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1. Physics research on the TCV tokamak facility: From conventional to alternative scenarios and beyond

Author

G. Tomaž, M. Weiland, J. Gath, Antti Hakola, Kevin Verhaegh, A.J. Thornton, Matthew Carr, J. Juul Rasmussen, S. Costea, Jorge Morales, A. Perek, X. Feng, F. Pesamosca, Marcelo Baquero-Ruiz, N. Vianello, A. Dal Molin, N. M. T. Vu, D. Hogeweij, G. Calabrò, Tom Wauters, Christian Hopf, E. Alessi, Aitor J. Garrido, Justin Ball, Daniele Carnevale, A. Czarnecka, S. Garavaglia, G. Ferro, George Wilkie, N. Krawczyk, M. Nocente, H. De Oliveira, Ivo Furno, W. Bin, O. Chellai, Stefano Coda, Fulvio Auriemma, Yann Camenen, W. A. J. Vijvers, Christian Theiler, A. N. Karpushov, M. Faitsch, Jérôme Bucalossi, Paolo Ricci, Antoine Merle, T. C. Blanken, Cristian Galperti, Duccio Testa, Ambrogio Fasoli, Y. Andrebe, F. Bagnato, S. Nowak, J. R. Harrison, O. Vasilovici, M. E. Puiatti, Stefan Kragh Nielsen, J. S. Allcock, L. Calacci, Matteo Zuin, V. Piergotti, P. Chmielewski, P. Molina Cabrera, Taina Kurki-Suonio, D. Micheletti, Emanuele Poli, Nuno Cruz, M. Farnik, Jonathan Graves, Alessandro Pau, Olivier Février, N. A. Kirneva, Bruce Lipschultz, E. Lazzaro, E. Havlickova, G. Giruzzi, Jens Madsen, L. Stipani, D. Brida, Ch. Schlatter, M. Wensing, R. O. Pavlichenko, F. Nespoli, J. Decker, Eva Macusova, Fulvio Militello, Nicola Offeddu, Heinz Isliker, A. Zisis, A. Marco, Laurie Porte, Marco Gobbin, Anna Salmi, S. Vartanian, J. Sinha, Matthias Komm, M. Spolaore, Anders Nielsen, T. Happel, R. D. Nem, A. Iantchenko, V.V. Plyusnin, C. Tsironis, V. Igochine, R. M. McDermott, Pär Strand, Benjamin Daniel Dudson, T. Ravensbergen, V. P. Loschiavo, H. Arnichand, E. Viezzer, Fabio Villone, Carlo Sozzi, Z. Huang, V. Pericoli Ridolfini, B. Linehan, L. Hesslow, P. Buratti, A. Casolari, M. Bernert, P. Mantica, H. Weisen, J-M Moret, Maiko Yoshida, N. Bonanomi, S. Feng, A. A. Teplukhina, Jakub Urban, F. Carpanese, C. Piron, S. Allan, Minh Quang Tran, C. Marini, Artur Palha, F.P. Orsitto, Roberto Ambrosino, A. S. Tema Biwole, Harry M. Meyer, Davide Galassi, J. Mlynář, N. Christen, M. Wischmeier, Mathias Hoppe, P. David, J. Horacek, M. Maraschek, G. Ciraolo, R. R. Sheeba, J. Zebrowski, M. Dreval, M. Silva, K. Gałązka, Olivier Sauter, Laure Vermare, A. Gallo, C. Reux, M. Gospodarczyk, O. Bogar, Roman Schrittwieser, C. Marchetto, Patrick J. McCarthy, Joël Rosato, G. Pucella, K. Wu, Volker Naulin, Bojan Mavkov, S. Elmore, Lorella Carraro, Gustavo Granucci, Christopher N. Bowman, O. Kudlacek, M. Gruca, A. Jardin, Federico Felici, Didier Mazon, D. C. van Vugt, D. Douai, Jose Boedo, Raffaele Albanese, U. A. Sheikh, Hugo Bufferand, R. Lombroni, T. Pütterich, Benedikt Geiger, X. Llobet, Izaskun Garrido, J.-Ph. Hogge, J. Ayllon-Guerola, Nicolas Fedorczak, Timothy Goodman, A. Mariani, E. Maljaars, Matteo Agostini, Lorenzo Frassinetti, S. E. Sharapov, C.K. Tsui, Vladimir E. Moiseenko, Robert Mumgaard, Amanda Hubbard, L. Pigatto, F. Matos, D. S. Gahle, Roberto Maurizio, I. Voitsekhovitch, Paolo Zanca, J. Buermans, A. Fil, T. Lunt, S. S. Henderson, D. Ricci, M. Kong, Ondrej Ficker, Matthias Wiesenberger, L. Cordaro, P. Innocente, Roberto Paccagnella, Benoit Labit, N. Rispoli, M. Rabinski, G. F. Harrer, Roch Kwiatkowski, A. Moro, A. A. Beletskii, M. Vallar, M. Reich, F. Reimold, P. Piovesan, Mirko Salewski, J. Hawke, Giuseppe Gorini, J. Čeřovský, F. Causa, H. Reimerdes, B. Esposito, Jernej Kovacic, P. V. Kazantzidis, H. Anand, Gergely Papp, M. Valisa, K. Mitosinkova, Vlado Menkovski, F. Bombarda, M. Fontana, Tommaso Bolzonella, Pascale Hennequin, T. Gyergyek, D. L. Keeling, T. Eich, M. Garcia-Munoz, Stefano Alberti, P. Blanchard, F. Bouquey, R. Shousha, M. Scheffer, B. S. Schneider, R. Jacquier, D. Choi, Nick Walkden, Ola Embréus, C. Ionita Schrittwieser, S. Saarelma, J. Garcia, M. G. Dunne, M. Tomes, R. Zagórski, Y. R. Martin, A. Kappatou, B. P. Duval, T. Tala, Swiss National Science Foundation, Universita degli studi di Napoli 'Parthenope' [Napoli], Max-Planck-Institut für Plasmaphysik [Garching] (IPP), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Consiglio Nazionale delle Ricerche [Roma] (CNR), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Department of Physics [Stockholm], Stockholm University, Laboratoire de Physique des Plasmas (LPP), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Observatoire de Paris, 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), EURATOM/CCFE Fusion Association, Culham Science Centre [Abingdon], York Plasma Institute (YPI), University of York [York, UK], Faculty of Mathematics and Physics [Praha/Prague], Charles University [Prague] (CU), Association EURATOM-CEA (CEA/DSM/DRFC), University College Cork (UCC), Department of Mechanical and Manufacturing Engineering [Aalborg] (M-TECH), Aalborg University [Denmark] (AAU), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Instituto de Plasmas e Fusão Nuclear [Lisboa] (IPFN), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Coda, S, Agostini, M, Albanese, R, Alberti, S, Alessi, E, Allan, S, Allcock, J, Ambrosino, R, Anand, H, Andrebe, Y, Arnichand, H, Auriemma, F, Ayllon-Guerola, J, Bagnato, F, Ball, J, Baquero-Ruiz, M, Beletskii, A, Bernert, M, Bin, W, Blanchard, P, Blanken, T, Boedo, J, Bogar, O, Bolzonella, T, Bombarda, F, Bonanomi, N, Bouquey, F, Bowman, C, Brida, D, Bucalossi, J, Buermans, J, Bufferand, H, Buratti, P, Calabro, G, Calacci, L, Camenen, Y, Carnevale, D, Carpanese, F, Carr, M, Carraro, L, Casolari, A, Causa, F, Cerovsky, J, Chellai, O, Chmielewski, P, Choi, D, Christen, N, Ciraolo, G, Cordaro, L, Costea, S, Cruz, N, Czarnecka, A, Dal Molin, A, David, P, Decker, J, De Oliveira, H, Douai, D, Dreval, M, Dudson, B, Dunne, M, Duval, B, Eich, T, Elmore, S, Embreus, O, Esposito, B, Faitsch, M, Farnik, M, Fasoli, A, Fedorczak, N, Felici, F, Feng, S, Feng, X, Ferro, G, Fevrier, O, Ficker, O, Fil, A, Fontana, M, Frassinetti, L, Furno, I, Gahle, D, Galassi, D, Galazka, K, Gallo, A, Galperti, C, Garavaglia, S, Garcia, J, Garcia-Munoz, M, Garrido, A, Garrido, I, Gath, J, Geiger, B, Giruzzi, G, Gobbin, M, Goodman, T, Gorini, G, Gospodarczyk, M, Granucci, G, Graves, J, Gruca, M, Gyergyek, T, Hakola, A, Happel, T, Harrer, G, Harrison, J, Havlickova, E, Hawke, J, Henderson, S, Hennequin, P, Hesslow, L, Hogeweij, D, Hogge, J, Hopf, C, Hoppe, M, Horacek, J, Huang, Z, Hubbard, A, Iantchenko, A, Igochine, V, Innocente, P, Ionita Schrittwieser, C, Isliker, H, Jacquier, R, Jardin, A, Kappatou, A, Karpushov, A, Kazantzidis, P, Keeling, D, Kirneva, N, Komm, M, Kong, M, Kovacic, J, Krawczyk, N, Kudlacek, O, Kurki-Suonio, T, Kwiatkowski, R, Labit, B, Lazzaro, E, Linehan, B, Lipschultz, B, Llobet, X, Lombroni, R, Loschiavo, V, Lunt, T, Macusova, E, Madsen, J, Maljaars, E, Mantica, P, Maraschek, M, Marchetto, C, Marco, A, Mariani, A, Marini, C, Martin, Y, Matos, F, Frisina, M, Mavkov, B, Mazon, D, Mccarthy, P, Mcdermott, R, Menkovski, V, Merle, A, Meyer, H, Micheletti, D, Militello, F, Mitosinkova, K, Mlynar, J, Moiseenko, V, Molina Cabrera, P, Morales, J, Moret, J, Moro, A, Mumgaard, R, Naulin, V, Nem, R, Nespoli, F, Nielsen, A, Nielsen, S, Nocente, M, Nowak, S, Offeddu, N, Orsitto, F, Paccagnella, R, Palha, A, Papp, G, Pau, A, Pavlichenko, R, Perek, A, Pericoli Ridolfini, V, Pesamosca, F, Piergotti, V, Pigatto, L, Piovesan, P, Piron, C, Plyusnin, V, Poli, E, Porte, L, Pucella, G, Puiatti, M, Putterich, T, Rabinski, M, Juul Rasmussen, J, Ravensbergen, T, Reich, M, Reimerdes, H, Reimold, F, Reux, C, Ricci, D, Ricci, P, Rispoli, N, Rosato, J, Saarelma, S, Salewski, M, Salmi, A, Sauter, O, Scheffer, M, Schlatter, C, Schneider, B, Schrittwieser, R, Sharapov, S, Sheeba, R, Sheikh, U, Shousha, R, Silva, M, Sinha, J, Sozzi, C, Spolaore, M, Stipani, L, Strand, P, Tala, T, Tema Biwole, A, Teplukhina, A, Testa, D, Theiler, C, Thornton, A, Tomaz, G, Tomes, M, Tran, M, Tsironis, C, Tsui, C, Urban, J, Valisa, M, Vallar, M, Van Vugt, D, Vartanian, S, Vasilovici, O, Verhaegh, K, Vermare, L, Vianello, N, Viezzer, E, Vijvers, W, Villone, F, Voitsekhovitch, I, Vu, N, Walkden, N, Wauters, T, Weiland, M, Weisen, H, Wensing, M, Wiesenberger, M, Wilkie, G, Wischmeier, M, Wu, K, Yoshida, M, Zagorski, R, Zanca, P, Zebrowski, J, Zisis, A, Zuin, M, Università degli Studi di Napoli 'Parthenope' = University of Naples (PARTHENOPE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Université Paris-Sud - Paris 11 (UP11)-Observatoire de Paris, Coda, S., Agostini, M., Albanese, R., Alberti, S., Alessi, E., Allan, S., Allcock, J., Ambrosino, R., Anand, H., Andrebe, Y., Arnichand, H., Auriemma, F., Ayllon-Guerola, J. M., Bagnato, F., Ball, J., Baquero-Ruiz, M., Beletskii, A. A., Bernert, M., Bin, W., Blanchard, P., Blanken, T. C., Boedo, J. A., Bogar, O., Bolzonella, T., Bombarda, F., Bonanomi, N., Bouquey, F., Bowman, C., Brida, D., Bucalossi, J., Buermans, J., Bufferand, H., Buratti, P., Calabro, G., Calacci, L., Camenen, Y., Carnevale, D., Carpanese, F., Carr, M., Carraro, L., Casolari, A., Causa, F., Cerovsky, J., Chellai, O., Chmielewski, P., Choi, D., Christen, N., Ciraolo, G., Cordaro, L., Costea, S., Cruz, N., Czarnecka, A., Dal Molin, A., David, P., Decker, J., De Oliveira, H., Douai, D., Dreval, M. B., Dudson, B., Dunne, M., Duval, B. P., Eich, T., Elmore, S., Embreus, O., Esposito, B., Faitsch, M., Farnik, M., Fasoli, A., Fedorczak, N., Felici, F., Feng, S., Feng, X., Ferro, G., Fevrier, O., Ficker, O., Fil, A., Fontana, M., Frassinetti, L., Furno, I., Gahle, D. S., Galassi, D., Galazka, K., Gallo, A., Galperti, C., Garavaglia, S., Garcia, J., Garcia-Munoz, M., Garrido, A. J., Garrido, I., Gath, J., Geiger, B., Giruzzi, G., Gobbin, M., Goodman, T. P., Gorini, G., Gospodarczyk, M., Granucci, G., Graves, J. P., Gruca, M., Gyergyek, T., Hakola, A., Happel, T., Harrer, G. F., Harrison, J., Havlickova, E., Hawke, J., Henderson, S., Hennequin, P., Hesslow, L., Hogeweij, D., Hogge, J. -P., Hopf, C., Hoppe, M., Horacek, J., Huang, Z., Hubbard, A., Iantchenko, A., Igochine, V., Innocente, P., Ionita Schrittwieser, C., Isliker, H., Jacquier, R., Jardin, A., Kappatou, A., Karpushov, A., Kazantzidis, P. -V., Keeling, D., Kirneva, N., Komm, M., Kong, M., Kovacic, J., Krawczyk, N., Kudlacek, O., Kurki-Suonio, T., Kwiatkowski, R., Labit, B., Lazzaro, E., Linehan, B., Lipschultz, B., Llobet, X., Lombroni, R., Loschiavo, V. P., Lunt, T., Macusova, E., Madsen, J., Maljaars, E., Mantica, P., Maraschek, M., Marchetto, C., Marco, A., Mariani, A., Marini, C., Martin, Y., Matos, F., Maurizio, R., Mavkov, B., Mazon, D., Mccarthy, P., Mcdermott, R., Menkovski, V., Merle, A., Meyer, H., Micheletti, D., Militello, F., Mitosinkova, K., Mlynar, J., Moiseenko, V., Molina Cabrera, P. A., Morales, J., Moret, J. -M., Moro, A., Mumgaard, R. T., Naulin, V., Nem, R. D., Nespoli, F., Nielsen, A. H., Nielsen, S. K., Nocente, M., Nowak, S., Offeddu, N., Orsitto, F. P., Paccagnella, R., Palha, A., Papp, G., Pau, A., Pavlichenko, R. O., Perek, A., Pericoli Ridolfini, V., Pesamosca, F., Piergotti, V., Pigatto, L., Piovesan, P., Piron, C., Plyusnin, V., Poli, E., Porte, L., Pucella, G., Puiatti, M. E., Putterich, T., Rabinski, M., Juul Rasmussen, J., Ravensbergen, T., Reich, M., Reimerdes, H., Reimold, F., Reux, C., Ricci, D., Ricci, P., Rispoli, N., Rosato, J., Saarelma, S., Salewski, M., Salmi, A., Sauter, O., Scheffer, M., Schlatter, C., Schneider, B. S., Schrittwieser, R., Sharapov, S., Sheeba, R. R., Sheikh, U., Shousha, R., Silva, M., Sinha, J., Sozzi, C., Spolaore, M., Stipani, L., Strand, P., Tala, T., Tema Biwole, A. S., Teplukhina, A. A., Testa, D., Theiler, C., Thornton, A., Tomaz, G., Tomes, M., Tran, M. Q., Tsironis, C., Tsui, C. K., Urban, J., Valisa, M., Vallar, M., Van Vugt, D., Vartanian, S., Vasilovici, O., Verhaegh, K., Vermare, L., Vianello, N., Viezzer, E., Vijvers, W. A. J., Villone, F., Voitsekhovitch, I., Vu, N. M. T., Walkden, N., Wauters, T., Weiland, M., Weisen, H., Wensing, M., Wiesenberger, M., Wilkie, G., Wischmeier, M., Wu, K., Yoshida, M., Zagorski, R., Zanca, P., Zebrowski, J., Zisis, A., Zuin, M., Coda, S. et al, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear., Universidad de Sevilla, Departamento de Ingeniería Mecánica y Fabricación, Universidad de Sevilla. TEP111: Ingeniería Mecánica, Universidad de Sevilla. RNM138: Física Nuclear Aplicada, EUROfusion MST1 Team, Control Systems Technology, Data Mining, Science and Technology of Nuclear Fusion, and Magneto-Hydro-Dynamic Stability of Fusion Plasmas

Subjects
Nuclear and High Energy Physics, Tokamak, Settore ING-INF/04, TK, UPGRADE, Cyclotron, Overview, Cyclotron resonance, overview, CONFINEMENT, DETACHMENT, 7. Clean energy, 01 natural sciences, 010305 fluids & plasmas, law.invention, law, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], CONTROL-SYSTEM, 0103 physical sciences, EUROfusion, 010306 general physics, tokamak, QC, plasma, nuclear fusion, Physics, PLASMA, Divertor, Magnetic confinement fusion, Plasma, Mechanics, TCV, MST1, Condensed Matter Physics, Neutral beam injection, Physics and Astronomy, 13. Climate action, confinement, detachment, Nuclear fusion, control-system, upgrade, TCV, MST1, Beam (structure), Tokamaks
Abstract

The research program of the TCV tokamak ranges from conventional to advanced-tokamak scenarios and alternative divertor configurations, to exploratory plasmas driven by theoretical insight, exploiting the device's unique shaping capabilities. Disruption avoidance by real-time locked mode prevention or unlocking with electron-cyclotron resonance heating (ECRH) was thoroughly documented, using magnetic and radiation triggers. Runaway generation with high-Z noble-gas injection and runaway dissipation by subsequent Ne or Ar injection were studied for model validation. The new 1 MW neutral beam injector has expanded the parameter range, now encompassing ELMy H-modes in an ITER-like shape and nearly non-inductive H-mode discharges sustained by electron cyclotron and neutral beam current drive. In the H-mode, the pedestal pressure increases modestly with nitrogen seeding while fueling moves the density pedestal outwards, but the plasma stored energy is largely uncorrelated to either seeding or fueling. High fueling at high triangularity is key to accessing the attractive small edge-localized mode (type-II) regime. Turbulence is reduced in the core at negative triangularity, consistent with increased confinement and in accord with global gyrokinetic simulations. The geodesic acoustic mode, possibly coupled with avalanche events, has been linked with particle flow to the wall in diverted plasmas. Detachment, scrape-off layer transport, and turbulence were studied in L- and H-modes in both standard and alternative configurations (snowflake, super-X, and beyond). The detachment process is caused by power 'starvation' reducing the ionization source, with volume recombination playing only a minor role. Partial detachment in the H-mode is obtained with impurity seeding and has shown little dependence on flux expansion in standard single-null geometry. In the attached L-mode phase, increasing the outer connection length reduces the in-out heat-flow asymmetry. A doublet plasma, featuring an internal X-point, was achieved successfully, and a transport barrier was observed in the mantle just outside the internal separatrix. In the near future variable-configuration baffles and possibly divertor pumping will be introduced to investigate the effect of divertor closure on exhaust and performance, and 3.5 MW ECRH and 1 MW neutral beam injection heating will be added., This work was supported in part by the Swiss National Science Foundation.

Published
2019
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2. Recent diagnostic developments on LHD

Author

S Sudo, Y Nagayama, B J Peterson, K Kawahata, T Akiyama, N Ashikawa, M Emoto, M Goto, Y Hamada, K Ida, T Ido, H Iguchi, S Inagaki, M Isobe, T Kobuchi, A Komori, Y Liang, S Masuzaki, T Minami, T Morisaki, S Morita, S Muto, Y Nakamura, H Nakanishi, M Narushima, K Narihara, M Nishiura, A Nishizawa, S Ohdachi, M Osakabe, T Ozaki, R O Pavlichenko, S Sakakibara, K Sato, M Shoji, N Tamura, K Tanaka, K Toi, T Tokuzawa, K Y Watanabe, T Watanabe, H Yamada, I Yamada, M Yoshinuma, P Goncharov, D Kalinina, T Kanaba, T Sugimoto, A Ejiri, Y Ono, H Hojo, K Ishii, N Iwama, Y Kogi, A Mase, M Sakamoto, K Kondo, H Nagasaki, S Yamamoto, N Nishino, S Okajima, T Saida, M Sasao, T Takeda, S Tsuji-Iio, D S Darrow, H Takahashi, Y Liu, J F Lyon, A Yu Kostrioukov, V B Kuteev, V Sergeev, I Viniar, A V Krasilnikov, A Sanin, L N Vyacheslavov, D Stutman, M Finkenthal, O Motojima, and LHD Group

Subjects
Physics, Plasma parameters, business.industry, Divertor, Bolometer, Polarimeter, Condensed Matter Physics, Laser, Photon counting, law.invention, Large Helical Device, Optics, Nuclear Energy and Engineering, law, Plasma diagnostics, business
Abstract

Standard diagnostics for fundamental plasma parameters and for plasma physics are routinely utilized for daily operation and physics studies in the large helical device (LHD) with high reliability. Diagnostics for steady-state plasma are under intensive development, especially for Te, ne (yttrium–aluminium garnet (YAG) laser Thomson, CO2 laser polarimeter), data acquisition in steady-state and heat-resistant probes. To clarify the plasma properties of the helical structure, two- or three-dimensional diagnostics are being aggressively developed: tangential cameras (fast SX TV, photon counting CCD, Hα TV); tomography (tangential SX CCD, bolometer); imaging (bolometer, ECE, reflectometer). Divertor and edge physics are important key issues for steady-state operation. Diagnostics for neutral flux (Hα array, Zeeman spectroscopy) and ne (fast scanning probe, Li beam probe, pulsed radar reflectometer) are also in advanced stages of development. In addition to these, advanced diagnostics are being intensively developed in LHD through domestic and international collaborations.

Published
2003
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3. Energy confinement and thermal transport characteristics of net current free plasmas in the Large Helical Device

Author

K. V. Khlopenkov, Hajime Suzuki, Sadao Satoh, Mamiko Sasao, Hiroshi Idei, Masami Fujiwara, Hideo Sugama, K.Y. Watanabe, G. Rewoldt, Ken Matsuoka, S. Morita, Yoshihide Oka, S. Yamamoto, Suguru Masuzaki, Naoki Tamura, Yuki Torii, Masaki Osakabe, T. Tokuzawa, N. Noda, T. Uda, S. Sudo, S. Murakami, H. Sasao, Takashi Notake, Akio Sagara, Hideya Nakanishi, Kunizo Ohkubo, Osamu Kaneko, H Funaba, Shinichiro Kado, Motoshi Goto, O. Motojima, Katsuyoshi Tsumori, Y. Liang, Takashi Shimozuma, Ichihiro Yamada, T. Watari, Akio Komori, Kenji Saito, T. Minami, Y. Hamada, Hiroshi Yamada, Y. Nakamura, Takashi Mutoh, K. Narihara, Ryuichi Sakamoto, I. Ohtake, N. Inoue, P. de Vries, K. Toi, K. Yamazaki, Mitsutaka Isobe, Tomohiro Morisaki, Kenji Tanaka, Noriyoshi Nakajima, Shigeru Inagaki, Kazuo Kawahata, Satoshi Ohdachi, Tetsuo Seki, Kimitaka Itoh, T. Kobuchi, Y. Nagayama, M. Emoto, S. Tanahashi, Masayuki Yokoyama, Masahide Sato, T. Ozaki, R. O. Pavlichenko, Manabu Takechi, Yasuo Yoshimura, Takashi Satow, Kuninori Sato, Y. Takeiri, B.J. Peterson, Shin Kubo, K. Nishimura, Sadatsugu Muto, Soichiro Yamaguchi, J. Miyazawa, Satoru Sakakibara, Mamoru Shoji, Katsumi Ida, Nobuyoshi Ohyabu, N. Ashikawa, Ryuhei Kumazawa, and Katsunori Ikeda

Subjects
Nuclear and High Energy Physics, Materials science, Ripple, Thermodynamics, Plasma, Collisionality, Condensed Matter Physics, Thermal conduction, law.invention, Core (optical fiber), Large Helical Device, Physics::Plasma Physics, law, Atomic physics, Scaling, Stellarator
Abstract

The energy confinement and thermal transport characteristics of net current free plasmas in regimes with much smaller gyroradii and collisionality than previously studied have been investigated in the Large Helical Device (LHD). The inward shifted configuration, which is superior from the point of view of neoclassical transport theory, has revealed a systematic confinement improvement over the standard configuration. Energy confinement times are improved over the International Stellarator Scaling 95 by a factor of 1.6 ±0.2 for an inward shifted configuration. This enhancement is primarily due to the broad temperature profile with a high edge value. A simple dimensional analysis involving LHD and other medium sized heliotrons yields a strongly gyro-Bohm dependence (τEΩ ∝ ρ*-3.8) of energy confinement times. It should be noted that this result is attributed to a comprehensive treatment of LHD for systematic confinement enhancement and that the medium sized heliotrons have narrow temperature profiles. The core stored energy still indicates a dependence of τEΩ ∝ ρ*-2.6 when data only from LHD are processed. The local heat transport analysis of discharges dimensionally similar except for ρ* suggests that the heat conduction coefficient lies between Bohm and gyro-Bohm in the core and changes towards strong gyro-Bohm in the peripheral region. Since the inward shifted configuration has a geometrical feature suppressing neoclassical transport, confinement improvement can be maintained in the collisionless regime where ripple transport is important. The stiffness of the pressure profile coincides with enhanced transport in the peaked density profile obtained by pellet injection.

Published
2001
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4. Role of core radiation during slow oscillations in LHD

Author

Byron J. Peterson, Takashi Notake, Suguru Masuzaki, Hajime Suzuki, Naoki Tamura, Shin Kubo, Kazuo Toi, Kazuo Kawahata, Mamiko Sasao, M. Takechi, Kenji Saito, Ryuhei Kumazawa, Ichihiro Yamada, Shinichiro Kado, T. Watari, Kazumichi Narihara, Kenji Tanaka, Hisamichi Funaba, Katsunori Ikeda, Masaki Osakabe, Soichiro Yamaguchi, Akio Komori, N. Ashikawa, Satoshi Ohdachi, M. Sato, Takashi Minami, Tetsuo Seki, Yasuhiko Takeiri, Katsuyoshi Tsumori, Masayuki Yokoyama, Ryuichi Sakamoto, Tomohiro Morisaki, Motoshi Goto, Y. Xu, Yuki Torii, K.Y. Watanabe, Tokihiko Tokuzawa, Takashi Mutoh, Satoru Sakakibara, K. Yamazaki, Y. Nakamura, Shigeru Sudo, Osamu Kaneko, Mitsutaka Isobe, Mamoru Shoji, T. Kobuchi, J. Miyazawa, Hiroshi Idei, Osamu Motojima, Katsumi Ida, Nobuyoshi Ohyabu, Akio Sagara, P.C. De Vries, S. Murakami, S. Yamamoto, Sadatsugu Muto, T. Ozaki, Kuninori Sato, Hideya Nakanishi, Masahiko Emoto, R. O. Pavlichenko, Yoshihide Oka, Takashi Shimozuma, Shigeru Inagaki, N. Noda, Yasuo Yoshimura, H. Sasao, Y. Liang, K. V. Khlopenkov, John Rice, N. Inoue, K. Nishimura, Yoshio Nagayama, and Hiroshi Yamada

Subjects
Nuclear and High Energy Physics, Electron density, Materials science, Physics::Plasma Physics, Sputtering, Impurity, Oscillation, Plasma parameters, Divertor, Electron temperature, Plasma, Atomic physics, Condensed Matter Physics
Abstract

During experiments in LHD using stainless steel divertor plates, a slow (~1 s) cyclic oscillation in the plasma parameters known as `breathing' plasma was observed during NBI heated long pulse discharges. Using an average ion, corona equilibrium model for the iron impurity cooling rate, the iron impurity density profile is calculated for 0.0

Published
2001
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5. Impact of pellet injection on extension of the operational region in LHD

Author

K. Nishimura, Y. Hamada, R. O. Pavlichenko, Larry R. Baylor, Yoshio Nagayama, Masahide Sato, Yasuo Yoshimura, K. V. Khlopenkov, J. Miyazawa, Hiroshi Yamada, Nobuyoshi Ohyabu, K.Y. Watanabe, Manabu Takechi, Takashi Shimozuma, Sadatsugu Muto, O. Motojima, K. Toi, N. Ashikawa, S. Murakami, T. Tokuzawa, Tetsuo Seki, Shinsuke Kato, Ryuichi Sakamoto, Hideya Nakanishi, Yoshihide Oka, Osamu Kaneko, Kuninori Sato, Y. Liang, Motoshi Goto, N. Noda, Mitsutaka Isobe, Hajime Suzuki, H. Sasao, Mamoru Shoji, Katsumi Ida, P. W. Fisher, Y. Takeiri, S. Sudo, T. Kobuchi, Ryuhei Kumazawa, Katsunori Ikeda, Michael J Gouge, Ichihiro Yamada, Naoki Tamura, T. Watari, Kenji Saito, Mamiko Sasao, T. Minami, Shinichiro Kado, Shigeru Inagaki, Satoshi Ohdachi, Masami Fujiwara, Masaki Osakabe, Takashi Mutoh, S. Morita, T. Ozaki, Y. Nakamura, Soichiro Yamaguchi, A. Komori, S.K. Combs, Kenji Tanaka, S. Yamamoto, Satoru Sakakibara, P. de Vries, M. Emoto, Tomohiro Morisaki, Katsuyoshi Tsumori, Takashi Notake, Hiroshi Idei, K. Yamazaki, Yuki Torii, Akio Sagara, H Funaba, Kazuo Kawahata, Suguru Masuzaki, K. Narihara, B.J. Peterson, and Shin Kubo

Subjects
Nuclear and High Energy Physics, Materials science, medicine.medical_treatment, Plasma, Condensed Matter Physics, Ablation, Ion, Large Helical Device, Nuclear magnetic resonance, Electromagnetic shielding, Stored energy, Pellet, medicine, Atomic physics, Penetration depth
Abstract

Pellet injection has been used as a primary fuelling scheme in the Large Helical Device. With pellet injection, the operational region of NBI plasmas has been extended to higher densities while maintaining a favourable dependence of energy confinement on density, and several important values, such as plasma stored energy of 0.88?MJ, energy confinement time of 0.3?s, ? of 2.4% at 1.3?T and density of 1.1 ? 1020?m -3, have been achieved. These parameters cannot be attained by gas puffing. Ablation and the subsequent behaviour of the plasma have been investigated. The measured pellet penetration depth estimated on the basis of the duration of the H? emission is shallower than the depth predicted from the simple neutral gas shielding (NGS) model. It can be explained by the NGS model with inclusion of the effect of fast ions on the ablation. Just after ablation, the redistribution of the ablated pellet mass was observed on a short timescale (~400?ms). The redistribution causes shallow deposition and low fuelling efficiency.

Published
2001
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6. The performance of ICRF heated plasmas in LHD

Author

Hiroshi Yamada, Naoki Tamura, Masaki Osakabe, Byron J. Peterson, R. O. Pavlichenko, K. V. Khlopenkov, Hisamichi Funaba, Yasuo Yoshimura, Tokihiko Tokuzawa, Takashi Mutoh, Kazuo Toi, Takashi Satow, Yasuhiko Takeiri, T. Kobuchi, Suguru Masuzaki, S. Tanahashi, A.T. Notake, S. Yamamoto, J. Miyazawa, Keisuke Matsuoka, Kunizo Ohkubo, K. Nishimura, Dirk Hartmann, Kazumichi Narihara, Yasuji Hamada, Shigeru Inagaki, Tetsuo Seki, N. Ashikawa, Sadatsugu Muto, Osamu Motojima, Katsuyoshi Tsumori, Sadao Satoh, Takashi Minami, Hiroshi Idei, Nobuyoshi Ohyabu, Mamoru Shoji, Kenji Tanaka, Tomo-Hiko Watanabe, Yan Ping Zhao, Y. Liang, Katsumi Ida, M. Sasao, Satoshi Ohdachi, Takashi Shimozuma, K. Yamazaki, A. V. Krasilnikov, Kimitaka Itoh, Yuki Torii, Hideya Nakanishi, Atsushi Fukuyama, Yoshihide Oka, Hiroyuki Okada, Kenji Saito, Masahiko Emoto, Yoshio Nagayama, N. Inoue, Shin Kubo, N. Noda, Shinichiro Kado, Motoshi Goto, T. Ozaki, Soichiro Yamaguchi, Akio Sagara, S. Murakami, Tomohiro Morisaki, H. Sasao, Ryuhei Kumazawa, Akio Komori, Masayuki Yokoyama, Satoru Sakakibara, M. Fujiwara, M. Sato, Katsunori Ikeda, Osamu Kaneko, Y. Nakamura, Kuninori Sato, Kazuo Kawahata, K.Y. Watanabe, Ryuichi Sakamoto, S. Morita, Masao Okamoto, Shigeru Sudo, Mitsutaka Isobe, Ichihiro Yamada, T. Watari, P.C. De Vries, Hajime Suzuki, and M. Takechi

Subjects
Nuclear and High Energy Physics, Materials science, Plasma parameters, Divertor, Cyclotron, Pulse duration, Plasma, Condensed Matter Physics, Magnetic field, law.invention, Ion, law, Atomic physics, Stellarator
Abstract

An ion cyclotron range of frequency (ICRF) heating experiment was conducted in the third campaign of LHD in 1999. 1.35 MW of ICRF power were injected into the plasma and 200 kJ of stored energy were obtained, which was maintained for 5 s by ICRF power only after the termination of ECH. The impurity problem was so completely overcome that the pulse length was easily extended to 68 s at a power level of 0.7 MW. The utility of a liquid stub tuner in steady state plasma heating was demonstrated in this discharge. The energy confinement time of the ICRF heated plasma has the same dependences on plasma parameters as those of the ISS95 stellarator scaling with a multiplication factor of 1.5, which is a high efficiency comparable to that of NBI. Such an improvement in performance was obtained by various means, including: (a) scanning of the magnetic field intensity and minority concentration, (b) improvement of particle orbits due to a shift of magnetic axis and (c) reduction of the number of impurity ions by means of titanium gettering and the use of carbon divertor plates. In the optimized heating regime, ion heating turned out to be the dominant heating mechanism, unlike in CHS and W7-AS. Owing to the high quality of the heating and the parameter range being extended far beyond that of previous experiments, the experiment can be regarded as the first complete demonstration of ICRF heating in stellarators.

Published
2001
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7. Overview of CHS experiments4

Author

Katsumi Ida, T. Kondo, K. A. Tanaka, K. V. Khlopenkov, Akihide Fujisawa, T. Minami, G. Matsunaga, Masaki Osakabe, R. O. Pavlichenko, Mitsutaka Isobe, Yasuo Yoshimura, S. Okamura, K. Toi, I. Nomura, Mamiko Sasao, S. Sudo, A. Shimizu, Ken Matsuoka, T. Yamamoto, C. Takahashi, M. Takechi, Ryuichi Akiyama, Seiya Nishimura, H. Iguchi, Shinichiro Kado, Y. Liang, K. Ohkuni, Shoji Takagi, and Chihiro Suzuki

Subjects
Physics, Complementary experiments, Nuclear Energy and Engineering, Nanotechnology, Electron, Electric potential, Plasma, Atomic physics, Condensed Matter Physics, Bifurcation
Abstract

Recent experimental results are summarized. One of them is the bifurcation phenomenon of the electric potential which manifests itself in various aspects of CHS plasmas. Here, electrons heated with ECH play an essential role. The CHS will be operated, after being moved to the Toki site, so as to perform complementary experiments to LHD.

Published
2000
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8. Density behaviour and particle losses in RF discharge plasmas of the URAGAN-3M torsatron

Author

N.I. Nazarov, A.P. Litvinov, V. Plyusnin, E.L. Sorokovoj, L.I. Grigor`eva, V.V. Chechkin, A.F. Shtan, R. O. Pavlichenko, I.M. Pankratov, I.P. Fomin, A.I. Skibenko, E.V. Trofimenko, and E.D. Volkov

Subjects
Nuclear and High Energy Physics, Electron density, Materials science, Plasma parameters, Divertor, Plasma, Condensed Matter Physics, law.invention, symbols.namesake, Physics::Plasma Physics, law, Ionization, symbols, Langmuir probe, Atomic physics, Neutral particle, Stellarator
Abstract

URAGAN-3M (U-3M) is an l=3, m=9 torsatron with R0=1 m, ā ≈ 12 cm and (ā) ≈ 0.4. The entire magnetic system is enclosed in a large vacuum chamber and there is no material limiter, so that an open helical divertor is realized in this device. A plasma is RF produced in 100% hydrogen gas and heated in the multimode Alfven resonance regime (ω ωci) at a continuous working gas leak-in. With an RF power of ~200 kW at B = 0.45 T, a quasi-steady (up to 50 ms) state of the plasma parameters sets in with e 2 × 1018 m-3, Ti(0) 130 eV and Te(0) equivalent to 300 eV. By using microwaves and Langmuir probes, the time and space behaviours of the electron density/ion saturation current are studied in the confinement volume, near the boundary of the confinement region, and in the divertor flux region. On the basis of ion saturation current profile measurements near the boundary of the confinement region the values of local particle flux density across the boundary are estimated: Γ⊥ ≈ 7 × 1020 m-2.s-1 far from the antenna and Γ⊥ approximately=1021 m-2.s-1, Γ⊥ ≈ 2 × 1021 m-2.s-1 near the antenna. Such flux densities and the corresponding diffusion coefficients are anomalously high, exceeding the neoclassical values by 2 to 3 orders of magnitude. On the other hand, these values are comparable with the flux densities and diffusivities obtained in edge plasma with similar parameters on other stellarators under NBI and ECR heating conditions. Therefore, it is claimed that the method of plasma heating that has been chosen in U-3M does not result in any substantial deterioration of particle confinement (with the possible exception of the region close to the antenna) as against other methods. Presumably, the anomalous particle transport across the boundary in U-3M is caused by destruction of magnetic surfaces and/or electrostatic drift wave turbulence. It is found that increasing the RF power results in an increase of the diverted plasma flow and of the hydrogen consumption necessary to maintain the average plasma density at a given level. This is considered as a manifestation of a common regularity, according to which particle losses grow with heating power, this effect having been observed recently on a stellarator type device under NBI and ECR heating conditions. An effect specific to U-3M, the increase of the average electron density, being observed within 1 to 2 ms after RF pulse termination, is attributed mainly to particle transport reduction due to plasma cooling, while the intensity of neutral particle ionization still remains sufficiently high in the confinement volume at the initial phase of cooling under continuous hydrogen leak-in conditions.

Published
1996
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9. Divertor studies in the l=3 URAGAN-3M torsatron

Author

N.I. Nazarov, A V Khodyachikh, V.S. Vojtsenya, R. O. Pavlichenko, E.D. Volkov, I.P. Fomin, V.V. Chechkin, V Y Bykov, V G Peletminskaya, E L Sorokovoj, L.I. Grigor'eva, V. Plyusnin, and A I Skibenko

Subjects
Materials science, Nuclear Energy and Engineering, Physics::Plasma Physics, Field line, Ionization, Divertor, RF power amplifier, Plasma diagnostics, Plasma, Antenna (radio), Atomic physics, Condensed Matter Physics, Microwave
Abstract

In the l=3, m=9 URAGAN-3M torsatron an open helical divertor is realized. Plasmas are RF produced and heated. The time and space characteristics of the plasma in the space between two coils of the helical winding and on the outward side of the helical winding are studied by microwave and probe techniques. The experimental measurements are preceded by numerical divertor field line tracing. As a result of the calculations and measurements, it is shown that the diverted plasma is formed due to (i) plasma transportation from the confinement volume; and (ii) neutral gas ionization by the near-antenna field. The flow of diverted plasma transported from the confinement volume increases with RF power. This is considered as direct evidence of an increase in particle loss with an increase in heating power, the effect having been deduced recently for a stellarator-type device under NBI and ECR heating conditions. An intense RF discharge along open field lines crossing the operating antenna results in a greatly increased diverted plasma density, in the appearance of a static positive plasma potential up to 150 V near the antenna, and possibly in significant additional RF power loss outside the confinement region.

Published
1995
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10. Progress in stellarator research in Kharkov IPP

Author

M N Makhov, M. M. Kozulya, A. A. Kasilov, M. I. Tarasov, V.D. Kotsubanov, N. B. Dreval, A.N. Shapoval, Ye.D. Kramskoi, A. E. Kulaga, V V Filippov, Vladimir E. Moiseenko, V.G. Konovalov, S.M. Maznichenko, I.M. Pankratov, R. O. Pavlichenko, A. F. Shtan, S. A. Tsybenko, A. A. Beletskii, N. V. Zamanov, V. S. Voitsenya, V. Ya. Chernyshenko, V.V. Chechkin, V.L. Berezhnyj, V.N. Bondarenko, A.S. Slavnyj, Yu.K. Mironov, Igor E. Garkusha, I. K. Tarasov, D. A. Sitnikov, L.I. Grigor'eva, V.B. Korovin, I. K. Nikolskij, A.V. Lozin, G G Lesnyakov, and V. S. Romanov

Subjects
Physics, Cyclotron, Electron, Fermion, Plasma, Condensed Matter Physics, Electromagnetic radiation, Atomic and Molecular Physics, and Optics, Computational physics, law.invention, Physics::Plasma Physics, law, Antenna (radio), Atomic physics, Radiant intensity, Mathematical Physics, Stellarator
Abstract

Recent results of the experimental program on the stellarator-type device Uragan-3M at the IPP in Kharkov are presented. Efforts were focused mainly on optimization of the operation of the frame-type radiofrequency antenna to produce a target plasma for the three-half-turn antenna. Different regimes of the Uragan-3M operation, which are characterized by different temporal behavior of the average plasma density, electron cyclotron emission radiation intensity and particle confinement time, are considered. Elementary atomic processes responsible for plasma creation are studied. The particle confinement time for the Uragan-3M plasmas is estimated. Measurements of energy spectra of charge exchange atoms are carried out. The principal possibility of realizing a 'stellarator–magnetic mirror' scheme as a prototype of a stellarator-mirror fusion–fission hybrid is shown for Uragan-2M. Future plans are discussed.

Published
2014
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11. RF plasma production and heating below ion-cyclotron frequencies in Uragan torsatrons

Author

A.I. Lyssoivan, V. S. Romanov, V.K. Pashnev, E. L. Sorokovoy, V.V. Chechkin, V.L. Berezhnyj, Vladimir E. Moiseenko, G.P. Glazunov, Francisco Castejón, R. Koch, V. I. Tereshin, Yu. S. Stadnik, V.N. Bondarenko, V.G. Konovalov, P. Ya. Burchenko, V. Ya. Chernyshenko, A.S. Slavnyi, A.I. Skibenko, A.N. Shapoval, Ye.D. Kramskoi, V.D. Kotsubanov, I.N. Mysiura, M. Dreval, L.I. Grigor'eva, V. K. Mironov, Igor E. Garkusha, D. A. Hartmann, V. S. Voitsenya, V.S. Taran, A.V. Lozin, C. Hidalgo, R. O. Pavlichenko, and A. E. Kulaga

Subjects
Nuclear and High Energy Physics, Materials science, Hydrogen, Cyclotron, chemistry.chemical_element, Plasma, Electron, Condensed Matter Physics, law.invention, Ion, symbols.namesake, chemistry, Maxwell's equations, Physics::Plasma Physics, law, Shielded cable, symbols, Atomic physics, Stellarator
Abstract

In the IPP-Kharkiv there are two torsatrons (stellarators) in operation, and in both of them Alfvén resonance heating under high-k ∥ conditions is used. This method of heating is advantageous for small-size devices, since in contrast to the minority and second-harmonic heating it can be realized at lower plasma densities. A series of experiments has been performed at the Uragan-3M torsatron with an aim to investigate the features of the discharge with a three-half-turn antenna. Electron temperatures in the range are achieved at plasma densities . The plasma energy content has increased by a factor of 2 with respect to the plasma produced with the frame antenna. A new four-strap shielded antenna has been manufactured and installed in the Uragan-2M. A high-frequency discharge for wall conditioning is introduced in the Uragan-2M torsatron. The discharge is sustained by a specially designed small frame antenna, and efficient hydrogen dissociation is achieved. A self-consistent model has been developed for simulation of plasma production in ICRF. The model includes a set of particle and energy-balance equations for the electrons, and the boundary problem for the Maxwell equations. The first calculation results on RF plasma production in the Uragan-2M stellarator with the frame-type antenna are presented.

Published
2011
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12. Characteristics of regular discharges in Uragan-3M torsatron.

Author

V E Moiseenko, A N Shapoval, A V Lozin, V V Nemov, V N Kalyuzhnyj, M M Kozulya, R O Pavlichenko, V G Konovalov, A E Kulaga, Yu K Mironov, V S Romanov, N V Zamanov, V N Bondarenko, Yu V Kovtun, and I E Garkusha

Subjects
ELECTRON temperature, PLASMA confinement, PLASMA heating, PLASMA temperature, HIGH temperatures, THOMSON scattering
Abstract

The Uragan-3M device is equipped with two antennas which are fed by RF power with the frequency below ion cyclotron. The frame antenna was used for pre-ionization and the three-half turn antenna makes plasma heating. In this experimental series, the radial profiles of C III, O V and C V optical line intensity and the second cyclotron harmonic emission are measured using a pulse-by-pulse technique. The results of these measurements and Biot–Savart calculations of the Uragan-3M magnetic configuration could be explained by the existence of a small central area with relatively high electron temperature and good plasma confinement surrounded by a zone where the electron temperature and confinement are worse. The relatively low average electron temperature and high RF power needed to sustain plasma are the consequences. [ABSTRACT FROM AUTHOR]

Published
2019
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13. Characterization of the 20 kHz transient MHD burst at the fast U-3M confinement modification stage.

Author

M B Dreval, R O Pavlichenko, A M Shapoval, V K Pashnev, E L Sorokovoy, A S Slavnyj, A A Beletskii, Yu K Mironov, V S Romanov, A E Kulaga, and N V Zamanov

Subjects
*PLASMA confinement, *PLASMA currents, *PLASMA Alfven waves, *RADIO frequency, *MAGNETIC fields
Abstract

In the URAGAN-3M (U-3M) torsatron the low-frequency transient 20–30 kHz mode is observed during the plasma confinement transition that occurs at a plasma current value of about 1 kA. The burst of this mode is always accompanied by the fast jump of the Alfvén eigenmode frequency. The transient 20–30 kHz mode contains two parts. The non-rotating part of the mode has higher amplitude and is localized in the stochastic region of the plasma. It is observed only in the vicinity of the radio-frequency antenna used for plasma production and does not propagate along the torus because of fast losses. Its high amplitude indicates that the major part of the 20–30 kHz mode is excited in the stochastic region near the antenna. In contrast, the second rotating part of the mode is localized everywhere along the torus near the plasma edge (ρ = 0.8–1). This is the n/m = 1/2 mode that rotates in the electron diamagnetic direction. It is observed in different toroidal cross-sections by various diagnostics (magnetic probe array, optics, Langmuir probe). Appearance of the 1/2 rational surface at the stochastic magnetic field line region near the plasma edge at 1 kA plasma current stage can be responsible for the mode generation. Modification of electron component gradients in the mode generation region near the antenna and the drop of the fast ion concentration (above 1 keV) in this region are observed simultaneously with the mode generation. The mode can be exited by the strong transient plasma gradients generated in the vicinity of the rational surface by the antenna. [ABSTRACT FROM AUTHOR]

Published
2018
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