ion heat flux at this radius within the experimental uncertainties. The simulations were performed based on a reference discharge for which δTe⊥/Te measurements were available, and Lr(Te⊥) and αnT were then predicted using synthetic diagnostics prior to measurements in a repeat discharge. While temperature fluctuation amplitudes are overestimated by >50% for all simulations within the sensitivity scans performed, good quantitative agreement is found for Lr(Te⊥) and αnT. A validation metric is used to quantify the level of agreement of individual simulations with experimental measurements, and the best agreement is found close to the experimental gradient values.
DOI
DOI : 10.1063/1.5018930
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titre
Poloidal asymmetries of flows in the Tore Supra tokamak
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, X. Garbet, Cyrille Honoré, F. Clairet, J-C. Giacalone, Pierre Morel, A. Storelli, Tore Supra Team
article
Physics of Plasmas, American Institute of Physics, 2018, 25 (2), pp.020704. ⟨10.1063/1.5022122⟩
resume
Simultaneous measurements of binormal velocity of density fluctuations using two separate Doppler backscattering systems at the low field side and at the top of the plasma show significant poloidal asymmetry. The measurements are performed in the core region between the radii 0.7 < ρ  <  0.95, over a limited number of L-mode discharges covering a wide range of plasma conditions in the Tore Supra tokamak. A possible generation mechanism by the ballooned structure of the underlying turbulence, in the form of convective cells, is proposed for explaining the observation of these poloidally asymmetric mean flows.
DOI
DOI : 10.1063/1.5022122
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titre
Drift-wave observation in a toroidal magnetized plasma and comparison with a modified Hasegawa-Wakatani model
auteur
Peter Donnel, Pierre Morel, Cyrille Honoré, Özgür Gürcan, V. Pisarev, C. Metzger, Pascale Hennequin
article
Physics of Plasmas, American Institute of Physics, 2018, 25 (6), pp.062127. ⟨10.1063/1.5025141⟩
resume
This paper presents the results of fluctuation measurements in a toroidal magnetized plasma, using Langmuir probes, and comparisons between the observed frequency modes and a Hasegawa-Wakatani model including curvature, adapted to the specifics of the toroidal device. More precisely, two kinds of signals are detected in the presence of an additional vertical magnetic field in the region of significant density and potential gradients. A high frequency, propagating component, corresponding to dissipative drift-waves in the curved magnetic field, is observed and the frequency and typical wavelengths are found to be in good agreement with the linear Hasegawa-Wakatani model including curvature effects. A second, low frequency component is observed at lower frequencies and is shown to correspond to large scale vertical electrostatic field structures. A significantly high level of cross correlation is observed between these two signals, with an identifiable time delay, which suggests an analogy to the time delayed quasi-periodic dynamics in predator-prey systems, and a similar phenomenon is observed between zonal flows and microturbulence in tokamaks and other magnetised plasma systems.
DOI
DOI : 10.1063/1.5025141
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Conference papers

titre
Plasma turbulence structure in the ASDEX Upgrade tokamak, Overview
auteur
Pascale Hennequin, T. Happel, J R Pinzón, Simon Freethy, T. Görler, G. D. Conway, C. Angioni, Elisée Trier, P. Schneider, U. Stroth, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
2nd Asia-Pacific Conference on Plasma Physics, 16 Nov 2018, Nov 2018, Kanazawa, Japan
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titre
WEST first plasma operation with all tungsten PFC
auteur
J. Bucalossi, C. Bourdelle, N. Fedorczak, T. Loarer, P. Moreau, E. Tsitronne, J.-F. Artaud, S. Brezinsek, H. Bufferand, X. Courtois, L. Delpech, C. Desgranges, P. Devynck, D. Douai, R. Dumont, A. Ekedahl, J. Garcia, J. Garpar, C. Gil, M. Goniche, J. Gunn, W. Helou, Pascale Hennequin, C. Keppler, P. Maget, Y. Marandet, D. Mazon, O. Meyer, J. Morales, E. Nardon, R. Nouailletas, Y. Peysson, Cedric Reux, F. Saint-Laurent, P. Tamain, Laure Vermare, D. Vezinet, The West Team
article
27th IAEA Fusion Energy Conference (FEC 2018), Oct 2018, Ahmenabad, India
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Plasma shape and fueling dependence on the small ELMs regime in TCV and AUG IAEA Fusion Energy Conference 2018 (IAEA FEC 2018)
auteur
B. Labit, T. Eich, G. Harrer, M. Bernert, H. de Oliveira, M. Dunne, L. Frassinetti, Pascale Hennequin, R. Maurizio, A. Merle, H. Meyer, P. Molina, J. Stober, E. Wolfrum, The Tcv Team, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
IAEA Fusion Energy Conference 2018 (IAEA FEC 2018), Oct 2018, Ahmenabad, India. pp.EX 2-5
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titre
Experimental investigation of the mean turbulent structure tilt angle in the ASDEX Upgrade tokamak
auteur
J R Pinzón, C. Angioni, T. Happel, Pascale Hennequin, E. Blanco, T. Estrada, U. Stroth, Mast The Asdex Upgrade, Teams Tcv
article
45th European Physical Society Conference on Plasma Physics, Jul 2018, Prague, Czech Republic
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titre
Poloidal asymmetry and dynamics of perpendicular flow in Tore Supra plasmas
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, Pierre Morel, A. Storelli, Peter Donnel, X. Garbet, J-C. Giacalone, And Tore Supra Team
article
45th European Physical Society Conference on Plasma Physics, Jul 2018, Prague, Czech Republic. pp.P5.1062
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titre
Experimental separation of core transport and edge pedestal isotope dependencies by variation of the plasma shape
auteur
P. Schneider, C. Angioni, M. Dunne, M. Cavedon, Pascale Hennequin, B. Kurzan, P. Manas, F. Mink, R.M. Mcdermott, F. Ryter, M. Willensdorfer, E. Wolfrum, The Asdex Upgrade Team
article
45th European Physical Society Conference on Plasma Physics, Jul 2018, Prague, Czech Republic. pp.P5.1078
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titre
Turbulence measurements and gyrokinetic validation at ASDEX Upgrade
auteur
Simon Freethy, T. Görler, A. J. Creely, G. D. Conway, S. Denk, T. Happel, Pascale Hennequin, A. E. White, The Asdex Upgrade Team
article
45th European Physical Society Conference on Plasma Physics, Jul 2018, Prague, Czech Republic. pp.O4.109
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titre
Studying ELM filaments with Doppler reflectometry in ASDEX Upgrade
auteur
Elisée Trier, Pascale Hennequin, J R Pinzón, M. Hoelzl, G. D. Conway, T. Happel, G. Harrer, F. Mink, F. Orain, E. Wolfrum, The Asdex Upgrade Team, The Mst1 Eurofusion Team
article
45th European Physical Society Conference on Plasma Physics (EPS2018), Jul 2018, Prague, Czech Republic. pp.P1.1023
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titre
The I-mode confinement regime on the ASDEX Upgrade tokamak: scrape-off layer properties and investigation of stationary and transient divertor heat loads
auteur
T. Happel, M. Griener, D. Silvagni, Simon Freethy, Pascale Hennequin, F. Janky, P. Manz, D. Nille, F. Ryter, The Asdex Upgrade Team
article
23rd International Conference on Plasma Surface Interactions in Controlled Fusion Devices, Jun 2018, Princeton, United States
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titre
Echelles et dynamique de la turbulence, observations par diffusion de la lumière dans les plasmas de tokamak
auteur
Pascale Hennequin
article
15eme Congres de la SFP division Plasmas, Jun 2018, Bordeaux, France
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titre
Fluctuations measurements from core to edge: examples of constraints for confrontation to simulations
auteur
Pascale Hennequin
article
May Mini Workshop on the interplay of turbulent transport in divertor, SOL, edge and core regions and impact on performance, May 2018, Cadarache, France
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titre
Advances in turbulence measurements using new Correlation ECE and nT-phase diagnostics at ASDEX Upgrade
auteur
Simon Freethy, T. Görler, A. J. Creely, G. D. Conway, T. Happel, C. Könen, Pascale Hennequin, A. E. White, The Asdex Upgrade Team
article
20th Joint Workshop on Electron Cyclotron Emission and Resonance Heating (EC-20), May 2018, Greifswald, Germany
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titre
Ion cyclotron emission (ICE) study on the ASDEX Upgrade tokamak
auteur
R. Ochoukov, V. Bobkov, M. Dunne, H. Faugel, M. García Muñoz, B. Geiger, Pascale Hennequin, K. Mcclement, D. Moseev, S. Nielsen, J. Rasmussen, P. Schneider, M. Weiland, J.-M. Noterdaeme, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
HTPD 2018: 22nd Topical Conference on High Temperature Plasma Diagnostics, Apr 2018, San Diego, California, United States
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Poster communications

titre
Signatures of non-local electron heat transport in fusion plasmas.
auteur
K. Höfler, T. Happel, Pascale Hennequin, F. Ryter, U. Stroth, Team Asdex Upgrade
article
DPG-Fruehjahrstagung der Sektion AMOP (DPG 2018), Mar 2018, Bremen, Germany. 2018
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2017

Journal articles

titre
Overview of ASDEX Upgrade results
auteur
A. Kallenbach, D. Aguiam, L. Aho-Mantila, C. Angioni, N. Arden, R. Arredondo Parra, O. Asunta, M. Baar, M. Balden, K. Behler, A. Bergmann, J. Bernardo, M. Bernert, M. Beurskens, A. Biancalani, R. Bilato, G. Birkenmeier, V. Bobkov, A. Bock, A. Bogomolov, T. Bolzonella, B. Boswirth, C. Bottereau, A. Bottino, H. Brand, S. Brezinsek, D. Brida, F. Brochard, C. Bruhn, J. Buchanan, A. Buhler, A. Burckhart, D. Cambon-Silva, Y. Camenen, P. Carvalho, G. Carrasco, C. Cazzaniga, M. Carr, D. Carralero, L. Casali, C. Castaldo, M. Cavedon, C. Challis, A. Chankin, I. Chapman, F. Clairet, I. Classen, S. Coda, R. Coelho, J. W. Coenen, L. Colas, G. Conway, S. Costea, D. P. Coster, G. Croci, G. Cseh, A. Czarnecka, O. d'Arcangelo, C. Day, R. Delogu, P. Marne, S. Denk, P. Denner, M. Dibon, R. d'Inca, A. Di Siena, D. Douai, A. Drenik, R. Drube, M. Dunne, B. P. Duval, R. Dux, T. Eich, S. Elgeti, K. Engelhardt, B. Erdos, I. Erofeev, B. Esposito, E. Fable, M. Faitsch, U. Fantz, H. Faugel, F. Felici, S. Fietz, A. Figueredo, R. Fischer, O. Ford, L. Frassinetti, S. Freethy, M. Froschle, G. Fuchert, J. C. Fuchs, H. Funfgelder, K. Galazka, J. Galdon-Quiroga, A. Gallo, Y. Gao, S. Garavaglia, M. Garcia-Munoz, B. Geiger, C. Cianfarani, L. Giannone, E. Giovannozzi, C. Gleason-Gonzalez, S. Gloggler, M. Gobbin, T. Gorler, T. Goodman, G. Gorini, D. Gradic, A. Grater, G. Granucci, H. Greuner, M. Griener, M. Groth, A. Gude, S. Gunter, L. Guimarais, G. Haas, A. H. Hakola, C. Ham, T. Happel, J. Harrison, D. Hatch, V. Hauer, T. Hayward, B. Heinemann, S. Heinzel, T. Hellsten, S. Henderson, P. Hennequin, A. Herrmann, E. Heyn, F. Hitzler, J. Hobirk, M. Holzl, T. Hoschen, J. H. Holm, C. Hopf, F. Hoppe, L. Horvath, A. Houben, A. Huber, V. Igochine, T. Ilkei, I. Ivanova-Stanik, W. Jacob, A. S. Jacobsen, J. Jacquot, F. Janky, A. Jardin, F. Jaulmes, F. Jenko, T. Jensen, E. Joffrin, C. Kasemann, S. Kalvin, M. Kantor, A. Kappatou, O. Kardaun, J. Karhunen, S. Kasilov, W. Kernbichler, D. Kim, S. Kimmig, A. Kirk, H. -J. Klingshirn, F. Koch, G. Kocsis, A. Kohn, M. Kraus, K. Krieger, A. Krivska, A. Kramer-Flecken, T. Kurki-Suonio, B. Kurzan, K. Lackner, F. Laggner, P. T. Lang, P. Lauber, N. Lazanyi, A. Lazaros, A. Lebschy, L. Li, M. Li, Y. Liang, B. Lipschultz, Y. Liu, A. Lohs, N. C. Luhmann, T. Lunt, A. Lyssoivan, J. Madsen, H. Maier, O. Maj, J. Mailloux, E. Maljaars, P. Manas, A. Mancini, A. Manhard, M. -E. Manso, P. Mantica, M. Mantsinen, P. Manz, M. Maraschek, C. Martens, P. Martin, L. Marrelli, A. Martitsch, S. Mastrostefano, A. Mayer, M. Mayer, D. Mazon, P. J. Mccarthy, R. Mcdermott, G. Meisl, H. Meister, A. Medvedeva, P. Merkel, R. Merkel, A. Merle, V. Mertens, D. Meshcheriakov, H. Meyer, O. Meyer, J. Miettunen, D. Milanesio, F. Mink, A. Mlynek, F. Monaco, C. Moon, R. Nazikian, A. Nemes-Czopf, G. Neu, R. Neu, A. H. Nielsen, S. K. Nielsen, V. Nikolaeva, M. Nocente, J. -M. Noterdaeme, S. Nowak, M. Oberkofler, M. Oberparleiter, R. Ochoukov, T. Odstrcil, J. Olsen, F. Orain, F. Palermo, G. Papp, I. Paradela Perez, G. Pautasso, F. Enzel, P. Petersson, J. Pinzon, P. Piovesan, C. Piron, B. Plaum, B. Plockl, V. Plyusnin, G. Pokol, E. Poli, L. Porte, S. Potzel, D. Prisiazhniuk, T. Putterich, M. Ramisch, C. Rapson, J. Rasmussen, G. Raupp, D. Refy, M. Reich, F. Reimold, T. Ribeiro, R. Riedl, D. Rittich, G. Rocchi, M. Rodriguez-Ramos, V. Rohde, A. Ross, M. Rott, M. Rubel, D. Ryan, F. Ryter, S. Saarelma, M. Salewski, A. Salmi, L. Sanchis-Sanchez, G. Santos, J. Santos, O. Sauter, A. Scarabosio, G. Schall, K. Schmid, O. Schmitz, P. A. Schneider, M. Schneller, R. Schrittwieser, M. Schubert, T. Schwarz-Selinger, J. Schweinzer, B. Scott, T. Sehmer, M. Sertoli, A. Shabbir, A. Shalpegin, L. Shao, S. Sharapov, M. Siccinio, B. Sieglin, A. Sigalov, A. Silva, C. Silva, P. Simon, J. Simpson, A. Snicker, C. Sommariva, C. Sozzi, M. Spolaore, M. Stejner, J. Stober, F. Stobbe, U. Stroth, E. Strumberger, G. Suarez, K. Sugiyama, H. -J. Sun, W. Suttrop, T. Szepesi, B. Tal, T. Tala, G. Tardini, M. Tardocchi, D. Terranova, W. Tierens, D. Told, O. Tudisco, G. Trevisan, W. Treutterer, E. Trier, M. Tripsky, M. Valisa, M. Valovic, B. Vanovac, P. Varela, S. Varoutis, G. Verdoolaege, D. Vezinet, N. Vianello, J. Vicente, T. Vierle, E. Viezzer, U. Toussaint, D. Wagner, N. Wang, X. Wang, M. Weidl, M. Weiland, A. E. White, M. Willensdorfer, B. Wiringer, M. Wischmeier, R. Wolf, E. Wolfrum, L. Xiang, Q. Yang, Z. Yang, Q. Yu, R. Zagorski, I. Zammuto, D. Zarzoso, W. Zhang, M. Zeeland, T. Zehetbauer, M. Zilker, S. Zoletnik, H. Zohm, Asdex Upgrade Team, Eurofusion Mst1 Team
article
Nuclear Fusion, IOP Publishing, 2017, 57 (10), ⟨10.1088/1741-4326/aa64f6⟩
resume
The ASDEX Upgrade (AUG) programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of 3-strap ICRF antennas, which were designed for a reduction of tungsten release during ICRF operation. As predicted, a factor two reduction on the ICRF-induced W plasma content could be achieved by the reduction of the sheath voltage at the antenna limiters via the compensation of the image currents of the central and side straps in the antenna frame. There are two main operational scenario lines in AUG. Experiments with low collisionality, which comprise current drive, ELM mitigation/suppression and fast ion physics, are mainly done with freshly boronized walls to reduce the tungsten influx at these high edge temperature conditions. Full ELM suppression and non-inductive operation up to a plasma current of I-p = 0.8 MA could be obtained at low plasma density. Plasma exhaust is studied under conditions of high neutral divertor pressure and separatrix electron density, where a fresh boronization is not required. Substantial progress could be achieved for the understanding of the confinement degradation by strong D puffing and the improvement with nitrogen or carbon seeding. Inward/outward shifts of the electron density profile relative to the temperature profile effect the edge stability via the pressure profile changes and lead to improved/decreased pedestal performance. Seeding and D gas puffing are found to effect the core fueling via changes in a region of high density on the high field side (HFSHD). The integration of all above mentioned operational scenarios will be feasible and naturally obtained in a large device where the edge is more opaque for neutrals and higher plasma temperatures provide a lower collisionality. The combination of exhaust control with pellet fueling has been successfully demonstrated. High divertor enrichment values of nitrogen E-N >= 10 have been obtained during pellet injection, which is a prerequisite for the simultaneous achievement of good core plasma purity and high divertor radiation levels. Impurity accumulation observed in the all-metal AUG device caused by the strong neoclassical inward transport of tungsten in the pedestal is expected to be relieved by the higher neoclassical temperature screening in larger devices.
DOI
DOI : 10.1088/1741-4326/aa64f6
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titre
Overview of the TCV tokamak program: scientific progress and facility upgrades
auteur
S. Coda, J. Ahn, R. Albanese, S. Alberti, E. Alessi, S. Allan, H. Anand, G. Anastassiou, Y. Andrebe, C. Angioni, M. Ariola, M. Bernert, M. Beurskens, W. Bin, P. Blanchard, T. C. Blanken, J. A. Boedo, T. Bolzonella, F. Bouquey, F. H. Braunmueller, H. Bufferand, P. Buratti, G. Calabro, Y. Camenen, D. Carnevale, F. Carpanese, F. Causa, R. Cesario, I. T. Chapman, O. Chellai, D. Choi, C. Cianfarani, G. Ciraolo, J. Citrin, S. Costea, F. Crisanti, N. Cruz, A. Czarnecka, J. Decker, G. de Masi, G. de Tommasi, D. Douai, M. Dunne, B. P. Duval, T. Eich, S. Elmore, B. Esposito, M. Faitsch, A. Fasoli, N. Fedorczak, F. Felici, O. Fevrier, O. Ficker, S. Fietz, M. Fontana, L. Frassinetti, I. Furno, S. Galeani, A. Gallo, C. Galperti, S. Garavaglia, I. Garrido, B. Geiger, E. Giovannozzi, M. Gobbin, T. P. Goodman, G. Gorini, M. Gospodarczyk, G. Granucci, J. P. Graves, R. Guirlet, A. Hakola, C. Ham, J. Harrison, J. Hawke, P. Hennequin, B. Hnat, D. Hogeweij, J. -Ph. Hogge, C. Honore, C. Hopf, J. Horacek, Z. Huang, V. Igochine, P. Innocente, C. Ionita Schrittwieser, H. Isliker, R. Jacquier, A. Jardin, J. Kamleitner, A. Karpushov, D. L. Keeling, N. Kirneva, M. Kong, M. Koubiti, J. Kovacic, A. Kramer-Flecken, N. Krawczyk, O. Kudlacek, B. Labit, E. Lazzaro, H. B. Le, B. Lipschultz, X. Llobet, B. Lomanowski, V. P. Loschiavo, T. Lunt, P. Maget, E. Maljaars, A. Malygin, M. Maraschek, C. Marini, P. Martin, Y. Martin, S. Mastrostefano, R. Maurizio, M. Mavridis, D. Mazon, R. Mcadams, R. Mcdermott, A. Merle, H. Meyer, F. Militello, I. G. Miron, P. A. Molina Cabrera, J. -M. Moret, A. Moro, D. Moulton, V. Naulin, F. Nespoli, A. H. Nielsen, M. Nocente, R. Nouailletas, S. Nowak, T. Odstrcil, G. Papp, R. Paprok, A. Pau, G. Pautasso, V. Pericoli Ridolfini, P. Piovesan, C. Piron, T. Pisokas, L. Porte, M. Preynas, G. Ramogida, C. Rapson, J. Juul Rasmussen, M. Reich, H. Reimerdes, C. Reux, P. Ricci, D. Rittich, F. Riva, T. Robinson, S. Saarelma, F. Saint-Laurent, O. Sauter, R. Scannell, Ch. Schlatter, B. Schneider, P. Schneider, R. Schrittwieser, F. Sciortino, M. Sertoli, U. Sheikh, B. Sieglin, M. Silva, J. Sinha, C. Sozzi, M. Spolaore, T. Stange, T. Stoltzfus-Dueck, P. Tamain, A. Teplukhina, D. Testa, C. Theiler, A. Thornton, L. Tophoj, M. Q. Tran, C. Tsironis, C. Tsui, A. Uccello, S. Vartanian, G. Verdoolaege, K. Verhaegh, L. Vermare, N. Vianello, W. A. J. Vijvers, L. Vlahos, N. M. T. Vu, N. Walkden, T. Wauters, H. Weisen, M. Wischmeier, P. Zestanakis, M. Zuin, Eurofusion Mst 1team
article
Nuclear Fusion, IOP Publishing, 2017, 57 (10), ⟨10.1088/1741-4326/aa6412⟩
resume
The TCV tokamak is augmenting its unique historical capabilities (strong shaping, strong electron heating) with ion heating, additional electron heating compatible with high densities, and variable divertor geometry, in a multifaceted upgrade program designed to broaden its operational range without sacrificing its fundamental flexibility. The TCV program is rooted in a three-pronged approach aimed at ITER support, explorations towards DEMO, and fundamental research. A 1 MW, tangential neutral beam injector (NBI) was recently installed and promptly extended the TCV parameter range, with record ion temperatures and toroidal rotation velocities and measurable neutral-beam current drive. ITER-relevant scenario development has received particular attention, with strategies aimed at maximizing performance through optimized discharge trajectories to avoid MHD instabilities, such as peeling-ballooning and neoclassical tearing modes. Experiments on exhaust physics have focused particularly on detachment, a necessary step to a DEMO reactor, in a comprehensive set of conventional and advanced divertor concepts. The specific theoretical prediction of an enhanced radiation region between the two X-points in the low-field-side snowflake-minus configuration was experimentally confirmed. Fundamental investigations of the power decay length in the scrape-off layer (SOL) are progressing rapidly, again in widely varying configurations and in both D and He plasmas; in particular, the double decay length in L-mode limited plasmas was found to be replaced by a single length at high SOL resistivity. Experiments on disruption mitigation by massive gas injection and electron-cyclotron resonance heating (ECRH) have begun in earnest, in parallel with studies of runaway electron generation and control, in both stable and disruptive conditions; a quiescent runaway beam carrying the entire electrical current appears to develop in some cases. Developments in plasma control have benefited from progress in individual controller design and have evolved steadily towards controller integration, mostly within an environment supervised by a tokamak profile control simulator. TCV has demonstrated effective wall conditioning with ECRH in He in support of the preparations for JT-60SA operation.
DOI
DOI : 10.1088/1741-4326/aa6412
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titre
The I-mode confinement regime at ASDEX Upgrade: global properties and characterization of strongly intermittent density fluctuations
auteur
T. Happel, P. Manz, F. Ryter, M. Bernert, M. Dunne, Pascale Hennequin, A. Hetzenecker, U. Stroth, G. D. Conway, L. Guimarais, Cyrille Honoré, E. Viezzer, The Asdex Upgrade Team
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2017, 59 (1), pp.014004. ⟨10.1088/0741-3335/59/1/014004⟩
resume
Properties of the I-mode confinement regime on the ASDEX Upgrade tokamak are summarized. A weak dependence of the power threshold for the L-I transition on the toroidal magnetic field strength is found. During improved confinement, the edge radial electric field well deepens. Stability calculations show that the I-mode pedestal is peeling-ballooning stable. Turbulence investigations reveal strongly intermittent density fluctuations linked to the weakly coherent mode in the confined plasma, which become stronger as the confinement quality increases. Across all investigated structure sizes ( ##IMG## [http://ej.iop.org/images/0741-3335/59/1/014004/ppcfaa3b87ieqn001.gif] k_\bot≈ 5 ?12?cm ?1 , with ##IMG## [http://ej.iop.org/images/0741-3335/59/1/014004/ppcfaa3b87ieqn002.gif] k_\bot the perpendicular wavenumber of turbulent density fluctuations), the intermittent turbulence bursts are observed. Comparison with bolometry data shows that they move poloidally toward the X-point and finally end up in the divertor. This might be indicative that they play a role in inhibiting the density profile growth, such that no pedestal is formed in the edge density profile.
DOI
DOI : 10.1088/0741-3335/59/1/014004
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titre
Explaining the isotope effect on heat transport in L-mode with the collisional electron-ion energy exchange
auteur
Philip Schneider, Andres Bustos, Pascale Hennequin, F. Ryter, Matthias Bernert, Marco Cavedon, M. Dunne, R. Fischer, T. Görler, T. Happel, V. Igochine, B. Kurzan, A. Lebschy, R.M. Mcdermott, Pierre Morel, M. Willensdorfer, Team The Asdex Upgrade, Team The Eurofusion Mst1
article
Nuclear Fusion, IOP Publishing, 2017, 57 (6), pp.066003. ⟨10.1088/1741-4326/aa65b3⟩
resume
In ASDEX Upgrade (AUG), the normalised gyroradius ##IMG## [http://ej.iop.org/images/0029-5515/57/6/066003/nfaa65b3ieqn001.gif] ρ_★ was varied via a hydrogen isotope scan while keeping other dimensionless parameters constant. This was done in L-mode, to minimise the impact of pedestal stability on confinement. Power balance and perturbative transport analyses reveal that the electron heat transport is unaffected by the differences in isotope mass. Nonlinear simulations with the G ene code suggest that these L-mode discharges are ion temperature gradient (ITG) dominated. The different gyroradii due to the isotope mass do not necessarily result in a change of the predicted heat fluxes. This result is used in simulations with the A stra transport code to match the experimental profiles. In these simulations the experimental profiles and confinement times are reproduced with the same transport coefficients for hydrogen and deuterium plasmas. The mass only enters in the energy exchange term between electrons and ions. These numerical observations are supported by additional experiments which show a lower ion energy confinement compared to that of the electrons. Additionally, hydrogen and deuterium plasmas have a similar confinement when the energy exchange time between electrons and ions is matched. This strongly suggests that the observed isotope dependence in L-mode is not dominated by a gyroradius effect, but a consequence of the mass dependence in the collisional energy exchange between electrons and ions.
DOI
DOI : 10.1088/1741-4326/aa65b3
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titre
Density profile and turbulence evolution during L-H transition studied with the ultra-fast swept reflectometer on ASDEX Upgrade
auteur
A. Medvedeva, C. Bottereau, F. Clairet, Pascale Hennequin, U. Stroth, G. Birkenmeier, M. Cavedon, G D Conway, T. Happel, S. Heuraux, D. Molina, A. Silva, M. Willensdorfer, Asdex Upgrade Team
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2017, 59 (12), pp.125014. ⟨10.1088/1361-6587/aa9251⟩
resume
The ultra-fast swept reflectometer with the sweep time of 1 ? s, inferior to the characteristic turbulent time scale, has provided the measurements of the fast density and density fluctuation evolution across major parts of tokamak plasma radius. The L-H transitions in a series of plasma discharges in ASDEX Upgrade have been studied with a high temporal resolution. The comparison of the density fluctuation behaviour in L- and H-mode is presented. The I-phase oscillation dynamics has been described in terms of the density fluctuation level, the radial electric field and the normalised electron pressure gradient. Indications for a phase shift between the turbulence and the radial electric field are observed in the beginning of the I-phase, where the turbulence grows first and the radial electric field increase follows. In the established I-phase the electric field and the turbulence are in phase.
DOI
DOI : 10.1088/1361-6587/aa9251
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titre
Comparison of detailed experimental wavenumber spectra with gyrokinetic simulation aided by two-dimensional full-wave simulations
auteur
T. Happel, T. Görler, Pascale Hennequin, C. Lechte, Matthias Bernert, G. D. Conway, Simon Freethy, Cyrille Honoré, J R Pinzón, Ulrich Stroth, Team The Asdex Upgrade
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2017, 59 (5), pp.054009. ⟨10.1088/1361-6587/aa645b⟩
resume
The importance of using a comprehensive suite of tools for the validation of a gyrokinetic code is described. This is detailed by presenting experimental wavenumber spectra which show pronounced differences, although they are measured at the same toroidal, poloidal and radial location. They are obtained via Doppler reflectometry and the differences are due to the probing beam polarization. These differences are reproduced convincingly using turbulence from a gyrokinetic simulation as input for two-dimensional full-wave simulation. It is demonstrated that the application of synthetic diagnostics is indispensable if non-trivial diagnostics are used in the experiment. Furthermore, the measurement of wavenumber spectra via Doppler reflectometry with X-mode probing beam polarization might be problematic due to nonlinear wave?plasma interactions and should be regarded with care when used for quantitative statements or the validation of gyrokinetic codes.
DOI
DOI : 10.1088/1361-6587/aa645b
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titre
Localized reversal of the perpendicular velocity in Tore Supra ohmic, L-mode, limited plasmas
auteur
Elisée Trier, Pascale Hennequin, Özgür Gürcan, R. Sabot, J. Bucalossi, Z.O. Guimarães-Filho, C. Bourdelle, F. Clairet, G. Falchetto, C. Fenzi, X. Garbet, P. Maget, Laure Vermare, Team The Tore Supra
article
Nuclear Fusion, IOP Publishing, 2017, 57 (4), pp.046021. ⟨10.1088/1741-4326/aa59bb⟩
resume
In Tore Supra plasmas, the perpendicular velocity measured by Doppler reflectometry was observed to reverse in a localized zone close to a normalized radius???0.5?0.6, changing from a negative value (corresponding to a negative radial electric field E r ) to a positive value ( ##IMG## [http://ej.iop.org/images/0029-5515/57/4/046021/nfaa59bbieqn001.gif] E_\textr>0 ). This occurs in L-mode, ohmic plasmas with a negligible external momentum input, a non-circular limited cross-section, and an edge safety factor close to 3. This reversal is favoured by a decrease in the magnetic field, or an increase in density. It is accompanied by a characteristic behaviour of the MHD activity signal, whose amplitude decrease during a ramp-down of the edge safety factor as it approaches ##IMG## [http://ej.iop.org/images/0029-5515/57/4/046021/nfaa59bbieqn002.gif] q_a∼ 3.1 ?3.2. A m / n ??=??2/1 mode is involved in the mechanism causing these observations.
DOI
DOI : 10.1088/1741-4326/aa59bb
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titre
E x B staircases and barrier permeability in magnetised plasmas
auteur
G. Hornung, G. Dif-Pradalier, F. Clairet, Y. Sarazin, R. Sabot, Pascale Hennequin, G. Verdoolaege
article
Nuclear Fusion, IOP Publishing, 2017, 57 (1), pp.014006. ⟨10.1088/0029-5515/57/1/014006⟩
resume
In-depth experimental characterisation of spontaneous shear flow patterning into a so-called ##IMG## [http://ej.iop.org/images/0029-5515/57/1/014006/nfaa42aaieqn003.gif] \mathbfE× \mathbfB staircase?named after its planetary analogue?is shown in magnetised plasma turbulence, using ultrafast-sweeping reflectometry in the Tore Supra tokamak. Staircase signatures are found in a large variety of L-mode plasma conditions. Sensitivity to the dominant source of free energy is highlighted for the first time. A connection between staircase shear layer permeability and deviation from gyro-Bohm confinement scaling is strongly suggested, opening new routes to understanding confinement in drift-wave turbulence.
DOI
DOI : 10.1088/0029-5515/57/1/014006
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titre
Turbulence characteristics of the I-mode confinement regime in ASDEX Upgrade
auteur
P. Manz, T. Happel, F. Ryter, M. Bernert, G. Birkenmeier, G. D. Conway, M. Dunne, L. Guimarais, Pascale Hennequin, A. Hetzenecker, Cyrille Honoré, P. Lauber, M. Maraschek, V. Nikolaeva, D. Prisiazhniuk, U. Stroth, E. Viezzer, Team2 The Asdex Upgrade
article
Nuclear Fusion, IOP Publishing, 2017, 57 (8), pp.086022. ⟨10.1088/1741-4326/aa7476⟩
resume
Besides strong geodesic acoustic mode (GAM) activity, turbulence in the I-mode confinement regime of ASDEX Upgrade exhibits two prominent features, the weakly coherent mode (WCM) and strongly intermittent solitary density perturbations. The nonlinear interaction between these structures is studied in detail by means of a conditional averaged wavelet-bicoherence analysis. The wavelet analysis reveals that these density perturbations are at the WCM frequency. The GAM is coupled to all frequency scales of the velocity fluctuations via a modulational instability. The WCM shows coupling to higher frequencies prior to the bursts, indicating a process resembling wave-steepening. A possible mechanism for the generation of such solitary density perturbations by a Korteweg?de Vries-like nonlinearity is discussed.
DOI
DOI : 10.1088/1741-4326/aa7476
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titre
Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution
auteur
H. Meyer, T. Eich, M. Beurskens, S. Coda, A. Hakola, P. Martin, J. Adamek, M. Agostini, D. Aguiam, J. Ahn, L. Aho-Mantila, R. Akers, R. Albanese, R. Aledda, E. Alessi, S. Allan, D. Alves, R. Ambrosino, L. Amicucci, H. Anand, G. Anastassiou, Y. Andrèbe, C. Angioni, G. Apruzzese, M. Ariola, H. Arnichand, W. Arter, A. Baciero, M. Barnes, L. Barrera, R. Behn, A. Bencze, J. Bernardo, M. Bernert, P. Bettini, P. Bilková, W. Bin, G. Birkenmeier, S. Bizarro, P. Blanchard, T. Blanken, M. Bluteau, V. Bobkov, O. Bogar, P. Böhm, T. Bolzonella, L. Boncagni, A. Botrugno, C. Bottereau, F. Bouquey, C. Bourdelle, S. Brémond, S. Brezinsek, D. Brida, F. Brochard, J. Buchanan, H. Bufferand, P. Buratti, P. Cahyna, G. Calabrò, Y. Camenen, R. Caniello, B. Cannas, A. Canton, A. Cardinali, D. Carnevale, M. Carr, D. Carralero, P. Carvalho, L. Casali, C. Castaldo, F. Castejón, R. Castro, F. Causa, R. Cavazzana, M. Cavedon, M. Cecconello, S. Ceccuzzi, R. Cesario, D. Challis, I. Chapman, S. Chapman, M. Chernyshova, D. Choi, C. Cianfarani, G. Ciraolo, Jonathan Citrin, F. Clairet, I. Classen, Rui Coelho, W. Coenen, L. Colas, G. Conway, Y. Corre, S. Costea, F. Crisanti, N. Cruz, G. Cseh, A. Czarnecka, O. D’arcangelo, M. de Angeli, G. de Masi, G. de Temmerman, G. de Tommasi, J. Decker, S. Delogu, R. Dendy, P. Denner, C. Di Troia, M. Dimitrova, R. D’inca, V. Dorić, D. Douai, A. Drenik, B. Dudson, D. Dunai, M. Dunne, P. Duval, L. Easy, S. Elmore, B. Erdös, B. Esposito, E. Fable, M. Faitsch, A. Fanni, N. Fedorczak, F. Felici, Jorge Ferreira, O. Février, O. Ficker, S. Fietz, Lorenzo Figini, António Figueiredo, Alexandre Fil, G. Fishpool, M. Fitzgerald, M. Fontana, O. Ford, L. Frassinetti, R. Fridström, D. Frigione, G. Fuchert, C. Fuchs, M. Furno Palumbo, S. Futatani, L. Gabellieri, K. Gałązka, J. Galdon-Quiroga, S. Galeani, D. Gallart, A. Gallo, C. Galperti, Y. Gao, S. Garavaglia, J. Garcia, A. Garcia-Carrasco, J. Garcia-Lopez, M. Garcia-Munoz, L. Gardarein, L. Garzotti, J. Gaspar, Elise Gauthier, P. Geelen, B. Geiger, P. Ghendrih, F. Ghezzi, L. Giacomelli, L. Giannone, Edmondo Giovannozzi, C. Giroud, C. Gleason González, M. Gobbin, P. Goodman, G. Gorini, M. Gospodarczyk, G. Granucci, M. Gruber, A. Gude, L. Guimarais, R. Guirlet, J. Gunn, P. Hacek, S. Hacquin, S. Hall, C. Ham, T. Happel, J. Harrison, D. Harting, V. Hauer, E. Havlickova, T. Hellsten, W. Helou, S. Henderson, P. Hennequin, M. Heyn, B. Hnat, M. Hölzl, D. Hogeweij, C. Honore, C. Hopf, J. Horáček, G. Hornung, L. Horvath, Z. Huang, A. Huber, J. Igitkhanov, V. Igochine, M. Imrisek, P. Innocente, C. Schrittwieser, H. Isliker, Irena Ivanova-Stanik, S. Jacobsen, P. Jacquet, M. Jakubowski, A. Jardin, F. Jaulmes, F. Jenko, T. Jensen, O. Jeppe Miki Busk, M. Jessen, E. Joffrin, O. Jones, T. Jonsson, A. Kallenbach, N. Kallinikos, S. Kálvin, A. Kappatou, J. Karhunen, A. Karpushov, S. Kasilov, G. Kasprowicz, A. Kendl, W. Kernbichler, D. Kim, A. Kirk, S. Kjer, I. Klimek, G. Kocsis, D. Kogut, M. Komm, S. Korsholm, R. Koslowski, M. Koubiti, J. Kovacic, K. Kovarik, N. Krawczyk, J. Krbec, K. Krieger, A. Krivska, R. Kube, O. Kudlacek, T. Kurki-Suonio, B. Labit, M. Laggner, L. Laguardia, A. Lahtinen, P. Lalousis, P. Lang, P. Lauber, N. Lazányi, A. Lazaros, B. Le, A. Lebschy, J. Leddy, Laurent Lefèvre, M. Lehnen, F. Leipold, A. Lessig, M. Leyland, L. Li, Y. Liang, B. Lipschultz, Y. Liu, T. Loarer, A. Loarte, T. Loewenhoff, B. Lomanowski, P. Loschiavo, T. Lunt, I. Lupelli, H. Lux, A. Lyssoivan, Jens Madsen, P. Maget, C. Maggi, R. Maggiora, M. Magnussen, J. Mailloux, B. Maljaars, A. Malygin, P. Mantica, Mervi Mantsinen, M. Maraschek, B. Marchand, N. Marconato, C. Marini, M. Marinucci, T. Markovic, D. Marocco, L. Marrelli, Y. Martin, R. Martin Solis, A. Martitsch, S. Mastrostefano, M. Mattei, G. Matthews, M. Mavridis, M. Mayoral, D. Mazon, P. Mccarthy, R. Mcadams, G. Mcardle, K. Mcclements, R. Mcdermott, B. Mcmillan, G. Meisl, Antoine Merle, O. Meyer, D. Milanesio, F. Militello, I. Miron, K. Mitosinkova, J. Mlynar, A. Mlynek, D. Molina, P. Molina, I. Monakhov, J. Morales, D. Moreau, Pierre Morel, M. Moret
article
Nuclear Fusion, IOP Publishing, 2017, ⟨10.1088/1741-4326/aa6084⟩
DOI
DOI : 10.1088/1741-4326/aa6084
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Conference papers

titre
Poloidal asymmetry of perpendicular velocity of the density fluctuations
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, Pierre Morel, A. Storelli, F. Clairet, X. Garbet, J-C. Giacalone, R. Sabot
article
44th EPS Conference on Plasma Physics, Jun 2017, Belfast, Ireland
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titre
Validation studies of ion-scale GENE simulations in L-mode plasmas at ASDEX Upgrade
auteur
Simon Freethy, A. J. Creely, T. Görler, G. D. Conway, T. Happel, Pascale Hennequin, J R Pinzón, D. Prisiazhniuk, U. Stroth, A. E. White, The Asdex Upgrade Team
article
44th EPS Conference on Plasma Physics, Jun 2017, Belfast, Ireland. pp.O4.122
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titre
Inter-ELM Fluctuations and Flows and their evolution when approaching the density limit in the ASDEX Upgrade tokamak
auteur
Pascale Hennequin, F. Laggner, F. Mink, E. Wolfrum, Elisée Trier, T. Eich, M. Bernert, G. Birkenmeier, G. D. Conway, T. Happel, Cyrille Honoré, Özgür Gürcan, P. Manz, A. Medvedeva, U. Stroth, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
44th EPS Conference on Plasma Physics, Jun 2017, Belfast, Ireland. pp.P1.167
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titre
Isotope dependence of limit-cycle oscillations in ASDEX Upgrade plasmas
auteur
G. Birkenmeier, T. Happel, Pascale Hennequin, G. D. Conway, P. Manz, M. Cavedon, A. Medvedeva, F. Ryter, E. Wolfrum, U. Stroth, The Asdex Upgrade Team
article
44th European Physical Society Conference on Plasma Physics, Jun 2017, Belfast, Ireland. pp.P1.166
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titre
ELM-induced cold pulses propagation in ASDEX Upgrade
auteur
Elisée Trier, E. Wolfrum, M. Willensdorfer, Q. Yu, F. Ryter, C. Angioni, M. Dunne, S. Denk, R. Fischer, Pascale Hennequin, B. Kurzan, T. Odstrcill, P. Schneider, U. Stroth, B. Vanovac, The Asdex Upgrade Team, The Eurofusion Mst1 Team
article
44th EPS Conference on Plasma Physics, Jun 2017, Belfast, Ireland. pp.P1.163
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titre
Investigation of turbulence properties via spectral broadening of Doppler reflectometry signals in ASDEX Upgrade
auteur
G. D. Conway, C. Lechte, Pascale Hennequin, P. Simon, The Asdex Upgrade Team
article
44th EPS Conference on Plasma Physics, Jun 2017, Belfast, Ireland. pp.O2.107
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titre
Fluctuation measurements in Laboratory Plasmas
auteur
Pascale Hennequin
article
Ecole de Physique des Houches, From Laboratories to Astrophysics : the expanding universe of plasma physics, May 2017, Les Houches, France
resume
http://ipag.osug.fr/~lesurg/plasmas2017/program.html,
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titre
Understanding of wavenumber spectra measured by Doppler reflectometry through simulation and related estimation of wave-plasma interaction regimes.
auteur
T. Happel, T. Görler, Pascale Hennequin, C. Lechte, J R Pinzón, M. Bernert, G. D. Conway, Simon Freethy, Cyrille Honoré, U. Stroth, The Asdex Upgrade Team
article
13th International Reflectometry Workshop for Fusion Plasma Diagnostics (IRW13), 2017, Daejon, Korea, Unknown Region
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titre
Measurements of density fluctuations in magnetic confined plasmas using Doppler backscattering technique
auteur
Laure Vermare, Pascale Hennequin, Cyrille Honoré, V. Pisarev, J-C. Giacalone
article
ECPD, 2017, Bordeaux, France
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2016

Journal articles

titre
Turbulence intermittency linked to the weakly coherent mode in ASDEX Upgrade I-mode plasmas
auteur
T. Happel, P. Manz, F. Ryter, Pascale Hennequin, A. Hetzenecker, G. D. Conway, L. Guimarais, Cyrille Honoré, U. Stroth, E. Viezzer, Team The Asdex Upgrade
article
Nuclear Fusion, IOP Publishing, 2016, 56 (6), pp.064004. ⟨10.1088/0029-5515/56/6/064004⟩
resume
This letter shows for the first time a pronounced increase of extremely intermittent edge density turbulence behavior inside the confinement region related to the I-mode confinement regime in the ASDEX Upgrade tokamak. With improving confinement, the perpendicular propagation velocity of density fluctuations in the plasma edge increases together with the intermittency of the observed density bursts. Furthermore, it is shown that the weakly coherent mode, a fluctuation feature generally observed in I-mode plasmas, is connected to the observed bursts. It is suggested that the large amplitude density bursts could be generated by a non-linearity similar to that in the Korteweg?de-Vries equation which includes the radial temperature gradient.
DOI
DOI : 10.1088/0029-5515/56/6/064004
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Conference papers

titre
Interesting Physics in Boring Plasmas: Validation & Open Issues
auteur
G. Dif-Pradalier, Ph. Ghendrih, Y. Sarazin, P.H. Diamond, X. Garbet, V. Grandgirard, Özgür Gürcan, Pascale Hennequin, Pierre Morel, Laure Vermare
article
21st Joint EU-US Transport Task Force Meeting, Sep 2016, Leysin, Switzerland
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titre
Isotope effect on confinement unraveled for L-mode in dimensionless ρ⋆ scan
auteur
Philip Schneider, Andreas Bustos, Pascale Hennequin, F. Ryter, M. Bernert, Marco Cavedon
article
43rd EPS Conference on Plasma Physics, Jul 2016, Leuven, Belgium. pp.O4.135
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titre
O- and X-mode Radial Correlation Doppler Reflectometry in 2D Full Wave Simulations and Experiments
auteur
Javier Pinzon, T. Happel, Pascale Hennequin, E. Blanco, T. Estrada, U. Stroth
article
43rd EPS Conference on Plasma Physics, Jul 2016, Leuven, Belgium. pp.P1.052
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titre
Density profile and turbulence evolution during L-H transition studied with the Ultra-fast swept reflectometer on ASDEX Upgrade
auteur
Anna Medvedeva, G. Birkenmeier, C. Bottereau, M. Cavedon, F. Clairet, G. D. Conway, Pascale Hennequin, S. Heuraux, D. Molina, A. Silva, U. Stroth, The Asdex Upgrade Team
article
43rd EPS Conference on Plasma Physics, Jul 2016, Leuven, Belgium. pp.P1.032
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titre
The I-mode confinement regime at ASDEX Upgrade: global properties and characterization of strongly intermittent density fluctuations
auteur
T. Happel, P. Manz, F. Ryter, M. Bernert, M. Dunne, Pascale Hennequin, A. Hetzenecker, G. Stroth, G. D. Conway, L. Guimarais, Cyrille Honoré, E. Viezzer, The Asdex Upgrade Team
article
43rd EPS Conference on Plasma Physics, Jul 2016, Leuven, Belgium. pp.I1.101
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Poster communications

titre
Dynamique prédateur proie dans les plasmas de fusion magnétique
auteur
Pierre Morel, Sumire Kobayashi, Peter Donnel, Vincent Berionni, Cyrille Honoré, V. Pisarev, Pascale Hennequin, Özgür Gürcan
article
Congrès de le Division Plasmas de la Société Française de Physique, Jun 2016, Nancy, France. 2016
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titre
Comparaisons simulation expérience : application d'un diagnostic synthétique de Rétro-Diffusion Doppler au plasma Tore Supra #45511 simulé par le code gyrocinétique GYSELA
auteur
Pierre Morel, Banda Gassama, Robin Leybros, G. Dif-Pradalier, Pascale Hennequin, Laure Vermare, Özgür Gürcan, V. Grandgirard, G. Latu, Y. Sarazin, Ph. Ghendrih, X. Garbet
article
Congrès de la Division Plasmas de la Société Française de Physique, Jun 2016, Nancy, France. 2016
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titre
Predator Prey Dynamics in Magnetized Fusion Plasmas
auteur
Pierre Morel, Sumire Kobayashi, Peter Donnel, Vincent Berionni, Cyrille Honoré, V. Pisarev, Pascale Hennequin, Özgür Gürcan
article
Vlasovia, May 2016, Copanello, Italy. 2016
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titre
Synthetic diagnostic of Doppler Back-Scattering measurements on the Tore Supra Plasma #TS45511 with a dedicated GYSELA non-linear gyrokinetic simulation
auteur
Pierre Morel, Banda Gassama, Robin Leybros, G. Dif-Pradalier, Pascale Hennequin, Laure Vermare, Özgür Gürcan, V. Grandgirard, G. Latu, Y. Sarazin, Ph. Ghendrih, X. Garbet
article
Vlasovia, May 2016, Copanello, Italy. 2016
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2015

Journal articles

titre
WEST Physics Basis
auteur
C. Bourdelle, J.F. Artaud, Vincent Basiuk, M. Bécoulet, S. Brémond, J. Bucalossi, H. Bufferand, G. Ciraolo, L. Colas, Y. Corre, X. Courtois, J. Decker, L. Delpech, P. Devynck, G. Dif-Pradalier, R.P. Doerner, D. Douai, Rémi Dumont, A. Ekedahl, N. Fedorczak, C. Fenzi, M. Firdaouss, J. Garcia, Philippe Ghendrih, C. Gil, G. Giruzzi, M. Goniche, C. Grisolia, A. Grosman, D. Guilhem, R. Guirlet, J. Gunn, Pascale Hennequin, J. Hillairet, T. Hoang, Frédéric Imbeaux, Irena Ivanova-Stanik, E. Joffrin, A. Kallenbach, J. Linke, T. Loarer, P. Lotte, P. Maget, Yannick Marandet, M.L. Mayoral, O. Meyer, M. Missirlian, P. Mollard, P. Monier-Garbet, P. Moreau, Eric Nardon, B. Pégourié, Y. Peysson, R. Sabot, F. Saint-Laurent, M. Schneider, J. M. Travère, E. Tsitrone, S. Vartanian, Laure Vermare, M. Yoshida, R. Zagorski, Contributors Jet
article
Nuclear Fusion, IOP Publishing, 2015, 55 (6), pp.063017. ⟨10.1088/0029-5515/55/6/063017⟩
resume
With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 [http://dx.doi.org/10.1016/j.fusengdes.2014.01.062] 907?12 ), the Tore Supra facility and team expertise (Dumont et al 2014 Plasma Phys. Control. Fusion 56 [http://dx.doi.org/10.1088/0741-3335/56/7/075020] 075020 ) is used to pave the way towards ITER divertor procurement and operation. It consists in implementing a divertor configuration and installing ITER-like actively cooled tungsten monoblocks in the Tore Supra tokamak, taking full benefit of its unique long-pulse capability. WEST is a user facility platform, open to all ITER partners. This paper describes the physics basis of WEST: the estimated heat flux on the divertor target, the planned heating schemes, the expected behaviour of the L?H threshold and of the pedestal and the potential W sources. A series of operating scenarios has been modelled, showing that ITER-relevant heat fluxes on the divertor can be achieved in WEST long pulse H-mode plasmas.
DOI
DOI : 10.1088/0029-5515/55/6/063017
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titre
Experimental turbulence studies for gyro-kinetic code validation using advanced microwave diagnostics
auteur
U. Stroth, A. Bañón Navarro, G. D. Conway, T. Görler, T. Happel, Pascale Hennequin, C. Lechte, P. Manz, P. Simon, A. Biancalani, E. Blanco, C. Bottereau, F. Clairet, S. Coda, T. Eibert, T. Estrada, A. Fasoli, L. Guimarais, Özgür Gürcan, Z. Huang, F. Jenko, W. Kasparek, C. Koenen, A. Krämer-Flecken, M.-E. Manso, A. Medvedeva, D. Molina, V. Nikolaeva, B. Plaum, L. Porte, D. Prisiazhniuk, T. Ribeiro, B.D. Scott, U. Siart, A. Storelli, Laure Vermare, S. Wolf
article
Nuclear Fusion, IOP Publishing, 2015, 55 (8), pp.083027. ⟨10.1088/0029-5515/55/8/083027⟩
resume
For a comprehensive comparison with theoretical models and advanced numerical turbulence simulations, a large spectrum of fluctuation parameters was measured on the devices ASDEX Upgrade, TCV, and Tore-Supra. Radial profiles of scale-resolved turbulence levels in H-mode discharges are measured and compared with GENE simulations in the transition range from ion-temperature-gradient to trapped-electron-mode turbulence. Correlation reflectometry is used to study the microscopic structure of turbulence and GAMs in discharges where poloidal flow damping was varied by means of variations of the shape of the poloidal plasma cross-section and collisionality. Full-wave codes and synthetic diagnostics are applied for the interpretation of the data.
DOI
DOI : 10.1088/0029-5515/55/8/083027
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titre
Comprehensive comparisons of geodesic acoustic mode characteristics and dynamics between Tore Supra experiments and gyrokinetic simulations
auteur
A. Storelli, Laure Vermare, Pascale Hennequin, Özgür Gürcan, G. Dif-Pradalier, Y. Sarazin, X. Garbet, T. Görler, Rameswar Singh, Pierre Morel, Virginie Grandgirard, Philippe Ghendrih, Team Tore Supra
article
Physics of Plasmas, American Institute of Physics, 2015, 22 (6), ⟨10.1063/1.4922845⟩
resume
In a dedicated collisionality scan in Tore Supra, the geodesic acoustic mode (GAM) is detected and identified with the Doppler backscattering technique. Observations are compared to the results of a simulation with the gyrokinetic code GYSELA. We found that the GAM frequency in experiments is lower than predicted by simulation and theory. Moreover, the disagreement is higher in the low collisionality scenario. Bursts of non harmonic GAM oscillations have been characterized with filtering techniques, such as the Hilbert-Huang transform. When comparing this dynamical behaviour between experiments and simulation, the probability density function of GAM amplitude and the burst autocorrelation time are found to be remarkably similar. In the simulation, where the radial profile of GAM frequency is continuous, we observed a phenomenon of radial phase mixing of the GAM oscillations, which could influence the burst autocorrelation time.
DOI
DOI : 10.1063/1.4922845
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titre
Investigation of drift velocity effects on the EDGE and SOL transport
auteur
R. Leybros, Hugo Bufferand, Guido Ciraolo, Nicolas Fedorczak, Philippe Ghendrih, Pascale Hennequin, Yannick Marandet, Eric Serre, Frédéric Schwander, Patrick Tamain
article
Journal of Nuclear Materials, Elsevier, 2015, 463, pp.489-492. ⟨10.1016/j.jnucmat.2014.10.079⟩
resume
To understand the mechanisms behind poloidal asymmetries of the transport in the edge and SOL plasma, it is important to take into account drift velocity in the transport model. We investigate the effects of an imposed radial electric field on the plasma equilibrium in the transport code SOLEDGE2D. In the edge, we show an important modification of the flow pattern due to poloidal E × B drift velocity. The drift velocity generates asymmetry of the density through the Pfirsch–Schluter flows which creates an important parallel rotation through the viscous balance. In comparison to heat load imbalance studies in the SOL of divertor tokamak, a strong link between the amplitude of the radial electric field and the heat load imbalance in the SOL of limiter tokamak has been highlighted using different amplitude of the imposed radial electric field.
DOI
DOI : 10.1016/j.jnucmat.2014.10.079
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titre
Geodesic acoustic modes in a fluid model of tokamak plasma: the effects of finite beta and collisionality
auteur
Rameswar Singh, A. Storelli, Özgür Gürcan, Pascale Hennequin, Laure Vermare, Pierre Morel, R. Singh
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2015, 57, pp.125002. ⟨10.1088/0741-3335/57/12/125002⟩
resume
Starting from the Braginskii equations, relevant for the tokamak edge region, a complete set of nonlinear equations for the geodesic acoustic modes (GAM) has been derived which includes collisionality, plasma beta and external sources of particle, momentum and heat. Local linear analysis shows that the GAM frequency increases with collisionality at low radial wave number and decreases at high . GAM frequency also decreases with plasma beta. Radial profiles of GAM frequency for two Tore Supra shots, which were part of a collisionality scan, are compared with these calculations. A discrepancy between experiment and theory is observed, which seems to be explained by a finite for the GAM when flux surface averaged density \langle n\rangle and temperature are assumed to vanish. It is shown that this agreement is incidental and self-consistent inclusion of and responses enhances the disagreement more with at high . So the discrepancy between the linear GAM calculation and experiment, (which also persist for more 'complete' linear models such as gyrokinetics) can probably not be resolved by simply adding a finite .
DOI
DOI : 10.1088/0741-3335/57/12/125002
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titre
Finding the Elusive E × B Staircase in Magnetized Plasmas
auteur
Guilhem Dif-Pradalier, G Hornung, Philippe Ghendrih, Yanick Sarazin, F Clairet, L Vermare, P Diamond, J Abiteboul, T Cartier-Michaud, C Ehrlacher, Daniel Estève, Xavier Garbet, Virginie Grandgirard, Özgür Gürcan, P Hennequin, Y Kosuga, Guillaume Latu, P Maget, Pierre Morel, C Norscini, R Sabot, A. Storelli
article
Physical Review Letters, American Physical Society, 2015, 114, pp.085004. ⟨10.1103/PhysRevLett.114.085004⟩
resume
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.
DOI
DOI : 10.1103/PhysRevLett.114.085004
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Conference papers

titre
Structure and scaling of GAMs in TCV, Satellite Workshop of the 42nd EPS Plasma Physics Conference, on Electric Fields, Turbulence and Self-Organisation in Magnetized Plasmas (Lisbon) (2015),
auteur
Z. Huang, S. Coda, G. Merlo, C. A. de Meijere, J.P. Graves, Stephan Brunner, M. Fontana, L. Porte, Laure Vermare, Ludovic Villard, C. Wahlberg, J. Dominski, Pascale Hennequin, A. Kraemer-Flecken
article
Satellite Workshop of the 42nd EPS Plasma Physics Conference, on Electric Fields, Turbulence and Self-Organisation in Magnetized Plasmas (EFTSOMP), Jun 2015, Lisbon, Portugal
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titre
Experimental Study of Turbulence spatial structure and its scaling with rho
auteur
Pascale Hennequin, Philip Schneider, T. Happel, F. Ryter, Gregor Birkenmeier, Andres Bustos, Anna Medvedeva, G. D. Conway, Christine Bottereau, F. Clairet, G. Dif-Pradalier, F. Jenko, X. Garbet, T. Görler, Luis Guimarais, Özgür Gürcan, Cyrille Honoré, Pierre Morel, V. Nikolaeva, D. Prisiazhniuk, P. Simon, Ulrich Stroth, Laure Vermare, The Asdex Upgrade Team
article
42nd EPS Conference on Plasma Physics, Jun 2015, Lisbon, Portugal. pp.I1.102
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titre
The electromagnetic geodesic acoustic mode in the eigenmode and multimode regimes in TCV.
auteur
S. Coda, Z. Huang, Stephan Brunner, C. A. de Meijere, J. Dominski, G. Merlo, L. Porte, Laure Vermare, L. Fontana, Pascale Hennequin, A. Kraemer-Flecken, Ludovic Villard
article
42nd EPS Conference on Plasma Physics, Jun 2015, Lisbon, Portugal. pp.I1.101
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titre
Turbulence spatial structure and its scaling with rho
auteur
Pascale Hennequin, Philip Schneider, T. Happel, F. Ryter, G. Birkenmeier, A. Medvedeva, G. D. Conway, C. Bottereau, F. Clairet, L. Guimarais, Özgür Gürcan, Cyrille Honoré, Pierre Morel, V. Nikolaeva, D. Prisiazhniuk, U. Stroth, Laure Vermare, Team Asdex Upgrade
article
12th International Reflectometry Workshop, May 2015, Jülich, Germany
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titre
Modeling of Radial Correlation Doppler Reflectometry response to density turbulence wave number spectra
auteur
Javier Pinzon, E. Blanco, T. Happel, G. D. Conway, T. Estrada, Pascale Hennequin, U. Stroth, The Asdex Upgrade Team
article
12th International Reflectometry Workshop, May 2015, Jülich, Germany
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titre
Observation of Strongly Intermittent Density Turbulence in ASDEX Upgrade I-mode plasmas.
auteur
T. Happel, A. Hetzenecker, P. Manz, Pascale Hennequin, F. Ryter, M. Bernert, G. D. Conway, S. Fietz, Cyrille Honoré, U. Stroth, E. Viezzer, The Asdex Upgrade Team
article
12th International Reflectometry Workshop, May 2015, Jülich, Germany
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titre
Experimental Study of Turbulence spatial structure and its scaling with rho
auteur
Pascale Hennequin, Philip Schneider, T. Happel, F. Ryter, G. Birkenmeier, A. Medvedeva, G. D. Conway, C. Bottereau, F. Clairet, L. Guimarais, Özgür Gürcan, Cyrille Honoré, Pierre Morel, V. Nikolaeva, D. Prisiazhniuk, U. Stroth, Laure Vermare, Team Asdex Upgrade
article
20th EU-US Transport Task Force meeting, Apr 2015, Salem, Massachusetts, United States
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titre
Observation of Strongly Intermittent Density Turbulence in ASDEX Upgrade I-mode plasmas
auteur
T. Happel, A. Hetzenecker, P. Manz, Pascale Hennequin, F. Ryter, M. Bernert, G. D. Conway, S. Fietz, Cyrille Honoré, U. Stroth, E. Viezzer, The Asdex Upgrade Team
article
20th EU-US Transport Task Force meeting., Apr 2015, Salem, Massachusetts, United States
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titre
Synthetic Doppler backscattering diagnostic for fluid turbulent simulations
auteur
Robin Leybros, G. Ciraolo, C. Colin, Pascale Hennequin, Y. Marandet, Pierre Morel, P. Tamain, Laure Vermare
article
Turbulence, magnetic fields and self organization in laboratory and astrophysical plasmas, Mar 2015, Les Houches, France
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Directions of work or proceedings

titre
The Plasma E × B Staircase: Turbulence Self-Regulation through Spontaneous Flow Patterning
auteur
Guilhem Dif-Pradalier, G Hornung, Philippe Ghendrih, R Clairet, P Diamond, Yanick Sarazin, L Vermare, J Abiteboul, T Cartier-Michaud, C Ehrlacher, D Estève, Xavier Garbet, Virginie Grandgirard, Özgür Gürcan, P Hennequin, Y Kosuga, Guillaume Latu, Pierre Morel, C Norscini, R Sabot
article
42nd European Physical Society Conference on Plasma Physics, Lisbon, Portugal, France. 2015
resume
The E × B staircase [1, 2] is a spontaneously formed, turbulence-driven self-organising pattern of quasi-regular, long-lived and localised shear flow [3] and stress layers. These layers coincide with long-lived pressure corrugations and are interspersed between regions of turbulent avalanching. The typical spacing between these layers is mesoscale, noted ∆ ∼ 25 − 30ρ i [1, 4] —in-between the turbulence auto-correlation length c ∼ 5ρ i at micro scales and the profile macroscale L 100ρ i , see e.g. Fig.2 in [1]— and sets the outer scale of the turbulent avalanching. Here ρ i is ion Larmor radius. Whilst arresting, statistically, to mesoscales the detrimental avalanching these layers, located at the " steps of the staircase " are beneficial to confinement. The E×B staircase is thus best understood as a self-organising and dynamical set of weak or permeable transport barriers. Strong mean zonal flows are generated and endure at the steps of the staircase, resulting in localised deviations of the poloidal flow from its oft-assumed neoclassical prediction [5].
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https://hal-cea.archives-ouvertes.fr/cea-01468381/file/15_GDP_EPS_4pages.pdf BibTex
titre
Further details on the plasma E × B staircase
auteur
Guilhem Dif-Pradalier, G Hornung, Philippe Ghendrih, Yanick Sarazin, F Clairet, L Vermare, P Diamond, J Abiteboul, T Cartier-Michaud, C Ehrlacher, D Esteve, Xavier Garbet, Virginie Grandgirard, Özgür Gürcan, P Hennequin, A Kosuga, Guillaume Latu, Pierre Morel, C Norscini, R Sabot, A. Storelli
article
7th IAEA Technical Meeting on "Theory of Plasmas Instabilities", Frascati, Italy, Mar 2015, France. 2015
resume
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.
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https://hal-cea.archives-ouvertes.fr/cea-01468382/file/15_IAEA.pdf BibTex

2014

Journal articles

titre
Phase space structures in gyrokinetic simulations of plasma turbulence
auteur
Philippe Ghendrih, C. Norscini, T. Cartier-Michaud, G. Dif-Pradalier, J. Abiteboul, Yue Dong, X. Garbet, Özgür Gürcan, Pascale Hennequin, Virginie Grandgirard, G. Latu, Pierre Morel, Y. Sarazin, A. Storelli, Laure Vermare
article
The European Physical Journal D : Atomic, molecular, optical and plasma physics, EDP Sciences, 2014, 68 (10), pp.303. ⟨10.1140/epjd/e2014-50210-8⟩
resume
Gyrokinetic simulations of fusion plasmas give extensive information in 5D on turbulence and transport. This paper highlights a few of these challenging physics in global, flux driven simulations using experimental inputs from Tore Supra shot TS45511. The electrostatic gyrokinetic code GYSELA is used for these simulations. The 3D structure of avalanches indicates that these structures propagate radially at localised toroidal angles and then expand along the field line at sound speed to form the filaments. Analysing the poloidal mode structure of the potential fluctuations (at a given toroidal location), one finds that the low modes m = 0 and m = 1 exhibit a global structure; the magnitude of the m = 0 mode is much larger than that of the m = 1 mode. The shear layers of the corrugation structures are thus found to be dominated by the m = 0 contribution, that are comparable to that of the zonal flows. This global mode seems to localise the m = 2 mode but has little effect on the localisation of the higher mode numbers. However when analysing the pulsation of the latter modes one finds that all modes exhibit a similar phase velocity, comparable to the local zonal flow velocity. The consequent dispersion like relation between the modes pulsation and the mode numbers provides a means to measure the zonal flow. Temperature fluctuations and the turbulent heat flux are localised between the corrugation structures. Temperature fluctuations are found to exhibit two scales, small fluctuations that are localised by the corrugation shear layers, and appear to bounce back and forth radially, and large fluctuations, also readily observed on the flux, which are associated to the disruption of the corrugations. The radial ballistic velocity of both avalanche events if of the order of 0.5ρ∗c0 where ρ∗ = ρ0/a, a being the tokamak minor radius and ρ0 being the characteristic Larmor radius, ρ0 = c0/Ω0. c0 is the reference ion thermal velocity and Ω0 = qiB0/mi the reference ion Larmor frequency for the characteristic amplitude of the magnetic field B0, qi and mi being, respectively, the ion charge and mass. The electric drift velocity is also found to exhibit a poloidal pattern, with maximum amplitude of the fluctuations either in the top or in the bottom regions of the machine depending on the sign of the zonal flow shear. This effect is found to be correlated to the stopping capability of the corrugation structures. The neoclassical properties stemming from the trapped particle drifts lead to large distortion of the distribution function. As expected, these prevail at the outer part of the simulation region despite the large collisionality. The distribution function fluctuations appear to be aligned along the v∥ = const. lines at constant poloidal angle. A specific symmetry is observed regarding the interplay of turbulence with the trapped-passing region.
DOI
DOI : 10.1140/epjd/e2014-50210-8
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titre
Complete multi-field characterization of the geodesic acoustic mode in the TCV tokamak
auteur
C. A. de Meijere, S. Coda, Z. Huang, Laure Vermare, T. Vernay, V. Vuille, Stephan Brunner, J. Dominski, Pascale Hennequin, A. Kraemer-Flecken, G. Merlo, L. Porte, Laurent Villard
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2014, 56 (7), pp.072001. ⟨10.1088/0741-3335/56/7/072001⟩
resume
The geodesic acoustic mode (GAM) is a coherently oscillating zonal flow that may regulate turbulence in toroidal plasmas. Uniquely, the complete poloidal and toroidal structure of the magnetic component of the turbulence-driven GAM has been mapped in the TCV tokamak. Radially localized measurements of the fluctuating density, ECE radiative temperature and poloidal flow show that the GAM is a fully coherent, radially propagating wave. These observations are consistent with electrostatic, gyrokinetic simulations.
DOI
DOI : 10.1088/0741-3335/56/7/072001
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Conference papers

titre
Preparing ITER Tungsten Divertor Operation in Tore Supra: Physics Basis for the WEST Project.
auteur
E. Tsitrone, C. Bourdelle, J. Bucalossi, R. Guirlet, J.-F. Artaud, V. Basiuk, M. Bécoulet, H. Bufferand, G. Ciraolo, Y. Corre, J. Decker, G. Dif-Pradalier, R. Dumond, A. Ekedahl, N. Fedorczak, M. Firdaouss, J. Garcia, Ph. Ghendrih, G. Giruzzi, C. Grisolia, A. Grosman, Pascale Hennequin, F. Imbeaux, P. Maget, Y. Marandet, O. Meyer, M. Missirlian, E. Nardon, B. Pégourié, M. Schneider, R. Zagorski
article
25th Fusion Energy Conference (FEC 2014), Oct 2014, Saint Petersburg, Russia. pp.EX/P5-48
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titre
Spatial Propagation of Turbulence and Formation of Mesoscopic Structures in Plasma Turbulence
auteur
G. Dif-Pradalier, Ph. Ghendrih, P.H. Diamond, X. Garbet, V. Grandgirard, C. Norscini, F. Palermo, Y. Sarazin, J. Abiteboul, Yue Dong, Özgür Gürcan, Pascale Hennequin, Pierre Morel, Laure Vermare, Y. Kosuga
article
KITP program : Wave-Flow Interaction in Geophysics, Climate, Astrophysics and Plasmas, 2014, KALVI Institute, Santa Barbara, California, United States
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Poster communications

titre
GAM frequency and dynamics compared between Tore Supra experiments and a GYSELA simulation
auteur
A. Storelli, Laure Vermare, Pascale Hennequin, G. Dif-Pradalier, Özgür Gürcan, Y. Sarazin, V. Grandgirard, Rameswar Singh, Pierre Morel, X. Garbet, Ph. Ghendrih, C. Bourdelle, Team Tore Supra
article
EU-US Joint Transport Task Force, Sep 2014, Culham, United Kingdom. 2014
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titre
Spatial structure of turbulence and its scaling with rho* : observations using radial correlation Doppler reflectometry on ASDEX Upgrade
auteur
Pascale Hennequin, T. Happel, P. Schneider, G. D. Conway, F. Ryter, U. Stroth, Cyrille Honoré, Laure Vermare, Özgür Gürcan, Pierre Morel
article
19th Joint EU−US Transport Task Force Meeting (TTF14), Sep 2014, Culham, Great britain, Unknown Region. 2014
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titre
Investigation of drift velocity effects on the EDGE and SOL transport.
auteur
Robin Leybros, H. Bufferand, G. Ciraolo, N. Fedorczak, Ph. Ghendrih, Pascale Hennequin, Y. Marandet, E. Serre, F. Schwander, P. Tamain
article
21st International Conference on Plasma Surface Interactions, 2014, Unknown, Japan. 2014
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2013

Journal articles

titre
Angular momentum transport modeling: achievements of a gyrokinetic quasi-linear approach
auteur
P. Cottier, C. Bourdelle, Y. Camenen, Özgür Gürcan, F.J. Casson, Xavier Garbet, P. Hennequin, T. Tala
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2013, 56, pp.015011. ⟨10.1088/0741-3335/56/1/015011⟩
resume
QuaLiKiz, a model based on a local gyrokinetic eigenvalue solver is expanded to include momentum flux modeling in addition to heat and particle fluxes. Essential for accurate momentum flux predictions, the parallel asymmetrization of the eigenfunctions is successfully recovered by an analytical fluid model. This is tested against self-consistent gyrokinetic calculations and allows for a correct prediction of the E×B shear impact on the saturated potential amplitude by means of a mixing length rule. Hence, the effect of the E×B shear is recovered on all the transport channels including the induced residual stress. Including these additions, QuaLiKiz remains ∼10 000 faster than non-linear gyrokinetic codes allowing for comparisons with experiments without resorting to high performance computing. The example is given of momentum pinch calculations in NBI modulation experiments.
DOI
DOI : 10.1088/0741-3335/56/1/015011
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https://hal.archives-ouvertes.fr/hal-00926719/file/Ang_mom_QLK.pdf BibTex
titre
Structure of nonlocality of plasma turbulence
auteur
Özgür Gürcan, Laure Vermare, Pascale Hennequin, Vincent Berionni, P.H. Diamond, G. Dif-Pradalier, X. Garbet, Philippe Ghendrih, Virginie Grandgirard, C.J. Mcdevitt, Pierre Morel, Y. Sarazin, A. Storelli, C. Bourdelle, Team Tore Supra
article
Nuclear Fusion, IOP Publishing, 2013, 53, pp.073029. ⟨10.1088/0029-5515/53/7/073029⟩
resume
Various indications on the weakly nonlocal character of turbulent plasma transport both from experimental fluctuation measurements from Tore Supra and observations from the full-f, flux-driven gyrokinetic code GYSELA are reported. A simple Fisher equation model of this weakly nonlocal dynamics can be formulated in terms of an evolution equation for the turbulent entropy density, which contains the basic phenomenon of radial turbulence spreading in addition to avalanche-like dynamics via coupling to profile modulations. A derivation of this model, which contains the so-called beach effect, a diffusive and convective flux components for the flux of turbulence intensity, in addition to linear group propagation is given, starting from the drift-kinetic equation. The proposed model has the form of a transport equation for turbulence intensity, and may be considered as an addition to transport modelling. The kinetic fluxes given, can be computed using model closures, or local gyrokinetics. The model is also used in a particular setup that represents the near edge region as a relatively stable zone between the core and edge region where the energy injection is locally more substantial. It is observed that with constant, physical coefficients, the model gives a convincing qualitative profile of fluctuation intensity when the turbulence is coming from the core region with either a group velocity or a convective flux.
DOI
DOI : 10.1088/0029-5515/53/7/073029
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titre
Transport of radial heat flux and second sound in fusion plasmas
auteur
Özgür Gürcan, P.H. Diamond, X. Garbet, Vincent Berionni, G. Dif-Pradalier, Pascale Hennequin, Pierre Morel, Y. Kosuga, Laure Vermare
article
Physics of Plasmas, American Institute of Physics, 2013, 20, pp.022307. ⟨10.1063/1.4792161⟩
resume
Simple flux-gradient relations that involve time delay and radial coupling are discussed. Such a formulation leads to a rather simple description of avalanches and may explain breaking of gyroBohm transport scaling. The generalization of the flux-gradient relation (i.e., constitutive relation), which involve both time delay and spatial coupling, is derived from drift-kinetic equation, leading to kinetic definitions of constitutive elements such as the flux of radial heat flux. This allows numerical simulations to compute these cubic quantities directly. The formulation introduced here can be viewed as an extension of turbulence spreading to include the effect of spreading of cross-phase as well as turbulence intensity, combined in such a way to give the flux. The link between turbulence spreading and entropy production is highlighted. An extension of this formulation to general quasi-linear theory for the distribution function in the phase space of radial position and parallel velocity is also discussed.
DOI
DOI : 10.1063/1.4792161
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titre
Dynamics of tilted eddies in a transversal flow at the edge of tokamak plasmas and the consequences for L-H transition
auteur
N. Fedorczak, Philippe Ghendrih, Pascale Hennequin, G.R. Tynan, P.H. Diamond, P. Manz
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2013, 55 (12), pp.124024. ⟨10.1088/0741-3335/55/12/124024⟩
resume
The dynamical interaction between eddies and shear flow is investigated through a simplified model of vorticity conservation with tilted eddies. Energy is transferred either to the flow or to eddies, depending on the eddy tilt with respect to the flow shear. When eddies are tilted in the shear direction, the system is favorable to shear increase: tilt instability (TI) or the negative viscosity phenomenon. When eddies are tilted in the opposite direction, the shear flow is damped via a Kelvin-Helmholtz (KH) process. The TI generally dominates the interaction on the largest radial scale, but a fraction of the energy cascades to smaller radial scales through the alternation of tilting and KH dynamics. Within this eddy description, we show that the symmetry breaking required to generate a net residual stress is set by the intrinsic eddy tilt. We recall that magnetic shear can provide an intrinsic tilt to ballooning modes at the edge of tokamak plasmas, with an orientation which depends on flux surface geometry. In L-mode weak shear regimes, this residual stress can dominate the Reynolds stress. Coupled to momentum sources acting in the scrape-off layer, it can induce a significant difference of the edge radial electric field between lower single null and upper single null geometries. A comparison with experimental profiles measured across the edge of Tore Supra L-mode plasmas is discussed.
DOI
DOI : 10.1088/0741-3335/55/12/124024
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titre
Interaction of plasma transport and turbulence on particle fuelling
auteur
Patrick Tamain, Gérard Bonhomme, Frédéric Brochard, Frédéric Clairet, C. Gil, J. Gunn, P. Hennequin, G. Hornung, J. L. Segui, L. Vermare, Philippe Ghendrih, Tore Supra Team
article
Journal of Nuclear Materials, Elsevier, 2013, 438 (S), pp.S148-S154. ⟨10.1016/j.jnucmat.2013.01.023⟩
resume
We report the results of an experimental investigation of the impact of Supersonic Molecular Beam Injection in the Tore Supra tokamak. Several diagnostics were synchronised with the injection to extract a global picture of the physics at play from the time scale of turbulence (similar to 10 mu s) to the full-recovery time (similar to 1 s). As previously reported, a strong impact of the injection on density and temperature profiles is observed. Both fields exhibit a complex dynamic response involving different phases and time scales. In particular, we show that the effective particle fuelling efficiency is determined by a period of degraded confinement that follows the injection, during which the edge density collapses, in some cases, lower than the initial one. This phase is characterised by a dramatic change in the turbulent transport, with a drop of the frequency spectrum and the observation of large coherent structures as opposed to small intermittent fluctuations before the injection.
DOI
DOI : 10.1016/j.jnucmat.2013.01.023
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Conference papers

titre
Investigation of drift velocity effects on the EDGE and SOL transport
auteur
Leybros R., Hugo Bufferand, Ciraolo G., Nicolas Fedorczak, Philippe Ghendrih, P. Hennequin, Marandet Y., Serre E., Schwander F., Patrick Tamain
article
21st International Conference on Plasma Surface Interactions in Controlled Fusion Devices (21st PSI), Nov 2013, Kanazawa City, Japan
resume
no abstract
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titre
Geometrical aspects of the turbulence at the edge of tokamak plasmas and consequences on L-H transition threshold
auteur
N. Fedorczak, P.H. Diamond, G.R. Tynan, P. Manz, Pascale Hennequin, G.S. Xu, J. Bucalossi, Laure Vermare
article
40th European Physical Society Conference on Plasma Physics, Jul 2013, Espoo, Finland
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titre
Multi-diagnostic characterization of geodesic acoustic modes in the TCV tokamak
auteur
Z. Huang, C. A. de Meijere, S. Coda, Laure Vermare, T. Vernay, V. Vuille, Stephan Brunner, Pascale Hennequin, A. Kraemmer-Flecken, L. Porte
article
40th EPS Conf. on Plasma Physics, Jul 2013, Espoo, Finland
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titre
Observation of a poloidal asymmetry of fluctuation perpendicular velocity measured by Doppler backscattering on Tore Supra plasmas
auteur
A. Storelli, Pascale Hennequin, Laure Vermare, Özgür Gürcan, Team Tore Supra
article
11th International Reflectometry Workshop (IRW11), Apr 2013, Palaiseau, France
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titre
Doppler backscattering measurements on TCV
auteur
Laure Vermare, S. Coda, Pascale Hennequin, K. de Meijere, Cyrille Honoré, J-C. Giacalone, Team Tcv
article
11th International Reflectometry Workshop (IRW11), Apr 2013, Palaiseau, France
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titre
The optimized steerable W-band Doppler reflectometer on ASDEX Upgrade: possibilities and issues
auteur
T. Happel, G. D. Conway, Pascale Hennequin, Cyrille Honoré, J-C. Giacalone, P. Simon, U. Stroth, Laure Vermare, The Asdex Upgrade Team
article
11th International Reflectometry Workshop (IRW11), Apr 2013, Palaiseau, France
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titre
Geodesic acoustic modes:ffsimultaneous observation of density,ff magnetic-field, and flow componentsff in the TCV tokamak
auteur
S. Coda, K. de Meijere, Z. Huang, Laure Vermare, T. Vernay, V. Vuille, Stephan Brunner, J. Dominski, Pascale Hennequin, A. Krämer-Flecken, G. Merlo, L. Porte
article
U.S.-E.U. Joint Transport Task Force Workshop, Apr 2013, Santa Rosa, California, United States
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titre
Damping of Geodesic Acoustic Modes.
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Pierre Morel, Team Tore Supra
article
U.S.-E.U. Joint Transport Task Force Workshop, Apr 2013, Santa Rosa, California, United States
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titre
Spatial propagation of turbulence and formation of mesoscopic structures in GK simulations
auteur
G. Dif-Pradalier, Ph. Ghendrih, P.H. Diamond, X. Garbet, V. Grandgirard, F. Palermo, Y. Sarazin, Antoine Strugarek, J. Abitboul, Özgür Gürcan, Pascale Hennequin, Pierre Morel, Laure Vermare
article
U.S. - E.U. Joint Transport Task Force Workshop, Apr 2013, Santa Rosa, California, United States
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titre
Radial correlation of density fluctuations by coupling IPP and LPP W-band Doppler reflectometers on ASDEX Upgrade
auteur
Pascale Hennequin, T. Happel, G. D. Conway, Cyrille Honoré, Laure Vermare, V. Pisarev, J-C. Giacalone, Özgür Gürcan, Team Asdex Upgrade
article
11th International Reflectometry Workshop (IRW11), 2013, Palaiseau, France
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2012

Journal articles

titre
Detection of geodesic acoustic mode oscillations, using multiple signal classification analysis of doppler backscattering signal on tore supra
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Team Tore Supra
article
Nuclear Fusion, IOP Publishing, 2012, 52, pp.063008. ⟨10.1088/0029-5515/52/6/063008⟩
resume
This paper presents the first observation of geodesic acoustic modes (GAMs) on Tore Supra plasmas. Using the Doppler backscattering system, the oscillations of the plasma flow velocity, localized between r/a = 0.85 and r/a = 0.95, and with a frequency, typically around 10 kHz, have been observed at the plasma edge in numerous discharges. When the additional heating power is varied, the frequency is found to scale with Cs/R. The MUltiple SIgnal Classification (MUSIC) algorithm is employed to access the temporal evolution of the perpendicular velocity of density fluctuations. The method is presented in some detail, and is validated and compared against standard methods, such as the conventional fast Fourier transform method, using a synthetic signal. It stands out as a powerful data analysis method to follow the Doppler frequency with a high temporal resolution, which is important in order to extract the dynamics of GAMs.
DOI
DOI : 10.1088/0029-5515/52/6/063008
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Conference papers

titre
Indications of Nonlocality of Plasma Turbulence
auteur
Özgür Gürcan, Laure Vermare, Pascale Hennequin, Vincent Berionni, P.H. Diamond, G. Dif-Pradelier, X. Garbet, Ph. Ghendrih, V. Grandgirard, C.J. Mcdevitt, Pierre Morel, Y. Sarazin, A. Storelli, C. Bourdelle, Team Tore Supra
article
24th Fusion Energy Conference, Oct 2012, San Diego, Califormia, United States
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titre
Is "near edge" transport non-local?
auteur
Özgür Gürcan, Laure Vermare, Pascale Hennequin, Vincent Berionni, P.H. Diamond, G. Dif-Pradelier, X. Garbet, Ph. Ghendrih, V. Grandgirard, C.J. Mcdevitt, Pierre Morel, Y. Sarazin, A. Storelli, C. Bourdelle, Team Tore Supra
article
17th Joint EU-US Transport Task Force Meeting, Sep 2012, Padova, Italy
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titre
Study of GAMs on Tore Supra using Doppler backscattering
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, A. Storelli
article
17th Joint EU-US Transport Task Force Meeting, Sep 2012, Padova, Italy
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titre
New regime of small scale density fluctuations in presence of electron heating in Tore Supra.
auteur
Pascale Hennequin, Laure Vermare, Özgür Gürcan, Pierre Morel, A. Storelli, C. Bourdelle, R. Dumont, Team Tore Supra
article
39th European Physical Society Conference & 16th Int. Congress on Plasma Physics, Jul 2012, Stockholm, Sweden
resume
ocs.ciemat.es/epsicpp2012pap/pdf/P1.069.pdf
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titre
Modulation of GAM frequency observed on Tore Supra using Doppler backscattering
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, A. Storelli, Team Tore Supra
article
US Transport Taskforce Workshop Meeting TTF 2012, Apr 2012, Annapolis, United States
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Poster communications

titre
New regime of small scale density fluctuations in presence of electron heating in Tore Supra
auteur
Pascale Hennequin, Laure Vermare, Özgür Gürcan, Pierre Morel, A. Storelli, C. Bourdelle, R. Dumont, Team Tore Supra
article
17th Joint EU-US Transport Task Force Meeting, Sep 2012, Padova, Italy. 2012
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titre
RF driven rotation in Tore Supra
auteur
C. Fenzi, B. Chouli, R. Dumont, D. Elbeze, Z. Guimaraes-Filho, Pascale Hennequin, P. Lotte, P. Maget, Team Tore Supra
article
17th Joint EU-US Transport Task Force Meeting, Sep 2012, Padova, Italy. 2012
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titre
Dependence of properties of Geodesic Acoustic Modes (GAM) on SOL and edge flows in Tore Supra
auteur
A. Storelli, Pascale Hennequin, Özgür Gürcan, Laure Vermare, Team Tore Supra
article
17th Joint EU-US Transport Task Force Meeting, Sep 2012, Padova, Italy. 2012
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2011

Journal articles

titre
Wavenumber spectrum of micro-turbulence in tokamak plasmas / Spectre en nombre d'onde de la micro-turbulence dans les plasmas de tokamak
auteur
Laure Vermare, Özgür Gürcan, Pascale Hennequin, Cyrille Honoré, X. Garbet, J-C. Giacalone, R. Sabot, F. Clairet, Team Tore Supra
article
Comptes Rendus. Physique, Académie des sciences (Paris), 2011, 12 (2), pp.115 - 122. ⟨10.1016/j.crhy.2010.11.003⟩
resume
A better understanding of turbulent transport in a tokamak plasma requires precise comparisons between experimental observation and theoretical prediction of micro-turbulence characteristics. The repartition of fluctuation energy over different spatial scales, which contains detailed information about the character of underlying instabilities and the mechanisms involved in energy transfer between different scales, is one of the few quantities allowing a high detail comparison. The present article reports the investigation performed on the Tore Supra tokamak on the wavenumber spectrum of micro-turbulence using Doppler backscattering. The theoretical approach consists of the derivation of spectral models that include interactions between fluctuations and large scale flow structures. Une meilleure compréhension du transport turbulent dans les plasmas de tokamak exige des comparaisons précises entre les observations expérimentales et les prédictions théoriques des caractéristiques de la micro-turbulence. La répartition de lʼénergie des fluctuations sur les différentes échelles spatiales, qui contient des informations sur le type instabilités sous-jacentes et sur les mécanismes de transfert dʼénergie entre échelles spatiales, est lʼune des rares quantités permettant une comparaison de niveau élevé. Cet article présente le travail mené sur le tokamak Tore Supra sur lʼétude du spectre en nombre dʼonde de la micro-turbulence mesuré par rétro-diffusion Doppler. Lʼapproche théorique consiste en la dérivation de modéles spectraux qui inclut les interactions entre les fluctuations et les structures dʼécoulement de grandes échelles.
DOI
DOI : 10.1016/j.crhy.2010.11.003
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titre
On plasma rotation with toroidal magnetic field ripple and no external momentum input
auteur
C. Fenzi, X. Garbet, Elisée Trier, Pascale Hennequin, C. Bourdelle, Thierry Aniel, G. Colledani, P. Devynck, C. Gil, Özgür Gürcan, L. Manenc, M. Schneider, J.-L. Segui, Team Tore Supra
article
Nuclear Fusion, IOP Publishing, 2011, 51, pp.103038. ⟨10.1088/0029-5515/51/10/103038⟩
resume
Ripple-induced thermal loss effect on plasma rotation is investigated in a set of Ohmic L-mode plasmas performed in Tore Supra, and comparisons with neoclassical predictions including ripple are performed. Adjusting the size of the plasma, the ripple amplitude has been varied from 0.5% to 5.5% at the plasma boundary, keeping the edge safety factor constant. The toroidal flow dynamics is understood as being likely dominated by turbulence transport driven processes at low ripple amplitude, while the ripple-induced toroidal friction becomes dominant at high ripple. In the latter case, the velocity tends remarkably towards the neoclassical prediction (counter-current rotation). The radial electric field is not affected by the ripple variation and remains well described by its neoclassical prediction. Finally, the poloidal velocity is of the order of the neoclassical prediction at high ripple amplitude, but significantly departs from it at low ripple.
DOI
DOI : 10.1088/0029-5515/51/10/103038
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titre
Impact of collisionality on fluctuation characteristics of micro-turbulence
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, C. Bourdelle, F. Clairet, X. Garbet, R. Sabot, Team Tore Supra
article
Physics of Plasmas, American Institute of Physics, 2011, 18, pp.012306. ⟨10.1063/1.3536648⟩
resume
The influence of changing collisionality on density fluctuation characteristics is studied during dedicated ν∗ scaling experiments, using Doppler backscattering system. First, the repartition of fluctuation energy over different spatial scales, as represented by the wavenumber spectrum, is investigated and a modification of the shape of the perpendicular wavenumber spectrum in the low wavenumber part of the spectrum is observed when changing collisionality. In addition, a new procedure to evaluate the dispersion relation of micro-turbulence is presented. From the behavior of the perpendicular mean velocity of density fluctuations with the perpendicular wavenumber, different dispersion relations are obtained between low and high collisionality cases.
DOI
DOI : 10.1063/1.3536648
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titre
Collisionality scaling in Tore Supra: detailed energy confinement analysis, turbulence measurements and gyrokinetic modelling
auteur
C. Bourdelle, T. Gerbaud, Laure Vermare, A. Casati, Thierry Aniel, J.F. Artaud, Vincent Basiuk, J. Bucalossi, F. Clairet, Y. Corre, P. Devynck, G. Falchetto, C. Fenzi, X. Garbet, R. Guirlet, Özgür Gürcan, S. Heuraux, Pascale Hennequin, G.T. Hoang, Frédéric Imbeaux, L. Manenc, P. Monier-Garbet, P. Moreau, R. Sabot, J.-L. Segui, A. Sirinelli, D. Villegas, Team Tore Supra
article
Nuclear Fusion, IOP Publishing, 2011, 51, pp.063037. ⟨10.1088/0029-5515/51/6/063037⟩
resume
This paper presents the first observation of geodesic acoustic modes (GAMs) on Tore Supra plasmas. Using the Doppler backscattering system, the oscillations of the plasma flow velocity, localized between r/a = 0.85 and r/a = 0.95, and with a frequency, typically around 10 kHz, have been observed at the plasma edge in numerous discharges. When the additional heating power is varied, the frequency is found to scale with Cs/R. The MUltiple SIgnal Classification (MUSIC) algorithm is employed to access the temporal evolution of the perpendicular velocity of density fluctuations. The method is presented in some detail, and is validated and compared against standard methods, such as the conventional fast Fourier transform method, using a synthetic signal. It stands out as a powerful data analysis method to follow the Doppler frequency with a high temporal resolution, which is important in order to extract the dynamics of GAMs.
DOI
DOI : 10.1088/0029-5515/51/6/063037
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Conference papers

titre
Impact of collisionality on characteristics of micro-turbulence on Tore Supra
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, C. Bourdelle, F. Clairet, X. Garbet, J-C. Giacalone, R. Sabot, Y. Sarazin, T. Goërler, F. Jenko
article
38th European Physical Society Conference on Plasma Physics, Jun 2011, Strasbourg, France
resume
(oral)
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titre
k spectra in Tore Supra : experiments, theory and modelling
auteur
Pascale Hennequin
article
Workshop on Electric Fields, Turbulence and Self-Organisation in Magnetized Plasmas, Jun 2011, Strasbourg, France
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titre
Flows and perpendicular velocity properties observed by Doppler reflectometry on Tore Supra
auteur
Pascale Hennequin, Laure Vermare, Özgür Gürcan, Elisée Trier, W. Ensing, J-C. Giacalone, N. Fedorczak, J. Bernardo, C. Fenzi, J. Gunn
article
10th International Reflectometry Workshop IRW10, May 2011, Padova, Italy
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titre
Fluctuation characteristics of micro-turbulence on Tore Supra using Doppler backscattering system
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, W. Ensing, C. Bourdelle, F. Clairet, X. Garbet, J.-C. Giaccalone, R. Sabot, Team Tore Supra
article
10th International Reflectometry Workshop IRW10, May 2011, Padova, Italy
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titre
Core turbulence in Tokamak plasmas : observations by EM wave scattering, reflectometry and others
auteur
Pascale Hennequin
article
Les Houches Winter School « Dynamics and turbulent transport in plasmas and conducting fluids », Feb 2011, Les Houches, France
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titre
Impact of collisionality on fluctuation characteristics of micro-turbulence
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, Vincent Berionni
article
Les Houches Winter School « Dynamics and turbulent transport in plasmas and conducting fluids, Feb 2011, Les Houches, France
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titre
Evolution of micro-turbulence characteristics with collisionality at the tokamak core-edge interface
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, Vincent Berionni, C. Bourdelle, A. Casati, F. Clairet, X. Garbet, J-C. Giacalone, R. Sabot, Team Tore Supra
article
Joint US-EU Transport Taskforce Workshop TTF 2011, 2011, San Diego, California, USA, Unknown Region
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2010

Journal articles

titre
Error analysis of dimensionless scaling experiments with multiple points using linear regression
auteur
Özgür Gürcan, Laure Vermare, Pascale Hennequin, C. Bourdelle
article
Nuclear Fusion, IOP Publishing, 2010, 50, pp.022003. ⟨10.1088/0029-5515/50/2/022003⟩
resume
A general method of error estimation in the case of multiple point dimensionless scaling experiments, using linear regression and standard error propagation, is proposed. The method reduces to the previous result of Cordey (2009 Nucl. Fusion 49 052001) in the case of a two-point scan. On the other hand, if the points follow a linear trend, it explains how the estimated error decreases as more points are added to the scan. Based on the analytical expression that is derived, it is argued that for a low number of points, adding points to the ends of the scanned range, rather than the middle, results in a smaller error estimate.
DOI
DOI : 10.1088/0029-5515/50/2/022003
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titre
Particle transport in low core turbulence Tore-Supra plasmas
auteur
R. Guirlet, A. Sirinelli, T. Parisot, R. Sabot, J.F. Artaud, C. Bourdelle, X. Garbet, Pascale Hennequin, G.T. Hoang, Frédéric Imbeaux, J.-L. Segui, D. Mazon, D. Villegas
article
Nuclear Fusion, IOP Publishing, 2010, 50, pp.095009. ⟨10.1088/0029-5515/50/9/095009⟩
resume
Electron and impurity transport has been studied in sawtoothing plasmas in the Tore-Supra tokamak. High time and space resolution measurements of the electron density reveal the existence of a flat profile region encompassing the q = 1 surface, on which is superimposed a density peak building up between sawtooth relaxations. For the first time in this regime, we have determined the underlying transport of both nickel and electrons independently of the effect of sawteeth in the central part of the plasma. Electron transport is consistent with the neoclassical expectations only in the close vicinity of the magnetic axis. Further out, it exceeds the neoclassical values as calculated with the NCLASS code, although the turbulence level is very low in the whole central region region. In contrast, nickel transport is in good agreement with the neoclassical calculations in the same region. The neoclassical effect on trapped particles of a persisting mode due to incomplete reconnection of the magnetic surfaces is consistent with these observations.
DOI
DOI : 10.1088/0029-5515/50/9/095009
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titre
Plasmas de Fusion Magnétique
auteur
Pascale Hennequin
article
FlashX, 2010, 12, pp.25-26
resume
ISSN : 1775-0385
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titre
Une recherche ITER...ative
auteur
Pascale Hennequin
article
Pour la science, Société Pour la Science 2010
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titre
Entropy production rate in tokamaks with nonaxisymmetric magnetic fields
auteur
X. Garbet, J. Abiteboul, Elisée Trier, Özgür Gürcan, Y. Sarazin, A. Smolyakov, S. Allfrey, C. Bourdelle, C. Fenzi, Virginie Grandgirard, Philippe Ghendrih, Pascale Hennequin
article
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.072505. ⟨10.1063/1.3454365⟩
resume
A variational principle based on an extremum of entropy production rate is derived for an integrable Hamiltonian system in the presence of two perturbations, which are resonant on neighboring or identical resonant surfaces. This method can be used to calculate the neoclassical transport in a magnetic fusion device with a nonaxisymmetric magnetic field. When applied to a tokamak with ripple, it provides an efficient means to discriminate between various regimes, depending on collisionality and ripple amplitude. This technique provides a means to test simplified collision operators suitable for gyrokinetic codes. It is found that these operators need only satisfy modest requirements in order to recover the correct neoclassical equilibrium, at least in the large aspect ratio limit. Finally, it appears that the toroidal viscous damping rate due to ripple is usually not negligible, thus removing the degeneracy between the radial electric field and the toroidal velocity.
DOI
DOI : 10.1063/1.3454365
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titre
Shell models and the possibility of application to fusion plasmas
auteur
Özgür Gürcan, Pascale Hennequin, Laure Vermare, X. Garbet, P.H. Diamond
article
Plasma Physics and Controlled Fusion, IOP Publishing, 2010, 52, pp.045002. ⟨10.1088/0741-3335/52/4/045002⟩
resume
An extensive study of spectral shell models with possibilities for application to fusion plasmas is discussed. A set of shell models addressing various aspects of the characteristics of fusion plasmas have been derived. Difficulties associated with plasma medium, namely its intrinsic excitability, and importance of mescals have been discussed. The numerical implementation of shell models is discussed. It was observed that depending on the parameter regime, they may lead to steady state or display characteristics of predator–prey dynamics.
DOI
DOI : 10.1088/0741-3335/52/4/045002
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titre
Residual parallel Reynolds stress due to turbulence intensity gradient in tokamak plasmas
auteur
Özgür Gürcan, P.H. Diamond, Pascale Hennequin, C.J. Mcdevitt, X. Garbet, C. Bourdelle
article
Physics of Plasmas, American Institute of Physics, 2010, 17, pp.112309. ⟨10.1063/1.3503624⟩
resume
A novel mechanism for driving residual stress in tokamak plasmas based on k∥ symmetry breaking by the turbulence intensity gradient is proposed. The physics of this mechanism is explained and its connection to the wave kinetic equation and the wave-momentum flux is described. Applications to the H-mode pedestal in particular to internal transport barriers, are discussed. Also, the effect of heat transport on the momentum flux is discussed.
DOI
DOI : 10.1063/1.3503624
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Conference papers

titre
On Plasma Rotation with Toroidal Magnetic Field Ripple and no External Momentum Input
auteur
C. Fenzi, X. Garbet, Elisée Trier, Pascale Hennequin, C. Bourdelle, T. Aniel, G. Colledani, P. Devynck, C. Gil, Özgür Gürcan, M. Schneider, J.-L. Ségui, The Tore Supra Team
article
23rd IAEA Fusion Energy Conference, Oct 2010, Daejon, Korea, Unknown Region
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titre
Impact of collisionality on fluctuation characteristics of micro-turbulence
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, C. Bourdelle, F. Clairet, X. Garbet, R. Sabot, Team Tore Supra
article
23rd IAEA Fusion Energy Conference, Oct 2010, Daejon, Korea, Unknown Region
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titre
Dynamics of wave-number spectrum of plasma turbulence
auteur
Özgür Gürcan, Pascale Hennequin, Laure Vermare, A. Casati, G. Falchetto, X. Garbet, C. Bourdelle, P.H. Diamond
article
23rd IAEA Fusion Energy Conference, Oct 2010, Daejon, Korea, Unknown Region
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titre
A renormalized quasi-linear approach to turbulent transport in tokamaks
auteur
Özgür Gürcan, A. Casati, Laure Vermare, M. Ottaviani, C. Bourdelle, Pascale Hennequin, Y. Sarazin, S. Allfrey, X. Garbet, P.H. Diamond
article
15th EU-US Transport Task Force Meeting and 3rd Transport Topical Group Meeting, Sep 2010, Córdoba, Spain
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titre
The effect of SOL flows on edge and core radial electric field and rotation in Tore Supra
auteur
Pascale Hennequin, Laure Vermare, N. Fedorczak, J. Bernardo, Özgür Gürcan, Elisée Trier, C. Fenzi, J. Gunn, P. Monier-Garbet, R. Ghendrih, X. Garbet
article
37th EPS Conference on Plasma Physics, Jun 2010, Dublin, Ireland
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titre
Fluctuations measurements from Doppler Reflectometry On Tore Supra
auteur
Pascale Hennequin
article
2010 International Conf. on Plasma Diag, Apr 2010, Pont-à Mousson, France
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titre
Shell Models and the possibility of application to fusion plasmas
auteur
Özgür Gürcan, Pascale Hennequin, X. Garbet, P.H. Diamond, Laure Vermare, A. Casati, G. Falchetto
article
URSI 2010 Journées Scientifiques Propagation et Plasmas, Mar 2010, Paris, France
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titre
Turbulence measurements during dimensionless parameters scans on Tore Supra using Doppler reflectometry
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, C. Bourdelle, T. Aniel, F. Clairet, R. Dumont, C. Fenzi, R. Sabot, Team Tore Supra
article
URSI 2010 Journées Scientifiques Propagation et Plasmas, Mar 2010, Paris, France
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titre
Measurements and Modeling of Turbulent Transport in the Tore Supra Tokamak
auteur
X. Garbet, J. Abiteboul, S. Benkadda, C. Bourdelle, A. Casati, F. Clairet, N. Dubuit, G. Falchetto, C. Fenzi, S. Futatani, V. Grandgirard, R. Guirlet, Özgür Gürcan, Pascale Hennequin, S. Heuraux, G.T. Hoang, Cyrille Honoré, R. Sabot, Y. Sarazin, J.-L. Ségui, A. Smolyakov, Elisée Trier, Laure Vermare, D. Villegas
article
INTERNATIONAL SYMPOSIUM ON WAVES, COHERENT STRUCTURES AND TURBULENCE IN PLASMAS, Jan 2010, Gandhinagar, India. pp.75-84, ⟨10.1063/1.3526165⟩
resume
This paper presents an overview of recent advances in modeling and measurements of turbulence in Tore Supra plasmas. Spatio‐temporal properties of turbulence are discussed in relation with transport models. An explanation is proposed for the k−3 decay of wave number spectra, which are observed by using both coherent laser scattering and Doppler reflectometry. Also the interplay between turbulence and flows has been investigated. It is shown that toroidal rotation results from a competition between neoclassical and turbulence flow generation. Finally a new method has been proposed to determine the transport coefficients of impurities. These coefficients are usually well above the neoclassical prediction.
DOI
DOI : 10.1063/1.3526165
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Poster communications

titre
Impact of collisionality on fluctuations characteristics of micro-turbulence
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, C. Bourdelle, F. Clairet, C. Fenzi, X. Garbet, R. Sabot, Team Tore Supra
article
15th EU-US Transport Task Force Meeting and 3rd Transport Topical Group Meeting, Sep 2010, Córdoba, Spain. 2010
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2009

Journal articles

titre
FLUCTUATION MEASUREMENTS AND THEIR LINK WITH TRANSPORT ON TORE SUPRA
auteur
R. Sabot, Pascale Hennequin, L. Colas
article
Fusion Science and Technology, Taylor & Francis, 2009, 56 (3), pp.1253-1272
resume
Measurement of turbulence properties provides key insight to understand anomalous transport in magnetic fusion devices. On Tore Supra, scattering diagnostics and reflectometers have been used to measure density fluctuations in the plasma core. A cross-polarization scattering diagnostic was also the first diagnostic to measure the turbulence magnetic fluctuations in a fusion plasma core. This paper presents the principle and the experimental setup of these diagnostics, with chosen results illustrating their capabilities to determine the spatial structure of the turbulence and to assess the link between energy transport and fluctuations. These flexible and complementary measurements made it possible to analyze the confinement and fluctuation scaling laws with non-dimensional parameters, which requires a wide variety of plasma conditions.
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titre
Wave-Number Spectrum of Drift-Wave Turbulence
auteur
Özgür Gürcan, X. Garbet, Pascale Hennequin, P.H. Diamond, A. Casati, G. L. Falchetto
article
Physical Review Letters, American Physical Society, 2009, 102, pp.255002. ⟨10.1103/PhysRevLett.102.255002⟩
resume
A simple model for the evolution of turbulence fluctuation spectra, which includes neighboring interactions leading to the usual dual cascade as well as disparate scale interactions corresponding to refraction by large scale structures, is derived. The model recovers the usual Kraichnan-Kolmogorov picture in the case of exclusively local interactions and midrange drive. On the other hand, when disparate scale interactions are dominant, a simple spectrum for the density fluctuations of the form |nk|2∝k−3/(1 k2)2 is obtained. This simple prediction is then compared to, and found to be in fair agreement with, Tore Supra CO2 laser scattering data.
DOI
DOI : 10.1103/PhysRevLett.102.255002
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titre
Validating a quasi-linear transport model versus nonlinear simulations
auteur
A. Casati, C. Bourdelle, X. Garbet, Frédéric Imbeaux, J. Candy, F. Clairet, G. Dif-Pradalier, G. Falchetto, T. Gerbaud, Virginie Grandgirard, Özgür Gürcan, Pascale Hennequin, J. Kinsey, M. Ottaviani, R. Sabot, Y. Sarazin, Laure Vermare, R. E. Waltz
article
Nuclear Fusion, IOP Publishing, 2009, 49, pp.085012. ⟨10.1088/0029-5515/49/8/085012⟩
resume
In order to gain reliable predictions on turbulent fluxes in tokamak plasmas, physics based transport models are required. Nonlinear gyrokinetic electromagnetic simulations for all species are still too costly in terms of computing time. On the other hand, interestingly, the quasi-linear approximation seems to retain the relevant physics for fairly reproducing both experimental results and nonlinear gyrokinetic simulations. Quasi-linear fluxes are made of two parts: (1) the quasi-linear response of the transported quantities and (2) the saturated fluctuating electrostatic potential. The first one is shown to follow well nonlinear numerical predictions; the second one is based on both nonlinear simulations and turbulence measurements. The resulting quasi-linear fluxes computed by QuaLiKiz (Bourdelle et al 2007 Phys. Plasmas 14 112501) are shown to agree with the nonlinear predictions when varying various dimensionless parameters, such as the temperature gradients, the ion to electron temperature ratio, the dimensionless collisionality, the effective charge and ranging from ion temperature gradient to trapped electron modes turbulence.
DOI
DOI : 10.1088/0029-5515/49/8/085012
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titre
Turbulence in the TORE SUPRA Tokamak: Measurements and Validation of Nonlinear Simulations
auteur
A. Casati, T. Gerbaud, P. Hennequin, Stéphane Heuraux
article
Physical Review Letters, American Physical Society, 2009, 102, pp.165005
resume
Turbulence measurements in TORE SUPRA tokamak plasmas have been quantitatively compared to predictions by nonlinear gyrokinetic simulations. For the first time, numerical results simultaneously match within experimental uncertainty (a) the magnitude of effective heat diffusivity, (b) rms values of density fluctuations, and (c) wave-number spectra in both the directions perpendicular to the magnetic field. Moreover, the nonlinear simulations help to revise as an instrumental effect the apparent experimental evidence of strong turbulence anisotropy at spatial scales of the order of ion-sound Larmor radius.
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Conference papers

titre
Gyrokinetic quasi-linear modelling of transport
auteur
C. Bourdelle, A. Casati, F. Imbeaux, X. Garbet, J. Candy, F. Clairet, Thomas Gerbaud, V. Grandgirard, Özgür Gürcan, Pascale Hennequin, R. Sabot, Y. Sarazin, Laure Vermare, R. E. Waltz
article
13th European Fusion Theory Conference, Oct 2009, Riga, Latvia
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titre
Observation of a localized radial electric field inversion in Tore Supra plasmas
auteur
Elisée Trier, Pascale Hennequin, C. Fenzi, Özgür Gürcan, R. Sabot, P. Maget, J. Bucalossi, X. Garbet, F. Clairet, Laure Vermare, C. Bourdelle, Z. Ghimares-Filho, G. Falchetto, G. Huysmans
article
36th EPS Conference On Plasma Physics and Controlled Fusion, Jun 2009, Sofia, Bulgaria
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titre
Heat and Particle Transport Experiments in Tore Supra and HL-2A with ECRH and SMBI
auteur
X. L. Zou, S. Song, G. Giruzzi, X. Garbet, Cyrille Honoré, J.-L. Ségui, D. Elbeze, F. Clairet, R. Sabot, J. Bucalossi, Pascale Hennequin, M. Lenholm, R. Magne, Team Tore Supra
article
36th EPS Conf. On Plasma Physics and Controlled Fusion, Jun 2009, Sofia, Bulgaria
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titre
Turbulence in Tore Supra plasmas: measurements and validation of nonlinear simulations
auteur
A. Casati, T. Gerbaud, Pascale Hennequin, C. Bourdelle, J. Candy, F. Clairet, X. Garbet, V. Grandgirard, Özgür Gürcan, S. Heuraux, G.T. Hoang, Cyrille Honoré, F. Imbeaux, R. Sabot, Y. Sarazin, Laure Vermare, R. E. Waltz
article
36th EPS Conference On Plasma Physics and Controlled Fusion., Jun 2009, Sofia, Bulgaria
resume
Oral
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titre
Scaling of Turbulence and Transport on Tore Supra with dimensionless parameters rho* and nu
auteur
Laure Vermare, C. Bourdelle, Pascale Hennequin, J.F. Artaud, V. Basiuk, F. Clairet, P. Devynck, G. Falchetto, C. Fenzi, F. Imbeaux, P. Monier-Garbet, Özgür Gürcan, R. Sabot, M. Schubert, J.-L. Ségui, Team Tore Supra
article
36th EPS Conference On Plasma Physics and Controlled Fusion, Jun 2009, Sofia, Bulgaria
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titre
A first comparison between probes, fast imaging, and reflectometry synchronous measurements of edge turbulence in Tore Supra
auteur
F. Brochard, N. Fedorczak, Gildas Bonhomme, F. Clairet, M. Farge, Ph. Ghendrih, J. Gunn, Pascale Hennequin, S. Heuraux, N. Lemoine, P. Monier-Garbet, R. Nguyen, S. Oldenburger, Laure Vermare
article
36th EPS Conference on Plasma Physics and Controlled Fusion, Jun 2009, Sofia, Bulgaria
resume
Oral
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titre
Turbulence measurements during dimensionless parameters scans on Tore Supra using Doppler reflectometry
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, C. Bourdelle, T. Aniel, F. Clairet, R. Dumont, C. Fenzi, R. Sabot, Team Tore Supra
article
9th International Reflectometry workshop IRW9, May 2009, Lisbon, Portugal
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High k spectra in Tore Supra : experiment, theory and modelling
auteur
Pascale Hennequin, Laure Vermare, Özgür Gürcan, Elisée Trier, Cyrille Honoré, C. Bourdelle, A. Casati, G. Dumont, G. Falchetto, X. Garbet, R. Sabot, F. Clairet, Team Tore Supra
article
US Transport Task Force Meeting, Apr 2009, San Diego, California, United States
resume
http://ttf2009.ucsd.edu/working/abₛtorage/afterₚresentation/HennequinTTF09.pdf
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titre
On plasma rotation in tokamak with magnetic field ripple and no external momentum input
auteur
C. Fenzi, Elisée Trier, T. Aniel, C. Bourdelle, F. Clairet, G. Falchetto, X. Garbet, C. Gil, Özgür Gürcan, Pascale Hennequin, J. Lasalle, R. Sabot, J.-L. Ségui, Laure Vermare, Team Tore Supra
article
US Transport Task Force Meeting, Apr 2009, San Diego, California, United States
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titre
Observation of a localized radial electric field inversion in Tore Supra plasmas.
auteur
Elisée Trier, Pascale Hennequin, C. Fenzi, Özgür Gürcan, R. Sabot, P. Maget, J. Bucalossi, X. Garbet, F. Clairet, Laure Vermare, C. Bourdelle, Z. Guimaraes-Filho, G. Falchetto, G. Huysmans
article
US Transport Task Force Meeting TTF, Apr 2009, San Diego, California, United States
resume
http://ttf2009.ucsd.edu/working/abₛtorage/afterₚresentation/trier_TTF09.pdf
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titre
Long range correlation studies : Tore Supra contribution, DREVE project
auteur
Laure Vermare, Pascale Hennequin, Özgür Gürcan, Cyrille Honoré, R. Sabot, J-C. Giacalone, Team Tore Supra
article
2nd EFDA Transport Topical Group Meeting., 2009, Culham, UK, Unknown Region
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titre
Cascade models in plasma turbulence: The role of sheared flows
auteur
Özgür Gürcan, X. Garbet, Pascale Hennequin, P.H. Diamond, A. Casati
article
Joint EU-US Transport Task Force Workshop TTF, 2009, San Diego, California, USA, Unknown Region
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Poster communications

titre
Shell models and the possibility of application to fusion plasmas
auteur
Özgür Gürcan, Pascale Hennequin, X. Garbet, P.H. Diamond
article
13th European Fusion Theory Conference, Oct 2009, Riga, Latvia. 2009
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titre
On plasma rotation in tokamaks with toroidal magnetic field ripple and no external momentum input
auteur
C. Fenzi, Elisée Trier, Pascale Hennequin, X. Garbet, C. Bourdelle, T. Aniel, F. Clairet, C. Gil, Özgür Gürcan, F. Imbeaux, R. Sabot, Team Tore Supra
article
36th European Physical Society Conference on Plasma Physics, Jun 2009, Sofia, Bulgaria. 2009
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