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202. Overview of gyrokinetic studies of finite-βmicroturbulence

Author

Terry, P.W., primary, Carmody, D., additional, Doerk, H., additional, Guttenfelder, W., additional, Hatch, D.R., additional, Hegna, C.C., additional, Ishizawa, A., additional, Jenko, F., additional, Nevins, W.M., additional, Predebon, I., additional, Pueschel, M.J., additional, Sarff, J.S., additional, and Whelan, G.G., additional

Published
2015
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205. Advances in the physics basis for the European DEMO design

Author

Wenninger, R., primary, Arbeiter, F., additional, Aubert, J., additional, Aho-Mantila, L., additional, Albanese, R., additional, Ambrosino, R., additional, Angioni, C., additional, Artaud, J.-F., additional, Bernert, M., additional, Fable, E., additional, Fasoli, A., additional, Federici, G., additional, Garcia, J., additional, Giruzzi, G., additional, Jenko, F., additional, Maget, P., additional, Mattei, M., additional, Maviglia, F., additional, Poli, E., additional, Ramogida, G., additional, Reux, C., additional, Schneider, M., additional, Sieglin, B., additional, Villone, F., additional, Wischmeier, M., additional, and Zohm, H., additional

Published
2015
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206. Advances in stellarator gyrokinetics

Author

Helander, P., primary, Bird, T., additional, Jenko, F., additional, Kleiber, R., additional, Plunk, G.G., additional, Proll, J.H.E., additional, Riemann, J., additional, and Xanthopoulos, P., additional

Published
2015
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210. Axially Symmetric Divertor Experiment (ASDEX) Upgrade Team (vol 81, 033507, 2010)

Author

Adamek, J., Angioni, C., Antar, G., Atanasiu, C.V., Balden, M., Becker, W., Behler, K., Behringer, K., Bergmann, A., Bilato, R., Bobkov, V., Boom, J., Bottino, A., Brambilla, M., Braun, F., Brüdgam, M., Buhler, A., Chankin, A., Classen, I., Conway, G.D., Coster, D.P., de Marne, P., D'Inca, R., Dodt, D., Doerk-Bendig, H., Drube, R., Dux, R., Eich, T., Endstrasser, N., Engelhardt, K., Fahrbach, H.-U., Fattorini, L., Fischer, R., Forest, C., Fuchs, J.C., Gal, K., Munoz, M.G., Adamov, M.G., Giannone, L., Görler, L., Gori, S., da Graca, S., Greuner, H., Gruber, O., Gude, A., Günter, S., Haas, G., Hammer, N., Hauff, T., Heinemann, B., Herrmann, A., Hicks, N., Hobirk, J., Hölzl, M., Holtum, D., Hopf, C., Huart, M., Igochine, V., Janzer, M., Jenko, F., Kagarmanov, A., Kallenbach, A., Kammel, A., Kalvin, S., Kardaun, O., Kaufmann, M., Kick, M., Kirk, A., Klingshirn, H.-J., Koscis, G., Kollotzek, H., Konz, C., Krieger, K., Kurki-Suonio, T., Kurzan, B., Lackner, K., Lang, P.T., Langer, B., Lauber, P., Laux, M., Leuterer, F., Likonen, J., Liu, L., Lohs, A., Lunt, T., Lyssoivan, A., Mank, K., Manso, M.-E., Mantsinen, M., Maraschek, M., Martin, P., Mayer, M., McCarthy, P., McCormick, K., McDermott, R., Meister, H., Meo, Fernando, Merkel, P., Merkel, R., Mertens, V., Merz, F., Meyer, H., Mlynek, A., Monaco, F., Müller, H.-W., Münich, M., Murmann, H., Neu, G., Neu, R., Neuhauser, J., Nold, B., Noterdaeme, J.M., Pautasso, G., Pereverzev, G., Poli, E., Potzel, S., Püschel, M., Pütterich, T., Raupp, G., Reich, M., Reiter, B., Ribeiro, T., Riedl, R., Rohde, V., Roth, J., Rott, M., Ryter, F., Sandmann, W., Santos, J., Sassenberg, K., Sauter, P., Scarabosio, A., Schall, G., Schmid, K., Schneider, P., Schneider, W., Schrittwieser, R., Schweinzer, J., Scott, B., Seidel, U., Sempf, M., Serra, F., Sertoli, M., Siccinio, M., Sigalov, A., Silva, A., Speth, E., Stäbler, A., Stadler, R., Steuer, K.-H., Stober, J., Streibl, B., Strumberger, E., Suttrop, W., Tardini, G., Tichmann, C., Treutterer, W., Urso, L., Vainonen-Ahlgren, E., Varela, P., Vorpahl, C., Wagner, D., Wigger, C., Wischmeier, M., Wolfrum, E., Würsching, E., Yadikin, D., Yu, Q., Zasche, D., Zehetbauer, T., Zilker, M., and Zohm, H.

Subjects
Fusion energy, Fusionsenergi, Fusionsenergiforskning
Published
2010

211. Impurity transport in ITG and TE mode dominated turbulence

Author

Andreas Skyman, Nordman, H., Strand, P., Jenko, F., and Merz, F.

Subjects
Physics::Fluid Dynamics, Plasma Physics (physics.plasm-ph), Physics::Plasma Physics, FOS: Physical sciences, Condensed Matter::Strongly Correlated Electrons, Physics - Plasma Physics
Abstract

In the present study, turbulent impurity transport in Deuterium tokamak plasmas, driven by Ion Temperature Gradient (ITG) and Trapped Electron (TE) modes, has been investigated using fluid and gyrokinetic models. The impurity diffusivity ($D_Z$) and convective velocity ($V_Z$) are calculated, and from these the zero-flux peaking factor ($PF_0$) is derived. This quantity expresses the impurity density gradient at which the convective and diffusive transport of impurities are exactly balanced. The sign of $PF_0$ is of special interest, as it determines whether the impurities are subject to an inward ($PF_0 > 0$) or outward ($PF_0 < 0$) pinch., 4 pages, 5 figures. Contribution for EPS 2010

Published
2010
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214. Ion temperature profile stiffness : non-linear gyrokinetic simulations and comparison with experiment

Author

Citrin, J., Jenko, F., Mantica, P., Told, D., Bourdelle, C., Dumont, R., Garcia, J., Haverkort, J. W., Hogeweij, G. M. D., Johnson, Thomas, Pueschel, M. J., Citrin, J., Jenko, F., Mantica, P., Told, D., Bourdelle, C., Dumont, R., Garcia, J., Haverkort, J. W., Hogeweij, G. M. D., Johnson, Thomas, and Pueschel, M. J.

Abstract

Recent experimental observations at JET show evidence of reduced ion temperature profile stiffness. An extensive set of nonlinear gyrokinetic simulations are performed based on the experimental discharges, investigating the physical mechanism behind the observations. The impact on the ion heat flux of various parameters that differ within the data-set are explored. These parameters include the safety factor, magnetic shear, toroidal flow shear, effect of rotation on the magnetohydrodynamic equilibrium, R/L-n, beta(e), Z(eff), T-e/T-i, and the fast-particle content. While previously hypothesized to be an important factor in the stiffness reduction, the combined effect of toroidal flow shear and low magnetic shear is not predicted by the simulations to lead to a significant reduction in ion heat flux, due both to an insufficient magnitude of flow shear and significant parallel velocity gradient destabilization. It is however found that nonlinear electromagnetic effects due to both thermal and fast-particle pressure gradients, even at low beta(e), can significantly reduce the ion heat flux, and is a key factor in explaining the experimental observations. A total of four discharges are examined, at both inner and outer radii. For all cases studied, the simulated and experimental ion heat flux values agree within reasonable variations of input parameters around the experimental uncertainties., QC 20140311

Published
2014
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215. Electromagnetic stabilization of tokamak microturbulence in a high-β regime

Author

Citrin, J., Garcia, J., Görier, T., Jenko, F., Mantica, P., Told, D., Bourdelle, C., Hatch, D. R., Hogeweij, G. M. D., Johnson, Thomas, Pueschel, M. J., Schneider, M., Citrin, J., Garcia, J., Görier, T., Jenko, F., Mantica, P., Told, D., Bourdelle, C., Hatch, D. R., Hogeweij, G. M. D., Johnson, Thomas, Pueschel, M. J., and Schneider, M.

Abstract

The impact of electromagnetic stabilization and flow shear stabilization on ITG turbulence is investigated. Analysis of a low-β JET L-mode discharge illustrates the relation between ITG stabilization, and proximity to the electromagnetic instability threshold. This threshold is reduced by suprathermal pressure gradients, highlighting the effectiveness of fast ions in ITG stabilization. Extensive linear and nonlinear gyrokinetic simulations are then carried out for the high-β JET hybrid discharge 75225, at two separate locations at inner and outer radii. It is found that at the inner radius, nonlinear electromagnetic stabilization is dominant, and is critical for achieving simulated heat fluxes in agreement with the experiment. The enhancement of this effect by suprathermal pressure also remains significant. It is also found that flow shear stabilization is not effective at the inner radii. However, at outer radii the situation is reversed. Electromagnetic stabilization is negligible while the flow shear stabilization is significant. These results constitute the high-β generalization of comparable observations found at low-β at JET. This is encouraging for the extrapolation of electromagnetic ITG stabilization to future devices. An estimation of the impact of this effect on the ITER hybrid scenario leads to a 20% fusion power improvement., QC 20170308

Published
2014

219. Overview of ASDEX upgrade results

Author

Zohm H., Adamek J., Angioni C., Antar G., Atanasiu C. V., Balden M., Becker W., Behler K., Behringer K., Bergmann A., Bertoncelli T., Bilato R., Bobkov V., Boom J., Bottino A., Brambilla M., Braun F., Bruedgam M., Buhler A., Chankin A., Classen I., Conway G. D., Coster D. P., de Marne P., D'Inca R., Drube R., Dux R., Eich T., Engelhardt K., Esposito B., Fahrbach H-U., Fattorini L., Fink J., Fischer R., Flaws A., Foley M., Forest C., Fuchs J. C., Gal K., Munoz M. Garcia, Adamov M. Gemisic, Giannone L., Goerler T., Gori S., da Graca S., Granucci G., Greuner H., Gruber O., Gude A., Guenter S., Haas G., Hahn D., Harhausen J., Hauff T., Heinemann B., Herrmann A., Hicks N., Hobirk J., Hoelzl M., Holtum D., Hopf C., Horton L., Huart M., Igochine V., Janzer M., Jenko F., Kallenbach A., Kalvin S., Kardaun O., Kaufmann M., Kick M., Kirk A., Klingshirn H-J., Koscis G., Kollotzek H., Konz C., Krieger K., Kurki-Suonio, Kurzan B., Lackner K., Lang P. T., Langer B., Lauber P., Laux M., Leuterer F., Likonen J., Liu L., Lohs A., Lunt T., Lyssoivan A., Maggi C. F., Manini A., Mank K., Manso M-E., Mantsinen M., Maraschek M., Martin P., Mayer M., McCarthy P., McCormick K., Meister H., Meo F., Merkel P., Merkel R., Mertens V., Merz F., Meyer H., Mlynek A., Monaco F., Mueller H-W., Muenich M., Murmann H., Neu G., Neu R., Neuhauser J., Nold B., Noterdaeme J-M., Pautasso G., Pereverzev G., Poli E., Potzel, Pueschel M., Puetterich T., Pugno R., Raupp G., Reich M., Reiter B., Ribeiro T., Riedl R., Rohde V., Roth J., Rott M., Ryter F., Sandmann W., Santos J., Sassenberg, Sauter P., Scarabosio A., Schall G., Schilling H-B., Schirmer J., Schmid A., Schmid K., Schneider W., Schramm G., Schrittwieser R., Schustereder W., Schweinzer J., Schweizer S., Scott B., Seidel U., Sempf M., Serra F., Sertoli M., Siccinio M., Sigalov A., Silva A., Sips C. C., Speth E., Staebler A., Stadler R., Steuer K-H., Stober J., Streibl B., Strumberger E., Suttrop W., Tardini G., Tichmann C., Treutterer W., Troester C., Urso L., Vainonen-Ahlgren E., Varela P., Vermare L., Volpe F., Wagner D., Wigger C., Wischmeier M., Wolfrum E., Wuersching E., Yadikin D., Yu Q., Zasche D., Zehetbauer T., and Zilker M.

Subjects
Nuclear and High Energy Physics, Materials science, Nuclear engineering, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, ASDEX Upgrade, ITER, 0103 physical sciences, tokamak physics, 010306 general physics, DEMO, nuclear fusion
Abstract

ASDEX Upgrade was operated with a fully W-covered wall in 2007 and 2008. Stationary H-modes at the ITER target values and improved H-modes with H up to 1.2 were run without any boronization. The boundary conditions set by the full W wall (high enough ELM frequency, high enough central heating and low enough power density arriving at the target plates) require significant scenario development, but will apply to ITER as well. D retention has been reduced and stationary operation with saturated wall conditions has been found. Concerning confinement, impurity ion transport across the pedestal is neoclassical, explaining the strong inward pinch of high-Z impurities in between ELMs. In improved H-mode, the width of the temperature pedestal increases with heating power, consistent with a β1/2pol,ped scaling. In the area of MHD instabilities, disruption mitigation experiments using massive Ne injection reach volume averaged values of the total electron density close to those required for runaway suppression in ITER. ECRH at the q = 2 surface was successfully applied to delay density limit disruptions. The characterization of fast particle losses due to MHD has shown the importance of different loss mechanisms for NTMs, TAEs and also beta-induced Alfven eigenmodes (BAEs). Specific studies addressing the first ITER operational phase show that O1 ECRH at the HFS assists reliable low-voltage breakdown. During ramp-up, additional heating can be used to vary li to fit within the ITER range. Confinement and power threshold in He are more favourable than in H, suggesting that He operation could allow us to assess H-mode operation in the non-nuclear phase of ITER operation.

Published
2009

222. Gyrokinetic microinstabilities in ASDEX Uprade edge plasmas

Author

Told, D., Jenko, F., Xanthopoulos, P., Horton, L. D., Wolfrum, E., ASDEX Upgrade Team, and ASDEX Upgrade Team

Subjects
Physics, Temperature gradient, Fusion, Tokamak, ASDEX Upgrade, law, Gyrokinetics, Electron temperature, Plasma, Atomic physics, Edge (geometry), Condensed Matter Physics, law.invention
Abstract

Results of linear gyrokinetic simulations of ASDEX Upgrade [O. Gruber et al., Nucl. Fusion 39, 1321 (1999)] edge plasmas, with experimentally determined geometry and input parameters, are presented. It is found that in the near-edge region, microtearing modes can exist under conditions found in conventional tokamaks. As one enters the steep-gradient region, the growth rate spectrum is dominated—down to very low wavenumbers—by electron temperature gradient modes. The latter tend to peak near the X-point(s) and possess properties which may explain the ratios of the density and temperature gradient scale lengths that have been observed in various experiments over the last decade.

Published
2008

223. Particle and impurity transport in the Axial Symmetric Divertor Experiment Upgrade and the Joint European Torus, experimental observations and theoretical understanding

Author

Angioni, C., Carraro, L., Dannert, T., Dubuit, N., Dux, R., Christoph Fuchs, Garbet, X., Garzotti, L., Giroud, C., Guirlet, R., Jenko, F., Kardaun, O. J. W. F., Lauro-Taroni, L., Mantica, P., Maslov, M., Naulin, V., Neu, R., Peeters, A. G., Pereverzev, G., Puiatti, M. E., Pütterich, T., Stober, J., Valovic, M., Valisa, M., Weisen, H., Zabolotsky, A., Asdex, Upgrade Team, Jet Efda, Contributors, ASDEX Upgrade Team, and JET EFDA Contributors

Subjects
Physics, Jet (fluid), Tokamak, Field (physics), Divertor, Joint European Torus, Plasma, ANOMALOUS PINCH, Condensed Matter Physics, ASDEX UPGRADE, law.invention, Nuclear physics, Upgrade, TOKAMAK PLASMAS, JET, law, H-MODE PLASMAS, DENSITY PROFILE, Particle
Abstract

Experimental observations on core particle and impurity transport from the Axial Symmetric Divertor Experiment Upgrade [O. Gruber, H.-S. Bosch, S. Gunter , Nucl Fusion 39, 1321 (1999)] and the Joint European Torus [J. Pamela, E. R. Solano, and JET EFDA Contributors, Nucl. Fusion 43, 1540 (2003)] tokamaks are reviewed and compared. Robust general experimental behaviors observed in both the devices and related parametric dependences are identified. The experimental observations are compared with the most recent theoretical results in the field of core particle transport. (C) 2007 American Institute of Physics.

Published
2007

224. Interaction of energetic particles with large and small scale instabilities

Author

Günter, S., Conway, G., da Graca, S., Fahrbach, H.-U., Forest, C., Garcia Munoz, M., Hauff, T., Hobirk, J., Igochine, V., Jenko, F., Lackner, K., Lauber, P., McCarthy, P., Maraschek, M., Martin, P., Poli, E., Sassenberg, K., Strumberger, E., Tardini, G., Wolfrum, E., Zohm, H., and ASDEX Upgrade Team

Published
2007

231. Overview of ASDEX Upgrade resultsâ€'development of integrated operating scenarios for ITER

Author

Guenter, S., Angioni, C., Apostoliceanu, M., Atanasiu, C., Balden, M., Becker, G., Becker, W., Behler, K., Behringer, K., Bergmann, A., Bilato, R., Bizyukov, I., Bobkov, V., Bolzonella, T., Borba, D., Borrass, K., Brambilla, M., Braun, F., Buhler, A., Carlson, A., Chankin, A., Chen, J., Chen, Y., Cirant, S., Conway, G., Coster, D., Dannert, T., Dimova, K., Drube, R., Dux, R., Eich, T., Engelhardt, K., Fahrbach, H. U., Fantz, U., Fattorini, L., Foley, M., Franzen, P., Fuchs, J. C., Gafert, J., Gal, K., Gantenbein, G., GARCA MUOZ, M., Gehre, O., Geier, A., Giannone, L., Gruber, O., Haas, G., Hartmann, D., Heger, B., Heinemann, B., Herrmann, A., Hobirk, J., Hohencker, H., Horton, L., Huart, M., Igochine, V., Jacchia, A., Jakobi, M., Jenko, F., Kallenbach, A., Klvin, S., Kardaun, O., Kaufmann, M., Keller, A., Kendl, A., Kick, M., Kim, J. W., Kirov, K., Klose, S., Kochergov, R., Kocsis, G., Kollotzek, H., Konz, C., Kraus, W., Krieger, K., KURKI SUONIO, T., Kurzan, B., Lackner, K., Lang, P. T., Lauber, P., Laux, M., Leuterer, F., Likonen, J., Lohs, A., Lorenz, A., Lorenzini, R., Lyssoivan, A., Maggi, C., Maier, H., Mank, K., Manini, A., Manso, M. E., Mantica, P., Maraschek, M., Martin, Piero, Mast, K. F., Mayer, M., Mccarthy, P., Meyer, H., Meisel, D., Meister, H., Menmuir, S., Meo, F., Merkel, P., Merkel, R., Merkl, D., Mertens, V., Monaco, F., Mck, A., Mller, H. W., Mnich, M., Murmann, H., Y. S., Na, Narayanan, R., Neu, G., Neu, R., Neuhauser, J., Nishijima, D., Nishimura, Y., Noterdaeme, J. M., Nunes, I., PACCO DCHS, M., Pautasso, G., Peeters, A. G., Pereverzev, G., Pinches, S., Poli, E., POSTHUMUS WOLFRUM, E., Ptterich, T., Pugno, R., Quigley, E., Radivojevic, I., Raupp, G., Reich, M., Riedl, R., Ribeiro, T., Rohde, V., Roth, J., Ryter, F., Saarelma, S., Sandmann, W., Santos, J., Schall, G., Schilling, H. B., Schirmer, J., Schneider, W., Schramm, G., Schweinzer, J., Schweizer, S., Scott, B., Seidel, U., Serra, F., Sihler, C., Silva, A., Sips, A., Speth, E., Stbler, A., Steuer, K. H., Stober, J., Streibl, B., Strintzi, D., Strumberger, E., Suttrop, W., Tardini, G., Tichmann, C., Treutterer, W., Troppmann, M., Tsalas, M., Urano, H., and Varela, P.

Published
2005

235. Controlling Turbulence in Present and Future Stellarators

Author

Xanthopoulos, P., primary, Mynick, H. E., additional, Helander, P., additional, Turkin, Y., additional, Plunk, G. G., additional, Jenko, F., additional, Görler, T., additional, Told, D., additional, Bird, T., additional, and Proll, J. H. E., additional

Published
2014
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242. Simulations of finite beta turbulence in Tokamaks and Stellarators

Author

Jenko, F., Scott, B., Dorland, W., Kendl, A., and Strintzi, D.

Subjects
Physics::Plasma Physics
Abstract

One of the central open questions in our attempt to understand microturbulence in fusion plas-mas concerns the role of finite β effects. Nonlinear codes trying to investigate this issue must go beyond the commonly used adiabatic electron approximation - a task which turns out to be a serious computational challenge. This step is necessary because the passing electrons are the prime contributor to the parallel currents which in turn produce the magnetic field fluctuations. Results at both ion and electron space-time scales from gyrokinetic and gyrofluid models are presented which shed light on the character of finite β turbulence in tokamaks and stellarators.

Published
2003

243. Overview of ASDEX Upgrade results

Author

Stroth, U, Adamek, J, Aho Mantila, L, Akaslompolo, S, Amdor, C, Angioni, C, Balden, M, Bardin, S, Orte, L, Behler, K, Belonohy, E, Bergmann, A, Bernert, M, Bilato, R, Birkenmeier, G, Bobkov, V, Boom, J, Bottereau, C, Bottino, A, Braun, F, Brezinsek, S, Brochard, T, Bruedgam, M, Buhler, A, Burckhart, A, Casson, F, Chankin, A, Chapman, I, Clairet, F, Classen, I, Coenen, J, Conway, G, Coster, D, Curran, D, da Silva, F, de Marne, P, D'Inca, R, Douai, D, Drube, R, Dunne, M, Dux, R, Eich, T, Eixenberger, H, Endstrasser, N, Engelhardt, K, Esposito, B, Fable, E, Fischer, R, Fuenfgelder, H, Fuchs, J, Gal, K, Munoz, M, Geiger, B, Giannone, L, Goerler, T, da Graca, S, Greuner, H, Gruber, O, Gude, A, Guimarais, L, Guenter, S, Haas, G, Hakola, A, Hangan, D, Happel, T, Haertl, T, Hauff, T, Heinemann, B, Herrmann, A, Hobirk, J, Hoehnle, H, Hoelzl, M, Hopf, C, Houben, A, Igochine, V, Ionita, C, Janzer, A, Jenko, F, Kantor, M, Kaesemann, C, Kallenbach, A, Kalvin, S, Kappatou, A, Kardaun, O, Kasparek, W, Kaufmann, M, Kirk, A, Klingshirn, H, Kocan, M, Kocsis, G, Konz, C, Koslowski, R, Krieger, K, Kubic, M, Kurki Suonio, T, Kurzan, B, Lackner, K, Lang, P, Lauber, P, Laux, M, Lazaros, A, Leipold, F, Leuterer, F, Lindig, S, Lisgo, S, Lohs, A, Lunt, T, Maier, H, Makkonen, T, Mank, K, Manso, M, Maraschek, M, Mayer, M, Mccarthy, P, Mcdermott, R, Mehlmann, F, Meister, H, Menchero, L, Meo, F, Merkel, P, Merkel, R, Mertens, V, Merz, F, Mlynek, A, Monaco, F, Mueller, S, Mueller, H, Muenich, M, Neu, G, Neu, R, Neuwirth, D, Nocente, M, Nold, B, Noterdaeme, J, Pautasso, G, Pereverzev, G, Ploeckl, B, Podoba, Y, Pompon, F, Poli, E, Polozhiy, K, Potzel, S, Pueschel, M, Puetterich, T, Rathgeber, S, Raupp, G, Reich, M, Reimold, F, Ribeiro, T, Riedl, R, Rohde, V, Rooij, G, Roth, J, Rott, M, Ryter, F, Salewski, M, Santos, J, Sauter, P, Scarabosio, A, Schall, G, Schmid, K, Schneider, P, Schneider, W, Schrittwieser, R, Schubert, M, Schweinzer, J, Scott, B, Sempf, M, Sertoli, M, Siccinio, M, Sieglin, B, Sigalov, A, Silva, A, Sommer, F, Staebler, A, Stober, J, Streibl, B, Strumberger, E, Sugiyama, K, Suttrop, W, Tala, T, Tardini, G, Teschke, M, Tichmann, C, Told, D, Treutterer, W, Tsalas, M, Van Zeeland, M, Varela, P, Veres, G, Vicente, J, Vianello, N, Vierle, T, Viezzer, E, Viola, B, Vorpahl, C, Wachowski, M, Wagner, D, Wauters, T, Weller, A, Wenninger, R, Wieland, B, Willensdorfer, M, Wischmeier, M, Wolfrum, E, Wuersching, E, Yu, Q, Zammuto, I, Zasche, D, Zehetbauer, T, Zhang, Y, Zilker, M, Zohm, H, McCarthy, P, McDermott, R, Zohm, H., NOCENTE, MASSIMO, Stroth, U, Adamek, J, Aho Mantila, L, Akaslompolo, S, Amdor, C, Angioni, C, Balden, M, Bardin, S, Orte, L, Behler, K, Belonohy, E, Bergmann, A, Bernert, M, Bilato, R, Birkenmeier, G, Bobkov, V, Boom, J, Bottereau, C, Bottino, A, Braun, F, Brezinsek, S, Brochard, T, Bruedgam, M, Buhler, A, Burckhart, A, Casson, F, Chankin, A, Chapman, I, Clairet, F, Classen, I, Coenen, J, Conway, G, Coster, D, Curran, D, da Silva, F, de Marne, P, D'Inca, R, Douai, D, Drube, R, Dunne, M, Dux, R, Eich, T, Eixenberger, H, Endstrasser, N, Engelhardt, K, Esposito, B, Fable, E, Fischer, R, Fuenfgelder, H, Fuchs, J, Gal, K, Munoz, M, Geiger, B, Giannone, L, Goerler, T, da Graca, S, Greuner, H, Gruber, O, Gude, A, Guimarais, L, Guenter, S, Haas, G, Hakola, A, Hangan, D, Happel, T, Haertl, T, Hauff, T, Heinemann, B, Herrmann, A, Hobirk, J, Hoehnle, H, Hoelzl, M, Hopf, C, Houben, A, Igochine, V, Ionita, C, Janzer, A, Jenko, F, Kantor, M, Kaesemann, C, Kallenbach, A, Kalvin, S, Kappatou, A, Kardaun, O, Kasparek, W, Kaufmann, M, Kirk, A, Klingshirn, H, Kocan, M, Kocsis, G, Konz, C, Koslowski, R, Krieger, K, Kubic, M, Kurki Suonio, T, Kurzan, B, Lackner, K, Lang, P, Lauber, P, Laux, M, Lazaros, A, Leipold, F, Leuterer, F, Lindig, S, Lisgo, S, Lohs, A, Lunt, T, Maier, H, Makkonen, T, Mank, K, Manso, M, Maraschek, M, Mayer, M, Mccarthy, P, Mcdermott, R, Mehlmann, F, Meister, H, Menchero, L, Meo, F, Merkel, P, Merkel, R, Mertens, V, Merz, F, Mlynek, A, Monaco, F, Mueller, S, Mueller, H, Muenich, M, Neu, G, Neu, R, Neuwirth, D, Nocente, M, Nold, B, Noterdaeme, J, Pautasso, G, Pereverzev, G, Ploeckl, B, Podoba, Y, Pompon, F, Poli, E, Polozhiy, K, Potzel, S, Pueschel, M, Puetterich, T, Rathgeber, S, Raupp, G, Reich, M, Reimold, F, Ribeiro, T, Riedl, R, Rohde, V, Rooij, G, Roth, J, Rott, M, Ryter, F, Salewski, M, Santos, J, Sauter, P, Scarabosio, A, Schall, G, Schmid, K, Schneider, P, Schneider, W, Schrittwieser, R, Schubert, M, Schweinzer, J, Scott, B, Sempf, M, Sertoli, M, Siccinio, M, Sieglin, B, Sigalov, A, Silva, A, Sommer, F, Staebler, A, Stober, J, Streibl, B, Strumberger, E, Sugiyama, K, Suttrop, W, Tala, T, Tardini, G, Teschke, M, Tichmann, C, Told, D, Treutterer, W, Tsalas, M, Van Zeeland, M, Varela, P, Veres, G, Vicente, J, Vianello, N, Vierle, T, Viezzer, E, Viola, B, Vorpahl, C, Wachowski, M, Wagner, D, Wauters, T, Weller, A, Wenninger, R, Wieland, B, Willensdorfer, M, Wischmeier, M, Wolfrum, E, Wuersching, E, Yu, Q, Zammuto, I, Zasche, D, Zehetbauer, T, Zhang, Y, Zilker, M, Zohm, H, McCarthy, P, McDermott, R, Zohm, H., and NOCENTE, MASSIMO

Abstract

The medium size divertor tokamak ASDEX Upgrade (major and minor radii 1.65 m and 0.5 m, respectively, magnetic-field strength 2.5 T) possesses flexible shaping and versatile heating and current drive systems. Recently the technical capabilities were extended by increasing the electron cyclotron resonance heating (ECRH) power, by installing 2 × 8 internal magnetic perturbation coils, and by improving the ion cyclotron range of frequency compatibility with the tungsten wall. With the perturbation coils, reliable suppression of large type-I edge localized modes (ELMs) could be demonstrated in a wide operational window, which opens up above a critical plasma pedestal density. The pellet fuelling efficiency was observed to increase which gives access to H-mode discharges with peaked density profiles at line densities clearly exceeding the empirical Greenwald limit. Owing to the increased ECRH power of 4 MW, H-mode discharges could be studied in regimes with dominant electron heating and low plasma rotation velocities, i.e. under conditions particularly relevant for ITER. The ion-pressure gradient and the neoclassical radial electric field emerge as key parameters for the transition. Using the total simultaneously available heating power of 23 MW, high performance discharges have been carried out where feed-back controlled radiative cooling in the core and the divertor allowed the divertor peak power loads to be maintained below 5 MW m -2. Under attached divertor conditions, a multi-device scaling expression for the power-decay length was obtained which is independent of major radius and decreases with magnetic field resulting in a decay length of 1 mm for ITER. At higher densities and under partially detached conditions, however, a broadening of the decay length is observed. In discharges with density ramps up to the density limit, the divertor plasma shows a complex behaviour with a localized high-density region in the inner divertor before the outer divertor detaches.

Published
2013

244. Quasilinear transport modelling at low magnetic shear

Author

Citrin, J., Bourdelle, C., Cottier, P., Escande, D.F., Gürcan, Ö.D., Hatch, D.R., Hogeweij, G.M.D., Jenko, F., Pueschel, J., Citrin, J., Bourdelle, C., Cottier, P., Escande, D.F., Gürcan, Ö.D., Hatch, D.R., Hogeweij, G.M.D., Jenko, F., and Pueschel, J.

Abstract

Accurate and computationally inexpensive transport models are vital for routine and robust predictions of tokamak turbulent transport. To this end, the QuaLiKiz [Bourdelle et al., Phys. Plasmas 14, 112501 (2007)] quasilinear gyrokinetic transport model has been recently developed. QuaLiKiz flux predictions have been validated by non-linear simulations over a wide range in parameter space. However, a discrepancy is found at low magnetic shear, where the quasilinear fluxes are significantly larger than the non-linear predictions. This discrepancy is found to stem from two distinct sources: the turbulence correlation length in the mixing length rule and an increase in the ratio between the quasilinear and non-linear transport weights, correlated with increased non-linear frequency broadening. Significantly closer agreement between the quasilinear and non-linear predictions is achieved through the development of an improved mixing length rule, whose assumptions are validated by non-linear simulations.

Published
2012

245. Multi-dimensional gyrokinetic parameter studies based on eigenvalue computations

Author

Universitat Politècnica de València. Instituto de Instrumentación para Imagen Molecular - Institut d'Instrumentació per a Imatge Molecular, Universitat Politècnica de València. Departamento de Sistemas Informáticos y Computación - Departament de Sistemes Informàtics i Computació, Ministerio de Ciencia e Innovación, Merz, F., Kowitz, C., Romero Alcalde, Eloy, Román Moltó, José Enrique, Jenko, F., Universitat Politècnica de València. Instituto de Instrumentación para Imagen Molecular - Institut d'Instrumentació per a Imatge Molecular, Universitat Politècnica de València. Departamento de Sistemas Informáticos y Computación - Departament de Sistemes Informàtics i Computació, Ministerio de Ciencia e Innovación, Merz, F., Kowitz, C., Romero Alcalde, Eloy, Román Moltó, José Enrique, and Jenko, F.

Abstract

Plasma microinstabilities, which can be described in the framework of the linear gyrokinetic equations, are routinely computed in the context of stability analyses and transport predictions for magnetic confinement fusion experiments. The GENE code, which solves the gyrokinetic equations, has been coupled to the SLEPc package for an efficient iterative, matrix-free, and parallel computation of rightmost eigenvalues. This setup is presented, including the preconditioner which is necessary for the newly implemented Jacobi-Davidson solver. The fast computation of instabilities at a single parameter set is exploited to make parameter scans viable, that is to compute the solution at many points in the parameter space. Several issues related to parameter scans are discussed, such as an efficient parallelization over parameter sets and subspace recycling. © 2011 Elsevier B.V. All rights reserved.

Published
2012

246. Fluid and gyrokinetic simulations of impurity transport at JET

Author

Nordman, H, Skyman, A, Strand, P, Giroud, C, Jenko, F, Merz, F, Naulin, Volker, Tala, T, Nordman, H, Skyman, A, Strand, P, Giroud, C, Jenko, F, Merz, F, Naulin, Volker, and Tala, T

Abstract

Impurity transport coefficients due to ion-temperature-gradient (ITG) mode and trapped-electron mode turbulence are calculated using profile data from dedicated impurity injection experiments at JET. Results obtained with a multi-fluid model are compared with quasi-linear and nonlinear gyrokinetic simulation results obtained with the code GENE. The sign of the impurity convective velocity (pinch) and its various contributions are discussed. The dependence of the impurity transport coefficients and impurity peaking factor −∇nZ/nZ on plasma parameters such as impurity charge number Z, ion logarithmic temperature gradient, collisionality, E × B shearing, and charge fraction are investigated. It is found that for the studied ITG dominated JET discharges, both the fluid and gyrokinetic results show an increase in the impurity peaking factor for low Z-values followed by a saturation at moderate values of impurity peaking, much below the neoclassical predictions, for large values of Z. The results are in qualitative agreement with the experimental trends observed for the injected impurities (Ne, Ar, Ni) whereas for the background carbon species the observed flat or weakly hollow C profiles are not well reproduced by the simulations.

Published
2011

247. Overview of ASDEX Upgrade results

Author

Kallenbach, A., Adamek, J., Aho-Mantila, L., Äkäslompolo, S., Angioni, C., Atanasiu, C.V., Balden, M., Behler, K., Belonohy, E., Bergmann, A., Bernert, M., Bilato, R., Bobkov, V., Boom, J., Bottino, A., Braun, F., Brüdgam, M., Buhler, A., Burckhart, A., Chankin, A., Classen, I.G.J., Conway, G.D., Coster, D.P., de Marné, P., D'Inca, R., Drube, R., Dux, R., Eich, T., Endstrasser, N., Engelhardt, K., Esposito, B., Fable, E., Fahrbach, H.-U., Fattorini, L., Fischer, R., Flaws, A., Fünfgelder, H., Fuchs, J.C., Gál, K., García Muñoz, M., Geiger, B., Gemisic Adamov, M., Giannone, L., Giroud, C., Görler, T., da Graca, S., Greuner, H., Gruber, O., Gude, A., Günter, S., Haas, G., Hakola, A.H., Hangan, D., Happel, T., Hauff, T., Heinemann, B., Herrmann, A., Hicks, N., Hobirk, J., Höhnle, H., Hölzl, M., Hopf, C., Horton, L., Huart, M., Igochine, V., Ionita, C., Janzer, A., Jenko, F., Käsemann, C.-P., Kálvin, S., Kardaun, O., Kaufmann, M., Kirk, A., Klingshirn, H.-J., Kocan, M., Kocsis, G., Kollotzek, H., Konz, C., Koslowski, R., Krieger, K., Kurki-Suonio, T., Kurzan, B., Lackner, K., Lang, P.T., Lauber, P., Laux, M., Leipold, Frank, Leuterer, F., Lohs, A., Luhmann, N.C., Jr, Lunt, T., Lyssoivan, A., Maier, H., Maggi, C., Mank, K., Manso, M.-E., Maraschek, M., Martin, P., Mayer, M., McCarthy, P.J., McDermott, R., Meister, H., Menchero, L., Meo, Fernando, Merkel, P., Merkel, R., Mertens, V., Merz, F., Mlynek, A., Monaco, F., Müller, H.W., Münich, M., Murmann, H., Neu, G., Neu, R., Nold, B., Noterdaeme, J.-M., Park, H.K., Pautasso, G., Pereverzev, G., Podoba, Y., Pompon, F., Poli, E., Polochiy, K., Potzel, S., Prechtl, M., Püschel, M.J., Pütterich, T., Rathgeber, S.K., Raupp, G., Reich, M., Reiter, B., Ribeiro, T., Riedl, R., Rohde, V., Roth, J., Rott, M., Ryter, F., Sandmann, W., Santos, J., Sassenberg, K., Sauter, P., Scarabosio, A., Schall, G., Schmid, K., Schneider, P.A., Schneider, W., Schramm, G., Schrittwieser, R., Schweinzer, J., Scott, B., Sempf, M., Serra, F., Sertoli, M., Siccinio, M., Sigalov, A., Silva, A., Sips, A.C.C., Sommer, F., Stäbler, A., Stober, J., Streibl, B., Strumberger, E., Sugiyama, K., Suttrop, W., Szepesi, T., Tardini, G., Tichmann, C., Told, D., Treutterer, W., Urso, L., Varela, P., Vincente, J., Vianello, N., Vierle, T., Viezzer, E., Vorpahl, C., Wagner, D., Weller, A., Wenninger, R., Wieland, B., Wigger, C., Willensdorfer, M., Wischmeier, M., Wolfrum, E., Würsching, E., Yadikin, D., Yu, Q., Zammuto, I., Zasche, D., Zehetbauer, T., Zhang, Y., Zilker, M., Zohm, H., Kallenbach, A., Adamek, J., Aho-Mantila, L., Äkäslompolo, S., Angioni, C., Atanasiu, C.V., Balden, M., Behler, K., Belonohy, E., Bergmann, A., Bernert, M., Bilato, R., Bobkov, V., Boom, J., Bottino, A., Braun, F., Brüdgam, M., Buhler, A., Burckhart, A., Chankin, A., Classen, I.G.J., Conway, G.D., Coster, D.P., de Marné, P., D'Inca, R., Drube, R., Dux, R., Eich, T., Endstrasser, N., Engelhardt, K., Esposito, B., Fable, E., Fahrbach, H.-U., Fattorini, L., Fischer, R., Flaws, A., Fünfgelder, H., Fuchs, J.C., Gál, K., García Muñoz, M., Geiger, B., Gemisic Adamov, M., Giannone, L., Giroud, C., Görler, T., da Graca, S., Greuner, H., Gruber, O., Gude, A., Günter, S., Haas, G., Hakola, A.H., Hangan, D., Happel, T., Hauff, T., Heinemann, B., Herrmann, A., Hicks, N., Hobirk, J., Höhnle, H., Hölzl, M., Hopf, C., Horton, L., Huart, M., Igochine, V., Ionita, C., Janzer, A., Jenko, F., Käsemann, C.-P., Kálvin, S., Kardaun, O., Kaufmann, M., Kirk, A., Klingshirn, H.-J., Kocan, M., Kocsis, G., Kollotzek, H., Konz, C., Koslowski, R., Krieger, K., Kurki-Suonio, T., Kurzan, B., Lackner, K., Lang, P.T., Lauber, P., Laux, M., Leipold, Frank, Leuterer, F., Lohs, A., Luhmann, N.C., Jr, Lunt, T., Lyssoivan, A., Maier, H., Maggi, C., Mank, K., Manso, M.-E., Maraschek, M., Martin, P., Mayer, M., McCarthy, P.J., McDermott, R., Meister, H., Menchero, L., Meo, Fernando, Merkel, P., Merkel, R., Mertens, V., Merz, F., Mlynek, A., Monaco, F., Müller, H.W., Münich, M., Murmann, H., Neu, G., Neu, R., Nold, B., Noterdaeme, J.-M., Park, H.K., Pautasso, G., Pereverzev, G., Podoba, Y., Pompon, F., Poli, E., Polochiy, K., Potzel, S., Prechtl, M., Püschel, M.J., Pütterich, T., Rathgeber, S.K., Raupp, G., Reich, M., Reiter, B., Ribeiro, T., Riedl, R., Rohde, V., Roth, J., Rott, M., Ryter, F., Sandmann, W., Santos, J., Sassenberg, K., Sauter, P., Scarabosio, A., Schall, G., Schmid, K., Schneider, P.A., Schneider, W., Schramm, G., Schrittwieser, R., Schweinzer, J., Scott, B., Sempf, M., Serra, F., Sertoli, M., Siccinio, M., Sigalov, A., Silva, A., Sips, A.C.C., Sommer, F., Stäbler, A., Stober, J., Streibl, B., Strumberger, E., Sugiyama, K., Suttrop, W., Szepesi, T., Tardini, G., Tichmann, C., Told, D., Treutterer, W., Urso, L., Varela, P., Vincente, J., Vianello, N., Vierle, T., Viezzer, E., Vorpahl, C., Wagner, D., Weller, A., Wenninger, R., Wieland, B., Wigger, C., Willensdorfer, M., Wischmeier, M., Wolfrum, E., Würsching, E., Yadikin, D., Yu, Q., Zammuto, I., Zasche, D., Zehetbauer, T., Zhang, Y., Zilker, M., and Zohm, H.

Abstract

The ASDEX Upgrade 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. After the finalization of the tungsten coating of the plasma facing components, the re-availability of all flywheel-generators allowed high-power operation with up to 20 MW heating power at Ip up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above ne = 1.2 × 1020 m−3 and low q95 operation at Bt = 1.8 T. Central O2-mode heating was successfully used in high P/R discharges with 20 MW total heating power and divertor load control with nitrogen seeding. Improved energy confinement is obtained with nitrogen seeding both for type-I and type-III ELMy conditions. The main contributor is increased plasma temperature, no significant changes in the density profile have been observed. This behaviour may be explained by higher pedestal temperatures caused by ion dilution in combination with a pressure limited pedestal and hollow nitrogen profiles. Core particle transport simulations with gyrokinetic calculations have been benchmarked by dedicated discharges using variations of the ECRH deposition location. The reaction of normalized electron density gradients to variations of temperature gradients and the Te/Ti ratio could be well reproduced. Doppler reflectometry studies at the L–H transition allowed the disentanglement of the interplay between the oscillatory geodesic acoustic modes, turbulent fluctuations and the mean equilibrium E × B flow in the edge negative Er well region just inside the separatrix. Improved pedestal diagnostics revealed also a refined picture of the pedestal transport in the fully developed H-mode type-I ELM cycle. Impurity ion transport turned out to be neoclassical in between ELMs. Electron and energy transport remain anomalous, but exhibit different recovery time scales after an ELM. After

Published
2011

250. Turbulent transport of fast ions in the Large Plasma Device

Author

Zhou, S, Zhou, S, Heidbrink, WW, Boehmer, H, McWilliams, R, Carter, T, Vincena, S, Tripathi, SKP, Popovich, P, Friedman, B, Jenko, F, Zhou, S, Zhou, S, Heidbrink, WW, Boehmer, H, McWilliams, R, Carter, T, Vincena, S, Tripathi, SKP, Popovich, P, Friedman, B, and Jenko, F

Abstract

Strong drift wave turbulence is observed in the Large Plasma Device [H. Gekelman, Rev. Sci. Instrum. 62, 2875 (1991)] on density gradients produced by a plate limiter. Energetic lithium ions orbit through the turbulent region. Scans with a collimated ion analyzer and with Langmuir probes give detailed profiles of the fast ion spatial distribution and the fluctuating fields. The fast ion transport decreases rapidly with increasing fast ion gyroradius. Unlike the diffusive transport caused by Coulomb collisions, in this case the turbulent transport is nondiffusive. Analysis and simulation suggest that such nondiffusive transport is due to the interaction of the fast ions with stationary two-dimensional electrostatic turbulence. © 2010 American Institute of Physics.

Published
2010

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