Author: "Matthias Otte" / Topic: 010305 fluids & plasmas - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Matthias Otte"' showing total 32 results

Start Over Author "Matthias Otte" Topic 010305 fluids & plasmas

32 results on '"Matthias Otte"'

1. Stable heat and particle flux detachment with efficient particle exhaust in the island divertor of Wendelstein 7-X

Author: B. Buttenschön, T. Sunn Pedersen, G. A. Wurden, J. P. Knauer, D. Zhang, S. Brezinsek, U. Wenzel, G. Schlisio, Heinke Frerichs, Victoria Winters, Dorothea Gradic, Yu Gao, P. Drewelow, T. Kremeyer, E. Pasch, U. Höfel, V. Perseo, Kenneth Hammond, Florian Effenberg, M. Krychowiak, E. Flom, Y. Feng, S. A. Bozhenkov, R. König, K. J. Brunner, O. P. Ford, Oliver Schmitz, P. Kornejew, Olaf Grulke, F. Reimold, G. Fuchert, M. W. Jakubowski, Andrea Pavone, Christoph Biedermann, L. Rudischhauser, Matthias Otte, Holger Niemann, T. Barbui, Uwe Hergenhahn, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Materials science, Divertor, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Nuclear physics, law, 0103 physical sciences, Particle, Wendelstein 7-X, ddc:620, 010306 general physics, Particle flux, Stellarator
Published: 2022

2. Overview of first Wendelstein 7-X high-performance operation

Author: V. Moncada, S. C. Liu, M. Winkler, P. Pölöskei, A. Tancetti, Naoki Tamura, H. Neilson, M. Krychowiak, Michael Drevlak, K. H. Schlüter, S. A. Henneberg, R. Vilbrandt, N. A. Pablant, M. Schröder, B. van Milligen, Bernd Heinemann, K. Rummel, Jonathan Schilling, Torsten Stange, G. Orozco, Christian Brandt, N. Krawczyk, Suguru Masuzaki, Yunfeng Liang, T. Estrada, Wolfgang Biel, J. H. Harris, B. Unterberg, M. Sleczka, M. Marushchenko, R. Lang, N. Rust, J. P. Kallmeyer, Laurie Stephey, P. Aleynikov, E. Blanco, Hans-Stephan Bosch, B. Buttenschön, D. Mellein, B. Shanahan, M. Vervier, M. Yokoyama, C. Suzuki, Seung Gyou Baek, A. Lücke, Felix Schauer, Ya. I. Kolesnichenko, V. Borsuk, Th. Rummel, B. Gonçalves, R. König, H. P. Laqua, G. Ehrke, K. J. McCarthy, Manfred Zilker, Venanzio Giannella, O. P. Ford, E. Flom, S. Murakami, Andreas Schlaich, P. Xanthopoulos, M. Zanini, E. Ascasíbar, C. Nührenberg, A. Carls, H. Viebke, Y. Feng, A. da Molin, H. Hunger, S. Paqay, Y. Wei, M. Blatzheim, M. W. Jakubowski, F. Köster, T. Wauters, J.C. Schmitt, M. Hubeny, P. van Eeten, H. Damm, Joris Fellinger, Gábor Cseh, Christoph Biedermann, G. Claps, L. Rudischhauser, R. Stadler, J. Mittelstaedt, Matteo Zuin, Z. Szökefalvi-Nagy, M. Knaup, Ch. Linsmeier, Francisco Castejón, J. P. Koschinsky, Bernardo B. Carvalho, L. Wegener, C. Guerard, J.M. Hernández Sánchez, B. Mendelevitch, A. Grosman, S. Pingel, Horacio Fernandes, M. Endler, N. Vianello, Jörg Schacht, Anett Spring, Yu Gao, V. Rohde, Samuel Lazerson, J.H. Matthew, W. Kasparek, R. Neu, R. Burhenn, N. Panadero, Jörg Weggen, P.A. Kurz, Walter H. Fietz, R. Schroeder, Andrea Pavone, G. Offermanns, Ryo Yasuhara, P. Sinha, Massimiliano Romé, José Luis Velasco, Carsten Killer, P. Drewelow, X. Han, T. Windisch, Nengchao Wang, Axel Könies, E.M. Edlund, K. P. Hollfeld, K. Aleynikova, Malte Henkel, Detlev Reiter, S. Brezinsek, Z. Huang, Heinz Grote, S. Langish, Matthias Otte, Alessandro Zocco, Daniel Papenfuß, G. Satheeswaran, Monika Kubkowska, S. Obermayer, G. A. Wurden, Carsten Lechte, F. Wagner, M. Gruca, H. Zhang, Olaf Neubauer, Peter Traverso, T. Ngo, V. Bykov, E. Sánchez, Matt Landreman, Dirk Naujoks, I. Vakulchyk, Andreas Langenberg, E. Wang, B. Hein, I. Ksiazek, S. Valet, Mark Cianciosa, G. Schlisio, Taina Kurki-Suonio, Oliver Schmitz, Adnan Ali, F. Reimold, Shinsuke Satake, Luis Vela Vela, C. Slaby, F. Remppel, David Gates, S. Schmuck, B. Roth, Zhirui Wang, Heinrich P. Laqua, F. Schluck, Olaf Grulke, S. Wadle, A. Runov, Manfred Thumm, Florian Effenberg, G. Fuchert, A. Vorköper, M. Banduch, Jonathan T. Green, J. Nührenberg, F. V. Chernyshev, H. Braune, Ewa Pawelec, David Maurer, A. Winter, A. Charl, Hiroshi Kasahara, T. Mizuuchi, D. Zhang, D. Höschen, J. Riemann, Thomas Klinger, W. Leonhardt, S. Sipliä, Katsumi Ida, T. Jesche, G. Pelka, U. Stridde, Riccardo Nocentini, Alexandra M. Freund, P. McNeely, A. Gogoleva, Victoria Winters, V. Szabó, Wolf-Dieter Schneider, D. A. Hartmann, Fabian Wilde, H. Schumacher, J. Howard, A. van Vuuren, J.L. Terry, M. Nagel, C. Hidalgo, Georg Kühner, S. Wolf, Boyd Blackwell, Michael Cole, Barbara Cannas, D. Rondeshagen, P. Hacker, Torsten Bluhm, J. Kacmarczyk, Kunihiro Ogawa, A. Zeitler, I. Yamada, P. Rong, Tamara Andreeva, Hiroshi Yamada, G. Anda, N. Panadero Alvarez, Wilfried Behr, F. Purps, H. Esteban, Dag Hathiramani, R. Bussiahn, David Ennis, A. H. Reiman, D. R. Mikkelsen, M. Borchardt, B. Israeli, M. Grahl, M. Losert, T. Dittmar, E. Pasch, U. Kamionka, Toru Ii Tsujimura, Gabriel G. Plunk, Felix Warmer, Jeremy Lore, F. Durodié, M. Balden, B.J. Peterson, J.P. Bähner, R. Schrittwieser, Morten Stejner, M.J. Cole, S. Zoletnik, Kian Rahbarnia, O. Marchuk, T. Bräuer, M. Hirsch, R. Riedl, W. Figacz, H. Trimino Mora, S. Degenkolbe, H. Greuner, B. Böswirth, B. Schweer, Dorothea Gradic, S. B. Ballinger, S. Ryosuke, B. Missal, Jiawu Zhu, J. H. E. Proll, M. Czerwinski, A. Cappa, B. Wiegel, J. Loizu Cisquella, Per Helander, Sehyun Kwak, S. Marsen, L. Carraro, T. Ilkei, D. Pilopp, Gábor Náfrádi, S. Récsei, M. Houry, A. de la Peña, Yu. Turkin, T.A. Scherer, T. Schröder, A. Galkowski, P. Drews, H. Frerichs, Benedikt Geiger, A. Krämer-Flecken, M. Dibon, L.-G. Böttger, A. Czarnecka, R. Krampitz, J. Wendorf, N. Chaudhary, T. Kremeyer, A. da Silva, R. Kleiber, R. Sakamoto, J.-M. Travere, I. Abramovic, T. Funaba, Andreas Meier, Fabio Pisano, Holger Niemann, Mirko Salewski, R. Brakel, M. Mayer, X. Huang, Stefan Illy, Ph. Mertens, Naoki Kenmochi, F. Köchl, Peter Lang, J. Geiger, Albert Mollén, A. Hölting, T. Barbui, M. Lennartz, T. Szabolics, Hayato Tsuchiya, S. Renard, A. Lorenz, J. Krom, C. D. Beidler, J. Cai, Andreas Dinklage, Anne White, Ye. O. Kazakov, P. Junghanns, W. Spiess, J. M. García Regaña, S. Elgeti, J. W. Coenen, Thomas Sunn Pedersen, C. Li, T. Mönnich, Miklos Porkolab, R. Laube, Burkhard Plaum, A. Benndorf, Michael Kramer, J. Ongena, J. Svensson, Dmitry Moseev, U. Wenzel, Chandra Prakash Dhard, S. Tulipán, M. C. Zarnstorff, M. Sibilia, A. von Stechow, G. M. Weir, H. Maaßberg, U. Höfel, P. Scholz, Alexey Mishchenko, R. C. Wolf, D. Carralero, G. Kocsis, Ivan Calvo, J. Tretter, Didier Chauvin, Y. Li, J. Boscary, A. Puig Sitjes, Fumimichi Sano, Andrey Samartsev, Tamás Szepesi, A. Kirschner, Dirk Nicolai, Francesco Cordella, M. Rack, A. Alonso, G. Czymek, E. R. Scott, M. E. Puiatti, Stefan Kragh Nielsen, M. Vergote, H. Schmitz, H. Jenzsch, Donald A. Spong, K. Czerski, A. Knieps, Arnold Lumsdaine, L. Ryć, M. N. A. Beurskens, Matthias F. Schneider, Simppa Äkäslompolo, Ulrich Neuner, V. Perseo, Jim-Felix Lobsien, Gerd Gantenbein, Roberto Guglielmo Citarella, L. Pacios Rodriguez, L. Vano, S. Bozhenkov, J. W. Oosterbeek, H. Röhlinger, J. P. Knauer, T. Nishizawa, A.H. Wright, M. Jia, A. Goriaev, H. Brand, D. Böckenhoff, H. M. Smith, J. P. Thomas, T. Fornal, J. Baldzuhn, D. Loesser, K. Risse, John Jelonnek, T. Wegner, S. Jablonski, Martina Huber, V. V. Lutsenko, S. Sereda, J. Ölmanns, Tomohiro Morisaki, H. Thomsen, J. A. Alcuson, P. Kornejew, J M Fontdecaba, Kai Jakob Brunner, A. Werner, T. Kobarg, European Commission, University of Greifswald, Max Planck Institute for Plasma Physics, Technical University of Denmark, Princeton University, National Institute for Fusion Science, CIEMAT, EURATOM HAS, Massachusetts Institute of Technology, University of Wisconsin-Madison, Research Center Julich, Australian National University, Eindhoven University of Technology, University of Cagliari, Consorzio RFX, Universidade de Lisboa, CEA Cadarache, St. Petersburg Scientific Centre, Oak Ridge National Laboratory, University of Salerno, ENEA Frascati Research Center, Institute of Plasma Physics and Laser Microfusion, University of Szczecin, University of Milano-Bicocca, Auburn University, Karlsruhe Institute of Technology, Universidad Carlos III de Madrid, University of Stuttgart, Austrian Academy of Sciences, National Academy of Sciences Ukraine, Technical University of Berlin, Opole University of Technology, Fusion and Plasma Physics, University of Maryland College Park, Consiglio Nazionale delle Ricerche (CNR), Kyoto University, Culham Centre for Fusion Energy, Physikalisch-Technische Bundesanstalt, Los Alamos National Laboratory, Department of Applied Physics, Aalto-yliopisto, and Aalto University
Subjects: Technology, CONFINEMENT, 01 natural sciences, impurities, 010305 fluids & plasmas, law.invention, ECR heating, Divertor, DENSITY LIMIT, law, Data_FILES, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), 004 Datenverarbeitung, Informatik, Physics, Glow discharge, Condensed Matter Physics, Content (measure theory), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Electron temperature, Atomic physics, ddc:620, Stellarator, Impurities, Nuclear and High Energy Physics, Technology and Engineering, plasma performance, chemistry.chemical_element, Atmospheric-pressure plasma, PHYSICS, stellarator, Physics::Plasma Physics, NBI heating, 0103 physical sciences, divertor, 010306 general physics, Helium, Plasma performance, turbulence, Física, W7-X, Turbulence, TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, chemistry, ddc:004, ddc:600, Energy (signal processing), SYSTEM
Abstract: The optimized superconducting stellarator device Wendelstein 7-X (with major radius , minor radius , and plasma volume) restarted operation after the assembly of a graphite heat shield and 10 inertially cooled island divertor modules. This paper reports on the results from the first high-performance plasma operation. Glow discharge conditioning and ECRH conditioning discharges in helium turned out to be important for density and edge radiation control. Plasma densities of with central electron temperatures were routinely achieved with hydrogen gas fueling, frequently terminated by a radiative collapse. In a first stage, plasma densities up to were reached with hydrogen pellet injection and helium gas fueling. Here, the ions are indirectly heated, and at a central density of a temperature of with was transiently accomplished, which corresponds to with a peak diamagnetic energy of and volume-averaged normalized plasma pressure . The routine access to high plasma densities was opened with boronization of the first wall. After boronization, the oxygen impurity content was reduced by a factor of 10, the carbon impurity content by a factor of 5. The reduced (edge) plasma radiation level gives routinely access to higher densities without radiation collapse, e.g. well above line integrated density and central temperatures at moderate ECRH power. Both X2 and O2 mode ECRH schemes were successfully applied. Core turbulence was measured with a phase contrast imaging diagnostic and suppression of turbulence during pellet injection was observed.
Published: 2019

3. Understanding detachment of the W7-X island divertor

Author: D. Mellein, M. Endler, G. Fuchert, U. Wenzel, W. Leonhardt, Oliver Schmitz, T. Kremeyer, T. Sunn Pedersen, Carsten Killer, K. J. Brunner, John Jelonnek, Rouven Lang, F. Reimold, Y. Feng, P. Drewelow, R. König, S. Wadle, E. Pasch, T. Kobarg, Yu Gao, Martina Huber, Florian Effenberg, Wendelstein X Team, G. Schlisio, Manfred Thumm, Kenneth Hammond, Gerd Gantenbein, M. Krychowiak, Detlev Reiter, Matthias Otte, Theo Scherer, Daniel Papenfuß, D. Zhang, Stefan Illy, Christoph Biedermann, L. Rudischhauser, Victoria Winters, M. W. Jakubowski, Per Helander, C. D. Beidler, J. P. Knauer, J. Geiger, S. A. Bozhenkov, Andreas Dinklage, Jörg Weggen, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Technology, Nuclear engineering, Divertor, 0103 physical sciences, 010306 general physics, Condensed Matter Physics, 01 natural sciences, ddc:600, 010305 fluids & plasmas
Abstract: The fundamental behavior of the W7-X island divertor under detached conditions, which has been theoretically predicted with the EMC3-Eirene code, is re-examined here under the experimental conditions achieved so far and compared with the first experimental results. Both simulations and experiments cover a range of divertor configurations and plasma parameters, and show the following common trends: (1) with rising impurity radiation, the target heat load decreases ‘uniformly’ over the entire target surface in the sense that both the peak and average heat loads can drop by an order of magnitude. Impurity radiation (mainly from intrinsic carbon) occurs primarily at the plasma edge and the resulting negative impact on the stored energy is less than 10%. (2) When the total radiation exceeds a critical level, the target particle flux (the recycling flux Γrecy) begins to fall and can drop by a factor of 3–5 at high radiation levels without an obvious indication of significant volume recombination. (3) While Γrecy decreases, the divertor neutral pressure continues to build up and reaches a maximum, at which point Γrecy has declined significantly. (4) During detachment, the electron temperature at the last closed flux surface falls in a way that is not quantitatively understandable from parallel classical heat conduction processes. This paper presents a physical explanation of the numerical/experimental results described above. Furthermore, using the EMC3-Eirene code as a diagnostic tool, we are able, apparently for the first time, to provide a full quantitative analysis of each transport channel in the island divertor, aiming to clarify how the island divertor plasma self-regulates to maintain particle, energy, and momentum balance under detached conditions.
Published: 2021

4. Understanding baffle overloads observed in high-mirror configuration on Wendelstein 7-X

Author: Christoph Biedermann, Thomas Sunn Pedersen, S. A. Bozhenkov, Chandra Prakash Dhard, M. W. Jakubowski, D. Zhang, Fabio Pisano, Matthias Otte, Barbara Cannas, M. Krychowiak, Y. Feng, Ralf König, Holger Niemann, J. Geiger, Yasuhiro Suzuki, M. Endler, Jiawu Zhu, Joris Fellinger, Aleix Puig Sitjes, P. Drewelow, Samuel Lazerson, Yu Gao, Dirk Naujoks, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Materials science, Divertor, Baffle, Mechanics, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Heat flux, law, 0103 physical sciences, Hotspot (geology), Wendelstein 7-X, 010306 general physics, Order of magnitude, Stellarator
Abstract: The operational regimes in the ﬁrst divertor campaign of W7-X were limited by unexpectedly high heat loads on certain baﬄe tiles. In the high-mirror conﬁguration, a permanent hotspot on the baﬄe plate was detected by the thermographic system, which was further conﬁrmed during the post-campaign inspections of the plasma-facing components. The maximum heat load on three baﬄe tiles reached about 4.5 MW m−2, which is almost an order of magnitude above its designed value of 0.5 MW m−2. The paper presents a detailed analysis to understand how the baﬄe plate, which is originally designed to screen the recycling neutrals and is therefore hidden from the hot plasma, can receive such a high heat load – a level that is expected for target plates. Three main causes have been identiﬁed: 1) the three baﬄe tiles are radially only about 5 mm away from a main heat channel towards a target, which is much shorter than the radial power decay length of several centimeters derived from the thermographic measurements in this region; 2) the three baﬄe tiles are intersected with ﬁeld-lines of about 30 m length, which are long enough to collect considerable amount of heat via cross-ﬁeld transport; 3) the baﬄe tiles have locally large grazing angles. In addition, the analysis method shown in this paper is of general use to estimate the heat ﬂows in shadow areas of targets and thus to evaluate heat loads on the potentially critical components occurring in these areas, especially required for the design of complex 3D divertors like the one in W7-X.
Published: 2020
Full Text: View/download PDF

5. High-performance plasmas after pellet injections in Wendelstein 7-X

Author: N. A. Pablant, G. A. Wurden, H. P. Laqua, Andreas Langenberg, P. Xanthopoulos, A. von Stechow, H. M. Smith, Samuel Lazerson, Matthias Otte, Kian Rahbarnia, J. Baldzuhn, Olaf Grulke, Dmitry Moseev, G. Fuchert, D. Zhang, Andrea Pavone, Torsten Stange, H. Thomsen, R. C. Wolf, E. Pasch, E. R. Scott, J. P. Knauer, U. Höfel, J. H. E. Proll, J. Geiger, M. Krychowiak, M. N. A. Beurskens, Z. Huang, M. Hirsch, O. P. Ford, H. Damm, Yu. Turkin, J. A. Alcuson, S. Bozhenkov, Kai Jakob Brunner, Javier Alonso, Ye. O. Kazakov, Christian Brandt, Nikolai B. Marushchenko, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Materials science, Hydrogen, Plasma parameters, Pellets, chemistry.chemical_element, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, stellarator, law, Physics::Plasma Physics, Phase (matter), 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Plasma, Condensed Matter Physics, chemistry, Heat transfer, Atomic physics, improved confinement, pellet injection, heat transport, Stellarator
Abstract: A significant improvement of plasma parameters in the optimized stellarator W7-X is found after injections of frozen hydrogen pellets. The ion temperature in the post-pellet phase exceeds 3 keV with 5 MW of electron heating and the global energy confinement time surpasses the empirical ISS04-scaling. The plasma parameters realized in such experiments are significantly above those in comparable gas-fuelled discharges. In this paper, we present details of these pellet experiments and discuss the main plasma properties during the enhanced confinement phases. Local power balance is applied to show that the heat transport in post-pellet phases is close to the neoclassical level for the ion channel and is about a factor of two above that level for the combined losses. In comparable gas-fuelled discharges, the heat transport is by about ten times larger than the neoclassical level, and thus is largely anomalous. It is further observed that the improvement in the transport is related to the peaked density profiles that lead to a stabilization of the ion-scale turbulence.
Published: 2020
Full Text: View/download PDF

6. Confinement in Wendelstein 7-X limiter plasmas

Author: Andreas Langenberg, Olaf Grulke, M. Krychowiak, Fabio Pisano, R. Brakel, N. Krawczyk, Monika Kubkowska, E. Blanco, Hans-Stephan Bosch, P. Kornejew, M. Hirsch, T. Fornal, J. Baldzuhn, Tamás Szepesi, Tamara Andreeva, Matthias Otte, H. P. Laqua, N. A. Pablant, A. Werner, M. W. Jakubowski, Nikolai B. Marushchenko, T. Schröder, C. D. Beidler, E. Pasch, A. Czarnecka, Samuel Lazerson, V. Moncada, Yu. Turkin, Torsten Stange, Christoph Biedermann, M. Endler, R. Burhenn, Dirk Naujoks, S. Marsen, J. Geiger, J. H. Harris, H. Trimino Mora, T. Estrada, A. Cappa, Andreas Dinklage, B. Buttenschön, R. König, Dmitry Moseev, H. Thomsen, G. M. Weir, J. P. Knauer, H. Maaßberg, A. Alonso, G. A. Wurden, S. A. Bozhenkov, D. Zhang, Thomas Sunn Pedersen, U. Wenzel, Hayato Tsuchiya, M. N. A. Beurskens, Laurie Stephey, Tom Wauters, Kian Rahbarnia, Thomas Klinger, G. Kocsis, I. Ksiazek, D. A. Hartmann, U. Höfel, A. Krämer-Flecken, G. Fuchert, R. C. Wolf, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, stellarator, confinement, 0103 physical sciences, 010306 general physics, Condensed Matter Physics, 01 natural sciences, energy confinement, 010305 fluids & plasmas
Abstract: Observations on confinement in the first experimental campaign on the optimized Stellarator Wendelstein 7-X are summarized. In this phase W7-X was equipped with five inboard limiters only and thus the discharge length restricted to avoid local overheating. Stationary plasmas are limited to low densities
Published: 2017

7. Tuning of the rotational transform in Wendelstein 7-X

Author: Yu Gao, Tamara Andreeva, Christoph Biedermann, L. Rudischhauser, Kenneth Hammond, M. Endler, Kian Rahbarnia, Fabio Pisano, R. König, Aleix Puig Sitjes, G. Satheeswaran, Samuel Lazerson, Monica Spolaore, P. Drewelow, Tamás Szepesi, Adnan Ali, S. Klose, Carsten Killer, G. A. Wurden, G. Kocsis, Kai Jakob Brunner, Ulrich Neuner, U. Wenzel, M. W. Jakubowski, Dirk Nicolai, Barbara Cannas, Holger Niemann, J. Geiger, J. P. Knauer, Boyd Blackwell, Olaf Grulke, G. Schlisio, Matthias Mulsow, S. A. Bozhenkov, H. Thomsen, Jonathan Schilling, Matthias Otte, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Thesaurus (information retrieval), superconducting coils, Nuclear engineering, Divertor, islands, error fields, magnetic field, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Magnetic field, stellarator, law, 0103 physical sciences, divertor, Wendelstein 7-X, 010306 general physics, Superconducting Coils, Stellarator
Abstract: The control of rotational transform in Wendelstein 7-X (W7-X) is key to both the island divertor operation and safety of plasma facing components. The island divenor concept in W7-X relies on an edge flux surface with rotational transform of t = 1 resonating with an intrinsic n/m = 5/5 resonance to form a five lobed island chain. This island chain intersects with divertor plates to give rise to the island divertor. Changes in the relative position of the rational surface and the divertor plates can result in changes in divenor performance, thus the control of the rotational transform is essential to operation of the W7-X device. During the first divertor campaign electromagnetic loads resulted in elastic deformations of the shaped modular stellarator coils. Such deformations made these coils more planar, reducing the vacuum rotational transform, subsequently shifting the t = 1 resonance outward. Unintended plasma wall interactions provided the first clear evidence of this effect during plasma operation. Flux surface measurements were utilized to estimate the correct level of current in the planar coils for correction of t, and found to be around similar to-100 A. Scans the planar coil current for iota correction were performed during plasma operation. These measurements suggest planar coil currents between -250 and similar to 0 A would place the strike lines at the designed distance from the pumping gaps. Divertor Langmuir and upstream probe measurements confirm these estimates along with measurements of divertor neutral gas pressure.
Published: 2019

8. Effects of toroidal plasma current on divertor power depositions on Wendelstein 7-X

Author: M. Zanini, D. Zhang, Yunfeng Liang, Tamara Andreeva, Kian Rahbarnia, Holger Niemann, J. Geiger, Yu Gao, S. A. Bozhenkov, Aleix Puig Sitjes, Torsten Stange, Matthias Otte, P. Drewelow, Samuel Lazerson, M. Rack, Adnan Ali, Heinrich P. Laqua, M. W. Jakubowski, Kenneth Hammond, M. Endler, Ulrich Neuner, Fabio Pisano, Barbara Cannas, A. Knieps, Tamás Szepesi, S. Marsen, H. Thomsen, Carsten Killer, Y. Feng, Jonathan Schilling, Yasuhiro Suzuki, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Toroid, Materials science, Divertor, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Magnetic field, Power (physics), Heat flux, Physics::Plasma Physics, 0103 physical sciences, Wendelstein 7-X, Electric current, Atomic physics, ddc:620, 010306 general physics, Deposition (law)
Abstract: The paper presents experimental observations and simulations for the effects of toroidal plasma current on divertor power depositions on W7-X. With increasing toroidal current accompanying changes in the island geometry result in a sweep of the strike line and a redistribution of the heat flux footprints. Good agreement between experiments, which partly used electron cyclotron current drive to generate an additional toroidal current contribution, and modelling using field line tracing in vacuum magnetic fields including an ad-hoc toroidal current on the magnetic axis is found for both standard and low-iota magnetic configurations.
Published: 2019

9. Measurements and correction of the 1/1 error field in Wendelstein 7-X

Author: Christoph Biedermann, R. C. Wolf, T. Sunn Pedersen, Samuel Lazerson, M. W. Jakubowski, Wendelstein X Team, Matthias Otte, S. A. Bozhenkov, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Condensed Matter Physics, Error field, 01 natural sciences, 010305 fluids & plasmas, Computational physics
Published: 2019

10. First divertor physics studies in Wendelstein 7-X

Author: Tom Wauters, Daniel Dunai, A. LeViness, Victoria Winters, P. Kornejew, Adnan Ali, U. Wenzel, Fabio Pisano, R. Brakel, J. H. Harris, Ye. O. Kazakov, J. Cosfeld, R. König, M. Krychowiak, M. Sleczka, Hans-Stephan Bosch, T. Ngo, Kenneth Hammond, A. Puig Sitjes, M. Vecsei, G. Kocsis, Yasuhiro Suzuki, Tamás Szepesi, J.C. Schmitt, Matthias Otte, E. Wang, V. Moncada, P. Drewelow, S. Brezinsek, A. Knieps, Suguru Masuzaki, Juri Romazanov, M. Kobayashi, D. Zhang, Joris Fellinger, Oliver Schmitz, J. Oelmann, Boyd Blackwell, T. Kremeyer, Malte Henkel, G. Anda, S. Sereda, B. Schweer, Olaf Neubauer, A. Goriaev, S. A. Bozhenkov, Y. Feng, H. Frerichs, T. Sunn Pedersen, Yu Gao, G. A. Wurden, Dorothea Gradic, O. P. Ford, G. Schlisio, Dag Hathiramani, T. Dittmar, S. Lazerzon, S. Wiesen, S. Zoletnik, Florian Effenberg, J. Baldzuhn, P. Drews, Holger Niemann, J. Geiger, T. Barbui, Andreas Dinklage, J. W. Coenen, A. Kirschner, Carsten Killer, M. Rack, G. Fuchert, J. Cai, Barbara Cannas, M. Endler, Jeremy Lore, Y. Li, M. W. Jakubowski, Marcin Rasinski, C. Li, S. C. Liu, Yunfeng Liang, Christoph Biedermann, L. Rudischhauser, V. Perseo, Max Planck Institut für Plasma Physik and Excellence Cluster, KFKI Research Institute for Particle and Nuclear Physics (KFKI-RMKI), University of Wisconsin, Madison, Australian National University, GeoForschungsZentrum (GFZ), Università degli Studi di Cagliari = University of Cagliari (UniCa), Laboratory for Plasma Physics, LPP-ERM/KMS, TEC Partner, Brussels, Belgium, Computer Science and Mathematics Division, Oak Ridge National Laboratory, National Institute for Fusion Science, Toki, Japan, Princeton, Thermadiag, ZA, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, University of Szczecin, Szczecin, Poland, Los Alamos National Laboratory (LANL), and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Divertor, Nuclear engineering, Fusion plasma, Magnetic confinement fusion, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, ddc:620, Wendelstein 7-X, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010306 general physics, Training programme, Stellarator
Abstract: International audience; The Wendelstein 7-X (W7-X) optimized stellarator fusion experiment,which went into operation in 2015, has been operating since 2017 with anun-cooled modular graphite divertor. This allowed first divertor physicsstudies to be performed at pulse energies up to 80 MJ, as opposed to 4MJ in the first operation phase, where five inboard limiters wereinstalled instead of a divertor. This, and a number of other upgrades tothe device capabilities, allowed extension into regimes of higher plasmadensity, heating power, and performance overall, e.g. setting a newstellarator world record triple product. The paper focuses on the firstphysics studies of how the island divertor works. The plasma heat loadsarrive to a very high degree on the divertor plates, with only minorheat loads seen on other components, in particular baffle structuresbuilt in to aid neutral compression. The strike line shapes andlocations change significantly from one magnetic configuration toanother, in very much the same way that codes had predicted they would.Strike-line widths are as large as 10 cm, and the wetted areas alsolarge, up to about 1.5 m2, which bodes well for futureoperation phases. Peak local heat loads onto the divertor were ingeneral benign and project below the 10 MW m?2 limit of thefuture water-cooled divertor when operated with 10 MW of heating power,with the exception of low-density attached operation in the high-iotaconfiguration. The most notable result was the complete (in all 10divertor units) heat-flux detachment obtained at high-density operationin hydrogen.
Published: 2019
Full Text: View/download PDF

11. Wendelstein 7-X–Commissioning of the Superconducting Magnet System

Author: Konrad Risse, Dietrich Birus, Stephan Bosch, Victor Bykov, Andre Carls, Chandra P. Dhard, Joris Fellinger, Thomas Monnich, Michael Nagel, Matthias Otte, Thomas Rummel, and Matthias Schneider
Subjects: Cryostat, Materials science, Nuclear engineering, Superconducting magnet, Superconducting magnetic energy storage, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, Electronic, Optical and Magnetic Materials, law.invention, Nuclear magnetic resonance, law, Magnet, 0103 physical sciences, Electrical and Electronic Engineering, Wendelstein 7-X, Resistor, 010306 general physics, Stellarator, Electronic circuit
Abstract: The Wendelstein 7-X stellarator (W7-X), one of the largest stellarator fusion experiments, is presently being taken into operation at the Max Planck Institute for Plasma Physics in Greifswald. The main objective of the experiment is to prove the reactor relevance of the optimized stellarator concept. The W7-X experiment has a superconducting magnet system with 50 nonplanar and 20 planar coils grouped in five equal modules, which are electrically connected in 7 circuits with 10 coils of each type. The connections between the coils are made by superconducting the bus bars using the same NbTi Cable-in-Conduit Conductor as used for the superconducting coils. Particularly developed high-temperature superconducting current leads feed the current into the cryostat by bridging the temperature gradient from room temperature down to the 4-K level. Seven power supplies provide individual currents in the seven circuits. The quench detection system permanently checks the superconducting system regarding the occurrence of a quench. In case of a quench, the magnet safety system has to be activated, and a set of switches lead the current into the dump resistors. The commissioning of the magnet system was successfully performed until July 2015 with tests of the complete magnet system functionality needed for plasma operation at a magnetic field of 2.5 T.
Published: 2016

12. Author Correction: Magnetic configuration effects on the Wendelstein 7-X stellarator

Author: John Jelonnek, Monika Kubkowska, Ewa Pawelec, Kenneth Hammond, Teresa Estrada, Ryuichi Sakamoto, Konrad Czerski, Naoki Tamura, Boudewijn Van Milligen, Gábor Náfrádi, Novimir Pablant, Grzegorz Krzesiński, Valeria Perseo, Udo Höfel, Aleksander Khilchenko, Piotr Marek, Massimiliano Romé, Sigitas Rimkevicius, Bruno Gonçalves, Manfred Thumm, Sebastijan Brezinsek, Tomasz Fornal, Gavin Weir, Lukasz Ciupinski, Matthias Otte, Nerea Panadero, Ireneusz Książek, Dirk Timmermann, Maarten Vergote, Nengchao Wang, Alexander Ivanov, Egidijus Urbonavicius, Angel de la Peña Gomez, Ben Israeli, Marek Barlak, Oliver P. Ford, Victoria Winters, Marcin Jakubowski, Agata Chomiczewska, Dirk Hartmann, Jacek Jagielski, Toru Tsujimura, Mantas Povilaitis, Suguru Masuzaki, Holger Niemann, Roman Schrittwieser, Gabor Cseh, Shaocheng Liu, Lorella Carraro, Andreas Dinklage, Florian Effenberg, Josep Maria Fontdecaba Climent, Robertas Alzbutas, Ivana Abramovic, Marek Scholz, Tadas Kaliatka, Manuel Garcia-munoz, Stefan Schmuck, Science and Technology of Nuclear Fusion, and Turbulence in Fusion Plasmas
Subjects: Physics, Nuclear physics, law, 0103 physical sciences, General Physics and Astronomy, Wendelstein 7-X, 010306 general physics, 01 natural sciences, Stellarator, 010305 fluids & plasmas, law.invention
Abstract: In the version of this Article originally published, and in the associated Publisher Correction, the members of the W7-X Team were not included. All versions of the Article, and the Publisher Correction, have now been amended to include these team members.
Published: 2018

13. Upgrades of edge, divertor and scrape-off layer diagnostics of W7‐X for OP1.2

Author: D. Chauvin, S. Mohr, David Ennis, D. Pilopp, Adnan Ali, P. Kornejew, U. Wenzel, V. Perseo, Joris Fellinger, M. Toth, A. Dudek, G. Anda, M. Mayer, Laurie Stephey, B. Schweer, G. Kocsis, H. T. Lambertz, Olaf Neubauer, H. Jenzsch, J. H. Harris, Florian Effenberg, P. Drewelow, R. König, M. Endler, G. Czymek, G. Ehrke, Chandra Prakash Dhard, O. P. Ford, M. Krause, Tamás Szepesi, K. Grosser, M. Schülke, T. Sunn Pedersen, G. A. Wurden, Oliver Schmitz, S. Zoletnik, S. Freundt, T. Barbui, Christoph Biedermann, L. Rudischhauser, M. W. Jakubowski, H. Hölbe, A. Charl, Dorothea Gradic, M. Knaup, T. Kremeyer, Matthias Otte, M. Krychowiak, Dag Hathiramani, Alexis Terra, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Materials science, Mechanical Engineering, Nuclear engineering, Divertor, chemistry.chemical_element, Plasma, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, Magnetic field, Nuclear Energy and Engineering, chemistry, law, 0103 physical sciences, Electromagnetic shielding, Limiter, Nuclear fusion, General Materials Science, ddc:530, 010306 general physics, Stellarator, Helium, Civil and Structural Engineering
Abstract: Wendelstein 7-X (W7‐X) is the world’s largest superconducting nuclear fusion experiment of the optimized stellarator type. In the first Operation Phase (OP1.1) helium and hydrogen plasmas were studied in limiter configuration. The heating energy was limited to 4 MJ and the main purpose of that campaign was the integral commissioning of the machine and diagnostics, which was achieved very successfully. Already from the beginning a comprehensive set of diagnostics was available to study the plasma. On the path towards high-power, high-performance plasmas, W7‐X will be stepwise upgraded from an inertially cooled (OP1.2, limited to 80 MJ) to an actively cooled island divertor (OP2, 10 MW steady-state plasma operation). The machine is prepared for OP1.2 with 10 inertially cooled divertor units, and the experimental campaign has started recently. The paper describes a subset of diagnostics which will be available for OP1.2 to study the plasma edge, divertor and scrape-off layer physics including those already available for OP1.1, plus modifications, upgrades and new systems. The focus of this summary will be on technical and engineering aspects, like feasibility and assembly but also on reliability, thermal loads and shielding against magnetic fields.
Published: 2018

14. Error fields in the Wendelstein 7-X stellarator

Author: Tamara Andreeva, Fabio Pisano, Barbara Cannas, Samuel Lazerson, S. A. Bozhenkov, Adnan Ali, Aleix Puig Sitjes, P. Drewelow, M. Endler, Victor Bykov, M. W. Jakubowski, Ben Israeli, Matthias Otte, Holger Niemann, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Computational physics, Magnetic field, Nuclear Energy and Engineering, law, Thermocouple, 0103 physical sciences, Measuring instrument, Limiter, Wendelstein 7-X, Diffusion (business), 010306 general physics, Stellarator
Published: 2018

15. Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited)

Author: Oliver Schmitz, E. Pasch, S. A. Bozhenkov, O. P. Ford, Ireneusz Książek, J. Svensson, Robert Wolf, M. Endler, R. Burhenn, G. M. Weir, Dirk Naujoks, Florian Effenberg, L. Ryć, M. N. A. Beurskens, Olaf Grulke, T. Sunn Pedersen, G. A. Wurden, S. Marsen, Ulrich Neuner, S. Jablonski, S. C. Liu, T. Fornal, J. Baldzuhn, B. Schweer, Yunfeng Liang, Thomas Klinger, T. Schröder, B. Wiegel, Monika Kubkowska, D. A. Hartmann, Boyd Blackwell, J. P. Knauer, H. Thomsen, A. Dzikowicka, A. O. Marchuk, M. W. Jakubowski, G. Fuchert, H.-J. Hartfuß, Dag Hathiramani, Gábor Cseh, U. Wenzel, A. Adnan, Helmut Schuhmacher, N. A. Pablant, A. Alonso, B. Standley, Philipp Drews, J. Kaczmarczyk, Matthias Otte, T. Kremeyer, Christoph Biedermann, T. Szabolics, P. Kornejew, Hayato Tsuchiya, V. Erckmann, A. Werner, M. Krychowiak, S. Schmuck, N. Krawczyk, Laurie Stephey, D. Zhang, Hans-Stephan Bosch, J. W. Oosterbeek, V. Moncada, J.-M. Travere, B. Buttenschön, H. Neilson, T. Estrada, A. Cappa, A. Krämer-Flecken, Andreas Langenberg, U. Höfel, H. P. Laqua, Samuel Lazerson, T. Bräuer, M. Hirsch, Torsten Stange, R. König, Olaf Neubauer, Wendelstein X Team, B. B. Carvalho, S. Zoletnik, Holger Niemann, Andreas Zimbal, J. Geiger, T. Barbui, A. Lorenz, Andreas Dinklage, Heinke Frerichs, Wolfgang Biel, J. H. Harris, Martin Laux, Wolf-Dieter Schneider, Tamara Andreeva, A. Czarnecka, T. Windisch, S. Klose, H. Trimino Mora, Fabio Pisano, R. Brakel, Tamás Szepesi, G. Kocsis, Kian Rahbarnia, Science and Technology of Nuclear Fusion, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, business.industry, Plasma parameters, Instrumentation, Plasma, 01 natural sciences, Radiation zone, 010305 fluids & plasmas, law.invention, Optics, law, 0103 physical sciences, Limiter, ddc:530, Plasma diagnostics, Wendelstein 7-X, 010306 general physics, business, Stellarator
Abstract: Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.
Published: 2016

16. Drift effects on W7-X divertor heat and particle fluxes

Author: Fabio Pisano, Ulrich Neuner, Barbara Cannas, A. Puig Sitjes, Olaf Grulke, Tamara Andreeva, Matthias Otte, L. Rudischhauser, Yu Gao, Samuel Lazerson, S. Klose, Philipp Drews, Y. Feng, Kian Rahbarnia, G. A. Wurden, P. Drewelow, Carsten Killer, M. W. Jakubowski, Boyd Blackwell, Holger Niemann, J. Geiger, Jonathan Schilling, Kenneth Hammond, Adnan Ali, J. P. Knauer, M. Endler, H. Thomsen, Kai Jakob Brunner, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Work (thermodynamics), media_common.quotation_subject, Divertor, Condensed Matter Physics, 01 natural sciences, Asymmetry, 010305 fluids & plasmas, Magnetic field, law.invention, Geomagnetic reversal, Nuclear physics, Nuclear Energy and Engineering, Heat flux, Physics::Plasma Physics, law, Electric field, 0103 physical sciences, 010306 general physics, Stellarator, media_common
Abstract: Classical particle drifts are known to have substantial impacts on fluxes of particles and heat through the edge plasmas in both tokamaks and stellarators. Here we present results from the first dedicated investigation of drift effects in the W7-X stellarator. By comparing similar plasma discharges conducted with a forward- and reverse-directed magnetic field, the impacts of drifts could be isolated through the observation of up-down asymmetries in flux profiles on the divertor targets. In low-density plasmas, the radial locations of the strike lines (i.e. peaks in the target heat flux profiles) exhibited discrepancies of up to 3 cm that reversed upon magnetic field reversal. In addition, asymmetric heat loads were observed in regions of the target that are shadowed by other targets from parallel flux from the core plasma. A comparison of these asymmetric features with the footprints of key topological regions of the edge magnetic field on the divertor suggests that the main driver of the asymmetries at low density is poloidal E × B drift due to radial electric fields in the scrape-off layer and private flux region. In higher-density plasmas, upper and lower targets collected non-ambipolar currents with opposite signs that also inverted upon field reversal. Overall, in these experiments, almost all up-down asymmetry could be attributed to the field reversal and, therefore, field-dependent drifts.
Published: 2019

17. First demonstration of radiative power exhaust with impurity seeding in the island divertor at Wendelstein 7-X

Author: Yu Gao, S. Brezinsek, Florian Effenberg, V. Perseo, M. W. Jakubowski, Heinke Frerichs, M. Krychowiak, R. König, G. Kocsis, Wendelstein X Team, F. Reimold, Sehyun Kwak, Oliver Schmitz, T. Sunn Pedersen, Uwe Hergenhahn, Matthias Otte, Tamás Szepesi, Andrea Pavone, Holger Niemann, T. Barbui, D. Zhang, Christoph Biedermann, Y. Feng, B. Buttenschön, R. Burhenn, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Materials science, Nuclear engineering, scrape-off layer, heat flux, 01 natural sciences, 010305 fluids & plasmas, law.invention, stellarator, Impurity, law, 0103 physical sciences, divertor, Radiative transfer, helical-axis advanced stellarator, 010306 general physics, nuclear fusion, power exhaust, Divertor, impurity seeding, Condensed Matter Physics, emc3-eirene, Power (physics), fusion energy, plasma-material interactions, island divertor, detachment, radiative cooling, Seeding, Wendelstein 7-X, Stellarator
Abstract: Radiative power exhaust by impurity seeding was demonstrated for the first time in island divertor configurations at the stellarator Wendelstein 7-X. Feasibility of stable plasma operation was shown during seeding with both neon (Ne) and nitrogen (N2). High radiative power losses (>=80%) were found to reduce the divertor heat loads globally by 2/3 with both seeding gases injected at a single toroidal location into one of five magnetic islands. Heat flux detachment was achieved for the price of a loss of (>=-15%) in the stored energy. Ne seeding allows for sustained enhancement of edge radiation with a very slow decay of line emission of several tens of seconds after the end of the injection indicating a high recycling of this noble gas at the carbon main plasma facing components. In N2 seeded discharges it is shown that a response of line emission and plasma parameters is in correlation to the puff duration which indicates a higher level of absorption of this seeding gas in the wall. Continuous N2 seeding results in global cooling of the scrape-off layer (SOL) and decay of radiation over several seconds after the injection. Damping of counter-streaming SOL flows, and divertor particle fluxes induced by Ne and N2 seeding have been measured and provide evidence for a reduction of the convective part of the divertor heat fluxes. Losses in density in response to seeding can be compensated by feedback controlled divertor fueling. The controlled reduction of heat fluxes within this complex 3D edge island geometry is a very promising finding concerning detachment control in a future all-metal divertor.
Published: 2019

18. First measurements of error fields on W7-X using flux surface mapping

Author: S. A. Bozhenkov, Matthias Otte, Samuel Lazerson, Thomas Sunn Pedersen, Christoph Biedermann, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Perturbation (astronomy), Condensed Matter Physics, Diagnostic system, 01 natural sciences, 010305 fluids & plasmas, law.invention, Surface mapping, Nuclear magnetic resonance, Amplitude, law, Electromagnetic coil, 0103 physical sciences, Atomic physics, 010306 general physics, Stellarator
Abstract: Error fields have been detected and quantified using the flux surface mapping diagnostic system on Wendelstein 7-X (W7-X). A low-field ‘ ι = 1 / 2 ’ magnetic configuration ( ι = ι / 2 π ), sensitive to error fields, was developed in order to detect their presence using the flux surface mapping diagnostic. In this configuration, a vacuum flux surface with rotational transform of n/m = 1/2 is created at the mid-radius of the vacuum flux surfaces. If no error fields are present a vanishingly small n/m = 5/10 island chain should be present. Modeling indicates that if an n = 1 perturbing field is applied by the trim coils, a large n/m = 1/2 island chain will be opened. This island chain is used to create a perturbation large enough to be imaged by the diagnostic. Phase and amplitude scans of the applied field allow the measurement of a small ∼ 0.04 m intrinsic island chain with a 130 ° phase relative to the first module of the W7-X experiment. These error fields are determined to be small and easily correctable by the trim coil system.
Published: 2016
Full Text: View/download PDF

19. The set of diagnostics for the first operation campaign of the Wendelstein 7-X stellarator

Author: S. Jablonski, H. P. Laqua, S. Klose, S. A. Bozhenkov, H. Thomsen, Andreas Langenberg, Olaf Grulke, V. Moncada, Helmut Schuhmacher, Ralf König, Torsten Stange, T. Estrada, P. Kornejew, Matthias Otte, G. A. Wurden, Wolf-Dieter Schneider, B. Buttenschön, A. Werner, E. Pasch, L. Ryć, Yunfeng Liang, Tamás Szepesi, A. Czarnecka, M. Hirsch, Ulrich Neuner, Wolfgang Biel, M. Krychowiak, Olaf Neubauer, S. Zoletnik, Oliver Schmitz, B. B. Carvalho, M. W. Jakubowski, J. Baldzuhn, T. Kremeyer, Hans-Stephan Bosch, A. Zimbal, T. Windisch, Gábor Cseh, J. Geiger, B. Wiegel, Robert Wolf, M. Endler, R. Burhenn, A. Lorenz, Thomas Sunn Pedersen, Christoph Biedermann, J. Kaczmarczyk, A. O. Marchuk, Martin Laux, U. Wenzel, N. A. Pablant, G. Kocsis, T. Bräuer, B. Schweer, Monika Kubkowska, V. Erckmann, Kian Rahbarnia, J. W. Oosterbeek, D. Zhang, J.-M. Travere, Thomas Klinger, Dag Hathiramani, D. A. Hartmann, A. Krämer-Flecken, Science and Technology of Nuclear Fusion, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Heating power, business.industry, Plasma parameters, Nuclear engineering, Nuclear instruments and methods for hot plasma diagnostics, Electrical engineering, 01 natural sciences, 010305 fluids & plasmas, law.invention, Plasma diagnostics - interferometry, spectroscopy and imaging, law, 0103 physical sciences, Plasma diagnostics - interferometry, spectroscopy and imaging, Limiter, Plasma diagnostics, Plasma diagnostics - probes, Wendelstein 7-X, 010306 general physics, business, Instrumentation, Mathematical Physics, Stellarator
Abstract: Wendelstein 7-X (W7-X) is a large optimized stellarator (B=2.5T, V=30m3) aiming at demonstrating the reactor relevance of the optimized stellarators. In 2015 W7-X will begin its first operation phase (OP1.1) with five inertially cooled inboard limiters made of graphite. Assuming the heat loads can be spread out evenly between the limiters, 1 second discharges at 2 MW of ECRH heating power could be run in OP1.1. The expected plasma parameters will be sufficient to demonstrate the readiness of the installed diagnostics and even to run a first physics program. The diagnostics available for this first operation phase, including some special limiter diagnostics, and their capabilities are being presented. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics
Published: 2015

20. Final integration, commissioning and start of the Wendelstein 7-X stellarator operation

Author: S. Marsen, H. P. Laqua, J. Baldzuhn, Wendelstein X Team, Anett Spring, P. Kornejew, K. Risse, H. Braune, V. Bykov, Dirk Naujoks, J. P. Knauer, Heinz Grote, U. Höfel, T. Braeuer, H. Trimino Mora, L. Wegener, R. Vilbrandt, Jörg Schacht, R. Brakel, Torsten Stange, J.-H. Feist, F. Füllenbach, M. Hirsch, A. Werner, R. Burhenn, T. Sunn Pedersen, M. Gasparotto, R. C. Wolf, P. van Eeten, Matthias Otte, Hans-Stephan Bosch, Thomas Klinger, Christoph Biedermann, Th. Rummel, M. Nagel, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Project commissioning, Nuclear engineering, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Phase (combat), 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, Limiter, Wendelstein 7-X, 010306 general physics, Stellarator
Abstract: The main objective of the Wendelstein 7-X (W7-X) stellarator is to demonstrate the integrated reactor potential of the optimized stellarator line. An important element of this mission is the achievement of high heating-power and high confinement in steady-state operation. Such an integrated plasma operation has not yet been demonstrated and represents the major scientific goal of W7-X. The way towards this goal is staged. In the first phase, called OP 1.1, December 2015-March 2016, a limiter configuration was used. In this paper, the preparation of the first operation phase as well as lessons learned during the first commissioning and the operation phase are discussed, while the physics results from OP 1.1 are reported elsewhere (Wolf et al 2017 Nucl. Fusion 57 102020).
Published: 2017

21. Error field measurement, correction and heat flux balancing on Wendelstein 7-X a

Author: Tamara Andreeva, S. A. Bozhenkov, Christoph Biedermann, David Gates, M. W. Jakubowski, Samuel Lazerson, G. Kocsis, Tamás Szepesi, Ben Israeli, J. Geiger, Matthias Otte, U. Wenzel, G. A. Wurden, Thomas Sunn Pedersen, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Heat flux, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Condensed Matter Physics, Error field, 01 natural sciences, 010305 fluids & plasmas, Computational physics
Published: 2017

22. Performance and properties of the first plasmas of Wendelstein 7-X

Author: T. Windisch, H. Maaßberg, Tom Wauters, S. Marsen, Matt Landreman, Olaf Grulke, Kian Rahbarnia, José Luis Velasco, A. Alonso, S. A. Bozhenkov, Peter Traverso, M. Hirsch, G. Kocsis, H. Thomsen, Andreas Langenberg, G. M. Weir, H. P. Laqua, J. Geiger, J. P. Knauer, E. Pasch, Tamás Szepesi, Andreas Dinklage, Samuel Lazerson, Matthias Otte, Thomas Klinger, R. Burhenn, Torsten Stange, N. A. Pablant, A. Krämer-Flecken, G. Fuchert, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear engineering, Plasma, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, Power (physics), Nuclear Energy and Engineering, law, Magnet, 0103 physical sciences, Limiter, ddc:530, Atomic physics, Wendelstein 7-X, 010306 general physics, Scaling, Stellarator
Abstract: The optimized, superconducting stellarator Wendelstein 7-X went into operation and delivered first measurement data after 15 years of construction and one year commissioning. Errors in the magnet assembly were confirmend to be small. Plasma operation was started with 5 MW electron cyclotron resonance heating (ECRH) power and five inboard limiters. Core plasma values of ${{T}_{\text{e}}}>8$ keV, ${{T}_{\text{i}}}>2$ keV at line-integrated densities $n\approx 3\centerdot {{10}^{19}}~{{\text{m}}^{-2}}$ were achieved, exceeding the original expectations by about a factor of two. Indications for a core-electron-root were found. The energy confinement times are in line with the international stellarator scaling, despite unfavourable wall conditions, i.e. large areas of metal surfaces and particle sources from the limiter close to the plasma volume. Well controlled shorter hydrogen discharges at higher power (4 MW ECRH power for 1 s) and longer discharges at lower power (0.7 MW ECRH power for 6 s) could be routinely established after proper wall conditioning. The fairly large set of diagnostic systems running in the end of the 10 weeks operation campaign provided first insights into expected and unexpected physics of optimized stellarators.
Published: 2016

23. Setup and initial results from the magnetic flux surface diagnostics at Wendelstein 7-X

Author: G. Kocsis, Samuel Lazerson, Thomas Sunn Pedersen, A. Dudek, S. A. Bozhenkov, D Aßmus, Tamás Szepesi, J. Geiger, T. Bräuer, Felix Schauer, Christoph Biedermann, Matthias Otte, and B. Standley
Subjects: Physics, Condensed matter physics, Flux, Magnetic confinement fusion, Plasma, Condensed Matter Physics, 01 natural sciences, Magnetic flux, 010305 fluids & plasmas, law.invention, Computational physics, Magnetic field, Nuclear Energy and Engineering, law, Magnet, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Stellarator
Abstract: Wendelstein 7-X is an optimized stellarator with superconducting magnetic field coils that just started plasma operation at the Max-Planck-Institut fur Plasmaphysik (IPP) Greifswald. Utilizing the electron beam technique the first vacuum flux surface measurements were performed during the commissioning of the magnet system. For the magnetic configurations investigated so far the existence of closed and nested flux surfaces has been validated. All features of the configuration designed for the initial plasma operation phase, including a predicted island chain, were confirmed. No evidence on significant magnetic field errors was found. Furthermore, the effect of the elastic deformation of the non-planar coils was confirmed by the measurements.
Published: 2016

24. The Heavy Ion Beam Probing Development for WEGA Stellarator

Author: Matthias Otte, G. N. Deshko, M. Shubert, S. V. Perfilov, A. V. Melnikov, A.A. Chmyga, L. I. Krupnik, A.S. Kozachek, A. D. Komarov, and A. I. Zhezhera
Subjects: Physics, Nuclear reaction, Nuclear and High Energy Physics, 020209 energy, Mechanical Engineering, Magnetic confinement fusion, 02 engineering and technology, Plasma, 01 natural sciences, 010305 fluids & plasmas, law.invention, Heavy ion beam, Nuclear Energy and Engineering, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, Plasma diagnostics, Atomic physics, Beam (structure), Stellarator, Civil and Structural Engineering, Plasma density
Abstract: A conceptual design for a heavy ion beam probe diagnostic for the stellarator WEGA in Greifswald (Germany) is developed to provide measurements of the radial profiles of the electric plasma potential, density, and their fluctuations. Calculations of probing Na + beam trajectories were done for the various WEGA diagnostics ports with B 0 from 0.087 to 0.5 T. They show that satisfactory access may be possible for C+ C- port combinations.
Published: 2006

25. Combining research with safety: Performance of the Wendelstein 7-X video diagnostic system

Author: S. A. Bozhenkov, Aleix Puig Sitjes, Andreas Dinklage, P. Drewelow, Matthias Otte, M. W. Jakubowski, Gábor Cseh, S. Zoletnik, Ralf König, Christoph Biedermann, Samuel Lazerson, J. Baldzuhn, Yu Gao, T. Szabolics, G. Kocsis, Simppa Äkäslompolo, Thomas Sunn Pedersen, Tamás Szepesi, A. Alonso, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Computer science, Mechanical Engineering, Real-time computing, Frame (networking), Torus, Plasma, 01 natural sciences, 010305 fluids & plasmas, law.invention, Set (abstract data type), Nuclear Energy and Engineering, law, 0103 physical sciences, General Materials Science, Light emission, Wendelstein 7-X, 010306 general physics, Stellarator, Order of magnitude, Civil and Structural Engineering
Abstract: A multi-purpose overview video system, based on EDICAM cameras, was set up at Wendelstein 7-X stellarator, in order to fulfill both machine protection and scientific observation purposes. Places of strong plasma-wall interaction, which can easily evolve to hot-spots, were detected by the EDICAM operators during plasma operation, based on intense local light emission. The EDICAM system was successfully used to avoid hot-spot formation during the commissioning of magnetic configurations with plasma operation. Featuring non-destructive readout capability, smaller areas of the torus interior could be monitored ca. two orders of magnitude faster, in parallel to the normal full frame overview. These fast measurements could be used to show the presence of plasma turbulence (filaments), also detected by other diagnostic systems.
Full Text: View/download PDF

26. Special Topic

Author: D. A. Hartmann, Florian Effenberg, H. Hölbe, D.A. Gates, H. P. Laqua, Samuel Lazerson, S. A. Bozhenkov, Hans-Stephan Bosch, Yuriy Turkin, Thomas Sunn Pedersen, M. Preynas, Matthias Otte, Torsten Stange, Oliver Schmitz, R. König, J. Geiger, Y. Feng, M. Endler, Tamara Andreeva, M. W. Jakubowski, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Computer science, Nuclear engineering, Divertor, Phase (waves), chemistry.chemical_element, Topology (electrical circuits), Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, chemistry, law, 0103 physical sciences, Limiter, Wendelstein 7-X, 010306 general physics, Stellarator, Helium
Abstract: Wendelstein 7-X (W7-X) is currently under commissioning in preparation for its initial plasma operation phase, operation phase 1.1 (OP1.1). This first phase serves primarily to provide an integral commissioning of all major systems needed for plasma operation, as well as systems, such as diagnostics, that need plasma operation to verify their foreseen functions. In OP1.1, W7-X will have a reduced set of in-vessel components. In particular, five graphite limiter stripes replace the later foreseen divertor. This paper describes the expected machine capabilities in OP1.1, as well as a selection of physics topics that can be addressed in OP1.1, despite the simplified configuration and the reduced machine capabilities. Physics topics include the verification and adjustment of the magnetic topology, the testing of the foreseen plasma start-up scenarios and the feed-forward control of plasma density and temperature evolution, as well as more advanced topics such as scrape-off layer (SOL) studies at short connection lengths and transport studies. Plasma operation in OP1.1 will primarily be performed in helium, with a hydrogen plasma phase at the end.
Full Text: View/download PDF

27. Major results from the first plasma campaign of the Wendelstein 7-X stellarator

Author: H. Maaßberg, M. Grahl, V. Moncada, Marek Scholz, Naoki Tamura, H. Neilson, R. Koziol, M. Krychowiak, A. Lücke, T. Estrada, R. Munk, M. Marushchenko, K. Toi, Heinrich P. Laqua, S. Paqay, Olaf Grulke, K. Baumann, A. Czermak, Ivan Calvo, Yasuhiro Suzuki, P.J. Heitzenroeder, H. Hölbe, G. Offermanns, Gintautas Dundulis, U. Stridde, H. Hunger, S. Valet, P. Denner, N. Krawczyk, O. Mishchenko, Andrey Samartsev, Mantas Povilaitis, Andrea Pavone, H. Schumacher, P. Aleynikov, H. P. Laqua, U. Wenzel, M. Sibilia, J. Ongena, Kian Rahbarnia, A. Galkowski, T.A. Scherer, C. Slaby, J. Nührenberg, H.-J. Roscher, Martin Köppen, L.-G. Böttger, A. Czarnecka, R. Krampitz, M. Zilker, T. Kremeyer, J. Wendorf, V. Bykov, A. Goriaev, Josef Preinhaelter, A. Alonso, Peter Titus, G. Czymek, Andreas Langenberg, Matteo Zuin, A. Gogoleva, F. Musielok, A. Zeitler, Andreas Schlaich, P. Xanthopoulos, Victoria Winters, M. Losert, D. A. Hartmann, Roberto Guglielmo Citarella, L. Pacios Rodriguez, Boyd Blackwell, E. Blanco, Hans-Stephan Bosch, R. König, R. Stadler, J. Mittelstaedt, Ch. Linsmeier, U. Höfel, N. Panadero Alvarez, E. Pasch, Francesco Cordella, M. Knaup, Fabian Wilde, M. C. Zarnstorff, B. Mendelevitch, Toru Ii Tsujimura, T. Szabolics, Hayato Tsuchiya, J.C. Schmitt, Tadas Kaliatka, Sadayoshi Murakami, Samuel Lazerson, W. Spiess, J. M. García Regaña, P. Junghans, María Sánchez, A. Grosman, I. Yamada, K. P. Hollfeld, K. Aleynikova, Gábor Náfrádi, T. Krings, Daniel Papenfuß, José Luis Velasco, P. Drewelow, N. A. Pablant, S. Renard, Alessandro Zocco, F. Wagner, D. Böckenhoff, S. Ryosuke, Michael Kramer, A. Vorkörper, M. Turnyanskiy, R. Riedl, W. Figacz, H. Trimino Mora, A. da Silva, D. Gradic, M. Keunecke, A. Pieper, M. Houry, S. Pingel, K. H. Schlüter, J. Loizu Cisquella, L. Carraro, S. Schmuck, M. Banduch, Sehyun Kwak, T. Ilkei, X. Huang, Stefan Illy, N. Fahrenkamp, I. Vakulchyk, G. Kocsis, Ph. Mertens, T. Morizaki, K. Czerski, F. V. Chernyshev, Bernd Heinemann, L. Lewerentz, B.J. Peterson, Francisco Castejón, Olaf Neubauer, D. Zhang, Torsten Bluhm, F. Köchl, C.P. von Thun, Michael Cole, Fabio Pisano, R. Brakel, Peter Traverso, G. Orozco, Wolf-Dieter Schneider, A. A. Ivanov, S. Sipliä, V. Szabó, D. Pilopp, A. Cappa, G. Anda, H. Braune, A. Krämer-Flecken, R. Sakamoto, A. Charl, Hiroshi Kasahara, Massimiliano Romé, J.-H. Feist, Mark Cianciosa, M. Führer, G. Schlisio, Taina Kurki-Suonio, F. Purps, H. Esteban, A. H. Reiman, J. Krom, C. D. Beidler, D. Loesser, H. M. Smith, Nengchao Wang, Axel Könies, Oliver Schmitz, T. Bräuer, M. Hirsch, Gabriel G. Plunk, Felix Warmer, R. Karalevicius, Riccardo Nocentini, J.L. Terry, John Jelonnek, Arnold Lumsdaine, L. Ryć, M. N. A. Beurskens, H. Jenzsch, Z. Sulek, Donald A. Spong, A. Khilchenko, P. Marek, R. Schroeder, T. Schröder, B. Standley, Manfred Thumm, B. Brünner, T. Fornal, Benedikt Geiger, H. Frerichs, R. Kleiber, T. Funaba, Andreas Meier, S. Degenkolbe, P. Rong, Dag Hathiramani, Matthias F. Schneider, Simppa Äkäslompolo, M. R. Stoneking, A. Dudek, Jiawu Zhu, X. Han, T. Windisch, Y. Wei, Detlev Reiter, J. Tretter, N. Rust, J. P. Kallmeyer, J. Baldzuhn, P. Bolgert, Dirk Timmermann, Shinsuke Satake, Luis Vela Vela, Yu. Turkin, Z. Szökefalvi-Nagy, Sigitas Rimkevicius, Naoki Kenmochi, Ulrich Neuner, M. Garcia-Munoz, V. Perseo, Matthias Otte, A. Puig Sitjes, Tamás Szepesi, A. da Molin, Alexis Terra, C. Guerard, J.M. Hernández Sánchez, A. Rodatos, J. Assmann, D. Höschen, Albert Mollén, A. Hölting, Tom Wauters, Adnan Ali, Ewa Pawelec, W. Kasparek, Ryo Yasuhara, D. Kinna, P. Sinha, B. Wiegel, Horacio Fernandes, M. E. Puiatti, S. Récsei, E. Ascasíbar, J.-M. Travere, C. Hidalgo, Joris Fellinger, H. Schmitz, Suguru Masuzaki, Katsumi Ida, G. Pelka, Jim-Felix Lobsien, S. Wolf, Jörg Schacht, J. Koshurinov, Han Zhang, P. Kornejew, J M Fontdecaba, T. Ngo, E. Wang, B. Hein, Gerd Gantenbein, Michael Drevlak, M. Vervier, J. W. Oosterbeek, H. Röhlinger, J. P. Knauer, B. Schweer, Jakub Urban, David Maurer, I. Ksiazek, David Gates, S. C. Liu, S. Massidda, F. Remppel, A.H. Wright, G. Satheeswaran, Monika Kubkowska, K. Rummel, Kai Jakob Brunner, Torsten Stange, J. Riemann, Thomas Klinger, S. Obermayer, H. Brand, Christine Hennig, A. Werner, N. Gierse, S. A. Henneberg, R. Vilbrandt, J. Wolowski, T. Sunn Pedersen, M. Dostal, G. A. Wurden, I. Abramovic, Carsten Lechte, R. Lang, S. A. Bozhenkov, G. Ehrke, K. J. McCarthy, Egidijus Urbonavicius, M. Schröder, S. Jablonski, Martina Huber, M. Nagel, Yunfeng Liang, O. P. Ford, Barbara Cannas, T. Mizuuchi, Anatoly Panin, Jan Skodzik, V. V. Lutsenko, R. Koslowski, R. Laube, Jonathan T. Green, B. Unterberg, Jeremy Lore, Laurie Stephey, J. H. E. Proll, M. Czerwinski, Venanzio Giannella, Jörg Weggen, S. Marsen, Clifford M Surko, Grzegorz Gawlik, B. Roth, D. Birus, Ch. Brandt, M. Mardenfeld, K. Riße, Y. Feng, Alexandra M. Freund, M. Vergote, S. Wadle, H. Thomsen, Wilfried Behr, A. Runov, L. Wegener, Burkhard Plaum, J. Svensson, Dmitry Moseev, Łukasz Ciupiński, G. M. Weir, E. Winkler, W. Pan, E. Erckmann, D. Mellein, B. Shanahan, Th. Kobarg, Marek Barlak, John Howard, Günter Dammertz, M. Endler, D.P. Dhard, N. Vianello, L. V. Lubyako, R. Burhenn, J. Thomas, N. Panadero, M. Gruca, T. Mönnich, J. Majano-Brown, Wolfgang Biel, S. Tulipán, J. H. Harris, C. Nührenberg, A. Carls, H. Viebke, Walter H. Fietz, L. Haiduk, S. Brezinsek, Heinz Grote, S. Langish, V. Huber, Jacek Jagielski, David Ennis, P. Kraszewsk, J. Kacmarczyk, Kunihiro Ogawa, U. Kamionka, O. Bertuch, F. Durodié, B. Missal, A. de la Peña, Robertas Alzbutas, Anett Spring, Yu Gao, Matt Landreman, Dirk Naujoks, Florian Effenberg, P. McNeely, Ya. I. Kolesnichenko, B. Gonçalves, B. van Millingen, M. Blatzheim, X. Peng, F. Harberts, M. W. Jakubowski, F. Köster, Gábor Cseh, Ph. Drews, Christoph Biedermann, G. Claps, L. Rudischhauser, Bernardo B. Carvalho, M. Yokoyama, Seung Gyou Baek, Felix Schauer, V. Borsuk, Th. Rummel, J. Boscary, Fumimichi Sano, J. R. Danielson, M. Rack, G. Fuchert, H.-J. Hartfuß, W. Leonhardt, Georg Kühner, D. R. Mikkelsen, M. Borchardt, A. Benndorf, P. Scholz, R. C. Wolf, I.V. Shikhovtsev, Holger Niemann, Andreas Zimbal, J. Geiger, T. Barbui, M. Lennartz, A. Lorenz, Andreas Dinklage, G. Krzesiński, J. Zajac, B. Israeli, R. Schrittwieser, M.J. Cole, S. Zoletnik, O. Marchuk, Per Helander, B. Buttenschön, P. van Eeten, Tamara Andreeva, Hiroshi Yamada, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, Max-Planck-Institut fur Plasmaphysik Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald, Germany, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), KFKI Research Institute for Particle and Nuclear Physics (KFKI-RMKI), Forschungszentrum Julich GmbH, Institut fur Energie- und Klimaforschung---Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), Wilhelm-Johnen-Strase, 52428 Julich, Germany, University of Maryland, Princeton, Laboratory for Plasma Physics of the Ecole Royale Militaire/Koninklijke Militaire School (LPP-ERM/KMS), Avenue de la Renaissance 30, 1000 Bruxelles, Belgien, Los Alamos National Laboratory (LANL), Institute of Physics, Massachusetts Institute of Technology, Cambridge, University of Wisconsin-Madison, National Centre for Nuclear Research (NCBJ), Institut für Experimentelle Kernphysik, Universität Karlsruhe (IEKP), Geoscience Australia, Max Planck Institut für Plasma Physik and Excellence Cluster, Eindhoven University of Technology, Università degli Studi di Cagliari = University of Cagliari (UniCa), Consorzio Interuniversitario per la Fisica Spaziale (CIFS), Instituto Superior Técnico, Universidade de Lisboa (IST), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Computer Science and Mathematics Division, Oak Ridge National Laboratory, Università di Milano, Warsaw University of Technology, ENEA-Frascati, IPPLM Institute of Plasma Physics and Laser Microfusion, 23 Hery Str., 01-497 Warsaw, Poland, Institute of Nuclear Physics PAN, University of Szczecin, 70-453, aleja Papieza Jana Pawla II 22A, Szczecin, Poland, Milano, University of California [San Diego] (UC San Diego), University of California (UC), International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, Brandenburg University of Technology Cottbus-Senftenberg, Universitatsplatz 1, 01968 Senftenberg, Germany, National Institute for Fusion Science (NIFS), 322-6 Oroshicho, Toki, Gifu Prefecture 509-5202, Japan, Universidad Carlos III de Madrid (UC3M), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Budker Institute of Nuclear Physics (BINP), 11, akademika Lavrentieva prospect, Novosibirsk, 630090, Russian Federation, Institut für Raumfahrtsysteme, Universität Stuttgart (IRS), Fraunhofer-Institut fur Schicht- und Oberflachentechnik IST, Bienroder Weg 54 E, 38108 Braunschweig, Germany, Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften (IWF), Kiev Institute for Nuclear Research, A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP), Institut für Optik und Atomare Physik, Technische Universität Berlin, University of Opole, plac Kopernika 11a, 45-001 Opole, Poland, School of Electrical Engineering, Aalto University, Physikalisch-Technische Bundesanstalt (PTB), Kyoto University, Institute of Plasma Physics, Chinese Academy of Sciences, 350 Shushanhu Rd., Hefei, Anhui 230031, People's Republic of China, Institute of Plasma Physics of the Czech Academy of Science, Za Slovankou 1782/3, 182 00 Prague 8---Liben, Czechia, Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche (IFP-CNR), Fraunhofer-Institut fur Werkzeugmaschinen und Umformtechnik IWU, Reichenhainer Strase 88, 09126 Chemnitz, Germany, Universität Rostock, Wayne State University, Consiglio Nazionale delle Ricerche, Piazzale Aldo Moro, 7, 00185 Roma, Italy, Max Planck Institute for Plasma Physics, CIEMAT, Wigner Research Centre for Physics, Jülich Research Centre, University of Maryland, College Park, Princeton University, Royal Military Academy, Los Alamos National Laboratory, Lithuanian Energy Institute, Massachusetts Institute of Technology, Narodowe Centrum Badań Jadrowych, Karlsruhe Institute of Technology, Australian National University, University of Cagliari, National Research Council of Italy, Instituto Superior Tecnico Lisboa, Ioffe Institute, Oak Ridge National Laboratory, University of Salerno, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Soltan Institute for Nuclear Studies, The Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences, University of Szczecin, University of Milan - Bicocca, University of California San Diego, Auburn University, Brandenburg University of Technology, National Institute for Fusion Science, Universidad Carlos III de Madrid, CEA, Culham Centre for Fusion Energy, RAS - Budker Institute of Nuclear Physics, University of Stuttgart, Fraunhofer Institute for Surface Engineering and Thin Films, Austrian Academy of Sciences, NASU - Institute of Nuclear Research, RAS - Institute of Applied Physics, Technical University of Berlin, University of Opole, Department of Applied Physics, Physikalisch-Technische Bundesanstalt, CAS - Institute of Plasma Physics, Czech Academy of Sciences, Istituto di Fisica Del Plasma Piero Caldirola, Fraunhofer Institute for Machine Tools and Forming Technology, University of Rostock, Lawrence University, Aalto-yliopisto, Aalto University, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, Claps, G., and Cordella, F
Subjects: Magnetic confinement, Nuclear and High Energy Physics, Technology and Engineering, Plasma heating, Cyclotron resonance, CONFINEMENT, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, PHYSICS, Nuclear physics, stellarator, current drive, magnetic confinement, plasma heating, Condensed Matter Physics, law, 0103 physical sciences, ddc:530, 010306 general physics, tellarator, Stellarator, Physics, Magnetic confinement fusion, Plasma, 530 Physik, TRANSPORT, Current drive, Electron temperature, Plasma diagnostics, Atomic physics, Wendelstein 7-X, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 × 1019 m−3 , central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre. EURATOM 633053
Full Text: View/download PDF

28. Retarding field analyzer for the wendelstein 7-X boundary plasma

Author: Malte Henkel, B. Schweer, G. Satheeswaran, Matthias Otte, S. C. Liu, Jiale Cai, Olaf Grulke, Yunfeng Liang, P. Drews, J. Geiger, A. Knieps, Gang Xu, Olaf Neubauer, Carsten Killer, Chijin Xiao, N. Sandri, Y. Y. Li, M. W. Jakubowski, Dirk Nicolai, D. Höschen, S. Brezinsek, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Spectrum analyzer, Materials science, Field (physics), business.industry, Mechanical Engineering, Divertor, Ion current, Plasma, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, Optics, Upgrade, Nuclear Energy and Engineering, law, 0103 physical sciences, General Materials Science, ddc:530, Wendelstein 7-X, 010306 general physics, business, Stellarator, Civil and Structural Engineering
Abstract: A bi-directional multi-channel retarding field analyzer (RFA) probe has been successfully developed for the first time on the Wendelstein 7-X (W7-X) stellarator boundary plasma. Modifications to the RFA prototype hardware and its upgrade for the two W7-X island divertor campaigns are presented, including the electronics. In this paper the experiences and challenges operation and customizing an RFA at W7-X are discussed, as well as the data analysis using a maximum coefficient of determination method to obtain the ion temperature based on the measured modulated ion current. Edge ion temperature profiles have been measured in the standard and high iota configurations. Previous article in issue
Full Text: View/download PDF

29. Advanced neutral alkali beam diagnostics for applications in fusion research (invited)

Author: J. Németh, Gergö Pokol, G. Anda, Guang-yue Hu, Daniel Dunai, G. Petravich, T. Krizsanóczi, D. Nagy, M. Vecsei, Matthias Otte, M. Berta, D. I. Refy, M. Aradi, S. Hegedűs, S. Bató, G. Demeter, B. Tal, S. Zoletnik, P. Hacek, W X Team, O. Asztalos, M. Lampert, A. Bencze, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: 010302 applied physics, Zeeman effect, Materials science, business.industry, Detector, Polarimetry, Zonal flow (plasma), 01 natural sciences, 010305 fluids & plasmas, symbols.namesake, Microsecond, Optics, 0103 physical sciences, symbols, Physics::Accelerator Physics, Plasma diagnostics, business, Spectroscopy, Instrumentation, Beam (structure)
Abstract: Diagnosing the density profile at the edge of high temperature fusion plasmas by an accelerated lithium beam is a known technique since decades. By knowledge of the relevant atomic physics rate coefficients, the plasma electron density profile can be calculated from the relatively calibrated light profile along the beam. Several additional possibilities have already been demonstrated: Charge Exchange Resonance Spectroscopy (CXRS) for ion temperature/flow and Zeeman polarimetry for edge plasma current; therefore the Li-beam diagnostic offers a wealth of information at the plasma edge. The weaknesses of the method are the relatively faint light signal, background light, and technical difficulties of the beam injector which usually seriously limit the applicability. In this talk, we present systematic developments in alkali-beam diagnostics (Li, Na) for the injector and the observation system and detectors which resulted in strongly increased capabilities. Advanced systems have been built, and microsecond scale density profile, turbulence, and zonal flow measurement have been demonstrated. A novel edge current measurement technique has also been designed, and components have been tested with potential microsecond-scale time resolution. Additional possibilities of these advanced systems for spectral measurements (CXRS and various Zeeman schemes) are also discussed.
Full Text: View/download PDF

30. Methods for measuring 1/1 error field in Wendelstein 7-X stellarator

Author: S. A. Bozhenkov, Samuel Lazerson, T. Sunn Pedersen, R. C. Wolf, Matthias Otte, and David Gates
Subjects: Physics, Nuclear and High Energy Physics, Field (physics), Divertor, Flux, Condensed Matter Physics, 01 natural sciences, Resonance (particle physics), 010305 fluids & plasmas, Computational physics, law.invention, Nuclear magnetic resonance, Heat flux, law, Screw axis, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Stellarator
Abstract: Wendelstein 7-X is an optimized helical axis stellarator that came into operation at the end of 2015. A m/n = 5/5 island chain is used in most of its configurations to form a divertor. This island chain at ι = 1 is sensitive to symmetry-breaking error fields, with the resonant 1/1 field being of particular concern because of its influence on the divertor heat flux distribution. Measurement and compensation of the 1/1 mode is therefore necessary. Experimentally, vacuum error fields in W7-X will be studied with a flux surface mapping diagnostic. In this paper numerical simulations for planning and analysing such measurements are presented. Two methods for determining the 1/1 mode are considered: measurement of the island width and measurement of a helical shift of the magnetic axis. Measurement of the resonant island width is a sensitive technique, but the island structure is also affected by other co-resonant components. A complementary method is to measure a helical shift of the magnetic axis in a configuration close to the resonance. This method has a simple interpretation and isolates the 1/1 error field from higher order resonant modes.
Full Text: View/download PDF

31. Measurement of the edge ion temperature in W7-X with island divertor by a retarding field analyzer probe

Author: D. Höschen, Florian Effenberg, Olaf Grulke, Matthias Otte, Z. Huang, Olaf Neubauer, M. W. Jakubowski, Gang Xu, Carsten Killer, S. C. Liu, Yunfeng Liang, Dirk Nicolai, Yan Li, B. Schweer, J. Cosfeld, P. Hacker, G. Satheeswaran, Malte Henkel, A. Knieps, Philipp Drews, S. Brezinsek, D. Zhang, Y. Feng, J. Q. Cai, J. Geiger, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Electron density, Materials science, Divertor, Radius, Plasma, Collisionality, Edge (geometry), Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Magnetic field, Ion, Physics::Plasma Physics, 0103 physical sciences, ddc:620, Atomic physics, 010306 general physics
Abstract: Knowledge of the edge ion temperature (T i) is important to understand the edge physics in fusion plasmas. The T i edge profile has been successfully measured at W7-X in an island divertor configuration using a retarding field analyzer probe on a reciprocating manipulator. The experimental observations show that in the standard configuration, an ion temperature shoulder at the plasma boundary has been observed near the location where a sudden change of the magnetic field connection length appears in the scrape-off layer (SOL) region. The value of the T i shoulder was observed to be dependent on the edge island structure modified by the control coils, SOL kinetic power, and electron density. A significant reduction and flattening in the edge ion temperature profile has been also observed during the nitrogen seeding from the upper horizontal divertor port. In addition, the edge ion-to-electron temperature ratio has been calculated, which gradually increases with the major radius and decreases with the normalized ion collisionality. An extended two-point model including upstream ion temperature is introduced to understand the experimental measurement.
Full Text: View/download PDF

32. Multi-diagnostic analysis of plasma filaments in the island divertor

Author: B. Shanahan, Christoph Biedermann, L. Zsuga, A D Carralero, M. Vecsei, W X Team, Matthias Otte, Gábor Cseh, Tamás Szepesi, G. Kocsis, G. Anda, S. Zoletnik, A. Krämer-Flecken, Carsten Killer, Daniel Dunai, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Turbulence, Nuclear engineering, Divertor, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Protein filament, Nuclear Energy and Engineering, Diagnostic analysis, law, 0103 physical sciences, 14. Life underwater, 010306 general physics, Stellarator
Abstract: Filaments or blobs are well known structures in turbulence in magnetic fusion devices, they are considered to be the major cross-transport channel in the scrape off layer. They originate at the last closed magnetic flux surface and propagate out on the low field side of toroidal devices due to polarization in the curved magnetic field. The Wendelstein 7-X stellarator has a complex three-dimensional magnetic field structure and additionally the plasma is bounded by a chain of magnetic islands, forming an island divertor. After the first observation of filaments in Wendelstein 7-X with video cameras a multi-diagnostic study is presented in this paper to reveal their 3D structure and dynamics. Filaments are seen to be born at the edge and, at least in some cases, seen to extend to up to 4 toroidal turns. After moving radially out a few cm they enter the edge island. Here they disappear from the equatorial plane and about 200 microseconds later reappear on the outboard side of the island. A long-wavelength (∼20–30 cm) quasi coherent mode is observed in both regions where filaments appear. The similarities and differences between the filaments seen in W7-X and other devices are discussed. Possible explanations for this strange radial propagation are considered, together with the likely role of filaments in the edge and island density profile.
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources

Refine your results

32 results on '"Matthias Otte"'

1. Stable heat and particle flux detachment with efficient particle exhaust in the island divertor of Wendelstein 7-X

2. Overview of first Wendelstein 7-X high-performance operation

3. Understanding detachment of the W7-X island divertor

4. Understanding baffle overloads observed in high-mirror configuration on Wendelstein 7-X

5. High-performance plasmas after pellet injections in Wendelstein 7-X

6. Confinement in Wendelstein 7-X limiter plasmas

7. Tuning of the rotational transform in Wendelstein 7-X

8. Effects of toroidal plasma current on divertor power depositions on Wendelstein 7-X

9. Measurements and correction of the 1/1 error field in Wendelstein 7-X

10. First divertor physics studies in Wendelstein 7-X

11. Wendelstein 7-X–Commissioning of the Superconducting Magnet System

12. Author Correction: Magnetic configuration effects on the Wendelstein 7-X stellarator

13. Upgrades of edge, divertor and scrape-off layer diagnostics of W7‐X for OP1.2

14. Error fields in the Wendelstein 7-X stellarator

15. Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited)

16. Drift effects on W7-X divertor heat and particle fluxes

17. First demonstration of radiative power exhaust with impurity seeding in the island divertor at Wendelstein 7-X

18. First measurements of error fields on W7-X using flux surface mapping

19. The set of diagnostics for the first operation campaign of the Wendelstein 7-X stellarator

20. Final integration, commissioning and start of the Wendelstein 7-X stellarator operation

21. Error field measurement, correction and heat flux balancing on Wendelstein 7-X a

22. Performance and properties of the first plasmas of Wendelstein 7-X

23. Setup and initial results from the magnetic flux surface diagnostics at Wendelstein 7-X

24. The Heavy Ion Beam Probing Development for WEGA Stellarator

25. Combining research with safety: Performance of the Wendelstein 7-X video diagnostic system

26. Special Topic

27. Major results from the first plasma campaign of the Wendelstein 7-X stellarator

28. Retarding field analyzer for the wendelstein 7-X boundary plasma

29. Advanced neutral alkali beam diagnostics for applications in fusion research (invited)

30. Methods for measuring 1/1 error field in Wendelstein 7-X stellarator

31. Measurement of the edge ion temperature in W7-X with island divertor by a retarding field analyzer probe

32. Multi-diagnostic analysis of plasma filaments in the island divertor

Catalog

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Journal

Database

Publisher

32 results on '"Matthias Otte"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources