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1. Armoring of the Wendelstein 7-X divertor-observation immersion-tubes based on NBI fast-ion simulations

Author

Dag Hathiramani, M. W. Jakubowski, Yu Gao, Adnan Ali, Dirk Hartmann, P. McNeely, Aleix Puig Sitjes, P. Drewelow, Simppa Äkäslompolo, R. C. Wolf, S. A. Bozhenkov, Holger Niemann, J. Geiger, Fabio Pisano, N. Rust, Joris Fellinger, Marcin Sleczka, Stefan Mohr, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Materials science, Mechanical Engineering, Nuclear engineering, Divertor, 7. Clean energy, 01 natural sciences, Neutral beam injection, 010305 fluids & plasmas, law.invention, Ion, Nuclear Energy and Engineering, law, 0103 physical sciences, Thermal, Thermography, General Materials Science, Wendelstein 7-X, 010306 general physics, Stellarator, Overheating (electricity), Civil and Structural Engineering
Abstract

The first neutral beam injector (NBI) experiments of the Wendelstein 7-X stellarator took place in summer 2018. The modelling of the fast ion production and slowing down processes predicts losses of the NBI fast ions to the first wall on the order of 15%. One location receiving a high load (possibly peaking at several M W/m2) is the immersion tube for optical and infrared monitoring of the divertor targets. The stainless steel face of the tube has three vacuum windows, which are sensitive to temperature gradients and overheating. To protect the windows from damage caused by the fast ions, different heat load mitigation techniques were investigated. Given the available time and resources until the first NBI experiments, a protective stainless steel collar mounted at the front of the immersion tubes was regarded the most realistic solution. This contribution describes the fast ion modelling of the loads, the new design, thermal modelling of the design, and finally experimental experience with the protective collar showing heat loads in excess of 1.5 M W/m2. The fast ion heat loads have been assessed computationally with the ASCOT code and experimentally with thermal imaging.

Published
2019
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2. 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

3. ASCOT simulations of 14 MeV neutron rates in W7-X: effect of magnetic configuration

Author

West Team, Simppa Äkäslompolo, J. P. Koschinsky, Joona Kontula, Taina Kurki-Suonio, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Thermonuclear fusion, FOS: Physical sciences, Plasma, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, Neutral beam injection, Physics - Plasma Physics, 010305 fluids & plasmas, 3. Good health, law.invention, Ion, Plasma Physics (physics.plasm-ph), Nuclear physics, Nuclear Energy and Engineering, Deuterium, law, Physics::Plasma Physics, 0103 physical sciences, Neutron, Production (computer science), 010306 general physics, Nuclear Experiment, Stellarator
Abstract

Neutron production rates in fusion devices are determined not only by the kinetic profiles but also the fast ion slowing-down distributions. In this work, we investigate the effect of magnetic configuration on neutron production rates in future deuterium plasmas in the Wendelstein 7-X (W7-X) stellarator. The neutral beam injection, beam and triton slowing-down distributions, and the fusion reactivity are simulated with the ASCOT suite of codes. The results indicate that the magnetic configuration has only a small effect on the production of 2.45 MeV neutrons from thermonuclear and beam-target fusion. The 14.1 MeV neutron production rates were found to be between $1.49 \times 10^{12}$ $\mathrm{s}^{-1}$ and $1.67 \times 10^{12}$ $\mathrm{s}^{-1}$, which is estimated to be sufficient for a time-resolved detection using a scintillating fiber detector, although only in high-performance discharges., 17 pages, 10 figures. Version submitted to Plasma Physics and Controlled Fusion

Published
2020

4. Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz

Author

I. Abramovic, West Team, Konstantinos A. Avramidis, J. Juul Rasmussen, Ioannis Gr. Pagonakis, Masaki Nishiura, Dmitry Moseev, Carsten Lechte, H. Braune, Simppa Äkäslompolo, W. Kasparek, R. C. Wolf, Søren Bang Korsholm, Stefan Kragh Nielsen, L. Krier, Gerd Gantenbein, S. Marsen, Mirko Salewski, H. P. Laqua, Alexander Marek, John Jelonnek, Manfred Thumm, A. Tancetti, Torsten Stange, Stefan Illy, Jianbo Jin, Science and Technology of Nuclear Fusion, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Thomson scattering, Cyclotron, Detector modelling and simulations I (interaction of radiation with matter, Inelastic scattering, 01 natural sciences, 030218 nuclear medicine & medical imaging, law.invention, Plasma diagnostics, 03 medical and health sciences, 0302 clinical medicine, Optics, law, Physics::Plasma Physics, Gyrotron, 0103 physical sciences, spectroscopy and imaging, Instrumentation, Mathematical Physics, etc), Physics, 010308 nuclear & particles physics, Scattering, business.industry, interaction of photons with matter, interferometry, interaction of hadrons with matter, Physics::Accelerator Physics, Wendelstein 7-X, business, ddc:600, Microwave
Abstract

The Collective Thomson Scattering (CTS) diagnostic measures the scattering spectrum of incident radiation off collective fluctuations in plasmas. In Wendelstein 7-X (W7-X) the diagnostic uses a 140 GHz heating gyrotron as a source of the probing radiation. At this frequency, the CTS spectra are heavily affected by the electron cyclotron emission, and the microwave beam propagation is restricted at typical W7-X plasma parameters. The diagnostic was successfully commissioned in the last experimental campaign and demonstrated ion temperature measurements. However, the signal-to-noise ratio was too low for measuring other quantities such as the fast-ion velocity distribution function or the fuel ion ratio. Currently, the W7-X CTS diagnostic is undergoing an upgrade to a frequency of 175 GHz. This will increase the sensitivity of the diagnostic, since the noise due to electron cyclotron emission will be reduced, and it will relax the constraints on microwave beam propagation in W7-X. Here we present the salient features of the upgraded CTS system and discuss its prospects for both thermal-ion and fast-ion measurements.

Published
2020

5. 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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6. Estimation of 14 MeV neutron rate from triton burn-up in future W7-X deuterium plasma campaigns

Author

Mitsutaka Isobe, J. P. Koschinsky, Simppa Äkäslompolo, R. C. Wolf, Felix Warmer, Christoph Biedermann, Kunihiro Ogawa, S. A. Bozhenkov, Wolf-Dieter Schneider, J. Kontula, G. A. Wurden, Max-Planck-Institut für Plasmaphysik, Department of Applied Physics, Aalto-yliopisto, Aalto University, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
neutron diagnostics, Materials science, fast ion physics, Nuclear Theory, Radiochemistry, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Deuterium plasma, W7-X, 010305 fluids & plasmas, Physics::Plasma Physics, 0103 physical sciences, Neutron, triton burn-up, Nuclear Experiment, 010306 general physics, deuterium plasmas
Abstract

openaire: EC/H2020/633053/EU//EUROfusion Fast ion confinement is of major importance for the ignition of a burning fusion plasma. In future deuterium plasma campaigns of the Wendelstein 7-X stellarator, W7-X, the amount of triton burn-up is one possible measure for fast ion confinement. A well-established technique to observe triton burn-up is the 14 MeV neutron rate. In this paper, it is estimated whether an existing scintillating fibre neutron detector is also suited to measure triton burn-up in W7-X with sufficient accuracy. An estimation is presented, which can be applied to any tokamak or stellarator design and is one-dimensional in the minor radius. The inputs are profiles of density, temperature, and differential volume element as well as the triton slowing-down time. The estimation calculates the thermal deuteron fusion rate and the associated deuteron-triton fusion rate; thus, the triton burn-up generated 14 MeV neutron rate. It neither takes triton diffusion nor explicit losses into account. This thermally generated fusion rate is comparedto the neutral beam injection heating induced beam-plasma fusion rate.

Published
2020
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7. Commissioning and initial operation of the W7-X neutral beam injection heating system

Author

R. Schroeder, Stefan Heinrich, Bernd Heinemann, O. P. Ford, P. Rong, W. Auerweck, R. Riedl, Simppa Äkäslompolo, Y. Drider, P. McNeely, R. Kairys, R. C. Wolf, Christian Hopf, D. A. Hartmann, S. Obermayer, and N. Rust

Subjects
Materials science, Mechanical Engineering, Nuclear engineering, RF power amplifier, Plasma, Injector, 7. Clean energy, 01 natural sciences, Neutral beam injection, 010305 fluids & plasmas, Ion, law.invention, Heating system, Nuclear Energy and Engineering, law, 0103 physical sciences, General Materials Science, 010306 general physics, Beam (structure), Stellarator, Civil and Structural Engineering
Abstract

The first, of two planned, neutral beam injectors for the stellarator Wendelstein 7-X (W7-X) was commissioned for and participated in the experimental campaign (OP1.2b) from July to October 2018. The injector was equipped with two RF driven ion sources from which 90A of positive hydrogen ions were extracted at 55 kV. After neutralization, the two sources provided >3 MW of neutral beam heating power to the stellarator plasma. During the experimental campaign >300 shots were successfully performed for plasma heating or to allow for measurement of the ion temperature profile by charge exchange recombination spectroscopy (CXRS). The initial operation of the NBI system on W7-X was very successful, demonstrating both increased central plasma density and stored plasma energy, or allowing for the collection of the time resolved ion temperature over the bulk of the plasma. This paper presents, briefly, source conditioning and performance, focusing on some of the initial problems encountered. Described in more detail is the most significant challenge overcome during commissioning: failure to couple RF power into one of the sources.

Published
2020

8. Serpent neutronics model of Wendelstein 7-X for 14.1 MeV neutrons

Author

J. P. Koschinsky, Jaakko Leppänen, Antti Snicker, Christoph Biedermann, West Team, G. A. Wurden, S. A. Bozhenkov, Joona Kontula, Simppa Äkäslompolo, R. C. Wolf, Taina Kurki-Suonio, W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, Department of Applied Physics, Aalto-yliopisto, and Aalto University

Subjects
Neutron transport, Astrophysics::High Energy Astrophysical Phenomena, 020209 energy, Nuclear Theory, FOS: Physical sciences, 02 engineering and technology, 7. Clean energy, law.invention, Nuclear physics, 0203 mechanical engineering, Neutron flux, law, 0202 electrical engineering, electronic engineering, information engineering, Wendelstein 7-X, Neutron detection, Serpent, General Materials Science, Neutron, Nuclear Experiment, Civil and Structural Engineering, Neutrons, Physics, Scintillating fibre, Mechanical Engineering, Torus, Plasma, Computational Physics (physics.comp-ph), Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), 020303 mechanical engineering & transports, Nuclear Energy and Engineering, Physics - Computational Physics, Simulation, Stellarator
Abstract

In this work, a Serpent 2 neutronics model of the Wendelstein 7-X (W7-X) stellarator is prepared, and an response function for the Scintillating-Fibre neutron detector (SciFi) is calculated using the model. The neutronics model includes the simplified geometry for the key components of the stellarator itself as well as the torus hall. The objective of the model is to assess the 14.1 MeV neutron flux from deuteron-triton fusions in W7-X, where the neutrons are modelled only until they have slowed down to 1 MeV energy. The key messages of this article are: demonstration of unstructured mesh geometry usage for stellarators, W7-X in particular; technical documentation of the model and first insights in fast neutron behaviour in W7-X, especially related to the SciFi: the model indicates that the superconducting coils are the strongest scatterers and block neutrons from large parts of the plasma. The back-scattering from e.g. massive steel support structures is found to be small. The SciFi will detect neutrons from an extended plasma volume in contrast to having an effective line-of-sight., Comment: Proceedings of the SOFT2020 conference, to be sumbitted to Fusion Engineering and Design

Published
2021
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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. Versatile fusion source integrator AFSI for fast ion and neutron studies in fusion devices

Author

Alexander Lukin, Stefan Matejcik, Soare Sorin, Francesco Romanelli, Otto Asunta, Bohdan Bieg, Jari Varje, Vladislav Plyusnin, José Vicente, Alberto Loarte, Bor Kos, Axel Jardin, Rajnikant Makwana, CHIARA MARCHETTO, Marco Wischmeier, Simppa Äkäslompolo, William Tang, Choong-Seock Chang, Manuel Garcia-munoz, and JET Contributors

Subjects
Physics, Nuclear and High Energy Physics, Jet (fluid), Fusion, Neutron transport, Monte Carlo method, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, Ion, Nuclear physics, fusion products, Physics::Plasma Physics, JET, ITER, Integrator, 0103 physical sciences, Nuclear fusion, neutronics, Neutron, 010306 general physics, Monte Carlo
Abstract

ASCOT Fusion Source Integrator AFSI, an efficient tool for calculating fusion reaction rates and characterizing the fusion products, based on arbitrary reactant distributions, has been developed and is reported in this paper. Calculation of reactor-relevant D-D, D-T and D-3He fusion reactions has been implemented based on the Bosch-Hale fusion cross sections. The reactions can be calculated between arbitrary particle populations, including Maxwellian thermal particles and minority energetic particles. Reaction rate profiles, energy spectra and full 4D phase space distributions can be calculated for the non-isotropic reaction products. The code is especially suitable for integrated modelling in self-consistent plasma physics simulations as well as in the Serpent neutronics calculation chain. Validation of the model has been performed for neutron measurements at the JET tokamak and the code has been applied to predictive simulations in ITER.

Published
2018
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11. Modelling of NBI ion wall loads in the W7-X stellarator

Author

T. Jesche, Yu. Turkin, Michael Drevlak, Simppa Äkäslompolo, R. C. Wolf, Taina Kurki-Suonio, J. Kontula, S. A. Bozhenkov, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, law, 0103 physical sciences, Atomic physics, 010306 general physics, Condensed Matter Physics, 01 natural sciences, Neutral beam injection, Stellarator, 010305 fluids & plasmas, Ion, law.invention
Published
2018
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12. Synthetic NPA diagnostic for energetic particles in JET plasmas

Author

Alexander Lukin, Stefan Matejcik, Soare Sorin, Francesco Romanelli, Bohdan Bieg, Jari Varje, Vladislav Plyusnin, José Vicente, Alberto Loarte, Axel Jardin, Rajnikant Makwana, CHIARA MARCHETTO, Marco Wischmeier, Simppa Äkäslompolo, William Tang, Choong-Seock Chang, Manuel Garcia-munoz, and JET Contributors

Subjects
Jet (fluid), Tokamak, Materials science, Energetic neutral atom, Astrophysics::High Energy Astrophysical Phenomena, Nuclear instruments and methods for hot plasma diagnostics, Plasma, 01 natural sciences, 010305 fluids & plasmas, law.invention, Ion, stomatognathic system, law, Physics::Plasma Physics, Physics::Space Physics, 0103 physical sciences, Analysis and statistical methods, Atomic physics, Simulation methods and programs, 010306 general physics, Neutral particle, Instrumentation, Mathematical Physics, Charge exchange
Abstract

Neutral particle analysis (NPA) is one of the few methods for diagnosing fast ions inside a plasma by measuring neutral atom fluxes emitted due to charge exchange reactions. The JET tokamak features an NPA diagnostic which measures neutral atom fluxes and energy spectra simultaneously for hydrogen, deuterium and tritium species. A synthetic NPA diagnostic has been developed and used to interpret these measurements to diagnose energetic particles in JET plasmas with neutral beam injection (NBI) heating. The synthetic NPA diagnostic performs a Monte Carlo calculation of the neutral atom fluxes in a realistic geometry. The 4D fast ion distributions, representing NBI ions, were simulated using the Monte Carlo orbit-following code ASCOT. Neutral atom density profiles were calculated using the FRANTIC neutral code in the JINTRAC modelling suite. Additionally, for rapid analysis, a scan of neutral profiles was precalculated with FRANTIC for a range of typical plasma parameters. These were taken from the JETPEAK database, which includes a comprehensive set of data from the flat-top phases of nearly all discharges in recent JET campaigns. The synthetic diagnostic was applied to various JET plasmas in the recent hydrogen campaign where different hydrogen/deuterium mixtures and NBI configurations were used. The simulated neutral fluxes from the fast ion distributions were found to agree with the measured fluxes, reproducing the slowing-down profiles for different beam isotopes and energies and quantitatively estimating the fraction of hydrogen and deuterium fast ions.

Published
2017
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13. Effect of Resonant Magnetic Perturbation Field on Energetic Ion Behavior in the Large Helical Device

Author

Y. Fujiwara, Simppa Äkäslompolo, Mitsutaka Isobe, Takeo Nishitani, Shuji Kamio, H. Nuga, Kunihiro Ogawa, S. A. Bozhenkov, Masaki Osakabe, Ryosuke Seki, and LHD Experiment Group

Subjects
neutron diagnostics, Physics, Large Helical Device, Field (physics), Condensed matter physics, Magnetic perturbation, Condensed Matter Physics, energetic ion confinement, resonant magnetic perturbation field, Ion
Abstract

A study of the resonant magnetic perturbation (RMP) effect on transit beam ion behavior is performed using the total neutron emission rate (Sn) measurement of the deuterium plasma in the Large Helical Device. We conducted no RMP field, one-half RMP field, and full RMP field discharges and compared Sn that reflects the global beam ion confinement information. It is determined that owing to the RMP field, Sn decreased by approximately 15 - 30%. Numerical calculations based on the classical confinement of beam ions were performed to investigate the bulk plasma parameter effect on Sn. The calculated Sn shows that the degradation of Sn by RMP is mainly caused by the degradation of the electron temperature owing to island formation which results in a shorter slowing down time of beam ions.

Published
2019
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14. Energy-and-pitch-angle-resolved escaping beam ion measurements by Faraday-cup-based fast-ion loss detector in Wendelstein 7-X

Author

Dirk Nicolai, Masayuki Yokoyama, Kunihiro Ogawa, Carsten Killer, Simppa Äkäslompolo, Olaf Grulke, G. Satheeswaran, R. C. Wolf, Mitsutaka Isobe, Masaki Osakabe, and S. A. Bozhenkov

Subjects
Materials science, Aperture, Faraday cup, Particle detectors, 01 natural sciences, 030218 nuclear medicine & medical imaging, Ion, 03 medical and health sciences, symbols.namesake, Particle identification methods, 0302 clinical medicine, Optics, Physics::Plasma Physics, 0103 physical sciences, Pitch angle, Instrumentation, Mathematical Physics, Range (particle radiation), 010308 nuclear & particles physics, business.industry, Neutral beam injection, symbols, Plasma diagnostics-charged-particle spectroscopy, Plasma diagnostics-probes, Physics::Accelerator Physics, Wendelstein 7-X, business, Beam (structure)
Abstract

With the objective of understanding the energetic-particle loss mechanism in three-dimensional plasmas, a Faraday-cup-based fast-ion loss detector (FILD) was developed and installed in OP1.2b in Wendelstein 7-X (W7-X) as a collaboration between the National Institute for Fusion Science and Max-Planck-Institute for Plasma Physics. The FILD, which consists of double apertures and thin aluminum foils, was based on a magnetic spectrometer using the magnetic field of the fusion device. The double aperture limits the thermal ion, but allows the energetic ion to enter the FILD box. The thin aluminum foils serve as the ion collector. Orbit-following calculations were performed in order to find a suitable position for the FILD. The results indicated that barely co- and counter-going transit ions reached the FILD position mounted on the multi-purpose manipulator installed on W7-X. Moreover, because the injection angle of neutral beams injector installed on W7-X was relatively perpendicular, the target range of pitch angle was set to from 91 degrees to 150 degrees. An energy-and-pitch-angle map was created using a grid calculation code in order to decide on the position/size of aperture and aluminum foil. The grid calculation code indicates the position where the energetic ion would strike on the aluminum foil. Here, the map was used as the basis for designing an aluminum foil pattern with two energies and four pitch angle ranges. Also, note that the lower energy range was designed so that it accommodates a neutral beam injection energy of 55 kV. Measurements of beam ion losses were performed in neutral beam (NB) blip experiments, where concurrent increases and decreases of barely co-going transit beam ion losses due to NB injections were observed. Furthermore, this study validated that the FILD installed on a midplane manipulator probe is capable of probing a range of radii spanning 1.0–1.5 cm, over which the beam ion loss current would vary significantly.

Published
2019
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15. EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

Author

Gloria Luisa Falchetto, Airila, Markus I., Alberto Morillas, A., Andersson Sundén, E., Thierry Aniel, Jean-Francois Artaud, Otto Asunta, Atanasiu, Calin V., Martine Baelmans, Vincent Basiuk, Roberto Bilato, Maarten Blommaert, Dmitry Borodin, Cédric Boulbe, Sergio Briguglio, Jonathan Citrin, Rui Coelho, Sean Conroy, David Coster, Doriæ, V., Rémi Dumont, Fable, E., Blaise Faugeras, Jorge Ferreira, Lorenzo Figini, António Figueiredo, Fogaccia, G., Fuchs, C., Edmondo Giovannozzi, Goloborod Ko, V., Hoenen, O., Phuong-Anh Huynh, Frédéric Imbeaux, Irena Ivanova-Stanik, Thomas Johnson, Denis Kalupin, Leon Kos, Ernesto Lerche, Jens Madsen, Omar Maj, Manduchi, G., Mervi Mantsinen, Yannick Marandet, Stefan Matejcik, Rafael Mayo-Garcia, Patrick Mccarthy, Antoine Merle, Eric Nardon, Anders Henry Nielsen, Nowak, S., Mullane, Martin O., Michal Owsiak, Pais, V., Bartek Palak, Grzegorz Pelka, Marcin Plociennik, Gergő Pokol, Dragan Poljak, Hari Radhakrishnan, Holger Reimerdes, Dirk Reiser, Juri Romazanov, Paulo Rodrigues, Xavier Saez, Debasmita Samaddar, Olivier Sauter, Schmid, K., Scott, B. D., Silvestar Šesnić, Jacqueline Signoret, Seppo Sipilä, Roman Stankiewicz, Pär Strand, Suchkov, E., Anna Šušnjara, Gabor Szepesi, Daniel Tegnered, Károly Tőkési, David Tskhakaya, Jakub Urban, Pablo Vallejos, Dirk van Eester, Laurent Villard, Fabio Villone, Viola, B., Gregorio Vlad, Egbert Westerhof, Yadykin, D., Zagorski, R., Zaitsev, F., Tomasz Żok, Zwingmann, W., Simppa Äkäslompolo, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), VTT Technical Research Centre of Finland (VTT), Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid] (CIEMAT), Department of Physics and Astronomy [Uppsala], Uppsala University, Aalto University, Tokamak energy, National Institute for Laser, Plasma and Radiation Physics (INFLPR), Department of Mechanical Engineering [Leuven], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Max-Planck-Institut für Plasmaphysik [Garching] (IPP), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Control, Analysis and Simulations for TOkamak Research (CASTOR), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jean Alexandre Dieudonné (JAD), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Jean Alexandre Dieudonné (JAD), Italian National agency for new technologies, Energy and sustainable economic development [Frascati] (ENEA), Dutch Institute for Fundamental Energy Research [Eindhoven] (DIFFER), Instituto de Plasmas e Fusão Nuclear [Lisboa] (IPFN), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), University of Split, Istituto di Fisica del Plasma [Milano] (IFP), Consiglio Nazionale delle Ricerche [Milano] (CNR), Institute of Applied Physics [Vienna] (TU Wien), Vienna University of Technology (TU Wien), Institute of Plasma Physics and Laser Microfusion [Warsaw] (IPPLM), Department of Fusion Plasma Physics [Stockholm] (KTH), Royal Institute of Technology [Stockholm] (KTH ), EUROfusion, University of Ljubljana, Laboratory for Plasma Physics (LPP), Ecole Royale Militaire / Koninklijke Militaire School (ERM KMS), Department of Physics [Lyngby], Technical University of Denmark [Lyngby] (DTU), Ricerca Formazione Innovazione (Consorzio RFX), Consiglio Nazionale delle Ricerche (CNR), Barcelona Supercomputing Center - Centro Nacional de Supercomputacion (BSC - CNS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Faculty of Mathematics, Physics and Informatics [Bratislava] (FMPH/UNIBA), Comenius University in Bratislava, University College Cork (UCC), Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Department of Physics [Glasgow], University of Strathclyde [Glasgow], Poznan Supercomputing and Networking Center (PSNC), Institute of Nuclear Techniques (NTI), Budapest University of Technology and Economics [Budapest] (BME), University of Cyprus [Nicosia], Culham Centre for Fusion Energy (CCFE), Department of Earth and Space Sciences [Göteborg], Chalmers University of Technology [Göteborg], Institute for Nuclear Research [Budapest] (ATOMKI), Hungarian Academy of Sciences (MTA), Institute of Plasma Physics, Association EURATOM (IPP PRAGUE), Czech Academy of Sciences [Prague] (CAS), Consorzio di Ricerca per l'Energia, l'Automazione e le Tecnologie dell'Elettromagnetismo (CREATE), ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, EUROfusion-IM Team, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jean Alexandre Dieudonné (LJAD), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire Jean Alexandre Dieudonné (LJAD), Danmarks Tekniske Universitet = Technical University of Denmark (DTU), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and University of Cyprus [Nicosia] (UCY)

Subjects
[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation
Abstract

International audience; Recent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper.

Published
2016

16. Effect of plasma response on the fast ion losses due to ELM control coils in ITER

Author

K. Särkimäki, Tuomas Koskela, Eero Hirvijoki, Seppo Sipilä, Simppa Äkäslompolo, Vassili Parail, Mario Gagliardi, Otto Asunta, Taina Kurki-Suonio, G. Saibene, Mario Cavinato, Yueqiang Liu, Antti Snicker, and Jari Varje

Subjects
Physics, Nuclear and High Energy Physics, Divertor, Nuclear engineering, Monte Carlo method, Plasma, Alpha particle, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Resonant magnetic perturbations, 010305 fluids & plasmas, Ion, Magnetic field, Nuclear physics, Physics::Plasma Physics, 13. Climate action, 0103 physical sciences, Particle, 010306 general physics
Abstract

Mitigating edge localized modes (ELMs) with resonant magnetic perturbations (RMPs) can increase energetic particle losses and resulting wall loads, which have previously been studied in the vacuum approximation. This paper presents recent results of fusion alpha and NBI ion losses in the ITER baseline scenario modelled with the Monte Carlo orbit following code ASCOT in a realistic magnetic field including the effect of the plasma response. The response was found to reduce alpha particle losses but increase NBI losses, with up to 4.2% of the injected power being lost. Additionally, some of the load in the divertor was found to be shifted away from the target plates toward the divertor dome.

Published
2016
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17. Effect of the European design of TBMs on ITER wall loads due to fast ions in the baseline (15 MA), hybrid (12.5 MA), steady-state (9 MA) and half-field (7.5 MA) scenarios

Author

Antti Snicker, G. Saibene, K. Särkimäki, Mario Gagliardi, Eero Hirvijoki, Jari Varje, Otto Asunta, Taina Kurki-Suonio, V.V. Parail, Seppo Sipilä, Simppa Äkäslompolo, and Mario Cavinato

Subjects
Nuclear and High Energy Physics, Thermonuclear fusion, Materials science, Nuclear engineering, Monte Carlo method, Ripple, Plasma, Blanket, Collisionality, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, Magnetic field, Physics::Plasma Physics, 13. Climate action, 0103 physical sciences, Thermal, 010306 general physics
Abstract

We assess the effect of the European design of the pebble-bed helium-cooled test blanket modules (TBM) on fast ion power loads on ITER material surfaces. For this purpose, the effect of not only the TBMs but also the ferritic inserts (FI), used for mitigating the toroidal field ripple, were included in unprecedented detail in the reconstruction of the 3-dimensional magnetic field. This is important because, due to their low collisionality, fast ions follow the magnetic geometry much more faithfully than the thermal plasma. The Monte Carlo orbit-following code ASCOT was used to simulate all the foreseen operating scenarios of ITER: the baseline 15 MA standard H-mode operation, the 12.5 MA hybrid scenario, the 9 MA advanced scenario, and the half-field scenario with helium plasma that will be ITER’s initial operating scenario. The effect of TBMs was assessed by carrying out the simulations in pairs: one including only the effect of ferritic inserts, and the other including also the perturbation due to TBMs. Both thermonuclear fusion alphas and NBI ions from ITER heating beams were addressed. The TBMs are found to increase the power loads, but the absolute values remain small. Neither do they produce any additional hot spots.

Published
2016

18. Calculating the 3D magnetic field of ITER for European TBM studies

Author

K. Särkimäki, Taina Kurki-Suonio, Otto Asunta, Seppo Sipilä, Eero Hirvijoki, Mario Gagliardi, Thijs Bergmans, Jose Galabert, Simppa Äkäslompolo, and Antti Snicker

Subjects
Ferromagnetic material properties, ta221, Test Blanket Module, FOS: Physical sciences, Magnetization, Nuclear magnetic resonance, ITER, General Materials Science, Ferritic insert, ta218, Civil and Structural Engineering, Physics, ta214, ta114, Mechanical Engineering, Mechanics, Plasma, Computational Physics (physics.comp-ph), Finite element method, Physics - Plasma Physics, Magnetic field, Plasma Physics (physics.plasm-ph), Nuclear Energy and Engineering, Integrator, Electromagnetic shielding, Physics - Computational Physics, Vector potential
Abstract

The magnetic perturbation due to the ferromagnetic test blanket modules (TBMs) may deteriorate fast ion confinement in ITER. This effect must be quantified by numerical studies in 3D. We have implemented a combined finite element method (FEM) -- Biot-Savart law integrator method (BSLIM) to calculate the ITER 3D magnetic field and vector potential in detail. Unavoidable geometry simplifications changed the mass of the TBMs and ferritic inserts (FIs) up to 26%. This has been compensated for by modifying the nonlinear ferromagnetic material properties accordingly. Despite the simplifications, the computation geometry and the calculated fields are highly detailed. The combination of careful FEM mesh design and using BSLIM enables the use of the fields unsmoothed for particle orbit-following simulations. The magnetic field was found to agree with earlier calculations and revealed finer details. The vector potential is intended to serve as input for plasma shielding calculations., In proceedings of the 28th Symposium on Fusion Technology

Published
2015

19. Monte Carlo method and High Performance Computing for solving Fokker–Planck equation of minority plasma particles

Author

Eero Hirvijoki, J. Miettunen, Jari Varje, Simppa Äkäslompolo, Tuomas Koskela, and Taina Kurki-Suonio

Subjects
Tokamak, Fluids & Plasmas, Monte Carlo method, FOS: Physical sciences, Atomic, law.invention, Collision operator, Ion, Particle and Plasma Physics, Physics::Plasma Physics, law, physics.plasm-ph, Nuclear, Statistical physics, Physics, Quantum Physics, Molecular, Plasma, Computational Physics (physics.comp-ph), Condensed Matter Physics, Supercomputer, Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), Distribution function, physics.comp-ph, Fokker–Planck equation, Physics - Computational Physics
Abstract

This paper explains how to obtain the distribution function of minority ions in tokamak plasmas using the Monte Carlo method. Since the emphasis is on energetic ions, the guiding-center transformation is outlined, including also the transformation of the collision operator. Even within the guiding-center formalism, the fast particle simulations can still be very CPU intensive and, therefore, we introduce the reader also to the world of high-performance computing. The paper is concluded with a few examples where the presented method has been applied., ITER International School 2014

Published
2015
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20. Simulations of fast ion wall loads in ASDEX Upgrade in the presence of magnetic perturbations due to ELM mitigation coils

Author

Simppa Äkäslompolo, M. Garcia-Munoz, Otto Asunta, Tuomas Koskela, Antti Snicker, Taina Kurki-Suonio, Seppo Sipilä, and ASDEX Upgrade Team

Subjects
Nuclear and High Energy Physics, Fluids & Plasmas, Perturbation (astronomy), FOS: Physical sciences, 01 natural sciences, Atomic, 010305 fluids & plasmas, Ion, Particle and Plasma Physics, ASDEX Upgrade, physics.plasm-ph, 0103 physical sciences, Nuclear, 010306 general physics, Plasma density, Physics, Detector, Magnetic field perturbation, Molecular, Computational Physics (physics.comp-ph), Condensed Matter Physics, Physics - Plasma Physics, Computational physics, Magnetic field, Plasma Physics (physics.plasm-ph), physics.comp-ph, Physics - Computational Physics, Beam (structure)
Abstract

The effect of ASDEX Upgrade (AUG) edge localized mode (ELM)-mitigation coils on fast ion wall loads was studied with the fast particle following Monte Carlo code ASCOT. Neutral beam injected particles were simulated in two AUG discharges both in the presence and in the absence of the magnetic field perturbation induced by the eight newly installed in-vessel coils. In one of the discharges (#26476) beams were applied individually, making it a useful basis for investigating the effect of the coils on different beams. However, no ELM mitigation was observed in #26476, probably due to the low plasma density. Therefore, another discharge (#26895) demonstrating clear ELM mitigation was also studied. The magnetic perturbation due to the in-vessel coils has a significant effect on the fast particle confinement, but only when total magnetic field, B tot, is low. When B tot was high, the perturbation did not increase the losses, but merely resulted in redistribution of the wall power loads. Hence, it seems to be possible to achieve ELM mitigation using in-vessel coils, while still avoiding increased fast ion losses, by simply using a strong B tot. Preliminary comparisons between simulated and experimental fast ion lost detector signals show a reasonable correspondence.

Published
2015
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21. ITER fast ion confinement in the presence of the European test blanket module

Author

Mario Gagliardi, Otto Asunta, G. Saibene, Jari Varje, Simppa Äkäslompolo, Mario Cavinato, Seppo Sipilä, Eero Hirvijoki, Antti Snicker, K. Särkimäki, and Taina Kurki-Suonio

Subjects
Physics, Nuclear and High Energy Physics, Thermonuclear fusion, Guiding center, Nuclear engineering, Monte Carlo method, chemistry.chemical_element, Plasma, Alpha particle, Blanket, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, Nuclear physics, chemistry, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Physics::Accelerator Physics, 010306 general physics, Beam (structure), Helium
Abstract

This paper addresses the confinement of thermonuclear alpha particles and neutral beam injected deuterons in the 15 MA Q = 10 inductive scenario in the presence of the magnetic perturbation caused by the helium cooled pebble bed test blanket module using the vacuum approximation. Both the flat top phase and plasma ramp-up are studied. The transport of fast ions is calculated using the Monte Carlo guiding center orbit-following code ASCOT. A detailed three-dimensional wall, derived from the ITER blanket module CAD data, is used for evaluating the fast ion wall loads. The effect of the test blanket module is studied for both overall confinement and possible hot spots. The study indicates that the test blanket modules do not significantly deteriorate the fast ion confinement.

Published
2015
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22. Influence of toroidal field ripple and resonant magnetic perturbations on global 13C transport in ASDEX Upgrade

Author

V. Lindholm, J. Miettunen, Simppa Äkäslompolo, Markus Airila, M. Groth, Tapani Makkonen, and ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Nuclear and High Energy Physics, Toroid, Chemistry, Ripple, Rotational symmetry, Rotation, Resonant magnetic perturbations, Magnetic field, Nuclear Energy and Engineering, ASDEX Upgrade, Physics::Plasma Physics, General Materials Science, Atomic physics, Deposition (chemistry)
Abstract

In this study, 3D orbit-following simulations with the ASCOT code of a tracer injection experiment on ASDEX Upgrade (AUG) are carried out to investigate the influence of toroidal field (TF) ripple and resonant magnetic perturbations (RMPs) on global 13 C transport in the scrape-off layer (SOL). The conducted ASCOT simulations predict ripple to induce toroidal periodicity into the 13 C deposition pattern. For resonant magnetic perturbations, the deposition pattern was observed to be locally influenced in the vicinity of the in-vessel coils creating the perturbations. In both cases, however, the global large-scale deposition of 13 C remained unchanged compared to the case of an axisymmetric magnetic field.

Published
2015
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23. ASCOT: Solving the kinetic equation of minority particle species in tokamak plasmas

Author

Otto Asunta, J. Miettunen, Tuomas Koskela, Taina Kurki-Suonio, Antti Snicker, Seppo Sipilä, Simppa Äkäslompolo, and Eero Hirvijoki

Subjects
Tokamak, Guiding center, Monte Carlo method, ta221, General Physics and Astronomy, FOS: Physical sciences, Mathematical Sciences, law.invention, orbit-following impurity tracing Monte Carlo, Stochastic differential equation, symbols.namesake, law, Physics::Plasma Physics, physics.plasm-ph, Information and Computing Sciences, Orbit-following, Statistical physics, fast ions, Monte Carlo, ta218, Physics, ta214, Impurity tracing, ta114, Fast ions, Nuclear & Particles Physics, Physics - Plasma Physics, Computational physics, Plasma Physics (physics.plasm-ph), Hardware and Architecture, Phase space, Physical Sciences, Dynamic Monte Carlo method, symbols, Test particle, Hamiltonian (quantum mechanics)
Abstract

A comprehensive description of methods, suitable for solving the kinetic equation for fast ions and impurity species in tokamak plasmas using Monte Carlo approach, is presented. The described methods include Hamiltonian orbit-following in particle and guiding center phase space, test particle or guiding center solution of the kinetic equation applying stochastic differential equations in the presence of Coulomb collisions, neoclassical tearing modes and Alfv\'en eigenmodes as electromagnetic perturbations relevant to fast ions, together with plasma flow and atomic reactions relevant to impurity studies. Applying the methods, a complete reimplementation of the well-established minority species code ASCOT is carried out as a response both to the increase in computing power during the last twenty years and to the weakly structured growth of the code, which has made implementation of additional models impractical. Also, a benchmark between the previous code and the reimplementation is accomplished, showing good agreement between the codes., Comment: 13 pages, 9 figures, submitted to Computer Physics Communications

Published
2014
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24. Fast-ion redistribution and loss due to edge perturbations in the ASDEX Upgrade, DIII-D and KSTAR tokamaks

Author

Matthias Hoelzl, M. Nocente, I. G. J. Classen, Jun Young Kim, R. M. McDermott, Diii-D, Kouji Shinohara, W. Suttrop, M. Rodriguez-Ramos, E. Viezzer, T. Lunt, N. Lazanyi, Todd Evans, M. Willensdorfer, J. E. Boom, Otto Asunta, T. L. Rhodes, X. Chen, Kstar Teams, R. K. Fisher, Simppa Äkäslompolo, V. Igochine, Benedikt Geiger, R. Dux, J. Kim, Ch. Fuchs, M. A. Van Zeeland, You-Moon Jeon, E. Wolfrum, David Pace, S. Fietz, M. Garcia-Munoz, B. Kurzan, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, ASDEX Upgrade Team, DIII-D Team, KSTAR Team, Science and Technology of Nuclear Fusion, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, Garcia Munoz, M, Akaslompolo, S, Asunta, O, Boom, J, Chen, X, Classen, I, Dux, R, Evans, T, Fietz, S, Fisher, R, Fuchs, C, Geiger, B, Hoelzl, M, Igochine, V, Jeon, Y, Kim, J, Kurzan, B, Lazanyi, N, Lunt, T, Mcdermott, R, Nocente, M, Pace, D, Rhodes, T, Rodriguez Ramos, M, Shinohara, K, Suttrop, W, Van Zeeland, M, Viezzer, E, Willensdorfer, M, and Wolfrum, E

Subjects
Physics, Nuclear and High Energy Physics, Tokamak, DIII-D, Computer Science::Neural and Evolutionary Computation, Magnetic confinement fusion, Plasma, Collisionality, Condensed Matter Physics, 01 natural sciences, gamma ray spectroscopy, Neutral beam injection, Fast ions, magnetic perturbations, 010305 fluids & plasmas, law.invention, neutron spectroscopy, ASDEX Upgrade, law, Physics::Plasma Physics, KSTAR, 0103 physical sciences, Atomic physics, 010306 general physics, nuclear fusion
Abstract

The impact of edge localized modes (ELMs) and externally applied resonant and non-resonant magnetic perturbations (MPs) on fast-ion confinement/transport have been investigated in the ASDEX Upgrade (AUG), DIII-D and KSTAR tokamaks. Two phases with respect to the ELM cycle can be clearly distinguished in ELM-induced fast-ion losses. Inter-ELM losses are characterized by a coherent modulation of the plasma density around the separatrix while intra-ELM losses appear as well-defined bursts. In high collisionality plasmas with mitigated ELMs, externally applied MPs have little effect on kinetic profiles, including fast-ions, while a strong impact on kinetic profiles is observed in low-collisionality, low q 95 plasmas with resonant and non-resonant MPs. In low-collisionality H-mode plasmas, the large fast-ion filaments observed during ELMs are replaced by a loss of fast-ions with a broad-band frequency and an amplitude of up to an order of magnitude higher than the neutral beam injection prompt loss signal without MPs. A clear synergy in the overall fast-ion transport is observed between MPs and neoclassical tearing modes. Measured fast-ion losses are typically on banana orbits that explore the entire pedestal/scrape-off layer. The fast-ion response to externally applied MPs presented here may be of general interest for the community to better understand the MP field penetration and overall plasma response. Ministerio de Economía y Empresa ((RYC-2011-09152 y ENE2012-31087) Marie Curie (Grant PCIG11-GA-2012-321455) US Department of Energy (DE-FC02-04ER54698, SC-G903402, DE-FG02-04ER54761, DE-AC02-09CH11466 and DE-FG02- 08ER54984) NRF Korea contract 2009-0082012 MEST under the KSTAR project

Published
2013
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25. Protecting ITER walls: fast ion power loads in 3D magnetic field

Author

Antti Snicker, V.V. Parail, Yueqiang Liu, Jari Varje, Eero Hirvijoki, Taina Kurki-Suonio, Seppo Sipilä, Mario Cavinato, G. Saibene, Juuso Terävä, K. Särkimäki, Simppa Äkäslompolo, Mario Gagliardi, and Otto Asunta

Subjects
Fusion, Materials science, Nuclear engineering, Perturbation (astronomy), Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Magnetic field, Ion, Nuclear magnetic resonance, Nuclear Energy and Engineering, 0103 physical sciences, 010306 general physics
Abstract

The fusion alpha and beam ion with steady-state power loads in all four main operating scenarios of ITER have been evaluated by the ASCOT code. For this purpose, high-fidelity magnetic backgrounds were reconstructed, taking into account even the internal structure of the ferritic inserts and tritium breeding modules (TBM). The beam ions were found to be almost perfectly confined in all scenarios, and only the so-called hybrid scenario featured alpha loads reaching 0.5 MW due to its more triangular plasma. The TBMs were not found to jeopardize the alpha confinement, nor cause any hot spots. Including plasma response did not bring dramatic changes to the load. The ELM control coils (ECC) were simulated in the baseline scenario and found to seriously deteriorate even the beam confinement. However, the edge perturbation in this case is so large that the sources have to be re-evaluated with plasma profiles that take into account the ECC perturbation.

Published
2016
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26. Modelling of 3D fields due to ferritic inserts and test blanket modules in toroidal geometry at ITER

Author

G. Saibene, Mario Cavinato, Li Li, Yueqiang Liu, Seppo Sipilä, Taina Kurki-Suonio, Simppa Äkäslompolo, F. Koechl, Jari Varje, K. Särkimäki, and Vassili Parail

Subjects
Physics, Nuclear and High Energy Physics, Steady state, Toroid, Field (physics), Screening effect, Nuclear engineering, Phase (waves), Plasma, Blanket, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Electromagnetic coil, 0103 physical sciences, 010306 general physics
Abstract

Computations in toroidal geometry are systematically performed for the plasma response to 3D magnetic perturbations produced by ferritic inserts (FIs) and test blanket modules (TBMs) for four ITER plasma scenarios: the 15 MA baseline, the 12.5 MA hybrid, the 9 MA steady state, and the 7.5 MA half-field helium plasma. Due to the broad toroidal spectrum of the FI and TBM fields, the plasma response for all the n = 1–6 field components are computed and compared. The plasma response is found to be weak for the high-n (n > 4) components. The response is not globally sensitive to the toroidal plasma flow speed, as long as the latter is not reduced by an order of magnitude. This is essentially due to the strong screening effect occurring at a finite flow, as predicted for ITER plasmas. The ITER error field correction coils (EFCC) are used to compensate the n = 1 field errors produced by FIs and TBMs for the baseline scenario for the purpose of avoiding mode locking. It is found that the middle row of the EFCC, with a suitable toroidal phase for the coil current, can provide the best correction of these field errors, according to various optimisation criteria. On the other hand, even without correction, it is predicted that these n = 1 field errors will not cause substantial flow damping for the 15 MA baseline scenario.

Published
2016
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27. 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.

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28. Synthetic diagnostics in the european union integrated tokamak modelling simulation platform

Author

Carsten Lechte, Andreas Dinklage, R. Coelho, A. Kus, Erik Andersson Sundén, R. Reimer, Sean Conroy, A. Sirinelli, E. Blanco, Stéphane Heuraux, S. Hacquin, Simppa Äkäslompolo, Itm-Tf Contributors, F. da Silva, G. D. Conway, Instituto de Plasmas e Fusão Nuclear [Lisboa] (IPFN), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), Association EURATOM-TEKES, Association EURATOM-TEKES, Helsinki University of Technology, Finland, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid] (CIEMAT), Max-Planck-Institut für Plasmaphysik [Garching] (IPP), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), UL, IJL, and ITM-TF Contributors

Subjects
Nuclear and High Energy Physics, Spectrum analyzer, Tokamak, 01 natural sciences, 010305 fluids & plasmas, law.invention, Conceptual design, law, code validation, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, media_common.cataloged_instance, General Materials Science, European union, Aerospace engineering, 010306 general physics, Neutral particle, Reflectometry, Civil and Structural Engineering, media_common, business.industry, integrated modeling, Mechanical Engineering, Workflow, Nuclear Energy and Engineering, synthetic diagnostics, [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Enhanced Data Rates for GSM Evolution, business
Abstract

Équipe 107 : Physique des plasmas chauds; International audience; The European Union Integrated Tokamak Modelling Task Force (ITM-TF) has developed a standardized platform and an integrated modeling suite of codes for the simulation and prediction of a complete plasma discharge in any tokamak. The framework developed by ITM-TF allows for the development of sophisticated integrated simulations (workflows) for physics application, e.g., free-boundary equilibrium with feedback control, magnetohydrodynamic stability analysis, core/edge plasma transport, and heating and current drive. A significant effort is also under way to integrate synthetic diagnostic modules in the ITM-TF environment, namely, focusing on three-dimensional reflectometry, motional Stark effect, and neutron and neutral particle analyzer diagnostics. This paper gives an overview of the conceptual design of ITM-TF and preliminary results of the aforementioned synthetic diagnostic modules

29. 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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30. Performance of the first neutral beam injector at the Wendelstein 7-X stellarator

Author

N. Rust, Thilo Romba, Simppa Äkäslompolo, R. Kairys, P. Rong, P. Pölöskei, A. Spanier, O. P. Ford, Christian Hopf, Bernd Heinemann, Dirk Hartmann, Niek den Harder, R. Riedl, Wendelstein X Team, R. C. Wolf, R. Schroeder, P. McNeely, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Materials science, Ion beam, Plasma parameters, Mechanical Engineering, Plasma, 01 natural sciences, 7. Clean energy, Neutral beam injection, 010305 fluids & plasmas, law.invention, Nuclear Energy and Engineering, law, 0103 physical sciences, Electron temperature, General Materials Science, Wendelstein 7-X, Atomic physics, 010306 general physics, Stellarator, Beam (structure), Civil and Structural Engineering
Abstract

The neutral beam injection (NBI) system at Wendelstein 7-X (W7-X) was operated for the first time in 2018. Detailed calorimetric measurements were carried out to accurately determine the energy flow within the NBI system and the injected power into the plasma. Of the electric energy put into the system (89± 6) % can be accounted for. The time-averaged injected NBI power is assessed to be Pinj ≈ (3.1 ± 0.8) MW for hydrogen injection with two positive ion sources at the maximum acceleration voltage of 54 kV. This corresponds to a conversion efficiency of the initially generated ion beam power to the injected neutral beam power of about 33%. The ionization in a plasma with an ion and electron temperature of Ti ≈ Te ≈ 1.3 keV and an electron density of ne ≈ 4 ·1019 m−3 is calorimetrically determined to be about 90%. The injected power is validated against beam emission spectroscopy applying Fast-Ion Dα analysis (FIDASIM). The inferred injected power leads to an energy confinement time of around τE ≈ 150 ms for pure NBI heating plasma experiments at W7-X with these heating and plasma parameters.

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31. Design of endoscopes for monitoring water-cooled divertor in W7-X

Author

Uwe Lippmann, Joris Fellinger, Mohamad Alhashimi, M. Schülke, P. Drewelow, Simppa Äkäslompolo, Ralf König, H. Greve, A. Lorenz, M. W. Jakubowski, W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, and Publica

Subjects
Materials science, divertor thermography, Plasma parameters, ECRH stray radiation, Radiation, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, Optics, law, Endoscope, 0103 physical sciences, Limiter, Wendelstein 7-X, General Materials Science, 010306 general physics, Civil and Structural Engineering, business.industry, Mechanical Engineering, Divertor, Plasma, Nuclear Energy and Engineering, Infrared / Materials, Pinhole (optics), Interrupt, business, Stellarator
Abstract

The modular stellarator Wendelstein 7-X (W7-X) in Greifswald (Germany) started operation in 2015 with short pulse limiter plasmas and continued with pulsed divertor plasmas in 2017−2018. In 2021, the next operation phase (OP) OP2 will start after installation of 10 water-cooled CFC armored divertors, allowing for steady state operation. Since divertor heat loads are very sensitive to plasma parameters, each water-cooled divertor needs to be monitored to interrupt or adapt plasma operation once overload is detected. For that purpose ten endoscopes are planned: two in module 3 and eight more in a different type of port in the other modules. The infrared (IR) radiation from the plasma facing surface as well as the plasma edge radiation in the visible (VIS) range is captured through a pinhole in a water-cooled plasma facing head and transmitted to the rear side outside the vacuum where the light is split and captured by an IR and VIS camera. The design challenge is to reach a high-resolution image of the entire target while capturing a large field of view (FOV) of 120 degrees. In this paper, the design and assembly strategy is presented, including the assessment of the optical, thermo-mechanical and hydraulic performance.

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