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1. First neutral beam experiments on Wendelstein 7-X

Author

Uwe Hergenhahn, Christian Brandt, P. Valson, Wendelstein X Team, E. Pasch, M. W. Jakubowski, P. Pölöskei, Nikolai B. Marushchenko, Aleix Puig Sitjes, Kian Rahbarnia, Kunihiro Ogawa, Manfred Thumm, L. Vano, Bernd Heinemann, Wolfgang Leonhardt, Dirk Hartmann, D. Mellein, Jonathan Schilling, Jörg Weggen, R. Riedl, Tamara Andreeva, Daniel Papenfuß, Adnan Ali, C. Slaby, Rouven Lang, R. Schroeder, Samuel Lazerson, R. Burhenn, Michael Drevlak, Torsten Stange, Birger Buttenschoゆ, A. Spanier, John Jelonnek, R. C. Wolf, R. Koenig, S. Wadle, T. Wegner, Martina Huber, G. M. Weir, H. Thomsen, Kai Jakob Brunner, Yu Gao, G. Fuchert, P. McNeely, E. R. Scott, R. Bussiahn, P. Traverso, N. Chaudhary, Holger Niemann, Stefan Illy, Theo Scherer, H. Damm, Christian Hopf, S. A. Bozhenkov, Gerd Gantenbein, O. P. Ford, Andreas Langenberg, M. N. A. Beurskens, Simppa Äkäslompolo, Ulrich Neuner, Yuriy Turkin, Naoki Tamura, Andrea Pavone, J. P. Knauer, Niek den Harder, Thorsten Kobarg, N. A. Pablant, U. Hoefel, N. Rust, Philipp Nelde, Department of Applied Physics, Aalto-yliopisto, Aalto University, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, Technology, Fast ions, Condensed Matter Physics, 01 natural sciences, Neutral beam, 010305 fluids & plasmas, law.invention, Nuclear physics, law, 0103 physical sciences, Energetic particles, Wendelstein 7-X, 010306 general physics, Fusion, ddc:600, Stellarator, Beam (structure)
Abstract

In the previous divertor campaign, the Wendelstein 7-X (W7-X) device injected 3.6 MW of neutral beam heating power allowing for the achievement of densities approaching 2 × 1020 m−3, and providing the first initial assessment of fast ion confinement in a drift optimized stellarator. The neutral beam injection (NBI) system on W7-X is comprised of two beam boxes with space for four radio frequency sources each. The 3.6 MW of heating reported in this work was achieved with two sources in the NI21 beam box. The effect of combined electron-cyclotron resonance heating (ECRH) and NBI was explored through a series of discharges varying both NBI and ECRH power. Discharges without ECRH saw a linear increase in the line-integrated plasma density, and strong peaking of the core density, over the discharge duration. The presence of 1 MW of ECRH power was found to be sufficient to control a continuous density rise during NBI operation. Simulations of fast ion wall loads were found to be consistent with experimental infrared camera images during operation. In general, NBI discharges were free from the presence of fast ion induced Alfvénic activity, consistent with low beam betas. These experiments provide data for future scenario development and initial assessment of fast-ion confinement in W7-X, a key topic of the project.

Published
2021

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
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3. Study of seed plasma generation for NBI plasma start-up using non-resonant microwave launch in Heliotron J

Author

Hiroshi Okada, K. Toi, Y. Otani, Yasuhiro Suzuki, Kazunobu Nagasaki, Shinichiro Kado, G. M. Weir, Shungo Yamamoto, Naoki Kenmochi, T. Mizuuchi, X Lu, A. Panith, Yuji Nakamura, S. Kobayashi, K. Hada, Shigeru Konoshima, Shinsuke Ohshima, Torsten Stange, and T. Minami

Subjects
Materials science, Nuclear Energy and Engineering, Plasma, Atomic physics, Condensed Matter Physics, Start up, Microwave
Published
2020

4. Characterization of the radial electric field and edge velocity shear in Wendelstein 7-X

Author

E. Pasch, Yu Gao, G. Fuchert, Daniel Carralero, N. A. Pablant, T. Windisch, José Luis Velasco, T. Estrada, M. N. A. Beurskens, S. A. Bozhenkov, G. M. Weir, Javier Alonso, H. Nieman, H. Damm, M. W. Jakubowski, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, Electric field, 0103 physical sciences, Wendelstein 7-X, Edge (geometry), 010306 general physics, Condensed Matter Physics, Velocity shear, 01 natural sciences, 010305 fluids & plasmas, Computational physics, Characterization (materials science)
Published
2020

5. Measurement of stray millimeter-wave radiation from a 70-GHz ECH/ECCD system in Heliotron J

Author

T. Mizuuchi, Hiroyuki Okada, Nikolai B. Marushchenko, T. Minami, Kazunobu Nagasaki, Akihiko Isayama, G. M. Weir, K. Sakamoto, Akihiro Ishizawa, Shigeru Konoshima, Shinsuke Ohshima, Shoji Yamamoto, Shin Kubo, Hiroe Igami, Shinichiro Kado, Yuji Nakamura, Shiro Kobayashi, and Shinya Watanabe

Subjects
Physics, Electron density, Toroid, business.industry, Mechanical Engineering, Detector, Cyclotron, Astrophysics::Instrumentation and Methods for Astrophysics, Plasma, Electron, Polarization (waves), 01 natural sciences, 010305 fluids & plasmas, law.invention, Optics, Nuclear Energy and Engineering, Physics::Plasma Physics, law, Physics::Space Physics, 0103 physical sciences, Extremely high frequency, General Materials Science, 010306 general physics, business, Civil and Structural Engineering
Abstract

Stray millimeter-wave radiation from a 70-GHz electron cyclotron heating and current drive (ECH/ECCD) system has been measured in the Heliotron J helical device. Two rotatable diode detectors located at the outboard side ports are used to pick up the stray radiation: one is installed at the ECH launcher port and the other is installed at a toroidal angle of 135 deg far from the ECH launcher port. Both detectors are rotated to measure the polarization of the stray radiation. The results show that at the toroidal position far from the ECH launcher, the polarization is not fully randomized before plasma breakdown, whereas the polarization is uniform after a quasi-stationary plasma is generated. The polarization near the ECH launcher is not uniform even in a quasi-stationary plasma. Plasma experiments scanning the electron density indicate that the EC power absorption estimated from the stray radiation at the toroidal position far from the ECH launcher is correlated with the single-pass absorption rate calculated by the TRAVIS ray-tracing code. These results indicate that the diagnostic using a simple diode detector can be used as a real-time monitor of EC power absorption only when the plasma with finite density is produced and the detector is placed far from the ECH launcher port.

Published
2019

6. Development of a correlation ECE radiometer for electron temperature fluctuation measurements in Heliotron J

Author

Kazunobu Nagasaki, Shinji Kobayashi, Akihiro Ishizawa, Takashi Minami, Hiroyuki Okada, M. Luo, Shinichiro Kado, Yasuo Yoshimura, Satoshi Yamamoto, G. M. Weir, Nikolai B. Marushchenko, Tohru Mizuuchi, L. Zang, Xiang-xun Lu, Shigeru Konoshima, Shinsuke Ohshima, Yuji Nakamura, and Jinxiang Zhu

Subjects
Physics, Radiometer, QC1-999, Local oscillator, Bandwidth (signal processing), Large dynamic range, Plasma, 01 natural sciences, 010305 fluids & plasmas, Computational physics, Intermediate frequency, Physics::Plasma Physics, 0103 physical sciences, Electron temperature, Heterodyne detection, 010306 general physics
Abstract

A radial correlation ECE radiometer diagnostic has been developed for electron temperature fluctuation measurements in the helical-axis heliotron device, Heliotron J. The radiometer consists of two heterodyne detection systems. One system scans the frequency of a local oscillator from 52 to 64 GHz with a single intermediate frequency filter, and the second system has a fixed frequency, 56 GHz local oscillator with four intermediate frequency filters. This frequency range covers measurement positions spanning from the plasma core to the half radius. Laboratory tests indicate that each system has narrow intermediate frequency bandwidth and high-sensitivity over a large dynamic range. During plasma experiments with NBI heating, radiation temperature fluctuation measured by the CECE radiometer decrease with increasing ECCD commensurate with previous measurements of energetic particle driven modes on Heliotron J.

Published
2019

7. Stellarators Resist Turbulent Transport on the Electron Larmor Scale

Author

G G, Plunk, P, Xanthopoulos, G M, Weir, S A, Bozhenkov, A, Dinklage, G, Fuchert, J, Geiger, M, Hirsch, U, Hoefel, M, Jakubowski, A, Langenberg, N, Pablant, E, Pasch, T, Stange, D, Zhang, The, W-X Team, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Scale (ratio), Field (physics), Turbulence, Phase (waves), General Physics and Astronomy, Astrophysics::Cosmology and Extragalactic Astrophysics, Mechanics, Electron, 01 natural sciences, law.invention, law, 0103 physical sciences, Thermal, Electron temperature, 010306 general physics, Stellarator
Abstract

Electron temperature gradient (ETG)-driven turbulence, despite its ultrafine scale, is thought to drive significant thermal losses in magnetic fusion devices---but what role does it play in stellarators? The first numerical simulations of ETG turbulence for the Wendelstein 7-X stellarator, together with power balance analysis from its initial experimental operation phase, suggest that the associated transport should be negligible compared to other channels. The effect, we argue, originates essentially from the geometric constraint of multiple field periods, a generic feature of stellarators.

Published
2019
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8. Measurement of Electron Temperature Profile and Fluctuation with ECE Radiometer System in Heliotron J

Author

Kazunobu Nagasaki, Shinji Kobayashi, Shinichiro Kado, Satoshi Yamamoto, G. M. Weir, Akihiro Ishizawa, Tohru Mizuuchi, Takashi Minami, Shigeru Konoshima, Shinsuke Ohshima, M. Luo, Hiroyuki Okada, and Yuji Nakamura

Subjects
Materials science, Radiometer, Thomson scattering, Energy transfer, Measuring instrument, Cyclotron resonance, Electron temperature, Plasma, Condensed Matter Physics, Electron cyclotron resonance, Computational physics
Published
2020
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9. Validation of the BEAMS3D neutral beam deposition model on Wendelstein 7-X

Author

Tamara Andreeva, M. N. A. Beurskens, P. Valson, Simppa Äkäslompolo, G. Fuchert, Ulrich Neuner, E. R. Scott, Adnan Ali, Dirk Hartmann, Carolin Nuehrenberg, N. A. Pablant, J. P. Knauer, E. Pasch, Kian Rahbarnia, M. Hirsch, P. Pölöskei, R. C. Wolf, U. Hoefel, N. Chaudhary, Andrea Pavone, M. W. Jakubowski, Nikolai B. Marushchenko, Mike Machielsen, N. Rust, Philipp Nelde, Yuriy Turkin, Jonathan Schilling, Holger Niemann, P. Traverso, Samuel Lazerson, S. A. Bozhenkov, O. P. Ford, Uwe Hergenhahn, A. Spanier, Andreas Langenberg, H. Thomsen, L. Vano, Christian Brandt, G. M. Weir, Aleix Puig Sitjes, Tristan W. C. Neelis, David Pfefferlé, R. Koenig, Yu Gao, Jonathan Graves, Kai Jakob Brunner, P. McNeely, H. Damm, Torsten Stange, Max-Planck-Institut für Plasmaphysik, Department of Applied Physics, Swiss Federal Institute of Technology Lausanne, Eindhoven University of Technology, University of Western Australia, United States Department of Energy, Auburn University, University of Wisconsin-Madison, Aalto-yliopisto, Aalto University, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Nuclear and High Energy Physics, neutral beam, Cyclotron, Plasma confinement, 01 natural sciences, 010305 fluids & plasmas, law.invention, stellarator, beams3d, law, 0103 physical sciences, Deposition (phase transition), fast ions, 010306 general physics, Stellarator, Plasma density, validation, Physics, magnetic confinement, Magnetic confinement fusion, simulation, Condensed Matter Physics, BEAMS3D, magnetic confnement, Wendelstein 7-X, Atomic physics, Beam (structure)
Abstract

openaire: EC/H2020/633053/EU//EUROfusion The neutral beam deposition model in the BEAMS3D code is validated against neutral beam attenuation data from Wendelstein 7-X (W7-X). A set of experimental discharges where the neutral beam injection system of W7-X was utilized were reconstructed. These discharges scanned the magnetic configurations and plasma densities of W7-X. The equilibrium reconstructions were performed using STELLOPT which calculates three-dimensional self-consistent ideal magnetohydrodynamic equilibria and kinetic profiles. These reconstructions leveraged new capabilities to incorporate electron cyclotron emission and X-ray imaging diagnostics in the STELLOPT code. The reconstructed equilibria and profiles served as inputs for BEAMS3D calculations of neutral beam deposition in W7-X. It is found that if reconstructed kinetic profiles are utilized, good agreement between measured and simulated beam attenuation is found. As deposition models provide initial conditions for fast-ion slowing down calculations, this work provides a first steptowards validating our ability to predict fast ion confinement in stellarators.

Published
2020
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10. Investigation of the neoclassical ambipolar electric field in ion-root plasmas on W7-X

Author

H. Maaßberg, Andreas Langenberg, Peter Traverso, A. Alonso, David Gates, M. Hirsch, Shinsuke Satake, H. P. Laqua, G. Fuchert, Ye. O. Kazakov, E. Pasch, José Luis Velasco, Samuel Lazerson, A. von Stechow, U. Höfel, Kai Jakob Brunner, M. Krychowiak, N. A. Pablant, O. Marchuck, R. Burhenn, J. Svensson, G. M. Weir, Matt Landreman, T. Schröder, Albert Mollén, Felix Warmer, D. Zhang, R. C. Wolf, J. P. Knauer, C. D. Beidler, S. A. Bozhenkov, O. P. Ford, J. Geiger, Andreas Dinklage, Andrea Pavone, Yuriy Turkin, H. M. Smith, J. Baldzuhn, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, Ambipolar diffusion, Root (chord), Magnetic confinement fusion, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Ion, law.invention, law, Electric field, 0103 physical sciences, Atomic physics, Wendelstein 7-X, 010306 general physics, Stellarator
Published
2020
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11. Observations of the effects of magnetic topology on the SOL characteristics of an electromagnetic coherent mode in the first experimental campaign of W7-X

Author

P. Drews, J. Geiger, E. Pasch, M. Rack, Xiuwen Han, Yu Gao, J. Cai, G. Fuchert, D. Höschen, Y. Wei, A. Knieps, J. Cosfeld, U. Hoefel, West Team, Nengchao Wang, Kian Rahbarnia, M. Hirsch, S. C. Liu, Malte Henkel, Olaf Grulke, Dirk Nicolai, Yunfeng Liang, B. Schweer, G. Satheeswaran, A. Charl, S. Sereda, E. Wang, Carsten Killer, A. Krämer-Flecken, G. M. Weir, N. Sandri, T. Windisch, R. König, Olaf Neubauer, K. P. Hollfeld, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, 0103 physical sciences, Mode (statistics), Topology (electrical circuits), 010306 general physics, Condensed Matter Physics, Topology, 01 natural sciences, 010305 fluids & plasmas
Published
2018
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12. Characteristics of electron internal transport barrier in Heliotron J

Author

T. Mizuuchi, Y. Otani, Shigeru Konoshima, Shinsuke Ohshima, G. M. Weir, C. Takahashi, Shiro Kobayashi, K. Nishioka, T. Minami, Yuji Nakamura, Naoki Kenmochi, Shoji Yamamoto, Kazunobu Nagasaki, Hiroyuki Okada, Shinichiro Kado, and S. Mochizuki

Subjects
plasma confinement, Electron density, Materials science, magnetic confinement, Cyclotron, electron internal transport barrier, Plasma, Electron, Condensed Matter Physics, Thermal diffusivity, plasma transport, 01 natural sciences, Heliotron J, 010305 fluids & plasmas, law.invention, Hysteresis, Nuclear Energy and Engineering, Physics::Plasma Physics, law, Electric field, 0103 physical sciences, Atomic physics, 010306 general physics, Microwave
Abstract

The formation of an electron internal transport barrier (eITB) has been observed for the first time with centrally focused electron cyclotron heating (ECH) microwaves injected into plasma in Heliotron J. When the heating power per electron density (${P}_{\mathrm{ECH}}/{\bar{n}}_{{\rm{e}}}$) exceeds a threshold of $250\times {10}^{-19}\,\mathrm{kW}\,{{\rm{m}}}^{3}$, transient increases of both the central Te and the core Te gradients are observed. A neoclassical (NC) calculation using the Sugama–Nishimura moment method predicts that the large positive radial electric field (Er) is formed in the core region. Heat transport analysis shows a significant reduction of the effective electron thermal diffusivity in the plasma with the eITB related to that without the eITB. The large gap between the experimentally obtained effective thermal diffusivity and the NC thermal diffusivity suggests that the suppression of anomalous transport contributes to the core improved confinement of the eITB plasma. The electron cyclotron emission measurement shows both the transient increase and the hysteresis phenomena during the eITB formation.

Published
2017
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13. 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
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14. Core radial electric field and transport in Wendelstein 7-X plasmas

Author

José Luis Velasco, E. Pasch, O. Marchuk, Peter Traverso, C. D. Beidler, Matt Landreman, D. Zhang, N. A. Pablant, G. M. Weir, A. Krämer-Flecken, K. W. Hill, J. Geiger, Shinsuke Satake, Andreas Dinklage, R. C. Wolf, T. Windisch, George H. Neilson, M. N. A. Beurskens, S. Massidda, M. Hirsch, R. Burhenn, L. F. Delgado-Aparicio, Manfred Bitter, Samuel Lazerson, M. Yokoyama, U. Höfel, J. Svennson, Andreas Langenberg, David Gates, G. Fuchert, J. P. Knauer, Yuriy Turkin, P. Valson, West Team, S. A. Bozhenkov, H. Maaßberg, A. Alonso, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Plasma, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, Computational physics, Flow velocity, Physics::Plasma Physics, law, Electric field, 0103 physical sciences, Perpendicular, Plasma diagnostics, Wendelstein 7-X, 010306 general physics, Reflectometry, Stellarator
Abstract

The results from the investigation of neoclassical core transport and the role of the radial electric field profile (Er) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the Er profile are expected to have a strong effect on both the particle and heat fluxes. Investigation of the radial electric field is important in understanding neoclassical transport and in validation of neoclassical calculations. The radial electric field is closely related to the perpendicular plasma flow (u⊥) through the force balance equation. This allows the radial electric field to be inferred from measurements of the perpendicular flow velocity, which can be measured using the x-ray imaging crystal spectrometer and correlation reflectometry diagnostics. Large changes in the perpendicular rotation, on the order of Δu⊥∼ 5 km/s (ΔEr ∼ 12 kV/m), have been observed within a set of experiments where the heating power was stepped down from 2 MW to 0.6 MW. The...

Published
2018
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15. Gyrokinetic studies of trapped electron mode turbulence in the Helically Symmetric eXperiment stellarator

Author

Paul Terry, G. M. Weir, B. J. Faber, M. J. Pueschel, J. H. E. Proll, Joseph Talmadge, Konstantin Likin, Pavlos Xanthopoulos, and Chris Hegna

Subjects
Physics, Turbulence, Plasma, Condensed Matter Physics, Molecular physics, law.invention, Wavelength, Helically Symmetric Experiment, Heat flux, law, Wavenumber, Microturbulence, Atomic physics, Stellarator
Abstract

Gyrokinetic simulations of plasma microturbulence in the Helically Symmetric eXperiment are presented. Using plasma profiles relevant to experimental operation, four dominant drift wave regimes are observed in the ion wavenumber range, which are identified as different flavors of density-gradient-driven trapped electron modes. For the most part, the heat transport exhibits properties associated with turbulence driven by these types of modes. Additionally, long-wavelength, radially localized, nonlinearly excited coherent structures near the resonant central flux surface, not predicted by linear simulations, can further enhance flux levels. Integrated heat fluxes are compatible with experimental observations in the corresponding density gradient range. Despite low shearing rates, zonal flows are observed to regulate turbulence but can be overwhelmed at higher density gradients by the long-wavelength coherent structures.

Published
2015

16. Stabilization of energetic-ion-driven MHD modes by ECCD in Heliotron J

Author

Kiyofumi Mukai, Y. Nagae, H.Y. Lee, G. M. Weir, Shigeru Konoshima, Shinsuke Ohshima, F. Sano, Naoki Kenmochi, Gen Motojima, L. Zang, Shinji Kobayashi, K. Sakamoto, Shohei Arai, Kai Masuda, Hiroyuki Okada, Francesco Volpe, K. Hashimoto, T. Estrada, Y. I. Nakamura, N. Shi, H. Fukushima, Y. Sugimoto, Yuji Nakamura, Hiroto Watada, Satoshi Yamamoto, T. Mizuuchi, Kazunobu Nagasaki, Takashi Minami, Y. Yoshimura, and Nikolai B. Marushchenko

Subjects
Physics, Nuclear and High Energy Physics, Cyclotron, Plasma, Electron, Condensed Matter Physics, law.invention, Physics::Plasma Physics, law, Excited state, Physics::Space Physics, Magnetohydrodynamic drive, Atomic physics, Magnetohydrodynamics, Beam (structure), Stellarator
Abstract

Second harmonic electron cyclotron current drive (ECCD) has been applied in the stellarator/heliotron (S/H) device, Heliotron J, to stabilize magnetohydrodynamic (MHD) modes. The energetic particle mode (EPM) of 60–90 kHz frequency, one of the energetic-ion-driven MHD modes, is excited in a plasma heated by co- and counter-neutral beam injection and electron cyclotron heating (ECH). The EPM has been stabilized by counter-ECCD which decreases the rotational transform. Localized EC current driven by a few kA at the central region modifies the rotational transform profile, ι/2π, leading to the formation of a high magnetic shear at the radius where the mode is excited. An experiment scanning the EC-driven current shows that there is a threshold in magnetic shear and/or rotational transform to stabilize the EPM.

Published
2013

17. 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
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18. Ray tracing and ECRH absorption modeling in the HSX stellarator

Author

G. M. Weir, Yuriy Turkin, Konstantin Likin, and Nikolai B. Marushchenko

Subjects
Physics, Nuclear and High Energy Physics, business.industry, Plasma, Electron, Tracing, Condensed Matter Physics, law.invention, Ray tracing (physics), Helically Symmetric Experiment, Optics, Transmission line, law, Gyrotron, business, Stellarator
Abstract

To increase flexibility in ECRH experiments on the helically symmetric experiment (HSX), a second gyrotron and transmission line have been installed. The second antenna includes a steerable mirror for off-axis heating, and the launched power may be modulated for use in heat pulse propagation experiments. The extraordinary wave at the second harmonic of the electron gyrofrequency or the ordinary wave at the fundamental resonance are used for plasma start-up and heating on HSX. The tracing visualized ray tracing code (Marushchenko et al 2007 Plasma Fusion Res. 2 S1129) is used to estimate single-pass absorption and to model multi-pass wave damping in the three-dimensional HSX geometry. The single-pass absorption of the ordinary wave at the fundamental resonance is calculated to be as high as 30%, while measurements of the total absorption indicate that 45% of the launched power is absorbed. A multi-pass ray tracing model correctly predicts the experimental absorption and indicates that the launched power is absorbed within the plasma core ().

Published
2015
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19. Profile stiffness measurements in the Helically Symmetric experiment and comparison to nonlinear gyrokinetic calculationsa)

Author

B. J. Faber, F.S.B. Anderson, Konstantin Likin, G. M. Weir, Joseph Talmadge, and David G. Anderson

Subjects
Physics, Temperature gradient, Helically Symmetric Experiment, Heat flux, Physics::Plasma Physics, Heat transfer, Electron temperature, Plasma diagnostics, Microturbulence, Atomic physics, Condensed Matter Physics, Thermal diffusivity
Abstract

Stiffness measurements are presented in the quasi-helically symmetric experiment (HSX), in which the neoclassical transport is comparable to that in a tokamak and turbulent transport dominates throughout the plasma. Electron cyclotron emission is used to measure the local electron temperature response to modulated electron cyclotron resonant heating. The amplitude and phase of the heat wave through the steep electron temperature gradient (ETG) region of the plasma are used to determine a transient electron thermal diffusivity that is close to the steady-state diffusivity. The low stiffness in the region between 0.2 ≤ r/a ≤ 0.4 agrees with the scaling of the steady-state heat flux with temperature gradient in this region. These experimental results are compared to gyrokinetic calculations in a flux-tube geometry using the gyrokinetic electromagnetic numerical experiment code with two kinetic species. Linear simulations show that the ETG mode may be experimentally relevant within r/a ≤ 0.2, while the Trapped Electron Mode (TEM) is the dominant long-wavelength microturbulence instability across most of the plasma. The TEM is primarily driven by the density gradient. Non-linear calculations of the saturated heat flux driven by the TEM and ETG bracket the experimental heat flux.

Published
2015
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20. Facultative parasites and host respiration III. Tissue which is actively parasitised

Author

G. M. Weir

Subjects
Fusarium, biology, Host (biology), Veterinary (miscellaneous), fungi, food and beverages, Stimulation, Metabolism, Plants, biology.organism_classification, Applied Microbiology and Biotechnology, Microbiology, Mycoses, Respiration, Animals, Parasites, Respiratory system, Agronomy and Crop Science, Pathogen, Mycelium
Abstract

Fusarium oxysporium f.lycopersici andVerticillium albo-atrum caused an increase in the rate of respiration of tomato stem tissue.V. albo-atrum caused an increase in the rate of respiration of potato haulm tissue. By comparison of the respiration of 1 g ofV. alboatrum mycelium with 1 g fresh weight infected tomato stem tissue it was concluded that the respiration of the pathogen in situ does not contribute markedly to the respiratory increase. It is suggested that the increase in respiration has its origin in the metabolism of the host, possibly due to stimulation by a fungal respiratory toxin but not due to the augmentative effect of the pathogen's respiration.

Published
1962
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21. Facultative parasites and host respiration. I. Healthy tissue adjacent to the site of infection

Author

G. M. Weir

Subjects
Facultative, Host (biology), Veterinary (miscellaneous), fungi, food and beverages, Healthy tissue, Plants, Biology, biology.organism_classification, Applied Microbiology and Biotechnology, Microbiology, Oxygen uptake, Metabolism, Mycoses, Respiration, Animals, Parasites, Tissue metabolism, Agronomy and Crop Science, Aroideae
Abstract

The respiration, as measured by oxygen uptake, was higher for healthy tissue adjacent to soft rots of apple (var. Bramley) caused byPenicillium expansum Link andThom. andBotrytis cinerea Fr. and of potato tuber (var. Arran Banner) caused byErwinia aroideae Townsend, than tissue at a more distant site. The respiration of tissue adjacent to a physiological rot caused by bruising was not affected. It was concluded that there is diffusion of a substance(s) from the site of infection which causes an increase in the rate of respiration of the adjacent tissue.

Published
1962
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23. 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

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24. Phased array Doppler reflectometry at Wendelstein 7-X

Author

S. Wolf, Olaf Grulke, E A Scott, M. Hirsch, T. Windisch, Thomas Klinger, S. A. Bozhenkov, E. Pasch, Wendelstein X Team, C. Lechte, Burkhard Plaum, H. Damm, W. Kasparek, G. M. Weir, G. Fuchert, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, business.industry, Phased array, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, Magnetic field, law.invention, symbols.namesake, Optics, law, 0103 physical sciences, Perpendicular, symbols, Physics::Accelerator Physics, Passive electronically scanned array, Wendelstein 7-X, 010306 general physics, business, Reflectometry, Instrumentation, Doppler effect, Stellarator
Abstract

A passive phased array Doppler reflectometry system has recently been installed in the Wendelstein-7X stellarator. In contrast to conventional Doppler reflectometry systems, the microwave beam can be steered on short time scales in the measurement plane perpendicular to the magnetic field in the range of ±25 degrees without mechanical steering components. This paper characterizes the design and properties of the phased array antenna system and presents the first measurement results from the latest OP1.2a campaign.

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25. Characteristics of electron internal transport barrier in Heliotron J.

Author

N Kenmochi, T Minami, C Takahashi, S Mochizuki, K Nishioka, S Kobayashi, K Nagasaki, Y Nakamura, H Okada, S Kado, S Yamamoto, S Ohshima, S Konoshima, G M Weir, Y Otani, and T Mizuuchi

Subjects
ELECTRON transport, ELECTRON cyclotron resonance heating, ELECTRON plasma, ELECTRON density, THERMAL diffusivity
Abstract

The formation of an electron internal transport barrier (eITB) has been observed for the first time with centrally focused electron cyclotron heating (ECH) microwaves injected into plasma in Heliotron J. When the heating power per electron density () exceeds a threshold of , transient increases of both the central Te and the core Te gradients are observed. A neoclassical (NC) calculation using the Sugama–Nishimura moment method predicts that the large positive radial electric field (Er) is formed in the core region. Heat transport analysis shows a significant reduction of the effective electron thermal diffusivity in the plasma with the eITB related to that without the eITB. The large gap between the experimentally obtained effective thermal diffusivity and the NC thermal diffusivity suggests that the suppression of anomalous transport contributes to the core improved confinement of the eITB plasma. The electron cyclotron emission measurement shows both the transient increase and the hysteresis phenomena during the eITB formation. [ABSTRACT FROM AUTHOR]

Published
2017
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