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1. Overview of ASDEX Upgrade results

Author

O. Gruber, R. Arslanbekov, C. Atanasiu, A. Bard, G. Becker, W. Becker, M. Beckmann, K. Behler, K. Behringer, A. Bergmann, R. Bilato, D. Bolshukin, K. Borrass, H.-S. Bosch, B. Braams, M. Brambilla, R. Brandenburg, F. Braun, H. Brinkschulte, R. Brückner, B. Brüsehaber, K. Büchl, A. Buhler, H. Bürbaumer, A. Carlson, M. Ciric, G. Conway, D.P. Coster, C. Dorn, R. Drube, R. Dux, S. Egorov, W. Engelhardt, H.-U. Fahrbach, U. Fantz, H. Faugel, M. Foley, P. Franzen, P. Fu, J.C. Fuchs, J. Gafert, G. Gantenbein, O. Gehre, A. Geier, J. Gernhardt, E. Gubanka, A. Gude, S. Günter, G. Haas, D. Hartmann, B. Heinemann, A. Herrmann, J. Hobirk, F. Hofmeister, H. Hohenöcker, L. Horton, L. Hu, D. Jacobi, M. Jakobi, F. Jenko, A. Kallenbach, O. Kardaun, M. Kaufmann, A. Kendl, J.-W. Kim, K. Kirov, R. Kochergov, H. Kollotzek, W. Kraus, K. Krieger, B. Kurzan, G. Kyriakakis, K. Lackner, P.T. Lang, R.S. Lang, M. Laux, L. Lengyel, F. Leuterer, A. Lorenz, H. Maier, K. Mank, M.-E. Manso, M. Maraschek, K.-F. Mast, P.J. McCarthy, D. Meisel, H. Meister, F. Meo, R. Merkel, V. Mertens, J.P. Meskat, R. Monk, H.W. Müller, M. Münich, H. Murmann, G. Neu, R. Neu, J. Neuhauser, J.-M. Noterdaeme, I. Nunes, G. Pautasso, A.G. Peeters, G. Pereverzev, S. Pinches, E. Poli, R. Pugno, G. Raupp, T. Ribeiro, R. Riedl, S. Riondato, V. Rohde, H. Röhr, J. Roth, F. Ryter, H. Salzmann, W. Sandmann, S. Sarelma, S. Schade, H.-B. Schilling, D. Schlögl, K. Schmidtmann, R. Schneider, W. Schneider, G. Schramm, J. Schweinzer, S. Schweizer, B.D. Scott, U. Seidel, F. Serra, S. Sesnic, C. Sihler, A. Silva, A. Sips, E. Speth, A. Stäbler, K.-H. Steuer, J. Stober, B. Streibl, E. Strumberger, W. Suttrop, A. Tabasso, A. Tanga, G. Tardini, C. Tichmann, W. Treutterer, M. Troppmann, N. Tsois, W. Ullrich, M. Ulrich, P. Varela, O. Vollmer, U. Wenzel, F. Wesner, R. Wolf, E. Wolfrum, R. Wunderlich, N. Xantopoulos, Q. Yu, M. Zarrabian, D. Zasche, T. Zehetbauer, H.-P. Zehrfeld, A. Zeiler, and H. Zohm

Subjects
Nuclear and High Energy Physics, 0103 physical sciences, 010306 general physics, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas
Published
2001
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2. Real-time disruption handling at ASDEX upgrade

Author

Gerhard Raupp, G. Pautasso, V. Mertens, D. Zasche, C. Tichmann, G. Neu, W. Treutterer, Th. Zehetbauer, A. Lorenz, and S. Egorov

Subjects
ComputingMilieux_GENERAL, Nuclear Energy and Engineering, ASDEX Upgrade, Soft landing, Artificial neural network, Computer science, Mechanical Engineering, Control system, Plasma control system, General Materials Science, Real-time operating system, Simulation, Civil and Structural Engineering
Abstract

A neural network for prediction of disruptions has been developed at ASDEX Upgrade with the goal to mitigate or avoid these. The novel idea is to compute the remaining time-to-disruption to indicate the stability level of the discharge. The neural network has been specified, trained and then implemented within the real-time plasma control system. The current version of the system terminates the discharge with an impurity pellet when the computed time-to-disruption falls below a threshold of 80 ms. Routine operation shows that disruptions are recognized reliably. Vessel currents and forces are considerably reduced. The system will be enhanced to avoid disruptions with a soft landing initiated in time.

Published
2001
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3. Linear stability studies including resistive wall effects with the CASTOR/STARWALL code

Author

C. Tichmann, P. Merkel, E. Strumberger, and Sibylle Günter

Subjects
Physics, History, Partial differential equation, Differential equation, media_common.quotation_subject, Mathematical analysis, Rotational symmetry, Inertia, Computer Science Applications, Education, Classical mechanics, Physics::Plasma Physics, Magnetohydrodynamics, Eigenvalues and eigenvectors, media_common, Energy functional, Linear stability
Abstract

CASTOR/STARWALL is a code package for linear stability studies consisting of the CASTROR_3DW code, the STARWALL code, and a hybrid version of both codes named CASTOR3D that is currently under development. The latter solves an extended eigenvalue problem consisting of the plasma part defined by the weak form of the perturbed single-fluid MagnetoHydroDynamic (MHD) equations, and a vacuum part which is derived from an energy functional. This new code can describe wall resistivity and plasma inertia simultaneously. Furthermore, besides the so far used straight field line coordinates, additionally, general flux coordinates are implemented which are more appropriate for the description of instabilities located close to the separatrix (e.g. Edge Localized Modes (ELMs)). The formulation of the eigenvalue problem in the new coordinates is not limited to axisymmetric equilibria, so that, finally, stability studies of resistive and rotating, 3D equilibria should be possible. In this paper we will sketch the theory, report on the progress of the code development, and present first results.

Published
2014

4. Overview of ASDEX Upgrade results

Author

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

Subjects
PHYSICS, Nuclear and High Energy Physics, 0103 physical sciences, TOKAMAK, 010306 general physics, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, REFLECTOMETRY
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 I p up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above n e = 1.2 × 1020 m−3 and low q 95 operation at B t = 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 T e/T i 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 E r 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 recovery of the pre-ELM profiles, strong fluctuations develop in the gradients of n e and T e. The occurrence of the next ELM cannot be explained by the local current diffusion time scale, since this turns out to be too short. Fast ion losses induced by shear Alfvén eigenmodes have been investigated by time-resolved energy and pitch angle measurements. This allowed the separation of the convective and diffusive loss mechanisms.

Published
2011
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5. Self-consistent three-dimensional computations of non-axisymmetric ITER equilibria

Author

C. Tichmann, E. Strumberger, P. Merkel, E. Schwarz, and Sibylle Günter

Subjects
Physics, Nuclear and High Energy Physics, Rotational symmetry, Perturbation (astronomy), Magnetic confinement fusion, Atmospheric-pressure plasma, Mechanics, Plasma, Blanket, Condensed Matter Physics, Magnetic field, Nuclear physics, Physics::Plasma Physics, Axial symmetry
Abstract

Three planned test blanket modules (TBMs) and 18 toroidal field coils break the axisymmetry of the ITER magnetic field. In this paper, the plasma response on these non-axisymmetric fields is studied quantitatively. For this purpose, self-consistent, three-dimensional, free-boundary equilibria of type ITER scenario 4 are computed. The resulting 3D equilibrium magnetic fields are then compared with the corresponding axisymmetric fields to which the vacuum perturbation fields are superimposed. The studies are performed for various normalized plasma pressures.

Published
2010

6. Addendum to papers from Axially Symmetric Divertor Experiment (ASDEX) Upgrade Team, published in Review of Scientific Instruments

Author

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

Subjects
Scientific instrument, Physics, ASDEX Upgrade, Divertor, Nuclear engineering, Addendum, Axial symmetry, Instrumentation, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Abstract

This addendum applies to papers authored by contributors from the Axially Symmetric Divertor Experiment (ASDEX) Upgrade Team published in Review of Scientific Instruments. This addendum provides the full list of ASDEX Upgrade Team contributors and their affiliations.

Published
2010
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7. Plasma wall interaction and its implication in an all tungsten divertor tokamak

Author

Emanuele Poli, Y. R. Martin, L. Fattorini, Fernando Meo, M. Sertoli, G. Tardini, M. Garcia Munoz, T T Ribeiro, Qiang Yu, E. Vainonen-Ahlgren, Laure Vermare, G. Haas, K. Lackner, W. Sandmann, O. J. W. F. Kardaun, M. Rott, R. Merkel, K.-H. Steuer, Piero Martin, A. Kallenbach, P. de Marne, K. Gál, Alberto Bottino, N. Hicks, M. Gemisic-Adamov, Michael Kaufmann, Bruce D. Scott, A. Gude, J. Stober, H. Zohm, V. Mertens, H. D. Murmann, C. V. Atanasiu, K.H. Behringer, D. Wagner, V. Igochine, J.-M. Noterdaeme, Th. Pütterich, K. Sassenberg, A. Flaws, M. Püschel, F. Serra, G. Neu, H. Kollotzek, A. Bergmann, R. Pugno, H. W. Müller, W. Schustereder, K. McCormick, H. Meister, H. Greuner, R. Bilato, M. Huart, Wolf-Dieter Schneider, A. Lohs, R. Schrittwieser, W. Becker, F. Ryter, F. Merz, V. Bobkov, H. F. Meyer, M. Mlynek, Julia Fuchs, M. Mayer, C. F. Maggi, D. Holtum, F. Braun, Peter Lang, J. Hobirk, Taina Kurki-Suonio, A. C. C. Sips, S. da Graca, W. Suttrop, M. Balden, Marco Brambilla, T. Eich, H. Maier, J. M. Santos, M. Wischmeier, C. Tröster, Garrard Conway, E. Würsching, B. Nold, T. Bertoncelli, B. Reiter, M. Zilker, Ana Elisa Bauer de Camargo Silva, Ch. Hopf, C. Angioni, Sibylle Günter, A. Stäbler, R. Riedl, E. Speth, G. Kocsis, Thomas Zehetbauer, Philipp Lauber, S. Kálvin, J. Schirmer, G. V. Pereverzev, K. Engelhardt, C. Tichmann, E. Wolfrum, P. Varela, A. Manini, Patrick J. McCarthy, J. Harhausen, J. Roth, S. Gori, H.-U. Fahrbach, A. Scarabosio, Bernd Heinemann, L. D. Horton, M. E. Manso, Lin Liu, A. Schmid, P. Merkel, Rudolf Neu, D. Yadikin, L. Giannone, C. Konz, M. Maraschek, F. Monaco, E. Strumberger, R. Fischer, J. Fink, K. Mank, S. Dietrich, G. Pautasso, R. Drube, R. Dux, V. Rohde, A. Sigalov, A. Buhler, Martin Laux, Jari Likonen, D. P. Coster, J. Schweinzer, L. Urso, G. Schall, D. Zasche, Ursel Fantz, G. Schramm, A. V. Chankin, K. Behler, Gerhard Raupp, K. Krieger, O. Gruber, K. Dimova, S. Schweizer, J. Neuhauser, A. Herrmann, M. Reich, B. Kurzan, P. Franzen, U. Seidel, M. Kick, and W. Treutterer

Subjects
Tokamak, Materials science, Divertor, Facing Components, Transport, chemistry.chemical_element, Flux, Plasma, Effective radiated power, Tungsten, Condensed Matter Physics, law.invention, Nuclear Energy and Engineering, Alcator C-Mod, chemistry, ASDEX Upgrade, Erosion, law, Iter-Like Wall, Atomic physics, Asdex Upgrade Divertor, Operation
Abstract

ASDEX Upgrade has recently finished its transition towards an all-W divertor tokamak, by the exchange of the last remaining graphite tiles to W-coated ones. The plasma start-up was performed without prior boronization. It was found that the large He content in the plasma, resulting from DC glow discharges for conditioning, leads to a confinement reduction. After the change to D glow for inter-shot conditioning, the He content quickly dropped and, in parallel, the usual H-Mode confinement with H factors close to one was achieved. After the initial conditioning phase, oxygen concentrations similar to that in previous campaigns with boronizations could be achieved. Despite the removal of all macroscopic carbon sources, no strong change in C influxes and C content could be observed so far. The W concentrations are similar to the ones measured previously in discharges with old boronization and only partial coverage of the surfaces with W. Concomitantly it is found that although the W erosion flux in the divertor is larger than the W sources in the main chamber in most of the scenarios, it plays only a minor role for the W content in the main plasma. For large antenna distances and strong gas puffing, ICRH power coupling could be optimized to reduce the W influxes. This allowed a similar increase of stored energy as yielded with comparable beam power. However, a strong increase of radiated power and a loss of H-Mode was observed for conditions with high temperature edge plasma close to the antennas. The use of ECRH allowed keeping the central peaking of the W concentration low and even phases of improved H-modes have already been achieved.

Published
2007
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8. Finite element and higher order difference formulations for modelling heat transport in magnetised plasmas

Author

C. Tichmann, Sibylle Günter, and K. Lackner

Subjects
Numerical Analysis, Diffusion equation, Physics and Astronomy (miscellaneous), Applied Mathematics, Numerical analysis, Mathematical analysis, Finite difference, Finite difference coefficient, Finite element method, Computer Science Applications, Computational Mathematics, Singularity, Classical mechanics, Modeling and Simulation, Coordinate singularity, Heat equation, Mathematics
Abstract

We present a finite element analogue to the second-order, finite difference scheme for the solution of the heat diffusion equation in strongly magnetised plasmas given in Gunter et al. S. Gunter et al., J. Comp. Phys. 209 (2005) 354]. Compared to standard finite element or finite difference formulations it strongly reduces the pollution of perpendicular heat fluxes by parallel ones even without resorting to field-aligned coordinates. We present both bi-linear and bi-quadratic versions of this scheme as well as a fourth-order extension of the original difference scheme of Gunter et al. (2005). In the second part of the paper, we address the formulation of the boundary conditions at walls with an oblique incidence of field lines and the treatment of the coordinate singularity at r=0 in cylindrical, or topologically equivalent coordinates with the reduced-pollution finite difference scheme. All tests shown indicate that both the finite-difference and the finite-element versions of the scheme should substantially alleviate the requirement for field-alignment of the coordinates over the realistic range of ??/?? in toroidal magnetic confinement devices.

Published
2007

9. MHD instabilities in 3D tokamaks

Author

Sibylle Günter, C. Tichmann, and E. Strumberger

Subjects
Physics, Nuclear and High Energy Physics, Tokamak, Computation, Ripple, Perturbation (astronomy), Fluid mechanics, Mechanics, Blanket, Condensed Matter Physics, Instability, law.invention, Classical mechanics, law, Magnetohydrodynamics
Abstract

Three-dimensional, ideal MHD tokamak equilibria are computed with the free-boundary NEMEC code, and their stability properties are investigated with the CAS3DN code, which is an ideal, linear MHD code. Numerical problems are discussed in detail by means of a test equilibrium with a large helical core. Further computations are performed for AUG-type equilibria perturbed by resonant magnetic perturbation (RMP) fields, and an ITER scenario taking into account the toroidal field ripple and perturbation fields caused by test blanket modules (TBMs). Moreover, a quantitative measure of the corrugation of the flux surfaces is introduced. It is found that the contour of the corrugation on equilibrium flux surfaces reflect the ideal kink structures of rational-q surfaces, and the periodicity of the external perturbation fields. Both stabilizing and destabilizing effects of the RMP fields, and the influence of the TBMs on the stability properties are observed.

Published
2014
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