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1. Implementation and performance evaluation of the real-time algorithms for Wendelstein 7-X divertor protection system for OP2.1

Author: Jabłoński, Bartłomiej, Puig Sitjes, Aleix, Makowski, Dariusz, Jakubowski, Marcin, Gao, Yu, Fischer, Simon, and Winter, Axel
Published: 2023
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2. A Deep Learning-Based Method to Detect Hot-Spots in the Visible Video Diagnostics of Wendelstein 7-X

Author: Máté Szűcs, Tamás Szepesi, Christoph Biedermann, Gábor Cseh, Marcin Jakubowski, Gábor Kocsis, Ralf König, Marco Krause, Aleix Puig Sitjes, and the W7-X Team
Subjects: first wall protection, video diagnostics, deep learning, Nuclear engineering. Atomic power, TK9001-9401
Abstract: Wendelstein 7-X (W7-X) is currently the largest optimized stellarator in operation in the world. Its main objective is to demonstrate long pulse operation and to investigate the suitability of this type of fusion device for a power plant. Maintaining the safety of the first wall is critical to achieving the desired discharge times of approximately 30 min while keeping a steady-state condition. We present a deep learning-based solution to detect the unexpected plasma-wall and plasma-object interactions, so-called hot-spots, in the images of the Event Detection Intelligent Camera (EDICAM) system. These events can pose a serious threat to the safety of the first wall, therefore, to the operation of the device. We show that sufficiently training a neural network with relatively small amounts of data is possible using our approach of mixing the experimental dataset with new images containing so-called synthetic hot-spots generated by us. Diversifying the dataset with synthetic hot-spots increases performance and can make up for the lack of data. The best performing YOLOv5 Small model processes images in 168 ms on average during inference, making it a good candidate for real-time operation. To our knowledge, we are the first ones to be able to detect events in the visible spectrum in stellarators with high accuracy, using neural networks trained on small amounts of data while achieving near-real-time inference times.
Published: 2022
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3. Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components

Author: O. Grulke, C. Albert, J.A. Alcuson Belloso, P. Aleynikov, K. Aleynikova, A. Alonso, G. Anda, T. Andreeva, M. Arvanitou, E. Ascasibar, E. Aymerich, K. Avramidis, J.-P. Bähner, S.-G. Baek, M. Balden, J. Baldzuhn, S. Ballinger, M. Banduch, S. Bannmann, A. Bañón Navarro, L. Baylor, C.D. Beidler, M. Beurskens, C. Biedermann, G. Birkenmeier, T. Bluhm, D. Boeckenhoff, D. Boeyaert, D. Bold, M. Borchardt, D. Borodin, H.-S. Bosch, H. Bouvain, S. Bozhenkov, T. Bräuer, H. Braune, C. Brandt, S. Brezinsek, K.J. Brunner, C. Büschel, R. Bussiahn, A. Buzás, B. Buttenschoen, V. Bykov, I. Calvo, A. Cappa, F. Carovani, D. Carralero, A. Carls, B. Carvalho, D. Castaño-Bardawil, N. Chaudhary, I. Chelis, S. Chen, D. Cipciar, J.W. Coenen, G. Conway, M. Cornelissen, Y. Corre, P. Costello, K. Crombe, G. Cseh, B. Csillag, H.I. Cu Castillo, G. Czymek, H. Damm, R.J. Davies, C. Day, S. Degenkolbe, R. De Wolf, W. Dekeyser, A. Demby, P. Despontin, C.P. Dhard, A. Dinklage, F.A. d’Isa, T. Dittmar, M. Dreval, M. Drevlak, P. Drews, J. Droste, D. Dunai, C. Dyhring, P. van Eeten, E. Edlund, M. Endler, D.A. Ennis, F.J. Escoto, M.S. Espinosa, T. Estrada, D. Fehling, L. Feuerstein, J. Fellinger, Y. Feng, D.L.C. Fernando, S. Fischer, E.R. Flom, O. Ford, T. Fornal, J. Frank, H. Frerichs, G. Fuchert, G. Gantenbein, Y. Gao, K. Garcia, I. García-Cortés, J.M. García-Regaña, B. Geiger, J. Geiger, P. Geissler, M. Gerard, G. Godino-Sedano, T. Gonda, A. González, A. Goriaev, D. Gradic, M. Grahl, H. Greuner, E. Grigore, M. Gruca, J.F. Guerrero Arnaiz, V. Haak, L. van Ham, K. Hammond, B. Hamstra, X. Han, S.K. Hansen, J. Harris, D. Hartmann, D. Hathiramani, S. Hegedus, S. Heinrich, P. Helander, F. Henke, S. Henneberg, L. Henschke, M. Hirsch, U. Hoefel, K. Hoefler, S. Hoermann, K.-P. Hollfeld, A. Holtz, D. Höschen, M. Houry, J. Huang, M. Hubeny, K. Hunger, D. Hwangbo, K. Ida, Y. Igitkhanov, S. Illy, Z. Ioannidis, M. Jablczynska, S. Jablonski, B. Jabłoński, B. Jagielski, M. Jakubowski, J. Jelonnek, F. Jenko, J. Jin, A. Johansson, G. Jouniaux, S. Kajita, J.-P. Kallmeyer, U. Kamionka, W. Kasparek, C. Kawan, Ye. O. Kazakov, N. Kenmochi, W. Kernbichler, A.K. Kharwandikar, M. Khokhlov, C. Killer, A. Kirschner, R. Kleiber, C.C. Klepper, T. Klinger, J. Knauer, A. Knieps, M. Kobayashi, G. Kocsis, Y. Kolesnichenko, A. Könies, J. Kontula, P. Kornejew, S.A. Korteweg, J. Koschinsky, J. Koster, Y. Kovtun, A. Krämer-Flecken, M. Krause, T. Kremeyer, L. Krier, D.M. Kriete, M. Krychowiak, I. Ksia¸zek, M. Kubkowska, M.D. Kuczyński, D. Kulla, A. Kumar, T. Kurki-Suonio, I. Kuzmych, S. Kwak, V. Lancelotti, A. Langenberg, H. Laqua, H.P. Laqua, M.R. Larsen, S. Lazerson, C. Lechte, B. Lee, A. LeViness, M. Lewerentz, Y. Liang, L. Liao, A. Litnovsky, J. Liu, J. Loizu, R. Lopez-Cansino, L.D. Lopez Rodriguez, A. Lorenz, R. Lunsford, Y. Luo, V. Lutsenko, N. Maaziz, M. Machielsen, R. Mackenbach, D. Makowski, E. Maragkoudakis, O. Marchuk, M. Markl, S. Marsen, J. Martínez, N. Marushchenko, S. Masuzaki, D.A. Maurer, M. Mayer, K.J. McCarthy, P. McNeely, D. Medina Roque, J. Meineke, S. Meitner, S. vaz Mendes, A. Menzel-Barbara, B. van Milligen, A. Mishchenko, V. Moiseenko, A. Möller, S. Möller, D. Moseev, G. Motojima, S. Mulas, P. Mulholland, M. Nagel, D. Nagy, Y. Narbutt, D. Naujoks, P. Nelde, R. Neu, O. Neubauer, U. Neuner, D. Nicolai, S. Nielsen, C. Nührenberg, R. Ochoukov, G. Offermanns, J. Ongena, J.W. Oosterbeek, M. Otte, N. Pablant, N. Panadero Alvarez, A. Pandey, G. Partesotti, E.A. Pasch, R. Pavlichenko, E. Pawelec, T.S. Pedersen, V. Perseo, B. Peterson, F. Pisano, B. Plaum, G. Plunk, L. Podavini, N.S. Polei, P. Poloskei, S. Ponomarenko, P. Pons-Villalonga, M. Porkolab, J. Proll, M.J. Pueschel, A. Puig Sitjes, R. Ragona, K. Rahbarnia, M. Rasiński, J. Rasmussen, D. Refy, F. Reimold, M. Richou, J.S. Riemann, K. Riße, J. de la Riva Villén, G. Roberg-Clark, E. Rodriguez, V. Rohde, J. Romazanov, T. Romba, D. Rondeshagen, M. Rud, T. Ruess, T. Rummel, A. Runov, C. Ruset, N. Rust, L. Ryc, T. Rzesnicki, M. Salewski, E. Sánchez, L. Sanchis Sanchez, G. Satheeswaran, J. Schacht, E. Scharff, J. Schilling, G. Schlisio, K. Schmid, J.C. Schmitt, O. Schmitz, M. Schneider, M. Van Schoor, T. Schröder, R. Schroeder, B. Schweer, S. Sereda, B. Shanahan, G. Sias, S. Simko, L. Singh, Y. Siusko, C. Slaby, M. Śle¸czka, B.S. Smith, D.R. Smith, H. Smith, M. Spolaore, A. Spring, T. Stange, A. von Stechow, I. Stepanov, M. Stern, U. Stroth, Y. Suzuki, C. Swee, L. Syrocki, T. Szabolics, T. Szepesi, R. Takacs, H. Takahashi, N. Tamura, C. Tantos, J. Terry, S. Thiede, H. Thienpondt, H. Thomsen, M. Thumm, T. Thun, S. Togo, T. Tork, H. Trimino Mora, A. Tsikouras, Y. Turkin, L. Vano, S. Varoutis, M. Vecsei, J.L. Velasco, M. Verstraeten, M. Vervier, E. Viezzer, J. Wagner, E. Wang, F. Wang, M. Wappl, F. Warmer, T. Wegner, Y. Wei, G. Weir, N. Wendler, U. Wenzel, A. White, F. Wilms, T. Windisch, A. Winter, V. Winters, R. Wolf, G. Wurden, P. Xanthopoulos, H.M. Xiang, S. Xu, H. Yamada, J. Yang, R. Yi, M. Yokoyama, B. Zamorski, M. Zanini, M. Zarnstorff, D. Zhang, S. Zhou, J. Zhu, J. Zimmermann, A. Zocco, and S. Zoletnik
Subjects: stellarator, long-pulse operation, magnetic fusion confinement, divertor detachment, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: After a long device enhancement phase, scientific operation resumed in 2022. The main new device components are the water cooling of all plasma facing components and the new water-cooled high heat flux divertor units. Water cooling allowed for the first long-pulse operation campaign. A maximum discharge length of 8 min was achieved with a total heating energy of 1.3 GJ. Safe divertor operation was demonstrated in attached and detached mode. Stable detachment is readily achieved in some magnetic configurations but requires impurity seeding in configurations with small magnetic pitch angle within the edge islands. Progress was made in the characterization of transport mechanisms across edge magnetic islands: Measurement of the potential distribution and flow pattern reveals that the islands are associated with a strong poloidal drift, which leads to rapid convection of energy and particles from the last closed flux surface into the scrape-off layer. Using the upgraded plasma heating systems, advanced heating scenarios were developed, which provide improved energy confinement comparable to the scenario, in which the record triple product for stellarators was achieved in the previous operation campaign. However, a magnetic configuration-dependent critical heating power limit of the electron cyclotron resonance heating was observed. Exceeding the respective power limit leads to a degradation of the confinement.
Published: 2024
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4. Heat and particle exhaust in high-performance plasmas in Wendelstein 7-X

Author: Yu Gao, Joachim Geiger, Marcin W. Jakubowski, Arun Pandey, Sergey Bozhenkov, Yuhe Feng, Michael Endler, Jürgen Baldzuhn, Valeria Perseo, Thierry Kremeyer, Georg Schlisio, Aleix Puig Sitjes, Matthias Otte, Dirk Naujoks, Maciej Krychowiak, Ralf König, Daihong Zhang, Tamás Szepesi, Gábor Kocsis, Gábor Cseh, Attila Buzás, Fabio Pisano, Alexander Knieps, and the W7-X Team
Subjects: W7-X, high performance, exhaust, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The paper reports for the first time the heat and particle exhaust at the plasma boundary through various edge diagnostics for the high-performance plasma obtained after pellet injection on Wendelstein 7-X. The plasma density at the edge is found to be reduced by a factor of 2 in the high-performance phase, supporting the previously reported density peaking at the plasma centre. The plasma beta effect on the magnetic topology is reflected by the appearance of the second strike line, which is well understood with simulation. However, during the rapid decay phase of the enhanced confinement, a transient localized heat flow of up to 16 MW m ^−2 is observed at the leading edge of a poorly cooled divertor component, which has not been understood but raises concerns about machine safety.
Published: 2024
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5. WEST full tungsten operation with an ITER grade divertor

Author: J. Bucalossi, A. Ekedahl, and the WEST Team, J. Achard, K. Afonin, O. Agullo, T. Alarcon, L. Allegretti, F. Almuhisen, H. Ancher, G. Antar, Y. Anquetin, S. Antusch, V. Anzallo, C. Arnas, J.F. Artaud, M.H. Aumeunier, S.G. Baek, X.Y. Bai, M. Balden, C. Balorin, T. Barbui, A. Barbuti, J. Barlerin, J. Barra, V. Basiuk, T. Batal, O. Baulaigue, A. Bec, M. Becoulet, E. Benoit, E. Bernard, J.M. Bernard, M. Bernert, N. Bertelli, E. Bertrand, P. Beyer, J. Bielecki, P. Bienvenu, R. Bisson, B. Bliewert, G. Bodner, S. Bose, C. Bottereau, C. Bouchand, Y. Boumendjel, F. Bouquey, C. Bourdelle, J. Bourg, S. Brezinsek, F. Brochard, C. Brun, V. Bruno, H. Bufferand, A. Bureau, S. Burles, Y. Camenen, B. Cantone, E. Caprin, M. Carole, S. Carpentier-Chouchana, G. Caulier, F. Causa, N. Cazanave, N. Chanet, O. Chellai, Y. Chen, M. Chernyshova, P. Chmielewski, W. Choe, A. Chomiczewska, G. Ciraolo, F. Clairet, J. Coenen, L. Colas, G. Colledani, J. Colnel, P. Coquillat, E. Corbel, Y. Corre, X. Courtois, T. Czarski, A. Da Ros, R. Daniel, J. Daumas, M. De Combarieu, P. De Vries, C. Dechelle, F. Deguara, R. Dejarnac, J.M. Delaplanche, L.F. Delgado-Aparicio, E. Delmas, L. Delpech, C. Desgranges, P. Devynck, J. Denis, S. Di Genova, R. Diab, A. Diallo, M. Diez, G. Dif-Pradalier, M. Dimitrova, R. Ding, T. Dittmar, L. Doceul, M. Domenes, D. Donovan, D. Douai, L. Dubus, N. Dumas, R. Dumont, F. Durand, A. Durif, F. Durodié, D. Elbeze, S. Ertmer, A. Escarguel, F. Escourbiac, B. Esposito, K. Ezato, F. Faisse, J.L. Farjon, N. Faure, N. Fedorczak, P. Fejoz, F. Felici, C. Fenzi-Bonizec, F. Ferlay, L. Ferrand, L. Fevre, M. Firdaouss, L. Fleury, D. Flouquet, T. Fonghetti, A. Gallo, X. Garbet, J. Garcia, J.L. Gardarein, L. Gargiulo, P. Garibaldi, S. Garitta, J. Gaspar, E. Gauthier, S. Gazzotti, F. Gely, J. Gerardin, G. Gervasini, E. Geulin, M. Geynet, P. Ghendrih, I. Giacalone, C. Gil, S. Ginoux, S. Girard, E. Giroux, G. Giruzzi, M. Goniche, V. Gorse, T. Gray, E. Grelier, C. Grisolia, A. Grosjean, A. Grosman, O. Grover, D. Guibert, D. Guilhem, C. Guillemaut, B. Guillermin, R. Guirlet, J.P. Gunn, Y. Gunsu, T. Gyergyek, S. Hacquin, A. Hakola, J. Harris, J.C. Hatchressian, W. Helou, P. Hennequin, C. Hernandez, L. Hijazi, J. Hillairet, T. Hirai, G.T. Hoang, C. Honoré, M. Houry, A. Huart, G. Huijsmans, P. Huynh, M. Iafrati, F. Imbeaux, N. Imbert, I. Ivanova-Stanik, P. Ivanova, R. Jalageas, A. Jamann, C. Jammes, A. Jardin, L. Jaubert, G. Jiolat, E. Joffrin, C. Johnson, A. Jonas, A. Kirschner, C.C. Klepper, M. Komm, M. Koubiti, S. Kosslow, J. Kovacic, M. Kozeiha, K. Krieger, K. Krol, I. Kudashev, B. Lacroix, L. Laguardia, V. Lamaison, V. Lapleigne, H. Laqua, C. Lau, Y. Lausenaz, R. Lé, M. Le Bohec, N. Lefevre, N. Lemoine, E. Lerche, Y. Lesourd, L. Letellier, M. Lewerentz, Y. Li, A. Liang, P. Linczuk, C. Linsmeier, M. Lipa, X. Litaudon, X. Liu, J. Llorens, T. Loarer, A. Loarte, T. Loewenhoff, G. Lombard, J. Lore, P. Lorenzetto, B. Lu, A. Lumsdaine, R. Lunsford, T. Lunt, G. Luo, P. Magaud, P. Maget, J.F. Mahieu, P. Maini, P. Malard, K. Malinowski, P. Manas, L. Manenc, V. Maquet, Y. Marandet, C. Martin, E.J. Martin, P. Martino, M. Mayer, D. Mazon, S. Mazzi, P. Messina, L. Meunier, D. Midou, G. Miglionico, Y. Mineo, M. Missirlian, R. Mitteau, B. Mitu, D. Moiraf, P. Mollard, G. Momparler, V. Moncada, T. Mondiere, C. Monti, J. Morales, M. Moreau, Ph. Moreau, Y. Moudden, G. Moureau, D. Mouyon, M. Muraglia, T. Nakano, E. Nardon, A. Neff, F. Nespoli, J. Nichols, L. Nicolas, S. Nicollet, R. Nouailletas, M. Ono, V. Ostuni, O. Paillat, C. Parish, H. Park, H. Parrat, J.Y. Pascal, B. Pegourie, F.P. Pellissier, Y. Peneliau, M. Peret, E. Pignoly, G. Pintsuk, R. Pitts, C. Pocheau, A. Podolnik, C. Portafaix, M. Poulos, P. Prochet, A. Puig Sitjes, R. Ragona, M. Rasinski, S. Ratynskaia, G. Raup, X. Regal-Mezin, C. Reux, J. Rice, M. Richou, F. Rigollet, N. Rivals, H. Roche, S. Rodrigues, J. Romazanov, G. Ronchi, C. Ruset, R. Sabot, A. Saille, R. Sakamoto, B. Salamon, F. Samaille, A. Santagiustina, B. Santraine, Y. Sarazin, O. Sauter, Y. Savoie-Peysson, L. Schiesko, M. Scholz, J.L. Schwob, E. Serre, H. Shin, S. Shiraiwa, Ja. Signoret, O. Skalli-Fettachi, P. Sogorb, Y. Song, A. Spring, P. Spuig, S. Sridhar, B. Stratton, C. Talatizi, P. Tamain, R. Tatali, Q. Tichit, A. Torre, L. Toulouse, W. Treutterer, E. Tsitrone, E.A. Unterberg, G. Urbanczyk, G. Van Rooij, N. Varadarajan, S. Vartanian, E. Velly, J.M. Verger, L. Vermare, D. Vezinet, N. Vignal, B. Vincent, S. Vives, D. Volpe, G. Wallace, E. Wang, L. Wang, Y. Wang, Y.S. Wang, T. Wauters, D. Weldon, B. Wirth, M. Wirtz, A. Wojenski, M. Xu, Q.X. Yang, H. Yang, B. Zago, R. Zagorski, B. Zhang, X.J. Zhang, X.L. Zou, and the EUROfusion Tokamak Exploitation Team
Subjects: nuclear fusion, magnetic confinement, tokamak, divertor, WEST, ITER, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The mission of WEST (tungsten-W Environment in Steady-state Tokamak) is to explore long pulse operation in a full tungsten (W) environment for preparing next-step fusion devices (ITER and DEMO) with a focus on testing the ITER actively cooled W divertor in tokamak conditions. Following the successful completion of phase 1 (2016-2021), phase 2 started in December 2022 with the lower divertor made entirely of actively cooled ITER-grade tungsten mono-blocks. A boronization prior the first plasma attempt allowed for a smooth startup with the new divertor. Despite the reduced operating window due to tungsten, rapid progress has been made in long pulse operation, resulting in discharges with a pulse length of 100 s and an injected energy of around 300 MJ per discharge. Plasma startup studies were carried out with equatorial boron nitride limiters to compare them with tungsten limiters, while Ion Cyclotron Resonance Heating assisted startup was attempted. High fluence operation in attached regime, which was the main thrust of the first campaigns, already showed the progressive build up of deposits and appearance of dust, impacting the plasma operation as the plasma fluence increased. In total, the cumulated injected energy during the first campaigns reached 43 GJ and the cumulated plasma time exceeded 5 h. Demonstration of controlled X-Point Radiator regime is also reported, opening a promising route for investigating plasma exhaust and plasma-wall interaction issues in more detached regime. This paper summarises the lessons learned from the manufacturing and the first operation of the ITER-grade divertor, describing the progress achieved in optimising operation in a full W environment with a focus on long pulse operation and plasma wall interaction.
Published: 2024
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6. Wendelstein 7-X on the path to long-pulse high-performance operation

Author: Endler, M., Baldzuhn, J., Beidler, C.D., Bosch, H.-S., Bozhenkov, S., Buttenschön, B., Dinklage, A., Fellinger, J., Feng, Y., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Hartmann, D., Jakubowski, M., König, R., Laqua, H.P., Lazerson, S., McNeely, P., Naujoks, D., Neuner, U., Otte, M., Pasch, E., Sunn Pedersen, T., Perseo, V., Puig Sitjes, A., Rahbarnia, K., Rust, N., Schmitz, O., Spring, A., Stange, T., von Stechow, A., Turkin, Y., Wang, E., and Wolf, R.C.
Published: 2021
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7. Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator

Author: C. Killer, P. Aleynikov, C. Biedermann, C.P. Dhard, P. Drews, Y. Gao, O. Grulke, M. Jakubowski, A. Knieps, G. Kocsis, D. Naujoks, A. Puig Sitjes, M. Spolaore, T. Stange, T. Szepesi, A. Tancetti, and H. Thomsen
Subjects: Stellarator, ECRH, Electric Probes, Electrons, Nuclear engineering. Atomic power, TK9001-9401
Abstract: Hot spots and bright patterns on plasma-facing components (PFC) in visible light are observed in electron cyclotron resonance heated (ECRH) plasmas at low densities in the stellarator Wendelstein 7-X. The events are often located far outside of any convective plasma loads and led in some cases to damages of diagnostic components, where the interaction zones qualitatively agree with fast particle loss simulations. Reciprocating electric probes indicate that this phenomenon is related to a non-thermal electron population that can have a beam like character, being directed in one parallel direction. Further, the electrons can be trapped on rational flux surfaces and be used to map magnetic islands.
Published: 2022
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8. Improvement in the simulation tools for heat distribution predictions and control of baffle and middle divertor loads in Wendelstein 7-X

Author: Yu Gao, Yuhe Feng, Michael Endler, Marcin W. Jakubowski, Joachim Geiger, Sergey Bozhenkov, Aleix Puig Sitjes, Fabio Pisano, Chandra Prakash Dhard, Dirk Naujoks, Maciej Krychowiak, Matthias Otte, Ralf König, Daihong Zhang, Georg Schlisio, Uwe Wenzel, Thomas Sunn Pedersen, and the W7-X Team
Subjects: W7-X, EMC3-Lite, heat loads, simulation, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: In the first divertor campaign in Wendelstein 7-X (W7-X), unexpected significant heat loads were observed at particular plasma-facing components (e.g. baffle tiles and middle divertor part) which were not designed to receive high heat flux. In a prior investigation, it was concluded that the previous diffusive field line tracing (DFLT) model used for divertor design in W7-X cannot reproduce these loads, due to the missing physics in simulating the heat transport in the shaded flux tubes. To tackle this issue, two new efficient codes (DFLT_rev and EMC3-Lite) are introduced and validated against various experimental heat distributions in different magnetic configurations. The new tungsten baffle tiles have been designed with these codes and mounted in the machine, aiming for mitigated heat loads in the upcoming campaign.
Published: 2023
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9. Combining research with safety: Performance of the Wendelstein 7-X video diagnostic system

Author: Szepesi, Tamás, Biedermann, Christoph, Cseh, Gábor, Kocsis, Gábor, Szabolics, Tamás, Zoletnik, Sándor, Gao, Yu, Akaslompolo, Simppa, Alonso, Arturo, Baldzuhn, Jürgen, Bozhenkov, Sergey, Dinklage, Andreas, Drewelow, Peter, Jakubowski, Marcin, König, Ralf, Lazerson, Samuel, Otte, Matthias, Puig Sitjes, Aleix, and Pedersen, Thomas Sunn
Published: 2019
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10. Armoring of the Wendelstein 7-X divertor-observation immersion-tubes based on NBI fast-ion simulations

Author: Äkäslompolo, Simppa, Drewelow, Peter, Gao, Yu, Ali, Adnan, Bozhenkov, Sergey, Fellinger, Joris, Geiger, Joachim, Hartmann, Dirk, Hathiramani, Dag, Jakubowski, Marcin, McNeely, Paul, Mohr, Stefan, Niemann, Holger, Pisano, Fabio, Rust, Norbert, Puig Sitjes, Aleix, Sleczka, Marcin, and Wolf, Robert
Published: 2019
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11. Investigation of 3D effects on heat fluxes in performance-optimized island divertor configurations at Wendelstein 7-X

Author: Effenberg, F., Niemann, H., Feng, Y., Geiger, J., Schmitz, O., Suzuki, Y., Ali, A., Barbui, T., Brezinsek, S., Frerichs, H., Jakubowski, M., König, R., Krychowiak, M., Puig Sitjes, A., Schmitt, J.C., and Sunn Pedersen, T.
Published: 2019
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12. Initial results from the hotspot detection scheme for protection of plasma facing components in Wendelstein 7-X

Author: A. Ali, H. Niemann, M. Jakubowski, T. Sunn Pedersen, R. Neu, Y. Corre, P. Drewelow, A. Puig Sitjes, G. Wurden, F. Pisano, B. Cannas, Y. Gao, and M. Ślęczka
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Abstract: One of the main aims of Wendelstein 7-X (W7-X), an advanced stellarator, is to investigate the quasi-steady state operation of magnetic confinement devices for nuclear fusion, for which power exhaust is an important issue. A dominant fraction of the energy leaving from the confined plasma region will be removed by 10 so-called island divertor units, which are designed to sustain a maximum heat flux of up to 10 MWm−2. An essential prerequisite for the safe operation of a steady-state device is automatic detection of hot spots and other abnormal events. Simple temperature limits in infrared (IR) thermographic images will not be enough on their own, because of plasma-generated surface coatings and other effects summarized in the following. To protect divertor elements from overheating, and to monitor power deposition onto the divertor elements, near real-time hotspot detection algorithms for the analysis of carbon plasma facing components (PFCs) were implemented and tested in the GLADIS facility.One of the difficulties in hotspot detection in a carbon-based machine is the deposition of plasma impurities as layers with a reduced thermal connection to the underlying bulk material. We have developed and successfully tested a method to classify surface layers and benchmarked the performance of the method with the Tore Supra IR data operating with actively cooled carbon PFCs. The surface layers can be detected in a steady plasma discharge during the initial rise and decay in temperature when a strike line touches parts of the divertor or wall. It can also be detected by modulating electron cyclotron resonance heating (ECRH) input power. This feature allows detection of overheated areas while reducing false positives. For the recent operational campaign, inertially cooled test divertor units (TDU) were installed to prepare for steady-state operation with water-cooled divertor units. Automatic, near real-time detection of hot spots and identification of surface layers in the W7-X divertor are presented. Results are compared with a best fit estimate of the heat transmission coefficient α which is used to calculate heat flux onto the divertor in the presence of surface layers. Keywords: W7-X, Divertor, Plasma facing components, Heat load, Infrared, Surface layers, Tore supra
Published: 2019
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13. Evaluation of NVIDIA Xavier NX Platform for Real-Time Image Processing for Plasma Diagnostics

Author: Bartłomiej Jabłoński, Dariusz Makowski, Piotr Perek, Patryk Nowak vel Nowakowski, Aleix Puig Sitjes, Marcin Jakubowski, Yu Gao, Axel Winter, and The W-X Team
Subjects: graphics processing unit, general-purpose computing on graphics processing units, image processing, plasma diagnostics, embedded system, Technology
Abstract: Machine protection is a core task of real-time image diagnostics aiming for steady-state operation in nuclear fusion devices. The paper evaluates the applicability of the newest low-power NVIDIA Jetson Xavier NX platform for image plasma diagnostics. This embedded NVIDIA Tegra System-on-a-Chip (SoC) integrates a Graphics Processing Unit (GPU) and Central Processing Unit (CPU) on a single chip. The hardware differences and features compared to the previous NVIDIA Jetson TX2 are signified. Implemented algorithms detect thermal events in real-time, utilising the high parallelism provided by the embedded General-Purpose computing on Graphics Processing Units (GPGPU). The performance and accuracy are evaluated on the experimental data from the Wendelstein 7-X (W7-X) stellarator. Strike-line and reflection events are primarily investigated, yet benchmarks for overload hotspots, surface layers and visualisation algorithms are also included. Their detection might allow for automating real-time risk evaluation incorporated in the divertor protection system in W7-X. For the first time, the paper demonstrates the feasibility of complex real-time image processing in nuclear fusion applications on low-power embedded devices. Moreover, GPU-accelerated reference processing pipelines yielding higher accuracy compared to the literature results are proposed, and remarkable performance improvement resulting from the upgrade to the Xavier NX platform is attained.
Published: 2022
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14. On the interaction between the island divertor heat fluxes, the scrape-off layer radial electric field and the edge turbulence in Wendelstein 7-X plasmas

Author: E. Maragkoudakis, D. Carralero, T. Estrada, T. Windisch, Y. Gao, C. Killer, M. Jakubowski, A. Puig Sitjes, F. Pisano, H. Sándor, M. Vecsei, S. Zoletnik, A. Cappa, and the W7-X Team
Subjects: Doppler reflectometry, stellarator, SOL, Wendelstein 7-X, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The formation of the radial electric field, $E_\textrm{r}$ in the scrape-off layer (SOL) has been experimentally studied for attached divertor conditions in stellarator W7-X. The main objective of this study is to test the validity in a complex three-dimensional (3D) island divertor of simple models, typically developed in tokamaks, relating $E_\textrm{r}$ in the SOL to the sheath potential drop gradient at the target. Additionally, we investigate the effect of the edge $E_\textrm{r}$ shear on the reduction of density fluctuation amplitude, a well-established phenomenon according to the existing bibliography. The main diagnostic for measurements in the SOL is a V-band Doppler reflectometer that can provide the measurement of the $E_\textrm{r}$ and density fluctuations with good spatial resolution. 3D measurements of divertor parameters have been carried out using infrared cameras, with the exponential decay length of the divertor heat flux ( $\lambda_\mathrm{q}$ ) resulting in a suitable proxy for the model-relevant $\lambda_\mathrm{T}$ , the exponential decay length of the temperature at the divertor. In the investigated attached regimes, it is shown for the first time that the formation of the $E_\textrm{r}$ in the SOL depends on parameters at the divertor, following a $E_\textrm{r} \propto T_\mathrm{e}/\lambda_\mathrm{q}$ qualitatively similar to that found in a tokamak. Then, from the analyzed plasmas, the observed $E_\textrm{r}$ shear at the edge is linked to a moderate local reduction of the amplitude of density fluctuations.
Published: 2022
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15. Real-Time Detection of Overloads on the Plasma-Facing Components of Wendelstein 7-X

Author: Aleix Puig Sitjes, Marcin Jakubowski, Dirk Naujoks, Yu Gao, Peter Drewelow, Holger Niemann, Joris Fellinger, Victor Moncada, Fabio Pisano, Chakib Belafdil, Raphael Mitteau, Marie-Hélène Aumeunier, Barbara Cannas, Josep Ramon Casas, Philippe Salembier, Rocco Clemente, Simon Fischer, Axel Winter, Heike Laqua, Torsten Bluhm, Karsten Brandt, and The W7-X Team
Subjects: Wendelstein 7-X, plasma facing components protection, imaging diagnostics, thermography, hot spot detection, thermal events detection, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract: Wendelstein 7-X (W7-X) is the leading experiment on the path of demonstrating that stellarators are a feasible concept for a future power plant. One of its major goals is to prove quasi-steady-state operation in a reactor-relevant parameter regime. The surveillance and protection of the water-cooled plasma-facing components (PFCs) against overheating is fundamental to guarantee a safe steady-state high-heat-flux operation. The system has to detect thermal events in real-time and timely interrupt operation if it detects a critical event. The fast reaction times required to prevent damage to the device make it imperative to automate fully the image analysis algorithms. During the past operational phases, W7-X was equipped with inertially cooled test divertor units and the system still required manual supervision. With the experience gained, we have designed a new real-time PFC protection system based on image processing techniques. It uses a precise registration of the entire field of view against the CAD model to determine the temperature limits and thermal properties of the different PFCs. Instead of reacting when the temperature limits are breached in certain regions of interest, the system predicts when an overload will occur based on a heat flux estimation, triggering the interlock system in advance to compensate for the system delay. To conclude, we present our research roadmap towards a feedback control system of thermal loads to prevent unnecessary plasma interruptions in long high-performance plasmas.
Published: 2021
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16. Detecting Plasma Detachment in the Wendelstein 7-X Stellarator Using Machine Learning

Author: Máté Szűcs, Tamás Szepesi, Christoph Biedermann, Gábor Cseh, Marcin Jakubowski, Gábor Kocsis, Ralf König, Marco Krause, Valeria Perseo, Aleix Puig Sitjes, and The Team W7-X
Subjects: fusion plasma physics, plasma detachment, machine learning, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, QD1-999
Abstract: The detachment regime has a high potential to play an important role in fusion devices on the road to a fusion power plant. Complete power detachment has been observed several times during the experimental campaigns of the Wendelstein 7-X (W7-X) stellarator. Automatic observation and signaling of such events could help scientists to better understand these phenomena. With the growing discharge times in fusion devices, machine learning models and algorithms are a powerful tool to process the increasing amount of data. We investigate several classical supervised machine learning models to detect complete power detachment in the images captured by the Event Detection Intelligent Camera System (EDICAM) at the W7-X at each given image frame. In the dedicated detached state the plasma is stable despite its reduced contact with the machine walls and the radiation belt stays close to the separatrix, without exhibiting significant heat load onto the divertor. To decrease computational time and resources needed we propose certain pixel intensity profiles (or intensity values along lines) as the input to these models. After finding the profile that describes the images best in terms of detachment, we choose the best performing machine learning algorithm. It achieves an F1 score of 0.9836 on the training dataset and 0.9335 on the test set. Furthermore, we investigate its predictions in other scenarios, such as plasmas with substantially decreased minor radius and several magnetic configurations.
Published: 2021
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17. Improvement in the simulation tools for heat distribution predictions and control of baffle and middle divertor loads in Wendelstein 7-X

Author: Gao, Yu, Feng, Yuhe, Endler, Michael, Jakubowski, Marcin W., Geiger, Joachim, Bozhenkov, Sergey, Puig Sitjes, Aleix, Pisano, Fabio, Dhard, Chandra Prakash, Naujoks, Dirk, Krychowiak, Maciej, Otte, Matthias, König, Ralf, Zhang, Daihong, Schlisio, Georg, Wenzel, Uwe, Sunn Pedersen, Thomas, Gantenbein, Gerd, Illy, Stefan, Jelonnek, John, Krier, Laurent, and Thumm, Manfred
Subjects: Technology, ddc:600
Published: 2023

18. Identification of fast ion wall loads in Wendelstein 7-X from thermographic measurements

Author: Mark J H Cornelissen, Samuel A Lazerson, Yu Gao, Josefine H E Proll, Paul McNeely, Norbert Rust, Dirk Hartmann, Marcin W Jakubowski, Adnan Ali, Fabio Pisano, Holger Niemann, Aleix Puig Sitjes, Ralf König, Robert C Wolf, the W7-X Team, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear Energy and Engineering, wall load, neutral-beam injection, Wendelstein 7-X, plasma-facing components, fast ions, Condensed Matter Physics, simulation, asymmetry, thermography
Abstract: Fast ion wall loads can result in excessively high heat fluxes to the plasma-facing components (PFCs). To allow for the development of mitigation strategies, and thereby protect the PFCs, the fast ion losses have to be predicted by faithful models. To ensure that fast ion models are an accurate representation of the real world, they need to be verified. The neutral-beam experiments performed in Wendelstein 7-X (W7-X) allow to investigate and verify models of the fast ion losses in the stellarator configuration. Infrared thermographic measurements were used to obtain the heat flux to both the baffle plates and the divertor. We found evidence of fast ion wall loads on the baffle plates, with loads between 100 kW m−2 and 1 MW m−2. The loads are attributed to fast ions which escape the main plasma via magnetic ripples. The fast ion wall loads on the baffle plates show up-down and toroidal asymmetry. The experimental results were compared to numerical simulations performed by the BEAMS3D and ASCOT codes. Qualitative agreement in up-down asymmetry is found, but the magnitude and toroidal asymmetry are not yet well predicted by the simulations. The asymmetries of the strike lines on the divertor suggest that fast ions also play a role here. Specifically, a second strike line emerged consistently in the high-iota configuration on the horizontal divertor. The shape and magnitude of the strike lines changed considerably during the neutral-beam injection (NBI) operation phase. Although no damage to steel components of W7-X was found, fast ion loads to the baffle plates could possibly limit the NBI operation in the upcoming campaigns of W7-X.
Published: 2022

19. Detecting Plasma Detachment in the Wendelstein 7-X Stellarator Using Machine Learning

Author: W7-X Team, Szűcs, Máté, Szepesi, Tamás, Biedermann, Christoph, Cseh, Gábor, Jakubowski, Marcin, Kocsis, Gábor, König, Ralf, Krause, Marco, Perseo, Valeria, Puig Sitjes, Aleix, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Fluid Flow and Transfer Processes, Technology, QH301-705.5, Process Chemistry and Technology, Physics, QC1-999, fusion plasma physics, plasma detachment, machine learning, General Engineering, Engineering (General). Civil engineering (General), 01 natural sciences, 010305 fluids & plasmas, Computer Science Applications, Chemistry, 0103 physical sciences, General Materials Science, TA1-2040, Biology (General), 010306 general physics, Instrumentation, ddc:600, QD1-999
Abstract: The detachment regime has a high potential to play an important role in fusion devices on the road to a fusion power plant. Complete power detachment has been observed several times during the experimental campaigns of the Wendelstein 7-X (W7-X) stellarator. Automatic observation and signaling of such events could help scientists to better understand these phenomena. With the growing discharge times in fusion devices, machine learning models and algorithms are a powerful tool to process the increasing amount of data. We investigate several classical supervised machine learning models to detect complete power detachment in the images captured by the Event Detection Intelligent Camera System (EDICAM) at the W7-X at each given image frame. In the dedicated detached state the plasma is stable despite its reduced contact with the machine walls and the radiation belt stays close to the separatrix, without exhibiting significant heat load onto the divertor. To decrease computational time and resources needed we propose certain pixel intensity profiles (or intensity values along lines) as the input to these models. After finding the profile that describes the images best in terms of detachment, we choose the best performing machine learning algorithm. It achieves an F1 score of 0.9836 on the training dataset and 0.9335 on the test set. Furthermore, we investigate its predictions in other scenarios, such as plasmas with substantially decreased minor radius and several magnetic configurations.
Published: 2022

20. Improvement in the simulation tools for heat distribution predictions and control of baffle and middle divertor loads in Wendelstein 7-X

Author: Gao, Yu, primary, Feng, Yuhe, additional, Endler, Michael Bernd Sebastian, additional, Jakubowski, Marcin, additional, Geiger, Joachim, additional, Bozhenkov, Sergey A, additional, Puig Sitjes, Aleix, additional, Pisano, Fabio, additional, Dhard, Chandra Prakash, additional, Naujoks, Dirk, additional, Krychowiak, Maciej, additional, Otte, Matthias, additional, Koenig, Ralf, additional, Zhang, Daihong, additional, Schlisio, Georg, additional, Wenzel, U, additional, and Sunn Pedersen, Thomas, additional
Published: 2022
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21. On the interaction between the island divertor heat fluxes, the scrape-off layer radial electric field and the edge turbulence in Wendelstein 7-X plasmas

Author: Maragkoudakis, E., primary, Carralero, D., additional, Estrada, T., additional, Windisch, T., additional, Gao, Y., additional, Killer, C., additional, Jakubowski, M., additional, Puig Sitjes, A., additional, Pisano, F., additional, Sándor, H., additional, Vecsei, M., additional, Zoletnik, S., additional, and Cappa, A., additional
Published: 2022
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22. Identification of fast ion wall loads in Wendelstein 7-X from thermographic measurements

Author: Cornelissen, Mark J H, primary, Lazerson, Samuel A, additional, Gao, Yu, additional, Proll, Josefine H E, additional, McNeely, Paul, additional, Rust, Norbert, additional, Hartmann, Dirk, additional, Jakubowski, Marcin W, additional, Ali, Adnan, additional, Pisano, Fabio, additional, Niemann, Holger, additional, Puig Sitjes, Aleix, additional, König, Ralf, additional, Wolf, Robert C, additional, and W7-X Team, the, additional
Published: 2022
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23. Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator

Author: Killer, C., primary, Aleynikov, P., additional, Biedermann, C., additional, Dhard, C.P., additional, Drews, P., additional, Gao, Y., additional, Grulke, O., additional, Jakubowski, M., additional, Knieps, A., additional, Kocsis, G., additional, Naujoks, D., additional, Puig Sitjes, A., additional, Spolaore, M., additional, Stange, T., additional, Szepesi, T., additional, Tancetti, A., additional, and Thomsen, H., additional
Published: 2022
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24. Tools for Image Analysis and First Wall Protection at W7-X

Author: Giuliana Sias, Barbara Cannas, Yu Gao, Alessandra Fanni, G. A. Wurden, V. Moncada, Aleix Puig Sitjes, P. Drewelow, Holger Niemann, Wendelstein X Team, M. Jakubowski, Fabio Pisano, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, business.industry, Computer science, Mechanical Engineering, Image processing, 7. Clean energy, 01 natural sciences, Monitoring and control, 010305 fluids & plasmas, law.invention, Image (mathematics), Nuclear Energy and Engineering, law, 0103 physical sciences, Thermography, General Materials Science, Computer vision, Artificial intelligence, 010306 general physics, business, Stellarator, Civil and Structural Engineering
Abstract: The Wendelstein 7-X (W7-X) is the most advanced operating stellarator in fusion research. The monitoring and control of the heat loads on the plasma-facing components (PFCs) will be critical during...
Published: 2020
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25. Software platform for imaging diagnostic exploitation applied to edge plasma physics and real-time PFC monitoring

Author: V. Moncada, X. Courtois, L. Dubus, E. Grelier, M. Houry, A. Puig Sitjes, and B. Zhang
Subjects: Nuclear Energy and Engineering, Mechanical Engineering, General Materials Science, Civil and Structural Engineering
Published: 2023
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26. Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator

Author: Killer, C., Aleynikov, P., Biedermann, C., Dhard, C. P., Drews, P., Gao, Y., Grulke, O., Jakubowski, M., Knieps, A., Kocsis, G., Naujoks, D., Puig Sitjes, A., Spolaore, M., Stange, T., Szepesi, T., Tancetti, A., Thomsen, H., Killer, C., Aleynikov, P., Biedermann, C., Dhard, C. P., Drews, P., Gao, Y., Grulke, O., Jakubowski, M., Knieps, A., Kocsis, G., Naujoks, D., Puig Sitjes, A., Spolaore, M., Stange, T., Szepesi, T., Tancetti, A., and Thomsen, H.
Abstract: Hot spots and bright patterns on plasma-facing components (PFC) in visible light are observed in electron cyclotron resonance heated (ECRH) plasmas at low densities in the stellarator Wendelstein 7-X. The events are often located far outside of any convective plasma loads and led in some cases to damages of diagnostic components, where the interaction zones qualitatively agree with fast particle loss simulations. Reciprocating electric probes indicate that this phenomenon is related to a non-thermal electron population that can have a beam like character, being directed in one parallel direction. Further, the electrons can be trapped on rational flux surfaces and be used to map magnetic islands.
Published: 2022

27. Identification of fast ion wall loads in Wendelstein 7-X from thermographic measurements

Author: Cornelissen, Mark J.H., Lazerson, Samuel A., Gao, Yu, Proll, Josefine H.E., McNeely, Paul, Rust, Norbert, Hartmann, Dirk, Jakubowski, Marcin W., Ali, Adnan, Pisano, Fabio, Niemann, Holger, Puig Sitjes, Aleix, König, Ralf, Wolf, Robert C., Cornelissen, Mark J.H., Lazerson, Samuel A., Gao, Yu, Proll, Josefine H.E., McNeely, Paul, Rust, Norbert, Hartmann, Dirk, Jakubowski, Marcin W., Ali, Adnan, Pisano, Fabio, Niemann, Holger, Puig Sitjes, Aleix, König, Ralf, and Wolf, Robert C.
Abstract: Fast ion wall loads can result in excessively high heat fluxes to the plasma-facing components (PFCs). To allow for the development of mitigation strategies, and thereby protect the PFCs, the fast ion losses have to be predicted by faithful models. To ensure that fast ion models are an accurate representation of the real world, they need to be verified. The neutral-beam experiments performed in Wendelstein 7-X (W7-X) allow to investigate and verify models of the fast ion losses in the stellarator configuration. Infrared thermographic measurements were used to obtain the heat flux to both the baffle plates and the divertor. We found evidence of fast ion wall loads on the baffle plates, with loads between 100 kW m−2 and 1 MW m−2. The loads are attributed to fast ions which escape the main plasma via magnetic ripples. The fast ion wall loads on the baffle plates show up-down and toroidal asymmetry. The experimental results were compared to numerical simulations performed by the BEAMS3D and ASCOT codes. Qualitative agreement in up-down asymmetry is found, but the magnitude and toroidal asymmetry are not yet well predicted by the simulations. The asymmetries of the strike lines on the divertor suggest that fast ions also play a role here. Specifically, a second strike line emerged consistently in the high-iota configuration on the horizontal divertor. The shape and magnitude of the strike lines changed considerably during the neutral-beam injection (NBI) operation phase. Although no damage to steel components of W7-X was found, fast ion loads to the baffle plates could possibly limit the NBI operation in the upcoming campaigns of W7-X.
Published: 2022

28. Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Author: Sunn Pedersen, Thomas, primary, Abramovic, I., additional, Agostinetti, P., additional, Agredano Torres, M., additional, Äkäslompolo, S., additional, Alcuson Belloso, J., additional, Aleynikov, P., additional, Aleynikova, K., additional, Alhashimi, M., additional, Ali, A., additional, Allen, N., additional, Alonso, A., additional, Anda, G., additional, Andreeva, T., additional, Angioni, C., additional, Arkhipov, A., additional, Arnold, A., additional, Asad, W., additional, Ascasibar, E., additional, Aumeunier, M.-H., additional, Avramidis, K., additional, Aymerich, E., additional, Baek, S.-G., additional, Bähner, J., additional, Baillod, A., additional, Balden, M., additional, Baldzuhn, J., additional, Ballinger, S., additional, Banduch, M., additional, Bannmann, S., additional, Banon Navarro, A., additional, Bañón Navarro, A., additional, Barbui, T., additional, Beidler, C., additional, Belafdil, C., additional, Bencze, A., additional, Benndorf, A., additional, Beurskens, M., additional, Biedermann, C., additional, Biletskyi, O., additional, Blackwell, B., additional, Blatzheim, M., additional, Bluhm, T., additional, Böckenhoff, D., additional, Bongiovi, G., additional, Borchardt, M., additional, Borodin, D., additional, Boscary, J., additional, Bosch, H., additional, Bosmann, T., additional, Böswirth, B., additional, Böttger, L., additional, Bottino, A., additional, Bozhenkov, S., additional, Brakel, R., additional, Brandt, C., additional, Bräuer, T., additional, Braune, H., additional, Brezinsek, S., additional, Brunner, K., additional, Buller, S., additional, Burhenn, R., additional, Bussiahn, R., additional, Buttenschön, B., additional, Buzás, A., additional, Bykov, V., additional, Calvo, I., additional, Camacho Mata, K., additional, Caminal, I., additional, Cannas, B., additional, Cappa, A., additional, Carls, A., additional, Carovani, F., additional, Carr, M., additional, Carralero, D., additional, Carvalho, B., additional, Casas, J., additional, Castano-Bardawil, D., additional, Castejon, F., additional, Chaudhary, N., additional, Chelis, I., additional, Chomiczewska, A., additional, Coenen, J.W., additional, Cole, M., additional, Cordella, F., additional, Corre, Y., additional, Crombe, K., additional, Cseh, G., additional, Csillag, B., additional, Damm, H., additional, Day, C., additional, de Baar, M., additional, De la Cal, E., additional, Degenkolbe, S., additional, Demby, A., additional, Denk, S., additional, Dhard, C., additional, Di Siena, A., additional, Dinklage, A., additional, Dittmar, T., additional, Dreval, M., additional, Drevlak, M., additional, Drewelow, P., additional, Drews, P., additional, Dunai, D., additional, Edlund, E., additional, Effenberg, F., additional, Ehrke, G., additional, Endler, M., additional, Ennis, D.A., additional, Escoto, F.J., additional, Estrada, T., additional, Fable, E., additional, Fahrenkamp, N., additional, Fanni, A., additional, Faustin, J., additional, Fellinger, J., additional, Feng, Y., additional, Figacz, W., additional, Flom, E., additional, Ford, O., additional, Fornal, T., additional, Frerichs, H., additional, Freundt, S., additional, Fuchert, G., additional, Fukuyama, M., additional, Füllenbach, F., additional, Gantenbein, G., additional, Gao, Y., additional, Garcia, K., additional, García Regaña, J.M., additional, García-Cortés, I., additional, Gaspar, J., additional, Gates, D.A., additional, Geiger, J., additional, Geiger, B., additional, Giudicotti, L., additional, González, A., additional, Goriaev, A., additional, Gradic, D., additional, Grahl, M., additional, Graves, J.P., additional, Green, J., additional, Grelier, E., additional, Greuner, H., additional, Groß, S., additional, Grote, H., additional, Groth, M., additional, Gruca, M., additional, Grulke, O., additional, Grün, M., additional, Guerrero Arnaiz, J., additional, Günter, S., additional, Haak, V., additional, Haas, M., additional, Hacker, P., additional, Hakola, A., additional, Hallenbert, A., additional, Hammond, K., additional, Han, X., additional, Hansen, S.K., additional, Harris, J.H., additional, Hartfuß, H., additional, Hartmann, D., additional, Hathiramani, D., additional, Hatzky, R., additional, Hawke, J., additional, Hegedus, S., additional, Hein, B., additional, Heinemann, B., additional, Helander, P., additional, Henneberg, S., additional, Hergenhahn, U., additional, Hidalgo, C., additional, Hindenlang, F., additional, Hirsch, M., additional, Höfel, U., additional, Hollfeld, K.P., additional, Holtz, A., additional, Hopf, D., additional, Höschen, D., additional, Houry, M., additional, Howard, J., additional, Huang, X., additional, Hubeny, M., additional, Hudson, S., additional, Ida, K., additional, Igitkhanov, Y., additional, Igochine, V., additional, Illy, S., additional, Ionita-Schrittwieser, C., additional, Isobe, M., additional, Jabłczyńska, M., additional, Jablonski, S., additional, Jagielski, B., additional, Jakubowski, M., additional, Jansen van Vuuren, A., additional, Jelonnek, J., additional, Jenko, F., additional, Jensen, T., additional, Jenzsch, H., additional, Junghanns, P., additional, Kaczmarczyk, J., additional, Kallmeyer, J., additional, Kamionka, U., additional, Kandler, M., additional, Kasilov, S., additional, Kazakov, Y., additional, Kennedy, D., additional, Kharwandikar, A., additional, Khokhlov, M., additional, Kiefer, C., additional, Killer, C., additional, Kirschner, A., additional, Kleiber, R., additional, Klinger, T., additional, Klose, S., additional, Knauer, J., additional, Knieps, A., additional, Köchl, F., additional, Kocsis, G., additional, Kolesnichenko, Ya.I., additional, Könies, A., additional, König, R., additional, Kontula, J., additional, Kornejew, P., additional, Koschinsky, J., additional, Kozulia, M.M., additional, Krämer-Flecken, A., additional, Krampitz, R., additional, Krause, M., additional, Krawczyk, N., additional, Kremeyer, T., additional, Krier, L., additional, Kriete, D.M., additional, Krychowiak, M., additional, Ksiazek, I., additional, Kubkowska, M., additional, Kuczynski, M., additional, Kühner, G., additional, Kumar, A., additional, Kurki-Suonio, T., additional, Kwak, S., additional, Landreman, M., additional, Lang, P.T., additional, Langenberg, A., additional, Laqua, H.P., additional, Laqua, H., additional, Laube, R., additional, Lazerson, S., additional, Lewerentz, M., additional, Li, C., additional, Liang, Y., additional, Linsmeier, Ch., additional, Lion, J., additional, Litnovsky, A., additional, Liu, S., additional, Lobsien, J., additional, Loizu, J., additional, Lore, J., additional, Lorenz, A., additional, Losada, U., additional, Louche, F., additional, Lunsford, R., additional, Lutsenko, V., additional, Machielsen, M., additional, Mackel, F., additional, Maisano-Brown, J., additional, Maj, O., additional, Makowski, D., additional, Manduchi, G., additional, Maragkoudakis, E., additional, Marchuk, O., additional, Marsen, S., additional, Martines, E., additional, Martinez-Fernandez, J., additional, Marushchenko, M., additional, Masuzaki, S., additional, Maurer, D., additional, Mayer, M., additional, McCarthy, K.J., additional, Mccormack, O., additional, McNeely, P., additional, Meister, H., additional, Mendelevitch, B., additional, Mendes, S., additional, Merlo, A., additional, Messian, A., additional, Mielczarek, A., additional, Mishchenko, O., additional, Missal, B., additional, Mitteau, R., additional, Moiseenko, V.E., additional, Mollen, A., additional, Moncada, V., additional, Mönnich, T., additional, Morisaki, T., additional, Moseev, D., additional, Motojima, G., additional, Mulas, S., additional, Mulsow, M., additional, Nagel, M., additional, Naujoks, D., additional, Naulin, V., additional, Neelis, T., additional, Neilson, H., additional, Neu, R., additional, Neubauer, O., additional, Neuner, U., additional, Nicolai, D., additional, Nielsen, S.K., additional, Niemann, H., additional, Nishiza, T., additional, Nishizawa, T., additional, Nührenberg, C., additional, Ochoukov, R., additional, Oelmann, J., additional, Offermanns, G., additional, Ogawa, K., additional, Okamura, S., additional, Ölmanns, J., additional, Ongena, J., additional, Oosterbeek, J., additional, Otte, M., additional, Pablant, N., additional, Panadero Alvarez, N., additional, Pandey, A., additional, Pasch, E., additional, Pavlichenko, R., additional, Pavone, A., additional, Pawelec, E., additional, Pechstein, G., additional, Pelka, G., additional, Perseo, V., additional, Peterson, B., additional, Pilopp, D., additional, Pingel, S., additional, Pisano, F., additional, Plöckl, B., additional, Plunk, G., additional, Pölöskei, P., additional, Pompe, B., additional, Popov, A., additional, Porkolab, M., additional, Proll, J., additional, Pueschel, M.J., additional, Puiatti, M.-E., additional, Puig Sitjes, A., additional, Purps, F., additional, Rahbarnia, K., additional, Rasiński, M., additional, Rasmussen, J., additional, Reiman, A., additional, Reimold, F., additional, Reisner, M., additional, Reiter, D., additional, Richou, M., additional, Riedl, R., additional, Riemann, J., additional, Riße, K., additional, Roberg-Clark, G., additional, Rohde, V., additional, Romazanov, J., additional, Rondeshagen, D., additional, Rong, P., additional, Rudischhauser, L., additional, Rummel, T., additional, Rummel, K., additional, Runov, A., additional, Rust, N., additional, Ryc, L., additional, Salembier, P., additional, Salewski, M., additional, Sanchez, E., additional, Satake, S., additional, Satheeswaran, G., additional, Schacht, J., additional, Scharff, E., additional, Schauer, F., additional, Schilling, J., additional, Schlisio, G., additional, Schmid, K., additional, Schmitt, J., additional, Schmitz, O., additional, Schneider, W., additional, Schneider, M., additional, Schneider, P., additional, Schrittwieser, R., additional, Schröder, T., additional, Schröder, M., additional, Schroeder, R., additional, Schweer, B., 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J., additional, Trier, E., additional, Trimino Mora, H., additional, Tsujimura, T., additional, Turkin, Y., additional, Tykhyi, A., additional, Unterberg, B., additional, van Eeten, P., additional, van Milligen, B.Ph., additional, van Schoor, M., additional, Vano, L., additional, Varoutis, S., additional, Vecsei, M., additional, Vela, L., additional, Velasco, J.L., additional, Vervier, M., additional, Vianello, N., additional, Viebke, H., additional, Vilbrandt, R., additional, Vogel, G., additional, Vogt, N., additional, Volkhausen, C., additional, von Stechow, A., additional, Wagner, F., additional, Wang, E., additional, Wang, H., additional, Warmer, F., additional, Wauters, T., additional, Wegener, L., additional, Wegner, T., additional, Weir, G., additional, Wenzel, U., additional, White, A., additional, Wilde, F., additional, Wilms, F., additional, Windisch, T., additional, Winkler, M., additional, Winter, A., additional, Winters, V., additional, Wolf, R., additional, Wright, A.M., additional, Wurden, G.A., additional, Xanthopoulos, P., additional, Xu, S., additional, Yamada, H., additional, Yamaguchi, H., additional, Yokoyama, M., additional, Yoshinuma, M., additional, Yu, Q., additional, Zamanov, M., additional, Zanini, M., additional, Zarnstorff, M., additional, Zhang, D., additional, Zhou, S., additional, Zhu, J., additional, Zhu, C., additional, Zilker, M., additional, Zocco, A., additional, Zohm, H., additional, Zoletnik, S., additional, and Zsuga, L., additional
Published: 2022
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29. Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

Author: Bucalossi, J., Achard, J., Agullo, O., Alarcon, T., Allegretti, L., Ancher, H., Antar, G., Antusch, S., Anzallo, V., Arnas, C., Arranger, D., Artaud, J. F., Aumeunier, M. H., Baek, S. G., Bai, X., Balbin, J., Balorin, C., Barbui, T., Barbuti, A., Barlerin, J., Basiuk, V., Batal, T., Baulaigue, O., Bec, A., Bécoulet, M., Benoit, E., Benard, E., Benard, J. M., Bertelli, N., Bertrand, E., Beyer, P., Bielecki, J., Bienvenu, P., Bisson, R., Bobkov, V., Bodner, G., Bottereau, C., Bouchand, C., Bouquey, F., Bourdelle, C., Bourg, J., Brezinsek, S., Brochard, F., Brun, C., Bruno, V., Bufferand, H., Bureau, A., Burles, S., Camenen, Y., Cantone, B., Caprin, E., Carpentier, S., Caulier, G., Chanet, N., Chellai, O., Chen, Y., Chernyshova, M., Chmielewski, P., Choe, W., Chomiczewska, A., Ciraolo, G., Clairet, F., Coenen, J., Colas, L., Colledani, G., Colnel, J., Coquillat, P., Corbel, E., Corre, Y., Costea, S., Courtois, X., Czarski, T., Daniel, R., Daumas, J., De Combarieu, M., Temmerman, G., De, De Vries, P., Dechelle, C., Deguara, F., Dejarnac, R., Delaplanche, J. M., Delgado-Aparicio, L. F., Delmas, E., Delpech, L., Desgranges, C., Devynck, P., Di Genova, S., Diab, R., Diallo, A., Diez, M., Dif-Pradalier, G., Dimitrova, M., Ding, B., Dittmar, T., Doceul, L., Domenes, M., Douai, D., Dougnac, H., Duan, X., Dubus, L., Dumas, N., Dumont, R., Durand, F., Durif, A., Durocher, A., Durodié, F., Ekedahl, A., Elbeze, D., Ertmer, S., Escarguel, A., Escourbiac, F., Ezato, K., Faisse, F., Faure, N., Fedorczak, N., Fejoz, P., Fenzi-Bonizec, C., Ferlay, F., Firdaouss, M., Fleury, L., Flouquet, D., Gallo, A., Gao, Y., Garbet, X., Garcia, J., Gardarein, J. L., Gargiulo, L., Garibaldi, P., Garitta, S., Gaspar, J., Gauthier, E., Gavila, P., Gazzotti, S., Gely, F., Geynet, M., Gharafi, S., Ghendrih, P., Giacalone, I., Gil, C., Ginoux, S., Girard, S., Giroux, E., Giruzzi, G., Goletto, C., Goniche, M., Gray, T., Grelier, E., Greuner, H., Grigore, E., Grisolia, C., Grosjean, A., Grosman, A., Guibert, D., Guilhem, D., Guillemaut, C., Guillermin, B., Guirlet, R., Gunn, J. P., Gunsu, Y., Gyergyek, T., Hakola, A., Harris, J., Hatchressian, J. C., Helou, W., Hennequin, P., Hernandez, C., Hill, K., Hillairet, J., Hirai, T., Hoang, G. T., Houry, M., Hutter, T., Imbeaux, F., Imbert, N., Ivanova-Stanik, I., Jalageas, R., Jardin, A., Jaubert, L., Jiolat, G., Jonas, A., Joubert, P., Kirschner, A., Klepper, C., Komm, M., Koubiti, M., Kovacic, J., Kozeiha, M., Krieger, K., Krol, K., Lacroix, B., Laguardia, L., Lamaison, V., Laqua, H., Lau, C., Lausenaz, Y., Lé, R., Le Bohec, M., Lefevre, N., Lemoine, N., Lerche, E., Lewerentz, M., Li, Y., Li, M., Liang, A., Linczuk, P., Linsmeier, C., Lipa, M., Litaudon, X., Liu, X., Llorens, J., Loarer, T., Loarte, A., Loewenhoff, T., Lombard, G., Lore, J., Lorenzetto, P., Lotte, P., Lozano, M., Lu, B., Lunsford, R., Luo, G., Magaud, P., Maget, P., Mahieu, J. F., Maini, P., Malard, P., Malinowski, K., Manas, P., Manenc, L., Marandet, Y., Marechal, J. L., Marek, S., Martin, C., Martin, E., Martinez, A., Martino, P., Mazon, D., Messina, P., Meunier, L., Midou, D., Mineo, Y., Missilian, M., Mitteau, R., Mitu, B., Mollard, P., Moncada, V., Mondiere, T., Morales, J., Moreau, M., Moreau, P., Moudden, Y., Moureau, G., Mouyon, D., Muraglia, M., Nagy, A., Nakano, T., Nardon, E., Neff, A., Nespoli, F., Nichols, J., Nicollet, S., Nouailletas, R., Ono, M., Ostuni, V., Parish, C., Park, H., Parrat, H., Pascal, J. Y., Pégourié, B., Pellissier, F. P., Peneliau, Y., Peret, M., Peysson, Y., Pignoly, E., Pintsuk, G., Pitts, R., Pocheau, C., Portafaix, C., Poulos, M., Prochet, P., Puig Sitjes, A., Rasinski, M., Raup, G., Regal-Mezin, X., Reux, C., Riccardi, B., Rice, J., Richou, M., Rigollet, F., Roche, H., Romazanov, J., Ruset, C., Sabot, R., Saille, A., Sakamoto, R., Salmon, T., Samaille, F., Santagiustina, A., Santraine, B., Sarazin, Y., Serre, E., Shin, H., Shiraiwai, S., Signoret, Ja., Signoret, Je., Simonin, A., Skalli Fettachi, O., Song, Y., Spring, A., Spuig, P., Sridhar, S., Stratton, B., Talatizi, C., Tamain, P., Tatali, R., Téna, M., Torre, A., Toulouse, L., Travère, J. M., Treutterer, W., Tsitrone, E., Unterberg, E., Urbanczyk, G., Van Eester, D., Van Rooij, G., Vartanian, S., Verger, J. M., Vermare, L., Vézinet, D., Vignal, N., Vincent, B., Vives, S., Volpe, D., Wallace, G., Wang, E., Wang, L., Wang, Yi., Wang, Yo., Wauters, T., Wirth, B., Wirtz, M., Wojenski, A., Wright, J., Xu, M., Yang, Q., Yang, H., Zago, B., Zagorski, Zhang, B., Zhang, X., Zou, X., Institut universitaire des systèmes thermiques industriels (IUSTI), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Nuclear and High Energy Physics, Tokamak, Materials science, WEST, Nuclear engineering, Phase (waves), chemistry.chemical_element, Tungsten, law.invention, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], law, ITER, divertor, DEMO, Engineering & allied operations, nuclear fusion, Superconductivity, [PHYS]Physics [physics], Divertor, RF power amplifier, magnetic confinement, Plasma, Condensed Matter Physics, chemistry, Heat flux, ddc:620, tokamak physics
Abstract: WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017–2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m−2 were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described.
Published: 2022
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30. Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Author: Thomas Sunn Pedersen, I. Abramovic, P. Agostinetti, M. Agredano Torres, S. Äkäslompolo, J. Alcuson Belloso, P. Aleynikov, K. Aleynikova, M. Alhashimi, A. Ali, N. Allen, A. Alonso, G. Anda, T. Andreeva, C. Angioni, A. Arkhipov, A. Arnold, W. Asad, E. Ascasibar, M.-H. Aumeunier, K. Avramidis, E. Aymerich, S.-G. Baek, J. Bähner, A. Baillod, M. Balden, J. Baldzuhn, S. Ballinger, M. Banduch, S. Bannmann, A. Banon Navarro, A. Bañón Navarro, T. Barbui, C. Beidler, C. Belafdil, A. Bencze, A. Benndorf, M. Beurskens, C. Biedermann, O. Biletskyi, B. Blackwell, M. Blatzheim, T. Bluhm, D. Böckenhoff, G. Bongiovi, M. Borchardt, D. Borodin, J. Boscary, H. Bosch, T. Bosmann, B. Böswirth, L. Böttger, A. Bottino, S. Bozhenkov, R. Brakel, C. Brandt, T. Bräuer, H. Braune, S. Brezinsek, K. Brunner, S. Buller, R. Burhenn, R. Bussiahn, B. Buttenschön, A. Buzás, V. Bykov, I. Calvo, K. Camacho Mata, I. Caminal, B. Cannas, A. Cappa, A. Carls, F. Carovani, M. Carr, D. Carralero, B. Carvalho, J. Casas, D. Castano-Bardawil, F. Castejon, N. Chaudhary, I. Chelis, A. Chomiczewska, J.W. Coenen, M. Cole, F. Cordella, Y. Corre, K. Crombe, G. Cseh, B. Csillag, H. Damm, C. Day, M. de Baar, E. De la Cal, S. Degenkolbe, A. Demby, S. Denk, C. Dhard, A. Di Siena, A. Dinklage, T. Dittmar, M. Dreval, M. Drevlak, P. Drewelow, P. Drews, D. Dunai, E. Edlund, F. Effenberg, G. Ehrke, M. Endler, D.A. Ennis, F.J. Escoto, T. Estrada, E. Fable, N. Fahrenkamp, A. Fanni, J. Faustin, J. Fellinger, Y. Feng, W. Figacz, E. Flom, O. Ford, T. Fornal, H. Frerichs, S. Freundt, G. Fuchert, M. Fukuyama, F. Füllenbach, G. Gantenbein, Y. Gao, K. Garcia, J.M. García Regaña, I. García-Cortés, J. Gaspar, D.A. Gates, J. Geiger, B. Geiger, L. Giudicotti, A. González, A. Goriaev, D. Gradic, M. Grahl, J.P. Graves, J. Green, E. Grelier, H. Greuner, S. Groß, H. Grote, M. Groth, M. Gruca, O. Grulke, M. Grün, J. Guerrero Arnaiz, S. Günter, V. Haak, M. Haas, P. Hacker, A. Hakola, A. Hallenbert, K. Hammond, X. Han, S.K. 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Kuczynski, G. Kühner, A. Kumar, T. Kurki-Suonio, S. Kwak, M. Landreman, P.T. Lang, A. Langenberg, H.P. Laqua, H. Laqua, R. Laube, S. Lazerson, M. Lewerentz, C. Li, Y. Liang, Ch. Linsmeier, J. Lion, A. Litnovsky, S. Liu, J. Lobsien, J. Loizu, J. Lore, A. Lorenz, U. Losada, F. Louche, R. Lunsford, V. Lutsenko, M. Machielsen, F. Mackel, J. Maisano-Brown, O. Maj, D. Makowski, G. Manduchi, E. Maragkoudakis, O. Marchuk, S. Marsen, E. Martines, J. Martinez-Fernandez, M. Marushchenko, S. Masuzaki, D. Maurer, M. Mayer, K.J. McCarthy, O. Mccormack, P. McNeely, H. Meister, B. Mendelevitch, S. Mendes, A. Merlo, A. Messian, A. Mielczarek, O. Mishchenko, B. Missal, R. Mitteau, V.E. Moiseenko, A. Mollen, V. Moncada, T. Mönnich, T. Morisaki, D. Moseev, G. Motojima, S. Mulas, M. Mulsow, M. Nagel, D. Naujoks, V. Naulin, T. Neelis, H. Neilson, R. Neu, O. Neubauer, U. Neuner, D. Nicolai, S.K. Nielsen, H. Niemann, T. Nishiza, T. Nishizawa, C. Nührenberg, R. Ochoukov, J. Oelmann, G. Offermanns, K. 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Zanini, M. Zarnstorff, D. Zhang, S. Zhou, J. Zhu, C. Zhu, M. Zilker, A. Zocco, H. Zohm, S. Zoletnik, L. Zsuga, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya. GPI - Grup de Processament d'Imatge i Vídeo, Universitat Politècnica de Catalunya. GREO - Grup de Recerca en Enginyeria Òptica, Pedersen, T, Abramovic, I, Agostinetti, P, Torres, M, Akaslompolo, S, Belloso, J, Aleynikov, P, Aleynikova, K, Alhashimi, M, Ali, A, Allen, N, Alonso, A, Anda, G, Andreeva, T, Angioni, C, Arkhipov, A, Arnold, A, Asad, W, Ascasibar, E, Aumeunier, M, Avramidis, K, Aymerich, E, Baek, S, Bahner, J, Baillod, A, Balden, M, Baldzuhn, J, Ballinger, S, Banduch, M, Bannmann, S, Navarro, A, Barbui, T, Beidler, C, Belafdil, C, Bencze, A, Benndorf, A, Beurskens, M, Biedermann, C, Biletskyi, O, Blackwell, B, Blatzheim, M, Bluhm, T, Bockenhoff, D, Bongiovi, G, Borchardt, M, Borodin, D, Boscary, J, Bosch, H, Bosmann, T, Boswirth, B, Bottger, L, Bottino, A, Bozhenkov, S, Brakel, R, Brandt, C, Brauer, T, Braune, H, Brezinsek, S, Brunner, K, Buller, S, Burhenn, R, Bussiahn, R, Buttenschon, B, Buzas, A, Bykov, V, Calvo, I, Mata, K, Caminal, I, Cannas, B, Cappa, A, Carls, A, Carovani, F, Carr, M, Carralero, D, Carvalho, B, Casas, J, Castano-Bardawil, D, Castejon, F, Chaudhary, N, Chelis, I, Chomiczewska, A, Coenen, J, Cole, M, Cordella, F, Corre, Y, Crombe, K, Cseh, G, Csillag, B, Damm, H, Day, C, de Baar, M, De la Cal, E, Degenkolbe, S, Demby, A, Denk, S, Dhard, C, Di Siena, A, Dinklage, A, Dittmar, T, Dreval, M, Drevlak, M, Drewelow, P, Drews, P, Dunai, D, Edlund, E, Effenberg, F, Ehrke, G, Endler, M, Ennis, D, Escoto, F, Estrada, T, Fable, E, Fahrenkamp, N, Fanni, A, Faustin, J, Fellinger, J, Feng, Y, Figacz, W, Flom, E, Ford, O, Fornal, T, Frerichs, H, Freundt, S, Fuchert, G, Fukuyama, M, Fullenbach, F, Gantenbein, G, Gao, Y, Garcia, K, Regana, J, Garcia-Cortes, I, Gaspar, J, Gates, D, Geiger, J, Geiger, B, Giudicotti, L, Gonzalez, A, Goriaev, A, Gradic, D, Grahl, M, Graves, J, Green, J, Grelier, E, Greuner, H, Gross, S, Grote, H, Groth, M, Gruca, M, Grulke, O, Grun, M, Arnaiz, J, Gunter, S, Haak, V, Haas, M, Hacker, P, Hakola, A, Hallenbert, A, Hammond, K, Han, X, Hansen, S, Harris, J, Hartfuss, H, Hartmann, D, Hathiramani, D, Hatzky, R, Hawke, J, Hegedus, S, Hein, B, Heinemann, B, Helander, P, Henneberg, S, Hergenhahn, U, Hidalgo, C, Hindenlang, F, Hirsch, M, Hofel, U, Hollfeld, K, Holtz, A, Hopf, D, Hoschen, D, Houry, M, Howard, J, Huang, X, Hubeny, M, Hudson, S, Ida, K, Igitkhanov, Y, Igochine, V, Illy, S, Ionita-Schrittwieser, C, Isobe, M, Jablczynska, M, Jablonski, S, Jagielski, B, Jakubowski, M, van Vuuren, A, Jelonnek, J, Jenko, F, Jensen, T, Jenzsch, H, Junghanns, P, Kaczmarczyk, J, Kallmeyer, J, Kamionka, U, Kandler, M, Kasilov, S, Kazakov, Y, Kennedy, D, Kharwandikar, A, Khokhlov, M, Kiefer, C, Killer, C, Kirschner, A, Kleiber, R, Klinger, T, Klose, S, Knauer, J, Knieps, A, Kochl, F, Kocsis, G, Kolesnichenko, Y, Konies, A, Konig, R, Kontula, J, Kornejew, P, Koschinsky, J, Kozulia, M, Kramer-Flecken, A, Krampitz, R, Krause, M, Krawczyk, N, Kremeyer, T, Krier, L, Kriete, D, Krychowiak, M, Ksiazek, I, Kubkowska, M, Kuczynski, M, Kuhner, G, Kumar, A, Kurki-Suonio, T, Kwak, S, Landreman, M, Lang, P, Langenberg, A, Laqua, H, Laube, R, Lazerson, S, Lewerentz, M, Li, C, Liang, Y, Linsmeier, C, Lion, J, Litnovsky, A, Liu, S, Lobsien, J, Loizu, J, Lore, J, Lorenz, A, Losada, U, Louche, F, Lunsford, R, Lutsenko, V, Machielsen, M, Mackel, F, Maisano-Brown, J, Maj, O, Makowski, D, Manduchi, G, Maragkoudakis, E, Marchuk, O, Marsen, S, Martines, E, Martinez-Fernandez, J, Marushchenko, M, Masuzaki, S, Maurer, D, Mayer, M, Mccarthy, K, Mccormack, O, Mcneely, P, Meister, H, Mendelevitch, B, Mendes, S, Merlo, A, Messian, A, Mielczarek, A, Mishchenko, O, Missal, B, Mitteau, R, Moiseenko, V, Mollen, A, Moncada, V, Monnich, T, Morisaki, T, Moseev, D, Motojima, G, Mulas, S, Mulsow, M, Nagel, M, Naujoks, D, Naulin, V, Neelis, T, Neilson, H, Neu, R, Neubauer, O, Neuner, U, Nicolai, D, Nielsen, S, Niemann, H, Nishiza, T, Nishizawa, T, Nuhrenberg, C, Ochoukov, R, Oelmann, J, Offermanns, G, Ogawa, K, Okamura, S, Olmanns, J, Ongena, J, Oosterbeek, J, Otte, M, Pablant, N, Alvarez, N, Pandey, A, Pasch, E, Pavlichenko, R, Pavone, A, Pawelec, E, Pechstein, G, Pelka, G, Perseo, V, Peterson, B, Pilopp, D, Pingel, S, Pisano, F, Plockl, B, Plunk, G, Poloskei, P, Pompe, B, Popov, A, Porkolab, M, Proll, J, Pueschel, M, Puiatti, M, Sitjes, A, Purps, F, Rahbarnia, K, Rasinski, M, Rasmussen, J, Reiman, A, Reimold, F, Reisner, M, Reiter, D, Richou, M, Riedl, R, Riemann, J, Risse, K, Roberg-Clark, G, Rohde, V, Romazanov, J, Rondeshagen, D, Rong, P, Rudischhauser, L, Rummel, T, Rummel, K, Runov, A, Rust, N, Ryc, L, Salembier, P, Salewski, M, Sanchez, E, Satake, S, Satheeswaran, G, Schacht, J, Scharff, E, Schauer, F, Schilling, J, Schlisio, G, Schmid, K, Schmitt, J, Schmitz, O, Schneider, W, Schneider, M, Schneider, P, Schrittwieser, R, Schroder, T, Schroder, M, Schroeder, R, Schweer, B, Schworer, D, Scott, E, Shanahan, B, Sias, G, Sichta, P, Singer, M, Sinha, P, Siplia, S, Slaby, C, Sleczka, M, Smith, H, Smoniewski, J, Sonnendrucker, E, Spolaore, M, Spring, A, Stadler, R, Stanczak, D, Stange, T, Stepanov, I, Stephey, L, Stober, J, Stroth, U, Strumberger, E, Suzuki, C, Suzuki, Y, Svensson, J, Szabolics, T, Szepesi, T, Szucs, M, Tabares, F, Tamura, N, Tancetti, A, Tantos, C, Terry, J, Thienpondt, H, Thomsen, H, Thumm, M, Travere, J, Traverso, P, Tretter, J, Trier, E, Mora, H, Tsujimura, T, Turkin, Y, Tykhyi, A, Unterberg, B, van Eeten, P, van Milligen, B, van Schoor, M, Vano, L, Varoutis, S, Vecsei, M, Vela, L, Velasco, J, Vervier, M, Vianello, N, Viebke, H, Vilbrandt, R, Vogel, G, Vogt, N, Volkhausen, C, von Stechow, A, Wagner, F, Wang, E, Wang, H, Warmer, F, Wauters, T, Wegener, L, Wegner, T, Weir, G, Wenzel, U, White, A, Wilde, F, Wilms, F, Windisch, T, Winkler, M, Winter, A, Winters, V, Wolf, R, Wright, A, Wurden, G, Xanthopoulos, P, Xu, S, Yamada, H, Yamaguchi, H, Yokoyama, M, Yoshinuma, M, Yu, Q, Zamanov, M, Zanini, M, Zarnstorff, M, Zhang, D, Zhou, S, Zhu, J, Zhu, C, Zilker, M, Zocco, A, Zohm, H, Zoletnik, S, Zsuga, L, Fusion and Plasma Physics, Department of Applied Physics, National Institute for Fusion Science, Aalto-yliopisto, Aalto University, Science and Technology of Nuclear Fusion, Group Heemels, Control Systems Technology, and Turbulence in Fusion Plasmas
Subjects: Magnetic confinement, Nuclear and High Energy Physics, Technology, Materials science, Detachment, Nuclear engineering, Física::Física de partícules [Àrees temàtiques de la UPC], Imatges -- Processament, stellarator, Divertor, Image processing, Physics::Plasma Physics, divertor, Wendelstein 7-X, ddc:530, FIS/03 - FISICA DELLA MATERIA, Neoclassical optimization, Stellarators, Reactors de fusió, magnetic confinement, Enginyeria de la telecomunicació::Processament del senyal::Processament de la imatge i del senyal vídeo [Àrees temàtiques de la UPC], Condensed Matter Physics, ddc, Fusion reactors, Physics and Astronomy, detachment, neoclassical optimization, ddc:620, ddc:600, Paper, FEC 2020 Summaries and Overviews
Abstract: We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under Grant Agreement No. 633053. Peer Reviewed Article signat per 497 autors/es: Thomas Sunn Pedersen1,2,∗ , I. Abramovic3, P. Agostinetti4, M. Agredano Torres1, S. Äkäslompolo1, J. Alcuson Belloso1, P. Aleynikov1, K. Aleynikova1, M. Alhashimi1, A. Ali1, N. Allen5, A. Alonso6, G. Anda7, T. Andreeva1, C. Angioni8, A. Arkhipov8, A. Arnold1, W. Asad8, E. Ascasibar6, M.-H. Aumeunier9, K. Avramidis10, E. Aymerich11, S.-G. Baek3, J. Bähner1, A. Baillod12, M. Balden1, M. Balden8, J. Baldzuhn1, S. Ballinger3, M. Banduch1, S. Bannmann1, A. Banon Navarro8, A. Bañon Navarro ´ 1, T. Barbui13, C. Beidler1, C. Belafdil9, A. Bencze7, A. Benndorf1, M. Beurskens1, C. Biedermann1, O. Biletskyi14, B. Blackwell15, M. Blatzheim1, T. Bluhm1, D. Böckenhoff1, G. Bongiovi16, M. Borchardt1, D. Borodin17, J. Boscary8, H. Bosch1,18, T. Bosmann19, B. Böswirth8, L. Böttger1, A. Bottino8, S. Bozhenkov1, R. Brakel1, C. Brandt1, T. Bräuer1, H. Braune1, S. Brezinsek17, K. Brunner1, S. Buller1, R. Burhenn1, R. Bussiahn1, B. Buttenschön1, A. Buzás7, V. Bykov1, I. Calvo6, K. Camacho Mata1, I. Caminal20, B. Cannas11, A. Cappa6, A. Carls1, F. Carovani1, M. Carr21, D. Carralero6, B. Carvalho22, J. Casas20, D. Castano-Bardawil17, F. Castejon6, N. Chaudhary1, I. Chelis23, A. Chomiczewska24, J.W. Coenen13,17, M. Cole1, F. Cordella25, Y. Corre9, K. Crombe26, G. Cseh7, B. Csillag7, H. Damm1, C. Day10, M. de Baar27, E. De la Cal6, S. Degenkolbe1, A. Demby13, S. Denk3, C. Dhard1, A. Di Siena8,28, A. Dinklage12, T. Dittmar17, M. Dreval14, M. Drevlak1, P. Drewelow1, P. Drews17, D. Dunai7, E. Edlund3, F. Effenberg29, G. Ehrke1, M. Endler1, D.A. Ennis5, F.J. Escoto6, T. Estrada6, E. Fable8, N. Fahrenkamp1, A. Fanni11, J. Faustin1, J. Fellinger1, Y. Feng1, W. Figacz4, E. Flom13, O. Ford1, T. Fornal24, H. Frerichs13, S. Freundt1, G. Fuchert1, M. Fukuyama30, F. Füllenbach1, G. Gantenbein10, Y. Gao1, K. Garcia13, J.M. García Regaña6, I. García-Cortés6, J. Gaspar31, D.A. Gates29, J. Geiger1, B. Geiger13, L. Giudicotti32, A. González6, A. Goriaev26,33, D. Gradic1, M. Grahl1, J.P. Graves12, J. Green13, E. Grelier9, H. Greuner8, S. Groß1, H. Grote1, M. Groth34, M. Gruca24, O. Grulke1,35, M. Grün1, J. Guerrero Arnaiz1, S. Günter8, V. Haak1, M. Haas1, P. Hacker1, A. Hakola36, A. Hallenbert1, K. Hammond29, X. Han17,37, S.K. Hansen3, J.H. Harris38, H. Hartfuß1, D. Hartmann1, D. Hathiramani1, R. Hatzky8, J. Hawke39, S. Hegedus7, B. Hein8, B. Heinemann8, P. Helander12, S. Henneberg1, U. Hergenhahn8,40, C. Hidalgo6, F. Hindenlang8, M. Hirsch1, U. Höfel1, K.P. Hollfeld17, A. Holtz1, D. Hopf8, D. Höschen17, M. Houry9, J. Howard19, X. Huang41, M. Hubeny17, S. Hudson29, K. Ida9, Y. Igitkhanov10, V. Igochine8, S. Illy10, C. Ionita-Schrittwieser42, M. Isobe39, M. Jabłczynska ´ 24, S. Jablonski24, B. Jagielski1, M. Jakubowski1, A. Jansen van Vuuren1, J. Jelonnek10, F. Jenko8, F. Jenko8, T. Jensen35, H. Jenzsch1, P. Junghanns8, J. Kaczmarczyk24, J. Kallmeyer1, U. Kamionka1, M. Kandler8, S. Kasilov43, Y. Kazakov26, D. Kennedy1, A. Kharwandikar1, M. Khokhlov1, C. Kiefer8, C. Killer1, A. Kirschner17, R. Kleiber1, T. Klinger12, S. Klose1, J. Knauer1, A. Knieps17, F. Köchl44, G. Kocsis7, Ya.I. Kolesnichenko45, A. Könies1, R. König1, J. Kontula34, P. Kornejew1, J. Koschinsky, M.M. Kozulia14, A. Krämer-Flecken17, R. Krampitz1, M. Krause1, N. Krawczyk24, T. Kremeyer1, L. Krier10, D.M. Kriete5, M. Krychowiak1, I. Ksiazek46, M. Kubkowska24, M. Kuczynski1, G. Kühner1, A. Kumar15, T. Kurki-Suonio34, S. Kwak1, M. Landreman47, P.T. Lang8, A. Langenberg1, H.P. Laqua12, H. Laqua1, R. Laube1, S. Lazerson1, M. Lewerentz1, C. Li17, Y. Liang17, Ch. Linsmeier17, J. Lion1, A. Litnovsky17,48, S. Liu37, J. Lobsien1, J. Loizu12, J. Lore38, A. Lorenz1, U. Losada6, F. Louche26, R. Lunsford29, V. Lutsenko45, M. Machielsen12, F. Mackel8, J. 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Zsuga7 // 1 Max Planck Institute for Plasma Physics, Garching and Greifswald, Germany: 2 University of Greifswald, Greifswald, Germany; 3 Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States of America; 4 Consorzio RFX, Corso Stati Uniti, 4-35127 Padova, Italy; 5 Auburn University, Auburn, AL 36849, United States of America; 6 CIEMAT, Avenida Complutense, 40, 28040 Madrid, Spain; 7 Center for Energy Research, Konkoly-Thegeut 29-33, 1121 Budapest, Hungary; 8 Max-Planck-Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching bei München, Germany; 9 CEA Cadarache, 13115 Saint-Paul-lez-Durance, France; 10 Karlsruhe Institute of Technology, Kaiserstr. 12, 76131 Karlsruhe, Germany; 11 University of Cagliari, Via Universita, 40, 09124 Cagliari, Italy; 12 École Polytechnique Fédérale de Lausanne, Swiss Plasma Center, CH-1015 Lausanne, Switzerland; 13 University of Wisconsin–Madison, Engineering Drive, Madison, WI 53706, United States of America; 14 Institute of Plasma Physics, National Science Center ‘Kharkiv Institute of Physics and Technology’, Kharkiv, Ukraine; 15 The Australian National University, Acton ACT 2601, Canberra, Australia; 16 Department of Engineering, University of Palermo, Viale delle Scienze, Edificio 6, Palermo, 90128, Italy; 17 Forschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung—Plasmaphysik, 52425 Jülich, Germany; 18 Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany; 19 Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands; 20 Universitat Politècnica de Catalunya. BarcelonaTech, C. Jordi Girona, 31, 08034 Barcelona, Spain; 21 Culham Center for Fusion Energy, Abingdon OX14 3EB, United Kingdom; 22 Instituto de Plasmas e Fusao Nuclear, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; 23 Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece; 24 Institute of Plasma Physics and Laser Microfusion, 23 Hery Str., 01-497 Warsaw, Poland; 25 ENEA—Centro Ricerche Frascati, Via Enrico Fermi, 45, 00044 Frascati RM, Italy; 26 Laboratory for Plasma Physics, LPP-ERM/KMS, TEC Partner, B-1000 Brussels, Belgium; 27 Dutch Institute for Fundamental Energy Research, PO Box 6336, 5600 HH Eindhoven, Netherlands; 28 University of Texas, Austin, TX, United States of America; 29 Princeton Plasma Physics Laboratory, Princeton, NJ 08543, United States of America; 30 Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan; 31 Aix-Marseille University, Jardin du Pharo, 58 Boulevard Charles Livon, 13007, Marseille, France; 32 Department of Physics and Astronomy, Padova University, Via Marzolo 8, 35131 Padova, Italy; 33 Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent, Belgium; 34 Aalto University, 02150 Espoo, Finland; 35 Department of Physics, Technical University of Denmark, Anker Engelunds Vej, 2800 Kgs Lyngby, Denmark; 36 VTT Technical Research Center of Finland Ltd., PO Box 1000, FI-02044 VTT, Finland; 37 Institute of Plasma Physics, Chinese Academy of Sciences, 230031 Hefei, Anhui, China; 38 Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37830, United States of America; 39 Los Alamos National Laboratory, NM 87545, United States of America; 40 Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany; 41 National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki, Gifu Prefecture 509-5292, Japan; 42 Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria; 43 Graz University of Technology, Rechbauerstraße 12, 8010 GRAZ, Austria; 44 Austrian Academy of Science, Doktor-Ignaz-Seipel-Platz 2, 1010 Wien, Austria; 45 Institute for Nuclear Research, prospekt Nauky 47, Kyiv 03028, Ukraine; 46 University of Opole, plac Kopernika 11a, 45-001 Opole, Poland; 47 University of Maryland, Paint Branch Drive, College Park, MA 20742, United States of America; 48 National Research Nuclear University MEPhI, 115409 Moscow, Russian Federation; 49 Department of Microelectronics and Computer Science, Lodz University of Technology, Wolczanska 221/223, 90-924 Lodz, Poland; 50 Consiglio Nazionale delle Ricerche, Piazzale Aldo Moro, 7, 00185 Roma, Italy; 51 Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Politekhnicheskaya, St Petersburg 194021, Russian Federation; 52 Istituto di Fisica del Plasma Piero Caldirola, Via Roberto Cozzi, 53, 20125 Milano, Italy; 53 University of Szczecin, 70-453, aleja Papieza Jana Pawła II 22A, Szczecin, Poland; 54 Lawrence University, 711 E Boldt Way, Appleton, WI 54911, United States of America; 55 Physik-Department E28, Technische Universität München, 85747 Garching, Germany; 56 Universidad Carlos III de Madrid, Av. de la Universidad, 30 Madrid, Spain; 57 Yale University, New Haven, CT 06520, United States of America; 58 University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chhiab 277-0882, Japan Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.a - Per a 2030, augmentar la cooperació internacional per tal de facilitar l’accés a la investigació i a les tecnologies energètiques no contaminants, incloses les fonts d’energia renovables, l’eficiència energètica i les tecnologies de combustibles fòssils avançades i menys contaminants, i promoure la inversió en infraestructures energètiques i tecnologies d’energia no contaminant
Published: 2022
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31. Detecting Plasma Detachment in the Wendelstein 7-X Stellarator Using Machine Learning

Author: Sz��cs, M��t��, Szepesi, Tam��s, Biedermann, Christoph, Cseh, G��bor, Jakubowski, Marcin, Kocsis, G��bor, K��nig, Ralf, Krause, Marco, Perseo, Valeria, Puig Sitjes, Aleix, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfu��, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, J��rg
Published: 2022
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32. 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

33. Distributions of deposits and hydrogen on the upper and lower TDUs3 target elements of Wendelstein 7-X

Author: W7-X Team, Zhao, Mingzhong, Masuzaki, S., Motojima, G., Tokitani, M., Yajima, M., Gao, Y., Jakubowski, M., Puig Sitjes, A., Pisano, F., Dhard, C. P., Naujoks, D., Romazanov, J., Brezinsek, S., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and w7-x team
Subjects: Technology, Nuclear and High Energy Physics, distribution pattern of deposits, hydrogen retention, Wendelstein 7-X, ddc:620, Condensed Matter Physics, ddc:600, up-down asymmetry
Abstract: Distributions of deposits and hydrogen (H) on the graphite divertor target elements TM4h4 and TM3v5 in the test divertor units 3 (TDUs3) of Wendelstein 7-X (W7-X) are studied. The TM4h4 and TM3v5 are located at the magnetically symmetric positions in the upper and lower divertor. The microstructure of the deposition layer is characterized by a transmission electron microscope (TEM) combined with a focused ion beam (FIB). Metallic deposits such as iron (Fe), molybdenum (Mo), chromium (Cr) are detected in the deposition layer by energy-dispersive x-ray spectroscopy (EDS). The depth-resolved distribution patterns of boron (B) and metallic deposits on upper and lower horizontal (h) divertor target elements TDUs3-TM4h4 as well as upper and lower vertical (v) divertor target elements TDUs3-TM3v5 are clarified by glow discharge optical emission spectrometry (GDOES). Results for both TDUs3-TM4h4 and TDUs3-TM3v5 show that the B deposition regions exhibit higher H retention due to the co-deposition with deposits. On the other hand, up-down asymmetries in B deposition caused by particle drift exist on both TDUs3-TM4h4 and TDUs3-TM3v5. The B deposition amount on upper TDUs3-TM4h4 is 40% smaller than that on lower TDUs3-TM4h4. While for the vertical target elements, the B deposition amount on upper TDUs3-TM3v5 is 35% larger than that on lower TDUs3-TM3v5. Meanwhile, a shift of around 3 cm in B deposition peaks is observed on upper and lower TDUs3-TM4h4 and TDUs3-TM3v5. Results of numerical simulation of carbon deposition/erosion profiles on the target elements using ERO2.0 code and power flux measured by infrared cameras are shown and compared with the above mentioned B profiles.
Published: 2022
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34. Thermographic reconstruction of heat load on the first wall of Wendelstein 7-X due to ECRH shine-through power

Author: W7-X Team, Corre, Y., Gaspar, J., Marsen, S., Moseev, D., Stange, T., Boscary, J., Drewelow, P., Gao, Y., Jakubowski, M., Hillairet, J., Laqua, H. P., Lechte, C., Moncada, V., Niemann, H., Preynas, M., Puig Sitjes, A., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut universitaire des systèmes thermiques industriels (IUSTI), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Plasmaphysik [Garching] (IPP), University of Stuttgart, ITER organization (ITER), European Project: 633053,H2020,EURATOM-Adhoc-2014-20,EUROfusion(2014), and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Ir thermography, [PHYS]Physics [physics], Nuclear and High Energy Physics, Technology, Materials science, business.industry, heat flux calculation, Condensed Matter Physics, 01 natural sciences, Electron Cyclotron Resonance Heating, 010305 fluids & plasmas, Power (physics), Optics, 0103 physical sciences, infrared thermography, Wendelstein 7-X, Heat load, 010306 general physics, business, ddc:600
Abstract: Electron cyclotron resonance heating (ECRH) is a powerful and flexible plasma heating technique that serves as the main heater at Wendelstein 7-X (W7-X) and will be used at ITER for start-up, heating, current drive and mitigation of plasma instabilities. In the case of poor or degraded microwave absorption, which is expected in the O2-mode heating scenario, a significant part of the beam directly hits the wall, leading to local overheating and potential damage. The ECRH shine-through power is mostly reflected onto the targets; only a small fraction is really absorbed through ohmic losses (typically 3% for graphite at 140 GHz). The ohmic losses do not only depend on the material properties and the frequency, but also on the polarization of the wave and the angle of incidence. This paper presents a thermographic analysis of ECRH experiments at W7-X, including heat load and temperature simulations of the first wall that include ECRH shine through. Two O-mode ECRH experiments with both a high temperature rise of the first wall and different angles of beam incidence on the wall’s surface are depicted. One experiment has 775 kW of power modulation (5 Hz) with mixed polarization (45% O-mode, 55% X-mode) and an EC beam angle almost normal to the first wall. The second has 550 kW of steady EC power with O-mode polarization, a shallow beam angle and increased power absorption by the material. It is shown that infrared thermography is a useful tool for measuring shine-through power and protecting wall components.
Published: 2021
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35. The evolution of the bound particle reservoir in Wendelstein 7-X and its influence on plasma control

Author: G. Schlisio, U. Wenzel, D. Naujoks, T.S. Pedersen, H. Grote, V.R. Winters, H. Niemann, M. Mulsow, M. Krychowiak, P. Drewelow, Y. Gao, M. Jakubowski, A. Puig Sitjes, H. Laqua, J. Knauer, K.J. Brunner, null the W7-X team, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: 010302 applied physics, Physics, Nuclear and High Energy Physics, Magnetic confinement fusion, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, Particle, Atomic physics, Wendelstein 7-X, Stellarator, Plasma control
Abstract: The investigation of fuel retention in fusion experiments is important in view of plasma density control as well as tritium inventory for future fusion reactors. We present a first gas balance of the stellarator Wendelstein 7-X with its inertially cooled graphite divertor. The gas balance is used to estimate the wall inventory and it is found that the wall plays an important and dynamic role, absorbing or releasing particles depending on the plasma conditions. Several different scenarios are presented and the effect of fueling and heating on the wall inventory is assessed. We find that the record duration plasma experiment of 100 s required previous shorter plasmas to be successfully conducted.
Published: 2021
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36. Learning control coil currents from heat-flux images using convolutional neural networks at Wendelstein 7-X

Author: Yu Gao, Fabio Pisano, Aleix Puig Sitjes, Wendelstein X Team, Barbara Cannas, Holger Niemann, Giuliana Sias, M. W. Jakubowski, Alessandra Fanni, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear Energy and Engineering, Heat flux, Electromagnetic coil, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, Condensed Matter Physics, Topology, 01 natural sciences, Convolutional neural network, 010305 fluids & plasmas
Abstract: An important goal of Wendelstein 7-X, the most advanced operating fusion experiment of the stellarator line, is to demonstrate the ability of stellarators to perform steady-state discharges. In this respect, the monitoring and control of the heat loads on the plasma facing components, especially of the strike-lines in the ten island divertors, will be critical during next operation phase OP2. In this paper, it is shown that deep convolutional neural networks are able to learn the relationship between the heat-flux images, obtained by the analysis of thermographic data, and the applied control coil currents in standard magnetic configuration experiments. This study is carried out in view of understanding and modeling the relationship between the heat-flux distribution in the divertor strike-lines and the actuators influencing them.
Published: 2021

37. Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarato

Author: W7-X Team, Lunsford, R., Killer, C., Nagy, A., Gates, D. A., Klinger, T., Dinklage, A., Satheeswaran, G., Kocsis, G., Lazerson, S. A., Nespoli, F., Pablant, N. A., Stechow, A. von, Alonso, A., Andreeva, T., Beurskens, M., Biedermann, C., Brezinsek, S., Brunner, K. J., Buttenschön, B., Carralero, D., Cseh, G., Drewelow, P., Effenberg, F., Estrada, T., Ford, O. P., Grulke, O., Hergenhahn, U., Höefel, U., Knauer, J., Krause, M., Krychowiak, M., Kwak, S., Langenberg, A., Neuner, U., Nicolai, D., Pavone, A., Puig Sitjes, A., Rahbarnia, K., Schilling, J., Svensson, J., Szepesi, T., Thomsen, H., Wauters, T., Windisch, T., Winters, V., Zhang, D., Zsuga, L., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Technology, Electron density, Plasma, Boron carbide, Condensed Matter Physics, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, Ion, chemistry.chemical_compound, chemistry, law, Electric field, 0103 physical sciences, ddc:530, Wendelstein 7-X, Atomic physics, 010306 general physics, ddc:600, Stellarator
Abstract: Pulsed injections of boron carbide granules into Wendelstein 7-X stellarator (W7-X) plasmas transiently increase the plasma stored energy and core ion temperatures above the reference W7-X experimental programs by up to 30%. In a series of 4 MW electron cyclotron resonance heating experiments, the PPPL Probe Mounted Powder Injector provided 50 ms bursts of 100 μm granules every 350 ms at estimated quantities ranging from approximately 1 mg/pulse to over 30 mg/pulse. For each injection, the stored energy was observed to initially drop and the radiated power transiently increased, while the radial electron density profile rose at the edge as material was assimilated. Once the injected boron carbide was fully absorbed, the density rise transitioned to the core while the stored energy increased above the previous baseline level by an amount linearly correlated with the injection quantity. During the injection, the ion temperature gradient steepened with peak core ion temperatures observed to increase from a nominal 1.7 keV to over 2.6 keV for the largest injection amounts. Enhanced performance is accompanied by a reversal of the radial electric field at ρ < 0.3, indicating that the core transport has switched to the ion root. These observations are suggestive of a change in transport and provide further evidence that externally induced profile modifications provide a possible path to enhanced W7-X performance metrics.I. INTRODUCTIO
Published: 2021
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38. 2D measurements of parallel counter-streaming flows in the W7-X scrape-off layer for attached and detached plasmas

Author: W7-X Team, Perseo, V., Winters, V., Feng, Y., Reimold, F., Ford, O. P., König, R., Bozhenkov, S. A., Brunner, K. J., Burhenn, R., Drewelow, P., Ennis, D. A., Gao, Y., Gradic, D., Hacker, P., Hergenhahn, U., Jakubowski, M. W., Knauer, J., Kremeyer, T., Kriete, D. M., Krychowiak, M., Kwak, S., Niemann, H., Pavone, A., Pisano, F., Puig Sitjes, A., Schlisio, G., Svensson, J., Zhang, D., Sunn Pedersen, T., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Technology, Nuclear and High Energy Physics, 0103 physical sciences, Plasma, 010306 general physics, Condensed Matter Physics, ddc:600, 01 natural sciences, Layer (electronics), 010305 fluids & plasmas, Computational physics
Abstract: Investigations of particle parallel flow velocities have been carried out for the scrape-off layer (SOL) of the Wendelstein 7-X (W7-X) stellarator, in order to gain insights on the SOL transport properties during attached and detached plasma scenarios. The experimental evidence is based on the coherence imaging spectroscopy (CIS) diagnostic, able to measure 2D impurity emission intensity and flow velocity. The impurity monitored by CIS is C2+, characterized by a line-emission intensity observed to be linearly proportional to the total plasma radiated power in both attached and detached plasmas. The related C2+ velocity shows a strong dependence on the line-averaged electron density while remaining insensitive to the input power. During attached plasmas, the velocity increases with increasing line-averaged density. The tendency reverses in the transition to and during detachment, in which the velocity decreases by at least a factor of 2. The sharp drop in velocity, together with a rise in line-emission intensity, is reliably correlated to the detachment transition and can therefore be used as one of its signatures. The impurity flow velocity appears to be well coupled with the main ions’ one, thus implying the dominant role of impurity-main ion friction in the parallelimpurity transport dynamics. In view of this SOL impurity transport regime, the CIS measurement results are here interpreted with the help of EMC3-Eirene simulations, and their major trends are already explainable with a simple 1D fluid model.
Published: 2021

39. Overview of the results from divertor experiments with attached and detached plasmas at Wendelstein 7-X and their implications for steady-state operation

Author: M. Jakubowski, M. Endler, Y. Feng, Y. Gao, C. Killer, R. König, M. Krychowiak, V. Perseo, F. Reimold, O. Schmitz, T.S. Pedersen, S. Brezinsek, A. Dinklage, P. Drewelow, H. Niemann, M. Otte, M. Gruca, K. Hammond, T. Kremeyer, M. Kubkowska, S. Jabłoński, A. Pandey, G. Wurden, D. Zhang, S. Bozhenkov, D. Böckenhoff, C.P. Dhard, J. Baldzuhn, D. Gradic, F. Effenberg, P. Kornejew, S. Lazerson, J. Lore, D. Naujoks, A Puig Sitjes, G. Schlisio, M. Ślęczka, U. Wenzel, V. Winters, null the W7-X Team, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Nuclear and High Energy Physics, Steady state (electronics), Nuclear engineering, Divertor, Plasma, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, ddc:620, Wendelstein 7-X, 010306 general physics, Stellarator
Abstract: Wendelstein 7-X (W7-X), the largest advanced stellarator, is built to demonstrate high power, high performance quasi-continuous operation. Therefore, in the recent campaign, experiments were performed to prepare for long pulse operation, addressing three critical issues: the development of stable detachment, control of the heat and particle exhaust, and the impact of leading edges on plasma performance. The heat and particle exhaust in W7-X is realized with the help of an island divertor, which utilizes large magnetic islands at the plasma boundary. This concept shows very efficient heat flux spreading and favourable scaling with input power. Experiments performed to overload leading edges showed that the island divertor yields good impurity screening. A highlight of the recent campaign was a robust detachment scenario, which allowed reducing power loads even by a factor of ten. At the same time, neutral pressures at the pumping gap entrance yielded the particle removal rate close to the values required for stable density control in steady-state operation.
Published: 2021
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40. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author: W7-X Team, Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S. A., Brunner, K. J., Damm, H., Drevlak, M., Ford, O. P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., Hirsch, M., Höfel, U., Kazakov, Ye. O., Kleiber, R., Krychowiak, M., Kwak, S., Langenberg, A., Laqua, H. P., Neuner, U., Pablant, N. A., Pasch, E., Pavone, A., Pedersen, T. S., Rahbarnia, K., Schilling, J., Scott, E. R., Stange, T., Svensson, J., Thomsen, H., Turkin, Y., Warmer, F., Wolf, R. C., Zhang, D., Abramovic, I., Äkäslompolo, S., Alcusón, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., Bähner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Böckenhoff, D., Böswirth, B., Böttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttenschön, B., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M., Cole, M. J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., Molin, A. da, Silva, A. da, Pena, A. de la, Degenkolbe, S., Dhard, C. P., Dibon, M., Dinklage, A., Dittmar, T., Drewelow, P., Drews, P., Durodie, F., Edlund, E., Effenberg, F., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Feng, Y., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., García Regaña, J., Gates, D., Geiger, B., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Grulke, O., Guerard, C., Hacker, P., Han, X., Harris, J. H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., Hölting, A., Höschen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ida, K., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J.-P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Killer, C., Kirschner, A., Klinger, T., Knauer, J., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., Köchl, F., Kolesnichenko, Y., Könies, A., König, R., Kornejew, P., Koschinsky, J.-P., Köster, F., Krämer, M., Krampitz, R., Krämer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., Kühner, G., Kurki-Suonio, T., Kurz, P. A., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lazerson, S., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J.-F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., Lücke, A., Lumsdaine, A., Lutsenko, V., Maaßberg, H., Marchuk, O., Matthew, J. H., Marsen, S., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., McCarthy, K., McNeely, P., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., Mönnich, T., Morisaki, T., Moseev, D., Murakami, S., Náfrádi, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., Nührenberg, C., Nührenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., Ölmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfuß, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., Pölöskei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., Récsei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., Röhlinger, H., Romé, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Rust, N., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., Sanchez, M., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schlüter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schröder, M., Schröder, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szabó, V., Szabolics, T., Szepesi, T., Szökefalvi-Nagy, Z., Tamura, N., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulipán, S., Unterberg, B., Vakulchyk, I., Valet, S., Vanó, L., Eeten, P. van, Milligen, B. van, Vuuren, A. J. van, Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Stechow, A. von, Vorköper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Wauters, T., Wegener, L., Weggen, J., Wegner, T., Wei, Y., Weir, G., Wendorf, J., Wenzel, U., Werner, A., White, A., Wiegel, B., Wilde, F., Windisch, T., Winkler, M., Winter, A., Winters, V., Wolf, S., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., Zuin, M., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, Applied Physics and Science Education, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and European Commission
Subjects: Magnetically Confined Plasmas, Tokamak, Design, Helias, Nuclear engineering, Magnetically confined plasmas, 01 natural sciences, 7. Clean energy, Article, Plasma physics, 010305 fluids & plasmas, law.invention, law, Physics::Plasma Physics, 0103 physical sciences, Nuclear fusion, 010306 general physics, Engineering & allied operations, Stellarator, Physics, Plasma fusion, Multidisciplinary, Toroid, biology, Plasma Physics, Física, Magnetic confinement fusion, Plasma, biology.organism_classification, Energía Nuclear, ddc:620, Wendelstein 7-X
Abstract: Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator’s non-turbulent ‘neoclassical’ energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization., Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device.
Published: 2021
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41. EMC3-EIRENE simulation of first wall recycling fluxes in W7-X with relation to H-alpha measurements

Author: W7-X Team, Winters, V. R., Reimold, F., König, R., Krychowiak, M., Romba, T., Biedermann, C., Bozhenkov, S., Drewelow, P., Endler, M., Feng, Y., Frerichs, H., Fuchert, G., Geiger, J., Gao, Y., Harris, J. H., Jakubowski, M., Kornejew, P., Kremeyer, T., Niemann, H., Pasch, E., Puig-Sitjes, A., Schlisio, G., Scott, E. R., Wurden, G. A., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Technology, Materials science, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Nuclear Energy and Engineering, law, 0103 physical sciences, H-alpha, Atomic physics, 010306 general physics, Spectroscopy, ddc:600, Stellarator
Abstract: In the Wendelstein 7-X stellarator, the main locations of particle sources are expected to be the carbon divertors, baffles and graphite heat shield first wall. In this paper, the heat shield is implemented in EMC3-EIRENE to understand the expected areas and magnitudes of the recycling flux to this component. It is found that in the simulation the heat shield is not a significant source of recycling neutrals. The areas of simulated recycling flux are shown to correlate well with footprints of plasma-wetting seen in post-experimental campaign in-vessel inspection photos. EMC3-EIRENE reconstruction of line-integrated H-alpha measurements at the heat shield indicate that the majority of emission does not come from local recycling neutrals. Rather, the H-alpha signals at the heat shield are dominated by ionization of neutrals which have leaked from the divertor/baffle region into the midplane. The magnitude of the H-alpha line emission from the synthetic reconstruction is consistent with the experiment, indicating that a large overestimation of heat shield recycling would occur if these measurements were assumed to be from local recycling sources. In the future, it may be possible to obtain some information of local recycling from the heat shield since it was found that the majority of the recycling flux occurs on two well-localized areas.
Published: 2021

42. Publisher Correction: Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author: Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S. A., Brunner, K. J., Damm, H., Drevlak, M., Ford, O. P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., Hirsch, M., H��fel, U., Kazakov, Ye. O., Kleiber, R., Krychowiak, M., Kwak, S., Langenberg, A., Laqua, H. P., Neuner, U., Pablant, N. A., Pasch, E., Pavone, A., Pedersen, T. S., Rahbarnia, K., Schilling, J., Scott, E. R., Stange, T., Svensson, J., Thomsen, H., Turkin, Y., Warmer, F., Wolf, R. C., Zhang, D., Abramovic, I., ��k��slompolo, S., Alcus��n, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., B��hner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., B��ckenhoff, D., B��swirth, B., B��ttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Br��uer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttensch��n, B., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M., Cole, M. J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., Da Molin, A., Da Silva, A., De La Pena, A., Degenkolbe, S., Dhard, C. P., Dibon, M., Dinklage, A., Dittmar, T., Drewelow, P., Drews, P., Durodie, F., Edlund, E., Effenberg, F., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Feng, Y., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., Garc��a Rega��a, J., Gates, D., Geiger, B., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Grulke, O., Guerard, C., Hacker, P., Han, X., Harris, J. H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., H��lting, A., H��schen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ida, K., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J.-P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Killer, C., Kirschner, A., Klinger, T., Knauer, J., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., K��chl, F., Kolesnichenko, Y., K��nies, A., K��nig, R., Kornejew, P., Koschinsky, J.-P., K��ster, F., Kr��mer, M., Krampitz, R., Kr��mer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., K��hner, G., Kurki-Suonio, T., Kurz, P. A., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lazerson, S., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J.-F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., L��cke, A., Lumsdaine, A., Lutsenko, V., Maa��berg, H., Marchuk, O., Matthew, J. H., Marsen, S., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., McCarthy, K., McNeely, P., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., M��nnich, T., Morisaki, T., Moseev, D., Murakami, S., N��fr��di, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., N��hrenberg, C., N��hrenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., ��lmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfu��, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., P��l��skei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., R��csei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., R��hlinger, H., Rom��, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Rust, N., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., S��nchez, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schl��ter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schr��der, M., Schr��der, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipli��, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szab��, V., Szabolics, T., Szepesi, T., Sz��kefalvi-Nagy, Z., Tamura, N., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulip��n, S., Unterberg, B., Vakulchyk, I., Valet, S., Van��, L., Van Eeten, P., Van Milligen, B., Van Vuuren, A. J., Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Von Stechow, A., Vork��per, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Wauters, T., Wegener, L., Weggen, J., Wegner, T., Wei, Y., Weir, G., Wendorf, J., Wenzel, U., Werner, A., White, A., Wiegel, B., Wilde, F., Windisch, T., Winkler, M., Winter, A., Winters, V., Wolf, S., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., and Zuin, M.
Subjects: Chemical engineering, ddc:660
Published: 2021

43. Real-Time Detection of Overloads on the Plasma-Facing Components of Wendelstein 7-X

Author: W7-X Team, Puig Sitjes, Aleix, Jakubowski, Marcin, Naujoks, Dirk, Gao, Yu, Drewelow, Peter, Niemann, Holger, Fellinger, Joris, Moncada, Victor, Pisano, Fabio, Belafdil, Chakib, Mitteau, Raphael, Aumeunier, Marie-Hélène, Cannas, Barbara, Casas, Josep Ramon, Salembier, Philippe, Clemente, Rocco, Fischer, Simon, Winter, Axel, Laqua, Heike, Bluhm, Torsten, Brandt, Karsten, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg
Subjects: Technology, ddc:600
Published: 2021
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44. First neutral beam experiments on Wendelstein 7-X

Author: Lazerson, Samuel A., primary, Ford, Oliver, additional, Äkaslompolö, Simppa, additional, Bozhenkov, Sergey, additional, Slaby, Christoph, additional, Vanó, Lilla, additional, Spanier, Annabelle, additional, McNeely, Paul, additional, Rust, Norbert, additional, Hartmann, Dirk, additional, Poloskei, Peter, additional, Buttenschoゆ, Birger, additional, Burhenn, Rainer, additional, Tamura, Naoki, additional, Bussiahn, Rene, additional, Wegner, Thomas, additional, Drevlak, Michael, additional, Turkin, Yuriy, additional, Ogawa, Kunihiro, additional, Knauer, Jens, additional, Brunner, Kai Jakob, additional, Pasch, Ekkehard, additional, Beurskens, Marc, additional, Damm, Hannes, additional, Fuchert, Golo, additional, Nelde, Philipp, additional, Scott, Evan, additional, Pablant, Novimir, additional, Langenberg, Andreas, additional, Traverso, Peter, additional, Valson, Pranay, additional, Hergenhahn, Uwe, additional, Pavone, Andrea, additional, Rahbarnia, Kian, additional, Andreeva, Tamara, additional, Schilling, Jonathan, additional, Brandt, Christian, additional, Neuner, Ulrich, additional, Thomsen, Henning, additional, Chaudhary, Neha, additional, Höefel, Udo, additional, Stange, Torsten, additional, Weir, Gavin, additional, Marushchenko, Nikolai, additional, Jakubowski, Marcin, additional, Ali, Adnan, additional, Gao, Yu, additional, Niemann, Holger, additional, Puig Sitjes, Aleix, additional, Koenig, Ralf, additional, Schroeder, Ralf, additional, den Harder, Niek, additional, Heinemann, Bernd, additional, Hopf, Christian, additional, Riedl, Rudolf, additional, Wolf, Robert C., additional, and W7-X Team, the, additional
Published: 2021
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45. 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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46. Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase

Author: Massachusetts Institute of Technology. Department of Physics, Wolf, R. C., Alonso, A., Äkäslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H.-S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K.-J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Höfel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., König, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., McNeely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, Miklos, Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., Zhang, D., Massachusetts Institute of Technology. Department of Physics, Wolf, R. C., Alonso, A., Äkäslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H.-S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K.-J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Höfel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., König, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., McNeely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, Miklos, Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., and Zhang, D.
Published: 2021

47. Validating the ASCOT modelling of NBI fast ions in Wendelstein 7-X stellarator

Author: Äkäslompolo, S., Drewelow, P., Gao, Y., Ali, A., Bellinger, J., Ford, O.P., Geiger, J., Hartmann, D.A., Hathiraman, D., ISOBE, Mitsutaka, JAKUBOWSKI, Marcin, Kazakov, Y., Killer, C., Lazerson, S., Mayer, M., McNeely, P., Naujoks, D., Neelis, T.W.C., Kontula, J., Kurki-Suonio, T., Niemann, H., OGAWA, Kunihoro, Pisano, F., Poloskei, P. Zs., Puig Sitjes, A., Rohbarnia, K., Rust, N., Schmitt, J.C., Sleczka, M., Vano, L., Vuurer, A. van, Wurden, G., Wolf, R.C., Äkäslompolo, S., Drewelow, P., Gao, Y., Ali, A., Bellinger, J., Ford, O.P., Geiger, J., Hartmann, D.A., Hathiraman, D., ISOBE, Mitsutaka, JAKUBOWSKI, Marcin, Kazakov, Y., Killer, C., Lazerson, S., Mayer, M., McNeely, P., Naujoks, D., Neelis, T.W.C., Kontula, J., Kurki-Suonio, T., Niemann, H., OGAWA, Kunihoro, Pisano, F., Poloskei, P. Zs., Puig Sitjes, A., Rohbarnia, K., Rust, N., Schmitt, J.C., Sleczka, M., Vano, L., Vuurer, A. van, Wurden, G., and Wolf, R.C.
Abstract: The first fast ion experiments in Wendelstein 7-X were performed in 2018. They are one of the first steps in demonstrating the optimised fast ion confinement of the stellarator. The fast ions were produced with a neutral beam injection (NBI) system and detected with infrared cameras (IR), a fast ion loss detector (FILD), fast ion charge exchange spectroscopy (FIDA), and post-mortem analysis of plasma facing components. The fast ion distribution function in the plasma and at the wall is being modelled with the ASCOT suite of codes. They calculate the ionisation of the injected neutrals and the consecutive slowing down process of the fast ions. The primary output of the code is the multidimensional fast ion distribution function within the plasma and the distribution of particle hit locations and velocities on the wall. Synthetic measurements based on ASCOT output are compared to experimental results to assess the validity of the modelling. This contribution presents an overview of the various fast ion measurements in 2018 and the current modelling status. The validation and data-analysis is on-going, but the wall load IR modelling already yield results that match with the experiments., source:Citation S. Äkäslompolo et al 2019 JINST 14 C10012, source:https://doi.org/10.1088/1748-0221/14/10/C10012
Published: 2021

48. Real-time detection of overloads on the plasma-facing components of Wendelstein 7-X

Author: Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya. GPI - Grup de Processament d'Imatge i Vídeo, Puig Sitjes, Aleix, Jakubowski, Marcin, Naujoks, Dirk, Gao, Yu, Drewelow, Peter, Niemann, Holger, Fellinger, Joris, Casas Pla, Josep Ramon, Salembier Clairon, Philippe Jean, Clemente Bonjour, Rocco, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya. GPI - Grup de Processament d'Imatge i Vídeo, Puig Sitjes, Aleix, Jakubowski, Marcin, Naujoks, Dirk, Gao, Yu, Drewelow, Peter, Niemann, Holger, Fellinger, Joris, Casas Pla, Josep Ramon, Salembier Clairon, Philippe Jean, and Clemente Bonjour, Rocco
Abstract: Wendelstein 7-X (W7-X) is the leading experiment on the path of demonstrating that stellarators are a feasible concept for a future power plant. One of its major goals is to prove quasi-steady-state operation in a reactor-relevant parameter regime. The surveillance and protection of the water-cooled plasma-facing components (PFCs) against overheating is fundamental to guarantee a safe steady-state high-heat-flux operation. The system has to detect thermal events in real-time and timely interrupt operation if it detects a critical event. The fast reaction times required to prevent damage to the device make it imperative to automate fully the image analysis algorithms. During the past operational phases, W7-X was equipped with inertially cooled test divertor units and the system still required manual supervision. With the experience gained, we have designed a new real-time PFC protection system based on image processing techniques. It uses a precise registration of the entire field of view against the CAD model to determine the temperature limits and thermal properties of the different PFCs. Instead of reacting when the temperature limits are breached in certain regions of interest, the system predicts when an overload will occur based on a heat flux estimation, triggering the interlock system in advance to compensate for the system delay. To conclude, we present our research roadmap towards a feedback control system of thermal loads to prevent unnecessary plasma interruptions in long high-performance plasmas., This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053., Peer Reviewed, Article signat per 22 autors/es: Aleix Puig Sitjes* 1, Marcin Jakubowski 1, Dirk Naujoks 1, Yu Gao 1, Peter Drewelow 1, Holger Niemann 1, Joris Fellinger 1, Victor Moncada 2, Fabio Pisano 3, Chakib Belafdil 2, Raphael Mitteau 2, Marie-Hélène Aumeunier 2, Barbara Cannas 3, Josep Ramon Casas 4, Philippe Salembier 4, Rocco Clemente 4, Simon Fischer 1, Axel Winter 1, Heike Laqua 1, Torsten Bluhm 1, Karsten Brandt 1, and The W7-X Team † 1. Max-Planck-Institut für Plasmaphysik, Wendelsteinstr. 1, 17491 Greifswald, Germany / 2. Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA), Institut de Recherche sur la Fusion par Confinement Magnétique (IRFM), F-13108 Saint Paul-lez-Durance, France / 3. Department of Electrical and Electronic Engineering, University of Cagliari (UniCa), Piazza d’Armi, 09126 Cagliari, Italy / 4. Department of Signal Theory and Communications, Universitat Politècnica de Catalunya (UPC), Jordi Girona 1-3, 08034 Barcelona, Spain / * Author to whom correspondence should be addressed. / † Membership of the Team Name is provided in Acknowledgments., Postprint (published version)
Published: 2021

49. Thermographic reconstruction of heat load on the first wall of Wendelstein 7-X due to ECRH shine-through power

Author: Corre, Y., primary, Gaspar, J., additional, Marsen, S., additional, Moseev, D., additional, Stange, T., additional, Boscary, J., additional, Drewelow, P., additional, Gao, Y., additional, Jakubowski, M., additional, Hillairet, J., additional, Laqua, H.P., additional, Lechte, C., additional, Moncada, V., additional, Niemann, H., additional, Preynas, M., additional, and Puig Sitjes, A., additional
Published: 2021
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50. EMC3-EIRENE simulation of first wall recycling fluxes in W7-X with relation to H-alpha measurements

Author: Winters, V R, primary, Reimold, F, additional, König, R, additional, Krychowiak, M, additional, Romba, T, additional, Biedermann, C, additional, Bozhenkov, S, additional, Drewelow, P, additional, Endler, M, additional, Feng, Y, additional, Frerichs, H, additional, Fuchert, G, additional, Geiger, J, additional, Gao, Y, additional, Harris, J H, additional, Jakubowski, M, additional, Kornejew, P, additional, Kremeyer, T, additional, Niemann, H, additional, Pasch, E, additional, Puig-Sitjes, A, additional, Schlisio, G, additional, Scott, E R, additional, and Wurden, G A, additional
Published: 2021
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