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1. Overview of the EUROfusion Tokamak Exploitation programme in support of ITER and DEMO

Author

E. Joffrin, M. Wischmeier, M. Baruzzo, A. Hakola, A. Kappatou, D. Keeling, B. Labit, E. Tsitrone, N. Vianello, the ASDEX Upgrade Team, JET Contributors, the MAST-U Team, the TCV Team, the WEST Team, the EUROfusion Tokamak Exploitation Team:, D. Abate, J. Adamek, M. Agostini, C. Albert, F.C.P. Albert Devasagayam, S. Aleiferis, E. Alessi, J. Alhage, S. Allan, J. Allcock, M. Alonzo, G. Anastasiou, E. Andersson Sunden, C. Angioni, Y. Anquetin, L. Appel, G.M. Apruzzese, M. Ariola, C. Arnas, J.F. Artaud, W. Arter, O. Asztalos, L. Aucone, M.H. Aumeunier, F. Auriemma, J. Ayllon, E. Aymerich, A. Baciero, F. Bagnato, L. Bähner, F. Bairaktaris, P. Balázs, L. Balbinot, I. Balboa, M. Balden, A. Balestri, M. Baquero Ruiz, T. Barberis, C. Barcellona, O. Bardsley, S. Benkadda, T. Bensadon, E. Bernard, M. Bernert, H. Betar, R. Bianchetti Morales, J. Bielecki, R. Bilato, P. Bilkova, W. Bin, G. Birkenmeier, R. Bisson, P. Blanchard, A. Bleasdale, V. Bobkov, A. Boboc, A. Bock, K. Bogar, P. Bohm, T. Bolzonella, F. Bombarda, N. Bonanomi, L. Boncagni, D. Bonfiglio, R. Bonifetto, M. Bonotto, D. Borodin, I. Borodkina, T.O.S.J. Bosman, C. Bourdelle, C. Bowman, S. Brezinsek, D. Brida, F. Brochard, R. Brunet, D. Brunetti, V. Bruno, R. Buchholz, J. Buermans, H. Bufferand, P. Buratti, A. Burckhart, J. Cai, R. Calado, J. Caloud, S. Cancelli, F. Cani, B. Cannas, M. Cappelli, S. Carcangiu, A. Cardinali, S. Carli, D. Carnevale, M. Carole, M. Carpita, D. Carralero, F. Caruggi, I.S. Carvalho, I. Casiraghi, A. Casolari, F.J. Casson, C. Castaldo, A. Cathey, F. Causa, J. Cavalier, M. Cavedon, J. Cazabonne, M. Cecconello, L. Ceelen, A. Celora, J. Cerovsky, C.D. Challis, R. Chandra, A. Chankin, B. Chapman, H. Chen, M. Chernyshova, A.G. Chiariello, P. Chmielewski, A. Chomiczewska, C. Cianfarani, G. Ciraolo, J. Citrin, F. Clairet, S. Coda, R. Coelho, J.W. Coenen, I.H. Coffey, C. Colandrea, L. Colas, S. Conroy, C. Contre, N.J. Conway, L. Cordaro, Y. Corre, D. Costa, S. Costea, D. Coster, X. Courtois, C. Cowley, T. Craciunescu, G. Croci, A.M. Croitoru, K. Crombe, D.J. Cruz Zabala, G. Cseh, T. Czarski, A. Da Ros, A. Dal Molin, M. Dalla Rosa, Y. Damizia, O. D’Arcangelo, P. David, M. De Angeli, E. De la Cal, E. De La Luna, G. De Tommasi, J. Decker, R. Dejarnac, D. Del Sarto, G. Derks, C. Desgranges, P. Devynck, S. Di Genova, L.E. di Grazia, A. Di Siena, M. Dicorato, M. Diez, M. Dimitrova, T. Dittmar, L. Dittrich, J.J. Domínguez Palacios Durán, P. Donnel, D. Douai, S. Dowson, S. Doyle, M. Dreval, P. Drews, L. Dubus, R. Dumont, D. Dunai, M. Dunne, A. Durif, F. Durodie, G. Durr Legoupil Nicoud, B. Duval, R. Dux, T. Eich, A. Ekedahl, S. Elmore, G. Ericsson, J. Eriksson, B. Eriksson, F. Eriksson, S. Ertmer, A. Escarguel, B. Esposito, T. Estrada, E. Fable, M. Faitsch, N. Fakhrayi Mofrad, A. Fanni, T. Farley, M. Farník, N. Fedorczak, F. Felici, X. Feng, J. Ferreira, D. Ferreira, N. Ferron, O. Fevrier, O. Ficker, A.R. Field, A. Figueiredo, N. Fil, D. Fiorucci, M. Firdaouss, R. Fischer, M. Fitzgerald, M. Flebbe, M. Fontana, J. Fontdecaba Climent, A. Frank, E. Fransson, L. Frassinetti, D. Frigione, S. Futatani, R. Futtersack, S. Gabriellini, D. Gadariya, D. Galassi, K. Galazka, J. Galdon, S. Galeani, D. Gallart, A. Gallo, C. Galperti, M. Gambrioli, S. Garavaglia, J. Garcia, M. Garcia Munoz, J. Gardarein, L. Garzotti, J. Gaspar, R. Gatto, P. Gaudio, M. Gelfusa, J. Gerardin, S.N. Gerasimov, R. Gerru Miguelanez, G. Gervasini, Z. Ghani, F.M. Ghezzi, G. Ghillardi, L. Giannone, S. Gibson, L. Gil, A. Gillgren, E. Giovannozzi, C. Giroud, G. Giruzzi, T. Gleiter, M. Gobbin, V. Goloborodko, A. González Ganzábal, T. Goodman, V. Gopakumar, G. Gorini, T. Görler, S. Gorno, G. Granucci, D. Greenhouse, G. Grenfell, M. Griener, W. Gromelski, M. Groth, O. Grover, M. Gruca, A. Gude, C. Guillemaut, R. Guirlet, J. Gunn, T. Gyergyek, L. Hagg, J. Hall, C.J. Ham, M. Hamed, T. Happel, G. Harrer, J. Harrison, D. Harting, N.C. Hawkes, P. Heinrich, S. Henderson, P. Hennequin, R. Henriques, S. Heuraux, J. Hidalgo Salaverri, J. Hillairet, J.C. Hillesheim, A. Hjalmarsson, A. Ho, J. Hobirk, E. Hodille, M. Hölzl, M. Hoppe, J. Horacek, N. Horsten, L. Horvath, M. Houry, K. Hromasova, J. Huang, Z. Huang, A. Huber, E. Huett, P. Huynh, A. Iantchenko, M. Imrisek, P. Innocente, C. Ionita Schrittwieser, H. Isliker, P. Ivanova, I. Ivanova Stanik, M. Jablczynska, S. Jachmich, A.S. Jacobsen, P. Jacquet, A. Jansen van Vuuren, A. Jardin, H. Järleblad, A. Järvinen, F. Jaulmes, T. Jensen, I. Jepu, S. Jessica, T. Johnson, A. Juven, J. Kalis, J. Karhunen, R. Karimov, A.N. Karpushov, S. Kasilov, Y. Kazakov, P.V. Kazantzidis, W. Kernbichler, HT. Kim, D.B. King, V.G. Kiptily, A. Kirjasuo, K.K. Kirov, A. Kirschner, A. Kit, T. Kiviniemi, F. Kjær, E. Klinkby, A. Knieps, U. Knoche, M. Kochan, F. Köchl, G. Kocsis, J.T.W. Koenders, L. Kogan, Y. Kolesnichenko, Y. Kominis, M. Komm, M. Kong, B. Kool, S.B. Korsholm, D. Kos, M. Koubiti, J. Kovacic, Y. Kovtun, E. Kowalska Strzeciwilk, K. Koziol, M. Kozulia, A. Krämer Flecken, A. Kreter, K. Krieger, U. Kruezi, O. Krutkin, O. Kudlacek, U. Kumar, H. Kumpulainen, M.H. Kushoro, R. Kwiatkowski, M. La Matina, M. Lacquaniti, L. Laguardia, P. Lainer, P. Lang, M. Larsen, E. Laszynska, K.D. Lawson, A. Lazaros, E. Lazzaro, M.Y.K. Lee, S. Leerink, M. Lehnen, M. Lennholm, E. Lerche, Y. Liang, A. Lier, J. Likonen, O. Linder, B. Lipschultz, A. Listopad, X. Litaudon, E. Litherland Smith, D. Liuzza, T. Loarer, P.J. Lomas, J. Lombardo, N. Lonigro, R. Lorenzini, C. Lowry, T. Luda di Cortemiglia, A. Ludvig Osipov, T. Lunt, V. Lutsenko, E. Macusova, R. Mäenpää, P. Maget, C.F. Maggi, J. Mailloux, S. Makarov, K. Malinowski, P. Manas, A. Mancini, D. Mancini, P. Mantica, M. Mantsinen, J. Manyer, M. Maraschek, G. Marceca, G. Marcer, C. Marchetto, S. Marchioni, A. Mariani, M. Marin, M. Markl, T. Markovic, D. Marocco, S. Marsden, L. Martellucci, P. Martin, C. Martin, F. Martinelli, L. Martinelli, J.R. Martin Solis, R. Martone, M. Maslov, R. Masocco, M. Mattei, G.F. Matthews, D. Matveev, E. Matveeva, M.L. Mayoral, D. Mazon, S. Mazzi, C. Mazzotta, G. McArdle, R. McDermott, K. McKay, A.G. Meigs, C. Meineri, A. Mele, V. Menkovski, S. Menmuir, A. Merle, H. Meyer, K. Mikszuta Michalik, D. Milanesio, F. Militello, A. Milocco, I.G. Miron, J. Mitchell, R. Mitteau, V. Mitterauer, J. Mlynar, V. Moiseenko, P. Molna, F. Mombelli, C. Monti, A. Montisci, J. Morales, P. Moreau, J.M. Moret, A. Moro, D. Moulton, P. Mulholland, M. Muraglia, A. Murari, A. Muraro, P. Muscente, D. Mykytchuk, F. Nabais, Y. Nakeva, F. Napoli, E. Nardon, M.F. Nave, R.D. Nem, A. Nielsen, S.K. Nielsen, M. Nocente, R. Nouailletas, S. Nowak, H. Nyström, R. Ochoukov, N. Offeddu, S. Olasz, C. Olde, F. Oliva, D. Oliveira, H.J.C. Oliver, P. Ollus, J. Ongena, F.P. Orsitto, N. Osborne, R. Otin, P. Oyola Dominguez, D.I. Palade, S. Palomba, O. Pan, N. Panadero, E. Panontin, A. Papadopoulos, P. Papagiannis, G. Papp, V.V. Parail, C. Pardanaud, J. Parisi, A. Parrott, K. Paschalidis, M. Passoni, F. Pastore, A. Patel, B. Patel, A. Pau, G. Pautasso, R. Pavlichenko, E. Pawelec, B. Pegourie, G. Pelka, E. Peluso, A. Perek, E. Perelli Cippo, C. Perez Von Thun, P. Petersson, G. Petravich, Y. Peysson, V. Piergotti, L. Pigatto, C. Piron, L. Piron, A. Pironti, F. Pisano, U. Plank, B. Ploeckl, V. Plyusnin, A. Podolnik, Y. Poels, G. Pokol, J. Poley, G. Por, M. Poradzinski, F. Porcelli, L. Porte, C. Possieri, A. Poulsen, I. Predebon, G. Pucella, M. Pueschel, P. Puglia, O. Putignano, T. Pütterich, V. Quadri, A. Quercia, M. Rabinski, L. Radovanovic, R. Ragona, H. Raj, M. Rasinski, J. Rasmussen, G. Ratta, S. Ratynskaia, R. Rayaprolu, M. Rebai, A. Redl, D. Rees, D. Refy, M. Reich, H. Reimerdes, B.C.G. Reman, O. Renders, C. Reux, D. Ricci, M. Richou, S. Rienacker, D. Rigamonti, F. Rigollet, F.G. Rimini, D. Ripamonti, N. Rispoli, N. Rivals, J.F. Rivero Rodriguez, C. Roach, G. Rocchi, S. Rode, P. Rodrigues, J. Romazanov, C.F. Romero Madrid, J. Rosato, R. Rossi, G. Rubino, J. Rueda Rueda, J. Ruiz Ruiz, P. Ryan, D. Ryan, S. Saarelma, R. Sabot, M. Salewski, A. Salmi, L. Sanchis, A. Sand, J. Santos, K. Särkimäki, M. Sassano, O. Sauter, G. Schettini, S. Schmuck, P. Schneider, N. Schoonheere, R. Schramm, R. Schrittwieser, C. Schuster, N. Schwarz, F. Sciortino, M. Scotto D’Abusco, S. Scully, A. Selce, L. Senni, M. Senstius, G. Sergienko, S.E. Sharapov, R. Sharma, A. Shaw, U. Sheikh, G. Sias, B. Sieglin, S.A. Silburn, C. Silva, A. Silva, D. Silvagni, B. Simmendefeldt Schmidt, L. Simons, J. Simpson, L. Singh, S. Sipilä, Y. Siusko, S. Smith, A. Snicker, E.R. Solano, V. Solokha, M. Sos, C. Sozzi, F. Spineanu, G. Spizzo, M. Spolaore, L. Spolladore, C. Srinivasan, A. Stagni, Z. Stancar, G. Stankunas, J. Stober, P. Strand, C.I. Stuart, F. Subba, G.Y. Sun, H.J. Sun, W. Suttrop, J. Svoboda, T. Szepesi, G. Szepesi, B. Tal, T. Tala, P. Tamain, G. Tardini, M. Tardocchi, D. Taylor, G. Telesca, A. Tenaglia, A. Terra, D. Terranova, D. Testa, C. Theiler, E. Tholerus, B. Thomas, E. Thoren, A. Thornton, A. Thrysoe, Q. TICHIT, W. Tierens, A. Titarenko, P. Tolias, E. Tomasina, M. Tomes, E. Tonello, A. Tookey, M. Toscano Jiménez, C. Tsironis, C. Tsui, A. Tykhyy, M. Ugoletti, M. Usoltseva, D.F. Valcarcel, A. Valentini, M. Valisa, M. Vallar, M. Valovic, SI. Valvis, M. van Berkel, D. Van Eester, S. Van Mulders, M. van Rossem, R. Vann, B. Vanovac, J. Varela Rodriguez, J. Varje, S. Vartanian, M. Vecsei, L. Velarde Gallardo, M. Veranda, T. Verdier, G. Verdoolaege, K. Verhaegh, L. Vermare, G. Verona Rinati, J. Vicente, E. Viezzer, L. Vignitchouk, F. Villone, B. Vincent, P. Vincenzi, M.O. Vlad, G. Vogel, I. Voitsekhovitch, I. Voldiner, P. Vondracek, N.M.T. VU, T. Vuoriheimo, C. Wade, E. Wang, T. Wauters, M. Weiland, H. Weisen, N. Wendler, D. Weston, A. Widdowson, S. Wiesen, M. Wiesenberger, T. Wijkamp, M. Willensdorfer, T. Wilson, A. Wojenski, C. Wuethrich, I. Wyss, L. Xiang, S. Xu, D. Yadykin, Y. Yakovenko, H. Yang, V. Yanovskiy, R. Yi, B. Zaar, G. Zadvitskiy, L. Zakharov, P. Zanca, D. Zarzoso, Y. Zayachuk, J. Zebrowski, M. Zerbini, P. Zestanakis, C. F. B. Zimmermann, M. Zlobinski, A. Zohar, V.K. Zotta, X. Zou, M. Zuin, M. Zurita, and I. Zychor

Subjects
JET, ASDEX Upgrade, MAST-U, TCV, WEST, Tokamak Exploitation Task Force, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Within the 9th European Framework programme, since 2021 EUROfusion is operating five tokamaks under the auspices of a single Task Force called ‘Tokamak Exploitation’. The goal is to benefit from the complementary capabilities of each machine in a coordinated way and help in developing a scientific output scalable to future largre machines. The programme of this Task Force ensures that ASDEX Upgrade, MAST-U, TCV, WEST and JET (since 2022) work together to achieve the objectives of Missions 1 and 2 of the EUROfusion Roadmap: i) demonstrate plasma scenarios that increase the success margin of ITER and satisfy the requirements of DEMO and, ii) demonstrate an integrated approach that can handle the large power leaving ITER and DEMO plasmas. The Tokamak Exploitation task force has therefore organized experiments on these two missions with the goal to strengthen the physics and operational basis for the ITER baseline scenario and for exploiting the recent plasma exhaust enhancements in all four devices (PEX: Plasma EXhaust) for exploring the solution for handling heat and particle exhaust in ITER and develop the conceptual solutions for DEMO. The ITER Baseline scenario has been developed in a similar way in ASDEX Upgrade, TCV and JET. Key risks for ITER such as disruptions and run-aways have been also investigated in TCV, ASDEX Upgrade and JET. Experiments have explored successfully different divertor configurations (standard, super-X, snowflakes) in MAST-U and TCV and studied tungsten melting in WEST and ASDEX Upgrade. The input from the smaller devices to JET has also been proven successful to set-up novel control schemes on disruption avoidance and detachment.

Published
2024
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2. 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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3. Multi-pellet injection into the NBI-heated phase of TJ-II plasmas

Author

K.J. McCarthy, I. García-Cortés, J.A. Alonso, A. Arias-Camisón, E. Ascasíbar, A. Baciero, A. Cappa, R. Carrasco, O.O. Chmyga, T. Estrada, R. García, J. Hernández-Sánchez, F.J. Hernanz, O.S. Kozachok, B. López Miranda, F. Medina, D. Medina-Roque, B. van Milligen, M. Navarro, M.A. Ochando, J.L. de Pablos, N. Panadero, I. Pastor, J. de la Riva, M. C. Rodríguez, D. Tafalla, V. Tribaldos, and TJ-II Team

Subjects
stellarator, pellet, confinement, operational regime, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

A pellet-induced enhanced confinement (PiEC) phase, with general characteristics similar to those reported for the stellarator W7-X, is observed after single pellet injection (>10 ^19 H atoms) into the neutral beam injection heated phase of plasmas in the mid-sized heliac-type stellarator TJ-II. In addition to a step-like increase in density, plasma diamagnetic energy content rises significantly with respect to that of reference discharges, energy confinement time is similarly enhanced when compared to International Stellarator Scaling law predictions (Yamada et al 2005 Nucl. Fusion 45 1684) renormalized for TJ-II, and the triple product, n _e · T _i · τ _E , exhibits a clear bifurcation towards an improved confinement branch when compared to the branch product predicted by the same law. In this work, multiple pellets are injected in series into NBI-heated plasmas in the TJ-II and post-injection plasma performance is reported and discussed. For instance, a charge-exchange recombination spectroscopy diagnostic reveals significantly increased core ion temperatures after pellet injection compared to temperatures achieved in comparable reference plasmas, this pointing to increased ion energy content and improved ion energy confinement during a PiEC phase. It is also found that enhanced performance is independent of whether co- or counter-NBI heating beam is employed. Finally, record stored diamagnetic energy content and plasma beta values are achieved when the largest available pellets are employed. The results indicate that pellet injections extend the operational regime well beyond limits previously achieved in TJ-II without pellets.

Published
2024
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4. Electrostatic microturbulence in W7-X: comparison of local gyrokinetic simulations with Doppler reflectometry measurements

Author

A. González-Jerez, J.M. García-Regaña, I. Calvo, D. Carralero, T. Estrada, E. Sánchez, M. Barnes, and the W7-X Team

Subjects
stellarator, gyrokinetic simulations, plasma turbulence, Doppler reflectometry, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

The first experimental campaigns of Wendelstein 7-X (W7-X) have shown that turbulence plays a decisive role in the performance of neoclassically optimized stellarators. This stresses the importance of understanding microturbulence from the theoretical and experimental points of view. To this end, this paper addresses a comprehensive characterization of the turbulent fluctuations by means of nonlinear gyrokinetic simulations performed with the code stella in two W7-X scenarios. In the first part of the paper, the amplitude of the density fluctuations is calculated and compared with measurements obtained by Doppler reflectometry (DR) in the OP1 experimental campaigns. It is found that the trend of the fluctuations along the radius is explained by the access of the DR system to different regions of the turbulence wavenumber spectrum. In the second part of the article, frequency spectra of the density fluctuations and the zonal component of the turbulent flow are numerically characterized for comparisons against future experimental analyses. Both quantities feature broad frequency spectra with dominant frequencies of O(1)–O(10) kHz.

Published
2024
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5. Density profiles in stellarators: an overview of particle transport, fuelling and profile shaping studies at TJ-II

Author

J.A. Alonso, D. Alegre, J. Alonso, R. Antón, A. Arias-Camisón, E. Ascasíbar, A. Baciero, J.M. Barcala, M. Barnes, E. Blanco, L. Bueno, A. Bustos, S. Cabrera, E. de la Cal, I. Calvo, A. Cappa, D. Carralero, R. Carrasco, B. Carreras, R. Castro, A. de Castro, L. Cebrián, M. Chamorro, A.A. Chmyga, P. Colino, J. Duque, F.J. Escoto, T. Estrada, A. Fernández, J. Fraguas, J.M. Fontdecaba, A. Gabriel, L. García, I. García-Cortés, R. García-Gómez, J.M. García-Regaña, G. Godino-Sedano, J. Gómez-Manchón, A. González, A. González-Jerez, V. Guisse, J. Hernández-Sánchez, J. Hernanz, C. Hidalgo, P. Ivanova, A. Jiménez-Denche, D. Jiménez-Rey, G. Kocsis, M. Koepke, A.S. Kozachek, F. Lapayese, M. Liniers, D. López, D. López-Bruna, B. López-Miranda, E. de la Luna, E. Maragkoudakis, F. Martín-Díaz, G. Martín-Gómez, J. Martínez-Fernández, K.J. McCarthy, F. Medina, D. Medina-Roque, M. Medrano, P. Méndez, F.J. Miguel, B. van Milligen, A. Molinero, G. Motojima, S. Mulas, M. Navarro, I. Nedzelskiy, R. Nuñez, M. Ochando, E. Oyarzábal, J.L. de Pablos, F. Palomares, N. Panadero, F.I. Parra, C. Pastor, I. Pastor, A. de la Peña, R. Peralta, A. Pereira, P. Pons-Villalonga, A.B. Portas, E. Poveda, F.J. Ramos, G.A. Rattá, M. Redondo, C. Reynoso, E. Rincón, J. de la Riva, C. Rodríguez-Fernández, A. Ros, E. Sánchez, J. Sánchez, E. Sánchez-Sarabia, J.A. Sebastián, E.R. Solano, A. Soleto, T. Szepesi, F.L. Tabarés, D. Tafalla, H. Takahashi, N. Tamura, H. Thienpondt, A. Tolkachev, V. Tribaldos, R. Unamuno, J. Varela, J. Vega, J.L. Velasco, and I. Voldiner

Subjects
particle transport, fuelling, cryogenic pellet injection, stellarator, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

We provide an overview of activities carried out at the TJ-II stellarator for improving our understanding of- and developing plasma physics models for particle density profiles in stellarators. Namely, we report on recent progress in turbulent particle transport simulation, validation of pellet deposition models, density profile shaping for performance control and new experimental techniques for edge turbulence and plasma-neutral interaction.

Published
2024
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6. Validating neutral-beam current drive simulations in the TJ-II stellarator

Author

S. Mulas, Á. Cappa, J. Martínez-Fernández, D. López Bruna, J.L. Velasco, T. Estrada, J.M. Gómez-Manchón, M. Liniers, K.J. McCarthy, I. Pastor, F. Medina, E. Ascasíbar, and TJ–II Team

Subjects
neutral beam current drive, stellarator, ASCOT, TJ-II, validation, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

In this paper, we analyze the results of neutral-beam current drive (NBCD) experiments performed in the TJ-II stellarator with the aim of validating the theoretical predictions. Both parallel and anti-parallel injection with respect to the magnetic field were explored using co (NBI1) and counter (NBI2) beams at different injected beam power and plasma densities. The fast-ion current driven by both beams was simulated with the Monte Carlo code ASCOT and the electron response to the fast-ion current was calculated analytically using a model valid for an arbitrary magnetic configuration and a low collisionality plasma. Despite the uncertainties associated to the determination of experimental inputs, the model reproduces with rather good agreement the toroidal current measured in NBI2 plasmas. However, the current driven by NBI1 is less than half the predicted one. Possible reasons for this discrepancy are discussed. Among the probable causes, yet to be studied, the most likely is the increased presence of lithium in the plasma when NBI1 is injected, this being the result of its irregular deposition during wall conditioning.

Published
2023
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7. 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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8. Overview of the TJ-II stellarator research programme towards model validation in fusion plasmas

Author

C. Hidalgo, E. Ascasíbar, D. Alegre, A. Alonso, J. Alonso, R. Antón, A. Baciero, J. Baldzuhn, J.M. Barcala, L. Barrera, E. Blanco, J. Botija, L. Bueno, S. Cabrera, A. de Castro, E. de la Cal, I. Calvo, A. Cappa, D. Carralero, R. Carrasco, B. Carreras, R. Castro, L. Cebrián, A.A. Chmyga, M. Chamorro, P. Colino, F. de Aragón, M. Drabinskiy, J. Duque, L. Eliseev, F.J. Escoto, T. Estrada, M. Ezzat, F. Fraguas, D. Fernández-Ruiz, J.M. Fontdecaba, A. Gabriel, D. Gadariya, L. García, I. García-Cortés, R. García-Gómez, J.M. García-Regaña, A. González-Jerez, G. Grenfell, J. Guasp, V. Guisse, J. Hernández-Sánchez, J. Hernanz, A. Jiménez-Denche, P. Khabanov, N. Kharchev, R. Kleiber, F. Koechl, T. Kobayashi, G. Kocsis, M. Koepke, A.S. Kozachek, L. Krupnik, F. Lapayese, M. Liniers, B. Liu, D. López-Bruna, B. López-Miranda, U. Losada, E. de la Luna, S.E. Lysenko, F. Martín-Díaz, G. Martín-Gómez, E. Maragkoudakis, J. Martínez-Fernández, K.J. McCarthy, F. Medina, M. Medrano, A.V. Melnikov, P. Méndez, F.J. Miguel, B. van Milligen, A. Molinero, G. Motojima, S. Mulas, Y. Narushima, M. Navarro, I. Nedzelskiy, R. Nuñez, M. Ochando, S. Ohshima, E. Oyarzábal, J.L. de Pablos, F. Palomares, N. Panadero, F. Papoušek, F. Parra, C. Pastor, I. Pastor, A. de la Peña, R. Peralta, A. Pereira, P. Pons-Villalonga, H. Polaino, A.B. Portas, E. Poveda, F.J. Ramos, G.A. Rattá, M. Redondo, C. Reynoso, E. Rincón, C. Rodríguez-Fernández, L. Rodríguez-Rodrigo, A. Ros, E. Sánchez, J. Sánchez, E. Sánchez-Sarabia, S. Satake, J.A. Sebastián, R. Sharma, N. Smith, C. Silva, E.R. Solano, A. Soleto, M. Spolaore, T. Szepesi, F.L. Tabarés, D. Tafalla, H. Takahashi, N. Tamura, H. Thienpondt, A. Tolkachev, R. Unamuno, J. Varela, J. Vega, J.L. Velasco, I. Voldiner, S. Yamamoto, null the TJ-II Team, and TJ-II Team

Subjects
Physics, Nuclear and High Energy Physics, Nuclear engineering, Fusion plasma, Condensed Matter Physics, law.invention, Model validation, stellarator, law, Physics::Plasma Physics, Physics::Space Physics, transport, Stellarator, plasma
Abstract

TJ-II stellarator results on modelling and validation of plasma flow asymmetries due to on-surface potential variations, plasma fuelling physics, Alfvén eigenmodes (AEs) control and stability, the interplay between turbulence and neoclassical (NC) mechanisms and liquid metals are reported. Regarding the validation of the neoclassically predicted potential asymmetries, its impact on the radial electric field along the flux surface has been successfully validated against Doppler reflectometry measurements. Research on the physics and modelling of plasma core fuelling with pellets and tracer encapsulated solid pellet injection has shown that, although post-injection particle radial redistributions can be understood qualitatively from NC mechanisms, turbulence and fluctuations are strongly affected during the ablation process. Advanced analysis tools based on transfer entropy have shown that radial electric fields do not only affect the radial turbulence correlation length but are also capable of reducing the propagation of turbulence from the edge into the scrape-off layer. Direct experimental observation of long range correlated structures show that zonal flow structures are ubiquitous in the whole plasma cross-section in the TJ-II stellarator. Alfvénic activity control strategies using ECRH and ECCD as well as the relation between zonal structures and AEs are reported. Finally, the behaviour of liquid metals exposed to hot and cold plasmas in a capillary porous system container was investigated.

Published
2022
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9. 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. Hansen, J.H. Harris, H. Hartfuß, D. Hartmann, D. Hathiramani, R. Hatzky, J. Hawke, S. Hegedus, B. Hein, B. Heinemann, P. Helander, S. Henneberg, U. Hergenhahn, C. Hidalgo, F. Hindenlang, M. Hirsch, U. Höfel, K.P. Hollfeld, A. Holtz, D. Hopf, D. Höschen, M. Houry, J. Howard, X. Huang, M. Hubeny, S. Hudson, K. Ida, Y. Igitkhanov, V. Igochine, S. Illy, C. Ionita-Schrittwieser, M. Isobe, M. Jabłczyńska, S. Jablonski, B. Jagielski, M. Jakubowski, A. Jansen van Vuuren, J. Jelonnek, F. Jenko, T. Jensen, H. Jenzsch, P. Junghanns, J. Kaczmarczyk, J. Kallmeyer, U. Kamionka, M. Kandler, S. Kasilov, Y. Kazakov, D. Kennedy, A. Kharwandikar, M. Khokhlov, C. Kiefer, C. Killer, A. Kirschner, R. Kleiber, T. Klinger, S. Klose, J. Knauer, A. Knieps, F. Köchl, G. Kocsis, Ya.I. Kolesnichenko, A. Könies, R. König, J. Kontula, P. Kornejew, J. Koschinsky, M.M. Kozulia, A. Krämer-Flecken, R. Krampitz, M. Krause, N. Krawczyk, T. Kremeyer, L. Krier, D.M. Kriete, M. Krychowiak, I. Ksiazek, M. Kubkowska, M. 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. Ogawa, S. Okamura, J. Ölmanns, J. Ongena, J. Oosterbeek, M. Otte, N. Pablant, N. Panadero Alvarez, A. Pandey, E. Pasch, R. Pavlichenko, A. Pavone, E. Pawelec, G. Pechstein, G. Pelka, V. Perseo, B. Peterson, D. Pilopp, S. Pingel, F. Pisano, B. Plöckl, G. Plunk, P. Pölöskei, B. Pompe, A. Popov, M. Porkolab, J. Proll, M.J. Pueschel, M.-E. Puiatti, A. Puig Sitjes, F. Purps, K. Rahbarnia, M. Rasiński, J. Rasmussen, A. Reiman, F. Reimold, M. Reisner, D. Reiter, M. Richou, R. Riedl, J. Riemann, K. Riße, G. Roberg-Clark, V. Rohde, J. Romazanov, D. Rondeshagen, P. Rong, L. Rudischhauser, T. Rummel, K. Rummel, A. Runov, N. Rust, L. Ryc, P. Salembier, M. Salewski, E. Sanchez, S. Satake, G. Satheeswaran, J. Schacht, E. Scharff, F. Schauer, J. Schilling, G. Schlisio, K. Schmid, J. Schmitt, O. Schmitz, W. Schneider, M. Schneider, P. Schneider, R. Schrittwieser, T. Schröder, M. Schröder, R. Schroeder, B. Schweer, D. Schwörer, E. Scott, B. Shanahan, G. Sias, P. Sichta, M. Singer, P. Sinha, S. Sipliä, C. Slaby, M. Sleczka, H. Smith, J. Smoniewski, E. Sonnendrücker, M. Spolaore, A. Spring, R. Stadler, D. Stańczak, T. Stange, I. Stepanov, L. Stephey, J. Stober, U. Stroth, E. Strumberger, C. Suzuki, Y. Suzuki, J. Svensson, T. Szabolics, T. Szepesi, M. Szücs, F.L. Tabarés, N. Tamura, A. Tancetti, C. Tantos, J. Terry, H. Thienpondt, H. Thomsen, M. Thumm, J.M. Travere, P. Traverso, J. Tretter, E. Trier, H. Trimino Mora, T. Tsujimura, Y. Turkin, A. Tykhyi, B. Unterberg, P. van Eeten, B.Ph. van Milligen, M. van Schoor, L. Vano, S. Varoutis, M. Vecsei, L. Vela, J.L. Velasco, M. Vervier, N. Vianello, H. Viebke, R. Vilbrandt, G. Vogel, N. Vogt, C. Volkhausen, A. von Stechow, F. Wagner, E. Wang, H. Wang, F. Warmer, T. Wauters, L. Wegener, T. Wegner, G. Weir, U. Wenzel, A. White, F. Wilde, F. Wilms, T. Windisch, M. Winkler, A. Winter, V. Winters, R. Wolf, A.M. Wright, G.A. Wurden, P. Xanthopoulos, S. Xu, H. Yamada, H. Yamaguchi, M. Yokoyama, M. Yoshinuma, Q. Yu, M. Zamanov, M. 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. Maisano-Brown3, O. Maj8, D. Makowski49, G. Manduchi50, E. Maragkoudakis6, O. Marchuk17, S. Marsen1, E. Martines4, J. Martinez-Fernandez6, M. Marushchenko1, S. Masuzaki41, D. Maurer5, M. Mayer8, K.J. McCarthy6, O. Mccormack4, P. McNeely1, H. Meister8, B. Mendelevitch8, S. Mendes1, A. Merlo1, A. Messian26, A. Mielczarek49, O. Mishchenko1, B. Missal1, R. Mitteau9, V.E. Moiseenko14, A. Mollen1, V. Moncada9, T. Mönnich1, T. Morisaki41, D. Moseev1, G. Motojima41, S. Mulas6, M. Mulsow1, M. Nagel1, D. Naujoks1, V. Naulin35, T. Neelis19, H. Neilson29, R. Neu8, O. Neubauer17, U. Neuner1, D. Nicolai17, S.K. Nielsen35, H. Niemann1, T. Nishiza1, T. Nishizawa1, T. Nishizawa8, C. Nührenberg1, R. Ochoukov8, J. Oelmann17, G. Offermanns17 K. Ogawa41, S. Okamura41, J. Ölmanns17, J. Ongena26, J. Oosterbeek1, M. Otte1, N. Pablant29, N. Panadero Alvarez6, N. Panadero Alvarez6, A. Pandey1, E. Pasch1, R. Pavlichenko14, A. Pavone1, E. Pawelec46, G. Pechstein1, G. Pelka24, V. Perseo1, B. Peterson41, D. Pilopp1, S. Pingel1, F. Pisano11, B. Plöckl8, G. Plunk1, P. Pölöskei1, B. Pompe2, A. Popov51, M. Porkolab3, J. Proll19, M.J. Pueschel19,27, M.-E. Puiatti52, A. Puig Sitjes1, F. Purps1, K. Rahbarnia1, M. Rasinski ´ 17, J. Rasmussen35, A. Reiman29, F. Reimold1, M. Reisner8, D. Reiter17, M. Richou9, R. Riedl8, J. Riemann1, K. Riße1, G. Roberg-Clark1, V. Rohde8, J. Romazanov17, D. Rondeshagen1, P. Rong1, L. Rudischhauser1, T. Rummel1, K. Rummel1, A. Runov1, N. Rust1, L. Ryc24, P. Salembier20, M. Salewski35, E. Sanchez6, S. Satake41, G. Satheeswaran17, J. Schacht1, E. Scharff1, F. Schauer8, J. Schilling1, G. Schlisio1, K. Schmid8, J. Schmitt5, O. Schmitz13, W. Schneider1, M. Schneider1, P. Schneider8, R. Schrittwieser42, T. Schröder1, M. Schröder1, R. Schroeder1, B. Schweer26, D. Schwörer1, E. Scott1, E. Scott8, B. Shanahan1, G. Sias11, P. Sichta29, M. Singer1, P. Sinha29, S. Sipliä34, C. Slaby1, M. Sleczka53, H. Smith1, J. Smoniewski54, E. Sonnendrücker8, M. Spolaore4, A. Spring1, R. Stadler8, D. Stanczak24, T. Stange1, I. Stepanov26, L. Stephey13, J. Stober8, U. Stroth8,55, E. Strumberger8, C. Suzuki41, Y. Suzuki41, J. Svensson1, T. Szabolics7, T. Szepesi7, M. Szücs7, F.L. Tabares6, N. Tamura41, A. Tancetti35, C. Tantos10, J. Terry3, H. Thienpondt6, H. Thomsen1, M. Thumm10, J.M. Travere9, P. Traverso5, J. Tretter8, E. Trier8, H. Trimino Mora1, T. Tsujimura41, Y. Turkin1, A. Tykhyi45, B. Unterberg17, P. van Eeten1, B.Ph. van Milligen6, M. van Schoor26, L. Vano1, S. Varoutis10, M. Vecsei7, L. Vela56, J.L. Velasco6, M. Vervier17, N. Vianello50, H. Viebke1, R. Vilbrandt1, G. Vogel8, N. Vogt1, C. Volkhausen1, A. von Stechow1, F. Wagner1, E. Wang17, H. Wang57, F. Warmer1, T. Wauters26, L. Wegener1, T. Wegner1, G. Weir1, U. Wenzel1, A. White3, F. Wilde1, F. Wilms1, T. Windisch1, M. Winkler1, A. Winter1, V. Winters1, R. Wolf118, A.M. Wright29, G.A. Wurden39, P. Xanthopoulos1, S. Xu17, H. Yamada58, H. Yamaguchi41, M. Yokoyama41, M. Yoshinuma41, Q. Yu8, M. Zamanov14, M. Zanini1, M. Zarnstorff29, D. Zhang1, S. Zhou17, J. Zhu1, C. Zhu29, M. Zilker8, A. Zocco1, H. Zohm8, S. Zoletnik7 and L. 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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10. 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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11. A feasibility study for a Doppler reflectometer system in the JT-60SA tokamak

Author

T. Tokuzawa, T. Happel, T. Estrada, E. de la Luna, A. Cappa, José Luis Martínez, D. Carralero, and J. Garcia

Subjects
Tokamak, Scope (project management), Computer science, Mechanical Engineering, Context (language use), Plan (drawing), 01 natural sciences, 010305 fluids & plasmas, law.invention, symbols.namesake, Nuclear Energy and Engineering, Installation, Conceptual design, law, 0103 physical sciences, Systems engineering, symbols, General Materials Science, Ray tracing (graphics), 010306 general physics, Doppler effect, Civil and Structural Engineering
Abstract

In this work we present a study on the viability and practicality of installing a Doppler reflectometer (DR) system in the JT-60SA advanced tokamak. First, we discuss its scientific scope in the context of the JT-60SA research plan. We identify a number of fields in which a DR would be very relevant for the accomplishment of said plan and outline a scientific program for the diagnostic. Then, starting from a number of design hypothesis, we use a ray tracing code to carry out a feasibility study for a number of relevant scenarios and identify a geometric solution for the installation of a DR such that both core and edge can be probed in the prescribed wave number range, thus achieving the proposed scientific objectives. Finally, we perform a preliminary discussion on the different possibilities for a conceptual design (including a minimum viable system and a baseline system) and their requirements in terms of components and space. We conclude that a viable conceptual design could be carried out using a small fraction of a horizontal port, leaving room for additional diagnostic systems.

Published
2021

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

Author

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

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

13. Confinement in Wendelstein 7-X limiter plasmas

Author

Andreas Langenberg, Olaf Grulke, M. Krychowiak, Fabio Pisano, R. Brakel, N. Krawczyk, Monika Kubkowska, E. Blanco, Hans-Stephan Bosch, P. Kornejew, M. Hirsch, T. Fornal, J. Baldzuhn, Tamás Szepesi, Tamara Andreeva, Matthias Otte, H. P. Laqua, N. A. Pablant, A. Werner, M. W. Jakubowski, Nikolai B. Marushchenko, T. Schröder, C. D. Beidler, E. Pasch, A. Czarnecka, Samuel Lazerson, V. Moncada, Yu. Turkin, Torsten Stange, Christoph Biedermann, M. Endler, R. Burhenn, Dirk Naujoks, S. Marsen, J. Geiger, J. H. Harris, H. Trimino Mora, T. Estrada, A. Cappa, Andreas Dinklage, B. Buttenschön, R. König, Dmitry Moseev, H. Thomsen, G. M. Weir, J. P. Knauer, H. Maaßberg, A. Alonso, G. A. Wurden, S. A. Bozhenkov, D. Zhang, Thomas Sunn Pedersen, U. Wenzel, Hayato Tsuchiya, M. N. A. Beurskens, Laurie Stephey, Tom Wauters, Kian Rahbarnia, Thomas Klinger, G. Kocsis, I. Ksiazek, D. A. Hartmann, U. Höfel, A. Krämer-Flecken, G. Fuchert, R. C. Wolf, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, stellarator, confinement, 0103 physical sciences, 010306 general physics, Condensed Matter Physics, 01 natural sciences, energy confinement, 010305 fluids & plasmas
Abstract

Observations on confinement in the first experimental campaign on the optimized Stellarator Wendelstein 7-X are summarized. In this phase W7-X was equipped with five inboard limiters only and thus the discharge length restricted to avoid local overheating. Stationary plasmas are limited to low densities

Published
2017
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14. The impact of edge radial electric fields on edge-scrape-off layer coupling in the TJ-II stellarator

Author

Carlos B. da Silva, C. Hidalgo, T. Estrada, Monica Spolaore, G. Grenfell, B. Ph. van Milligen, U. Losada, and B. Liu

Subjects
Physics, Coupling, turbulent transport processes, Nuclear and High Energy Physics, Condensed matter physics, Edge (geometry), Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, law, Electric field, 0103 physical sciences, stellarators, 010306 general physics, Layer (electronics), Stellarator, turbulence propagation
Published
2019
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15. 3D effects on transport and plasma control in the TJ-II stellarator

Author

G. Wolfers, E. Ascasíbar, F. Fernández-Marina, Javier Alonso, Macarena Liniers, F. Martín-Díaz, P. Méndez, A.S. Kozachoek, A. Cappa, Jesús Vega, E. Oyarzábal, K. Sarksian, María Sánchez, M. Medrano, J. Hernández, J. Botija, J. Martínez-Fernández, Marley Vanegas Chamorro, Isabel García-Cortés, B. Momo, K. J. McCarthy, A. Tolkachev, D. Alegre, A. Pereira, L. I. Krupnik, G. Velasco, R. Carrasco, Raul Moreno, Ivan Calvo, U. Losada, F. Medina, E. Sánchez, A.A. Chmyga, G. Martín-Gómez, J. Guasp, F. Castejón, F. J. Miguel, A. Jiménez-Denche, N. Panadero, M. Borchardt, Jesús Herranz, B. Rojo, A. Molinero, L.G. Eliseev, A. Alonso, R. García-Gómez, E. R. Solano, J. Olivares, T. Estrada, Roman Hatzky, M. A. Ochando, J.M. Barcala, R. Merino, F. Lapayese, J.A. Sebastián, Y. Narushima, Shinsuke Satake, L. Melón, E. Sánchez-Sarabia, I. Kirpitchev, A. Martin de Aguilera, A.D. Komarov, M. Martínez, A. de la Peña, F. Martín-Hernández, B. Liu, C. Hidalgo, G. Catalán, Francisco L. Tabarés, E. Rincón, A.B. Martín-Rojo, J. M. Garcia-Regana, B. J. Sun, B. van Milligen, S. Cabrera, J. Sánchez, S. Petrov, A. de Bustos, M. A. Pedrosa, C. Rodríguez, B. Zurro, J. Hernanz, Eric Hollmann, A. Ros, Carlos A. Silva, J.L. de Pablos, S. Tallents, Luis F. Pacios, Ralf Kleiber, A. de Castro, José Luis Velasco, Luis Rios, B. López-Miranda, I. Pastor, E. Poveda, A. E. Petrov, P. Monreal, J. López-Razola, Luis Garcia, G.A. Rattá, M. Navarro, D. López-Bruna, E. de la Cal, J. M. Fontdecaba, A. Portas, M. Yokoyama, D. Tafalla, E. de la Luna, A. Soleto, R. Castro, D. Baião, Andreas Dinklage, A. López-Fraguas, A.V. Melnikov, A. Baciero, E. Blanco, and I. S. Nedzelskiy

Subjects
Physics, Nuclear and High Energy Physics, Magnetic confinement fusion, Plasma confinement, Transport theory, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, Charged particle, 010305 fluids & plasmas, Ion, law.invention, law, Dispersion relation, 0103 physical sciences, Atomic physics, 010306 general physics, Stellarator, Plasma control
Abstract

The effects of 3D geometry are explored in TJ-II from two relevant points of view: neoclassical transport and modification of stability and dispersion relation of waves. Particle fuelling and impurity transport are studied considering the 3D transport properties, paying attention to both neoclassical transport and other possible mechanisms. The effects of the 3D magnetic topology on stability, confinement and Alfvén Eigenmodes properties are also explored, showing the possibility of controlling Alfvén modes by modifying the configuration; the onset of modes similar to geodesic acoustic modes are driven by fast electrons or fast ions; and the weak effect of magnetic well on confinement. Finally, we show innovative power exhaust scenarios using liquid metals.

Published
2017

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

Author

Oliver Schmitz, E. Pasch, S. A. Bozhenkov, O. P. Ford, Ireneusz Książek, J. Svensson, Robert Wolf, M. Endler, R. Burhenn, G. M. Weir, Dirk Naujoks, Florian Effenberg, L. Ryć, M. N. A. Beurskens, Olaf Grulke, T. Sunn Pedersen, G. A. Wurden, S. Marsen, Ulrich Neuner, S. Jablonski, S. C. Liu, T. Fornal, J. Baldzuhn, B. Schweer, Yunfeng Liang, Thomas Klinger, T. Schröder, B. Wiegel, Monika Kubkowska, D. A. Hartmann, Boyd Blackwell, J. P. Knauer, H. Thomsen, A. Dzikowicka, A. O. Marchuk, M. W. Jakubowski, G. Fuchert, H.-J. Hartfuß, Dag Hathiramani, Gábor Cseh, U. Wenzel, A. Adnan, Helmut Schuhmacher, N. A. Pablant, A. Alonso, B. Standley, Philipp Drews, J. Kaczmarczyk, Matthias Otte, T. Kremeyer, Christoph Biedermann, T. Szabolics, P. Kornejew, Hayato Tsuchiya, V. Erckmann, A. Werner, M. Krychowiak, S. Schmuck, N. Krawczyk, Laurie Stephey, D. Zhang, Hans-Stephan Bosch, J. W. Oosterbeek, V. Moncada, J.-M. Travere, B. Buttenschön, H. Neilson, T. Estrada, A. Cappa, A. Krämer-Flecken, Andreas Langenberg, U. Höfel, H. P. Laqua, Samuel Lazerson, T. Bräuer, M. Hirsch, Torsten Stange, R. König, Olaf Neubauer, Wendelstein X Team, B. B. Carvalho, S. Zoletnik, Holger Niemann, Andreas Zimbal, J. Geiger, T. Barbui, A. Lorenz, Andreas Dinklage, Heinke Frerichs, Wolfgang Biel, J. H. Harris, Martin Laux, Wolf-Dieter Schneider, Tamara Andreeva, A. Czarnecka, T. Windisch, S. Klose, H. Trimino Mora, Fabio Pisano, R. Brakel, Tamás Szepesi, G. Kocsis, Kian Rahbarnia, Science and Technology of Nuclear Fusion, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, business.industry, Plasma parameters, Instrumentation, Plasma, 01 natural sciences, Radiation zone, 010305 fluids & plasmas, law.invention, Optics, law, 0103 physical sciences, Limiter, ddc:530, Plasma diagnostics, Wendelstein 7-X, 010306 general physics, business, Stellarator
Abstract

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.

Published
2016
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17. The set of diagnostics for the first operation campaign of the Wendelstein 7-X stellarator

Author

S. Jablonski, H. P. Laqua, S. Klose, S. A. Bozhenkov, H. Thomsen, Andreas Langenberg, Olaf Grulke, V. Moncada, Helmut Schuhmacher, Ralf König, Torsten Stange, T. Estrada, P. Kornejew, Matthias Otte, G. A. Wurden, Wolf-Dieter Schneider, B. Buttenschön, A. Werner, E. Pasch, L. Ryć, Yunfeng Liang, Tamás Szepesi, A. Czarnecka, M. Hirsch, Ulrich Neuner, Wolfgang Biel, M. Krychowiak, Olaf Neubauer, S. Zoletnik, Oliver Schmitz, B. B. Carvalho, M. W. Jakubowski, J. Baldzuhn, T. Kremeyer, Hans-Stephan Bosch, A. Zimbal, T. Windisch, Gábor Cseh, J. Geiger, B. Wiegel, Robert Wolf, M. Endler, R. Burhenn, A. Lorenz, Thomas Sunn Pedersen, Christoph Biedermann, J. Kaczmarczyk, A. O. Marchuk, Martin Laux, U. Wenzel, N. A. Pablant, G. Kocsis, T. Bräuer, B. Schweer, Monika Kubkowska, V. Erckmann, Kian Rahbarnia, J. W. Oosterbeek, D. Zhang, J.-M. Travere, Thomas Klinger, Dag Hathiramani, D. A. Hartmann, A. Krämer-Flecken, Science and Technology of Nuclear Fusion, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Heating power, business.industry, Plasma parameters, Nuclear engineering, Nuclear instruments and methods for hot plasma diagnostics, Electrical engineering, 01 natural sciences, 010305 fluids & plasmas, law.invention, Plasma diagnostics - interferometry, spectroscopy and imaging, law, 0103 physical sciences, Plasma diagnostics - interferometry, spectroscopy and imaging, Limiter, Plasma diagnostics, Plasma diagnostics - probes, Wendelstein 7-X, 010306 general physics, business, Instrumentation, Mathematical Physics, Stellarator
Abstract

Wendelstein 7-X (W7-X) is a large optimized stellarator (B=2.5T, V=30m3) aiming at demonstrating the reactor relevance of the optimized stellarators. In 2015 W7-X will begin its first operation phase (OP1.1) with five inertially cooled inboard limiters made of graphite. Assuming the heat loads can be spread out evenly between the limiters, 1 second discharges at 2 MW of ECRH heating power could be run in OP1.1. The expected plasma parameters will be sufficient to demonstrate the readiness of the installed diagnostics and even to run a first physics program. The diagnostics available for this first operation phase, including some special limiter diagnostics, and their capabilities are being presented. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

Published
2015

18. Towards an emerging understanding of non-locality phenomena and non-local transport

Author

Zhongbing Shi, Satoru Sugita, Mikio Yoshinuma, S. Oldenbürger, X.L. Zou, Kensaku Kamiya, C. Hidalgo, Jiaqi Dong, Özgür D. Gürcan, T. Kobayashi, Xuantong Ding, H. J. Sun, A. R. Field, Patrick Diamond, Min Jiang, Sang-hee Hahn, S.-I. Itoh, Suk-Ho Hong, You-Moon Jeon, Yoshiteru Sakamoto, Katsumi Ida, Shigeru Inagaki, T.S. Hahm, Kimitaka Itoh, John Rice, Guilhem Dif-Pradalier, Yusuke Kosuga, Naoki Tamura, T. Estrada, 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)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), 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), Massachusetts Institute of Technology. Plasma Science and Fusion Center, and Rice, John E

Subjects
Physics, Nuclear and High Energy Physics, Fluids & Plasmas, Theoretical models, Molecular, Condensed Matter Physics, Space (mathematics), Non local, Atomic, Momentum, Quantum nonlocality, Particle and Plasma Physics, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], transport, Nuclear, non-local, Statistical physics, Transport phenomena, plasma
Abstract

In this paper, recent progress on experimental analysis and theoretical models for non-local transport (non-Fickian fluxes in real space) is reviewed. The non-locality in the heat and momentum transport observed in the plasma, the departures from linear flux-gradient proportionality, and externally triggered non-local transport phenomena are described in both L-mode and improved-mode plasmas. Ongoing evaluation of 'fast front' and 'intrinsically non-local' models, and their success in comparisons with experimental data, are discussed, United States. Department of Energy (Contract DE-FC02-99ER54512)

Published
2015
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19. Causality detection and turbulence in fusion plasmas

Author

B. Ph. van Milligen, G. Birkenmeier, Mirko Ramisch, T. Estrada, C. Hidalgo, and A. Alonso

Subjects
Physics, Nuclear and High Energy Physics, Work (thermodynamics), Turbulence, Fusion plasma, FOS: Physical sciences, Zonal flow (plasma), Fusion power, Condensed Matter Physics, Physics - Plasma Physics, Plasma Physics (physics.plasm-ph), Causality (physics), Nonlinear system, Amplitude, Physics::Plasma Physics, Statistical physics
Abstract

This work explores the potential of an information-theoretical causality detection method for unraveling the relation between fluctuating variables in complex nonlinear systems. The method is tested on some simple though nonlinear models, and guidelines for the choice of analysis parameters are established. Then, measurements from magnetically confined fusion plasmas are analyzed. The selected data bear relevance to the all-important spontaneous confinement transitions often observed in fusion plasmas, fundamental for the design of an economically attractive fusion reactor. It is shown how the present method is capable of clarifying the interaction between fluctuating quantities such as the turbulence amplitude, turbulent flux, and Zonal Flow amplitude, and uncovers several interactions that were missed by traditional methods., 26 pages, 14 figures

Published
2013

20. Spatio-temporal evolution of the H -> L back transition

Author

Özgür D. Gürcan, George Tynan, Patrick Diamond, K. Miki, T. Estrada, D. C. McDonald, L. W. Schmitz, 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), and 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)

Subjects
Physics, Condensed matter physics, Turbulence, Prandtl number, Mechanics, Condensed Matter Physics, 01 natural sciences, Nusselt number, 010305 fluids & plasmas, Temperature gradient, symbols.namesake, Hysteresis, Pedestal, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, Zonal flow, symbols, Electron temperature, 010306 general physics
Abstract

International audience; Since ITER will operate close to threshold and with limited control, the H → L back transition is a topic important for machine operations as well as physics. Using a reduced mesoscale model [Miki et al., Phys. Plasmas 19, 092306 (2012)], we investigate ELM-free H → L back transition dynamics in order to isolate transport physics effects. Model studies indicate that turbulence spreading is the key process which triggers the back transition. The transition involves a feedback loop linking turbulence and profiles. The I-phase appears during the back transition following a slow power ramp down, while fast ramp-downs reveal a single burst of zonal flow during the back transition. The I-phase nucleates at the pedestal shoulder, as this is the site of the residual turbulence in H-mode. Hysteresis in the profile gradient scale length is characterized by the Nusselt number, where Nu = χi,turb/χi,neo. Relative hysteresis of temperature gradient vs density gradient is sensitive to the pedestal Prandtl number, where Prped = Dped/χi,neo. We expect the H-mode to be somewhat more resilient in density than in temperature.

Published
2013
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21. Stabilization of energetic-ion-driven MHD modes by ECCD in Heliotron J

Author

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

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

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

Published
2013

22. Dynamics of flows and confinement in the TJ-II stellarator

Author

Juan Miguel Insúa Arévalo, Enrique Ascasibar, S. Petrov, A. Martin, M. A. Pedrosa, L. I. Krupnik, A. Cappa, E. Oyarzábal, E. Sánchez, R. Carrasco, J. Hernández, E. R. Solano, A. E. Petrov, A. S. Kozachok, A.D. Komarov, Ralf Kleiber, J. López-Razola, D. López-Bruna, A. Tolkachev, M. Sánchez, E. Sánchez-Sarabia, A. de la Peña, G. Velasco, Kieran J. McCarthy, J.A. Sebastián, A. Soleto, Roman Hatzky, J. Vega, M. Navarro, J. Hernanz, M. A. Ochando, C. Hidalgo, D. Tafalla, P. Méndez, I. Kirpitchev, José Luis Velasco, B. J. Sun, I.S. Nedzelskiy, Luis Garcia, F. Martín-Hernández, J. Martínez-Fernández, M. Medrano, I. Pastor, Carlos A. Silva, Marley Vanegas Chamorro, M. Borchardt, J.A. Jiménez, A. Pereira, C. Rodríguez, A. Baciero, P. Álvarez, P. Monreal, F. Fernández, K. Sarksian, A. Alonso, L. Ríos, J. Herranz, Francisco L. Tabarés, P. García-Sánchez, F. Lapayese, R. García-Gómez, A. Bustos, A. Jiménez-Denche, D. Carralero, D. Alegre, B. van Milligen, J. Sánchez, L. Pacios, M. Tereshchenko, L.G. Eliseev, J. Olivares, L. Melón, A. Portas, J. A. Alonso, E. de la Cal, J. M. Fontdecaba, A.V. Melnikov, E. Blanco, A.A. Chmyga, J. Botija, T. Estrada, J.A. Romero, Ivan Calvo, J.L. de Pablos, R. Castro, Francisco Castejón, B. Rojo, E. Rincón, G. Catalán, G. Wolfers, F. Martín-Díaz, F. Medina, A. López-Fraguas, M. Liniers, S. da Graca, A.B. Martín-Rojo, B. Zurro, A. Ros, J. Guasp, and D. Baiao

Subjects
Physics, Nuclear and High Energy Physics, Work (thermodynamics), Turbulence, Flow (psychology), Observable, Mechanics, Condensed Matter Physics, law.invention, Physics::Fluid Dynamics, Viscosity, law, Relaxation (physics), Statistical physics, Shear flow, Stellarator
Abstract

This work deals with the results on flow dynamics in TJ-II plasmas under Li-coated wall conditions, which produces low recycling and facilitates the density control and access to improved confinement transitions. The low-density transition, characterized by the emergence of the shear flow layer, is described from first principles and within the framework of neoclassical theory. The vanishing of the neoclassical viscosity when approaching the transition from below explains the observation of a number of turbulent phenomena reported in TJ-II in recent years; a unifying picture is provided in which zonal, i.e. large scale, radially structured, perturbations are observable when the neoclassical damping is sufficiently small. Preliminary linear, collisionless gyrokinetic simulations are carried out to assess that the measured time scale of relaxation of such perturbations is reasonably understood theoretically. In higher density regimes, the physical mechanisms behind the L–H transition have been experimentally studied. The spatial, temporal and spectral structure of the interaction between turbulence and flows has been studied close to the L–H transition threshold conditions. The temporal dynamics of the turbulence-flow interaction displays a predator–prey relationship and both radial outward and inward propagation velocities of the turbulence-flow front have been measured. Finally, a non-linear relation between turbulent fluxes and gradients is observed.

Published
2013

23. Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X

Author

H.-S. Bosch, R.C. Wolf, T. Andreeva, J. Baldzuhn, D. Birus, T. Bluhm, T. Bräuer, H. Braune, V. Bykov, A. Cardella, F. Durodié, M. Endler, V. Erckmann, G. Gantenbein, D. Hartmann, D. Hathiramani, P. Heimann, B. Heinemann, C. Hennig, M. Hirsch, D. Holtum, J. Jagielski, J. Jelonnek, W. Kasparek, T. Klinger, R. König, P. Kornejew, H. Kroiss, J.G. Krom, G. Kühner, H. Laqua, H.P. Laqua, C. Lechte, M. Lewerentz, J. Maier, P. McNeely, A. Messiaen, G. Michel, J. Ongena, A. Peacock, T.S. Pedersen, R. Riedl, H. Riemann, P. Rong, N. Rust, J. Schacht, F. Schauer, R. Schroeder, B. Schweer, A. Spring, A. Stäbler, M. Thumm, Y. Turkin, L. Wegener, A. Werner, D. Zhang, M. Zilker, T. Akijama, R. Alzbutas, E. Ascasibar, M. Balden, M. Banduch, Ch. Baylard, W. Behr, C. Beidler, A. Benndorf, T. Bergmann, C. Biedermann, B. Bieg, W. Biel, M. Borchardt, G. Borowitz, V. Borsuk, S. Bozhenkov, R. Brakel, H. Brand, T. Brown, B. Brucker, R. Burhenn, K.-P. Buscher, C. Caldwell-Nichols, A. Cappa, A. Carls, P. Carvalho, Ł. Ciupiński, M. Cole, J. Collienne, A. Czarnecka, G. Czymek, G. Dammertz, C.P. Dhard, V.I. Davydenko, A. Dinklage, M. Drevlak, S. Drotziger, A. Dudek, P. Dumortier, G. Dundulis, P.v. Eeten, K. Egorov, T. Estrada, H. Faugel, J. Fellinger, Y. Feng, H. Fernandes, W.H. Fietz, W. Figacz, F. Fischer, J. Fontdecaba, A. Freund, T. Funaba, H. Fünfgelder, A. Galkowski, D. Gates, L. Giannone, J.M. García Regaña, J. Geiger, S. Geißler, H. Greuner, M. Grahl, S. Groß, A. Grosman, H. Grote, O. Grulke, M. Haas, L. Haiduk, H.-J. Hartfuß, J.H. Harris, D. Haus, B. Hein, P. Heitzenroeder, P. Helander, R. Heller, C. Hidalgo, D. Hildebrandt, H. Höhnle, A. Holtz, E. Holzhauer, R. Holzthüm, A. Huber, H. Hunger, F. Hurd, M. Ihrke, S. Illy, A. Ivanov, S. Jablonski, N. Jaksic, M. Jakubowski, R. Jaspers, H. Jensen, H. Jenzsch, J. Kacmarczyk, T. Kaliatk, J. Kallmeyer, U. Kamionka, R. Karaleviciu, S. Kern, M. Keunecke, R. Kleiber, J. Knauer, R. Koch, G. Kocsis, A. Könies, M. Köppen, R. Koslowski, J. Koshurinov, A. Krämer-Flecken, R. Krampitz, Y. Kravtsov, M. Krychowiak, G. Krzesinski, I. Ksiazek, M. Kubkowska, A. Kus, S. Langish, R. Laube, M. Laux, S. Lazerson, M. Lennartz, C. Li, R. Lietzow, A. Lohs, A. Lorenz, F. Louche, L. Lubyako, A. Lumsdaine, A. Lyssoivan, H. Maaßberg, P. Marek, C. Martens, N. Marushchenko, M. Mayer, B. Mendelevitch, Ph. Mertens, D. Mikkelsen, A. Mishchenko, B. Missal, T. Mizuuchi, H. Modrow, T. Mönnich, T. Morizaki, S. Murakami, F. Musielok, M. Nagel, D. Naujoks, H. Neilson, O. Neubauer, U. Neuner, R. Nocentini, J.-M. Noterdaeme, C. Nührenberg, S. Obermayer, G. Offermanns, H. Oosterbeek, M. Otte, A. Panin, M. Pap, S. Paquay, E. Pasch, X. Peng, S. Petrov, D. Pilopp, H. Pirsch, B. Plaum, F. Pompon, M. Povilaitis, J. Preinhaelter, O. Prinz, F. Purps, T. Rajna, S. Récsei, A. Reiman, D. Reiter, J. Remmel, S. Renard, V. Rhode, J. Riemann, S. Rimkevicius, K. Riße, A. Rodatos, I. Rodin, M. Romé, H.-J. Roscher, K. Rummel, Th. Rummel, A. Runov, L. Ryc, J. Sachtleben, A. Samartsev, M. Sanchez, F. Sano, A. Scarabosio, M. Schmid, H. Schmitz, O. Schmitz, M. Schneider, W. Schneider, L. Scheibl, M. Scholz, G. Schröder, M. Schröder, J. Schruff, H. Schumacher, I.V. Shikhovtsev, M. Shoji, G. Siegl, J. Skodzik, M. Smirnow, E. Speth, D.A. Spong, R. Stadler, Z. Sulek, V. Szabó, T. Szabolics, T. Szetefi, Z. Szökefalvi-Nagy, A. Tereshchenko, H. Thomsen, D. Timmermann, H. Tittes, K. Toi, M. Tournianski, U.v. Toussaint, J. Tretter, S. Tulipán, P. Turba, R. Uhlemann, J. Urban, E. Urbonavicius, P. Urlings, S. Valet, D. Van Eester, M. Van Schoor, M. Vervier, H. Viebke, R. Vilbrandt, M. Vrancken, T. Wauters, M. Weissgerber, E. Weiß, A. Weller, J. Wendorf, U. Wenzel, T. Windisch, E. Winkler, M. Winkler, J. Wolowski, J. Wolters, G. Wrochna, P. Xanthopoulos, H. Yamada, M. Yokoyama, D. Zacharias, J. Zajac, G. Zangl, M. Zarnstorff, H. Zeplien, S. Zoletnik, M. Zuin, Control Systems Technology, Science and Technology of Nuclear Fusion, Soft Matter and Biological Physics, Sensorics for fusion reactors, and Publica

Subjects
Nuclear and High Energy Physics, Steady state (electronics), LIMIT ANALYSIS, PLASMA, Nuclear engineering, MAGNET SYSTEM, Plasma, Fusion power, Condensed Matter Physics, W7-X, Electron cyclotron resonance, law.invention, PHYSICS, Data acquisition, Heating system, law, Wendelstein 7-X, Stellarator
Abstract

The next step in the Wendelstein stellarator line is the large superconducting device Wendelstein 7-X, currently under construction in Greifswald, Germany. Steady-state operation is an intrinsic feature of stellarators, and one key element of the Wendelstein 7-X mission is to demonstrate steady-state operation under plasma conditions relevant for a fusion power plant. Steady-state operation of a fusion device, on the one hand, requires the implementation of special technologies, giving rise to technical challenges during the design, fabrication and assembly of such a device. On the other hand, also the physics development of steady-state operation at high plasma performance poses a challenge and careful preparation. The electron cyclotron resonance heating system, diagnostics, experiment control and data acquisition are prepared for plasma operation lasting 30 min. This requires many new technological approaches for plasma heating and diagnostics as well as new concepts for experiment control and data acquisition.

Published
2013
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24. Spatiotemporal Structure of the Interaction between Turbulence and Flows at the L-H Transition in a Toroidal Plasma

Author

T. Estrada, C. Hidalgo, Patrick Diamond, and T. Happel

Subjects
Physics, General Physics, Toroid, Turbulence, Oscillation, K-epsilon turbulence model, Front (oceanography), General Physics and Astronomy, Mechanics, Plasma, Edge (geometry), Mathematical Sciences, Physics::Fluid Dynamics, Engineering, Physical Sciences, Shear flow
Abstract

The spatiotemporal behavior of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge region (ρ≥0.7) of TJ-II plasmas. The temporal dynamics of the interaction displays an oscillatory behavior with a characteristic predator-prey relationship. The spatial evolution of this turbulence-flow oscillation pattern has been measured, showing both radial outward and inward propagation velocities of the turbulence-flow front. The results indicate that the edge shear flow linked to the L-H transition can behave either as a slowing-down, damping mechanism of outward propagating turbulent-flow oscillating structures, or as a source of inward propagating turbulence-flow events. © 2011 American Physical Society.

Published
2011
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25. Integrated data analysis at TJ-II: The density profile

Author

R. Fischer, T. Estrada, I. García-Cortés, E. Ascasíbar, J. A. Jiménez, B. Ph. van Milligen, A. Lopez Fraguas, D. Tafalla, D. López-Bruna, and Andreas Dinklage

Subjects
Physics, Electron density, business.industry, Thomson scattering, Biasing, Bayesian inference, law.invention, Interferometry, Optics, Physics::Plasma Physics, law, Reflectometry, business, Instrumentation, Stellarator, Beam (structure)
Abstract

An integrated data analysis system based on Bayesian inference has been developed for the TJ-II stellarator. It reconstructs the electron density profile at a single time point, using data from interferometry, reflectometry, Thomson scattering, and the Helium beam, while providing a detailed error analysis. In this work, we present a novel analysis of the ambiguity inherent in profile reconstruction from reflectometry and show how the integrated data analysis approach elegantly resolves it. Several examples of the application of the technique are provided, in both low-density discharges with and without electrode biasing, and in high-density discharges with an (L-H) confinement transition.

Published
2011

26. Scale-selective turbulence reduction in H-mode plasmas in the TJ-II Stellarator

Author

T. Happel, Ulrich Stroth, Garrard Conway, C. Hidalgo, E. Blanco, T. Estrada, Tj-Ii Team, and TJ-II Team

Subjects
Physics, Condensed matter physics, K-epsilon turbulence model, Turbulence, Reynolds stress, Condensed Matter Physics, law.invention, Computational physics, Vortex, Physics::Fluid Dynamics, law, Vortex stretching, Wavenumber, Phase velocity, Stellarator
Abstract

Wavenumber spectra of density turbulence in L- and H-mode plasmas have been measured in the TJ-II stellarator by means of Doppler reflectometry. A pronounced suppression of the density fluctuation level is observed in H-mode close to the radial position of maximum radial electric field (Er) shear. Furthermore, intermediate scale density turbulence is reduced preferentially. This effect can be interpreted within the framework of vortex stretching feeding energy through Reynolds stress into zonal flows, while shear decorrelation of turbulent structures might not play a central role in TJ-II. Moreover, it is shown that in both L- and H-mode, the phase velocity of density fluctuations does not depend on the structure scale.

Published
2011

27. Ion heating in transitions to CERC in the stellarator TJ-II

Author

José Luis Velasco, Alfonso Tarancón, T. Estrada, Francisco Castejón, L. A. Fernandez, and Victor Martin-Mayor

Subjects
Nuclear and High Energy Physics, Materials science, Física-Modelos matemáticos, Física, Electron, Plasma, Condensed Matter Physics, Electron cyclotron resonance, Ion, law.invention, Heat flux, law, Physics::Plasma Physics, Electron temperature, Atomic physics, Ion transporter, Stellarator
Abstract

In TJ-II stellarator plasmas, in the electron cyclotron heating regime, an increase in the ion temperature is observed, synchronized with that of the electron temperature, during the transition to the core electron-root confinement (CERC) regime. This rise in ion temperature should be attributed to the joint action of the electron–ion energy transfer (which changes slightly during the CERC formation) and an enhancement of the ion confinement. This improvement must be related to the increase in the positive electric field in the core region. In this paper, we confirm this hypothesis by estimating the ion collisional transport in TJ-II under the physical conditions established before and after the transition to CERC. We calculate a large number of ion orbits in the guiding-centre approximation considering the collisions with a background plasma composed of electrons and ions. The ion temperature profile and the thermal flux are calculated in a self-consistent way, so that the change in the ion heat transport can be assessed.

Published
2008

30. Radial electric fields and confinement in the TJ-II stellarator.

Author

L. Krupnik, A. Alonso, E. Ascasibar, T. Estrada, C. Hidalgo, B. van Milligen, M. Ochando, M. Pedrosa, J. L. de Pablos, V. Tribaldos, A. Chmyga, N. Dreval, G. Deshko, S. Khrebtov, A. Komarov, A. Kozachok, V. Tereshin, L. Eliseev, A. Melnikov, and C. Silva

Abstract

Abstract Radial plasma potential profiles have been obtained in the TJ-II by the Heavy Ion Beam Probing (HIBP) diagnostics. Results show that the potential increases up to 1 kV near the magnetic axis in ECRH low-density plasmas. The secondary ion current profiles, which directly reflect the plasma density, are hollow. In low-density ECRH operation, radial electric fields are found to be positive in the plasma core, however, a reduction in these fields is observed with increasing density. Radial plasma potential profiles show evidence of structures in configurations with low-order rational surfaces. In particular, HIBP measurements have permitted characterization of the plasma potential profile during e-ITB formation. Experiments in TJ-II have shown that it is possible to modify the global confinement and edge plasma parameters with limiter biasing, illustrating the direct impact of radial electric fields on confinement properties. Plasma potential measurements by the HIBP diagnostic show a strong impact of heating method (ECRH versus NBI) on radial electric fields. [ABSTRACT FROM AUTHOR]

Published
2005
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32. Computer Science approach to the stellar fabric of violent starforming regions in AGN.

Author

Terlevich, Elena, Terlevich, R., Papaqui, J. P. Torres, Piedra, T. Estrada, Fuentes, O., Solorio, T., and Bressan, S.

Abstract

In order to analyse the large numbers of Seyfert galaxy spectra available at present, we are testing new techniques to derive their physical parameters fastly and accurately.We present an experiment on such a new technique to segregate old and young stellar populations in galactic spectra using machine learning methods. We used an ensemble of classifiers, each classifier in the ensemble specializes in young or old populations and was trained with locally weighted regression and tested using ten-fold cross-validation. Since the relevant information concentrates in certain regions of the spectra we used the method of sequential floating backward selection offline for feature selection.Very interestingly, the application to Seyfert galaxies proved that this technique is very insensitive to the dilution by the Active Galactic Nucleus (AGN) continuum. Comparing with exhaustive search we concluded that both methods are similar in terms of accuracy but the machine learning method is faster by about two orders of magnitude.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html [ABSTRACT FROM PUBLISHER]

Published
2004
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33. The impact of edge radial electric fields on edge–scrape-off layer coupling in the TJ-II stellarator.

Author

G. Grenfell, B.Ph. van Milligen, U. Losada, T. Estrada, B. Liu, C. Silva, M. Spolaore, C. Hidalgo, and Team, the TJ-II

Subjects
ELECTRIC fields, FUSION reactors, PLASMA boundary layers, EDGES (Geometry)
Abstract

In this letter, we investigate the impact of edge radial electric fields (Er) on turbulence propagation and the coupling between the plasma edge and the scrape-off layer (SOL) during slow electron–ion–electron root transitions in the TJ-II stellarator. The plasma edge was monitored with a set of electrostatic probes and Doppler reflectometry. It is shown, for the first time, that Er does not only affect the radial turbulence correlation length—a well-known effect—but it is also capable of reducing and nearly blocking the propagation of turbulence from the edge into the SOL. Specifically, in the ion root phase (Er  <  0 in the edge), the SOL turbulence penetration depth was strongly reduced, as compared to the electron root phase (Er  >  0). This result was obtained using a technique based on the transfer entropy, which quantifies the propagation of information. These observations are considered highly relevant in the framework of the understanding of the mechanisms that determine the SOL width, a vital parameter for future fusion reactors. [ABSTRACT FROM AUTHOR]

Published
2020
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34. Measurement of the tilt angle of turbulent structures in magnetically confined plasmas using Doppler reflectometry.

Author

J R Pinzón, T Estrada, T Happel, P Hennequin, E Blanco, U Stroth, Upgrade, the ASDEX, and Teams, TJ-II

Subjects
*PLASMA confinement, *PLASMA turbulence, *REFLECTOMETRY, *PLASMA flow, *TURBULENCE
Abstract

The mean tilt angle of turbulent structures is a key element for describing the turbulence and its interplay with plasma flows in magnetically confined plasmas. It is a quantity predicted by theories and gyrokinetic simulations, which can provide information on the type of the dominant micro-instability, and also on the turbulence anisotropy induced by sheared flows. A new method for measuring the tilt angle of turbulent structures using Doppler reflectometry has been recently introduced (Pinzón et al 2019 Nucl. Fusion59 074002). It is based on the time delay of the cross-correlation between microwaves backscattered at radially displaced positions. In this paper, the method is presented in detail and is successfully applied on the ASDEX Upgrade tokamak and the TJ-II stellarator. Measurements of the tilt angle in the core of both machines are reported, in the TJ-II case, for the first time. [ABSTRACT FROM AUTHOR]

Published
2019
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35. On the interplay between turbulent forces and neoclassical particle losses in zonal flow dynamics.

Author

R. Gerrú, S. Mulas, U. Losada, F. Castejón, B. Liu, T. Estrada, B.Ph. van Milligen, and C. Hidalgo

Subjects
MONTE Carlo method, REYNOLDS stress, ELECTRIC fields, RADIAL distribution function, MAGNITUDE (Mathematics), ELECTRORHEOLOGY
Abstract

This study presents an investigation into the connection between radial electric fields, Reynolds stress gradients and long range correlations (LRCs), with the latter being a proxy for zonal flows (ZFs), in different plasma scenarios in the TJ-II stellarator. Monte Carlo simulations showed that radial electric fields with a similar size to those experimentally measured affect neoclassical orbit losses. Although the order of magnitude of turbulent acceleration was comparable to the neoclassical damping of perpendicular flows, we found that the dependence of this acceleration on the radial electric field did not correlate with the evolution of the LRC amplitude, indicating that turbulent acceleration alone cannot explain the dynamics of ZFs. These results are in line with the expectation that the interplay between turbulent and neoclassical mechanisms is an important ingredient of the dynamics of edge ZF. [ABSTRACT FROM AUTHOR]

Published
2019
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36. Validation of global gyrokinetic simulations in stellarator configurations.

Author

E. Sánchez, T. Estrada, J.L. Velasco, I. Calvo, A. Cappa, A. Alonso, J.M. García-Regaña, R. Kleiber, J. Riemann, and Team, the TJ-II

Subjects
*STELLARATORS, *POWER spectra, *IONS spectra, *PLASMA boundary layers, *REFLECTOMETRY
Abstract

In this paper, recent simulations carried out with the global gyrokinetic code EUTERPE in configurations of the TJ-II stellarator are presented. The simulations are compared with experimental measurements from the Doppler reflectometry (DR) system in dedicated experiments carried out in TJ-II. Electron-driven modes are found to be unstable in the plasma edge region in linear simulations. The range of unstable wavenumbers and the radial location of maximum instability found in simulations are consistent with the experimental density fluctuations spectra and their variation with the radius. A qualitative agreement is found between the poloidal propagation of unstable modes found in simulations and the perpendicular velocities measured by the DR system. No dependency of the power spectra with the bulk ion mass is observed in simulations or experimentally, which is consistent with the electron-driven modes found unstable in the simulations. Instabilities are localized toroidally and poloidally in the simulations, the location of maximum instability being affected by the rotational transform. A systematic difference is found between the density fluctuation spectra measured by the DR system at poloidally separated positions on the same flux-surface, which is also affected by the rotational transform. However, a discrepancy between the location of maximum fluctuations in simulations and experiments is found so far. [ABSTRACT FROM AUTHOR]

Published
2019
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37. Turbulence and perpendicular plasma flow asymmetries measured at TJ-II plasmas.

Author

T. Estrada, E. Sánchez, J.M. García-Regaña, J.A. Alonso, E. Ascasíbar, I. Calvo, A. Cappa, D. Carralero, C. Hidalgo, M. Liniers, I. Pastor, J.L. Velasco, and Team, the TJ-II

Subjects
*PLASMA turbulence, *PLASMA flow, *PLASMA density, *PLASMA potentials, *ELECTRIC potential, *MOLECULAR rotation
Abstract

Dedicated experiments have been carried out for a systematic comparison of turbulence wavenumber spectra and perpendicular rotation velocity measured at poloidally separated positions on the same flux-surface in the stellarator TJ-II. The rationale behind this study is twofold, namely, validation of the spatial localization of instabilities predicted by gyrokinetic simulations in stellarators and validation of the electrostatic potential variation on the flux surface as calculated by neoclassical codes and its possible impact on the radial electric field. Perpendicular wavenumber spectra and perpendicular rotation velocity profiles have been measured using Doppler reflectometry in two plasma regions poloidally separated as both positive and negative probing beam angles with respect to normal incidence can be selected. A systematic comparison has been carried out showing differences in the perpendicular wavenumber spectrum measured at poloidally separated positions on the same flux-surface, that depend on plasma density, heating conditions and magnetic configuration. The asymmetry found in the standard magnetic configuration under some plasmas conditions, reverses in the high iota configuration. The different intensity in the density fluctuation spectra can be related to the poloidal localization of instabilities found in gyrokinetic simulations. Differences in the radial electric field profile are also found that could be explained to be due to on-surface plasma potential variations. [ABSTRACT FROM AUTHOR]

Published
2019
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38. Experimental investigation of the tilt angle of turbulent structures in the core of fusion plasmas.

Author

J.R. Pinzón, T. Happel, P. Hennequin, C. Angioni, T. Estrada, A. Lebschy, U. Stroth, and Team, the ASDEX Upgrade

Subjects
PLASMA turbulence, PLASMA flow, PLASMA dynamics, TURBULENCE, REFLECTOMETRY
Abstract

The tilt angle of turbulent structures stands for the anisotropy of turbulence which is essential for understanding the dynamics of magnetized plasmas. It is a quantity predicted by theory and simulations, that provides information on the interplay between turbulence, micro-instabilities and plasma flows. A new method for measuring the tilt angle of turbulent structures in the core region of fusion plasmas using Doppler reflectometry is presented. First measurements of this type on the ASDEX Upgrade tokamak have shown a significant difference of tilt angle for different plasma conditions. The dominance of sheared flows in determining the structure tilt is experimentally demonstrated for different turbulence regimes. [ABSTRACT FROM AUTHOR]

Published
2019
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39. Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator.

Author

T. Kobayashi, U. Losada, B. Liu, T. Estrada, B.Ph. van Milligen, R. Gerrú, M. Sasaki, and C. Hidalgo

Subjects
PLASMA beam injection heating, NEUTRAL beams, ELECTRON cyclotron resonance heating
Abstract

In this letter, we investigate the spatial structure of a low frequency global potential oscillation, which is likely ascribed as the low frequency zonal flows, in TJ-II laboratory plasmas. In two plasmas produced by different heating schemes (electron cyclotron resonance heating and neutral beam injection heating) and characterized by different mean radial electric field structures, frequency-space-decomposed spectra of the global potential oscillation are obtained. In both cases, the oscillatory field has a single-peaked potential structure and a dipole radial electric field structure. The oscillating structure depends on its frequency as well as on the heating scheme. [ABSTRACT FROM AUTHOR]

Published
2019
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40. The impact of fast electrons on pellet injection in the stellarator TJ-II.

Author

team1, TJ-II, group2, L. H. D. experiment, N Panadero, E Ascasíbar, T Estrada, J M Fontdecaba, R García, J Hernández Sánchez, M Liners, I Pastor, B Rojo, K J McCarthy, S K Combs, N Tamura, M Calvo, A Chmyga, P Khabanov, and A V Melnikov

Subjects
PLASMA physics, NUCLEAR fusion, ELECTRONS, SPECTROGRAPHS, POPULATION
Abstract

Efficient plasma core fuelling is a critical issue for achieving steady-state scenarios in magnetically confined fusion devices. The current preferred method to achieve this goal is cryogenic pellet injection (PI). PI’s are now installed in most medium- and large-sized fusion devices. In this paper, recent results from PI experiments in the stellarator TJ-II are reported. Of particular interest is the influence of fast electrons. Whilst edge populations of such electrons do not affect PI in the TJ-II, fast electrons residing in its hot core have significant influence on both pellet ablation and fuelling efficiency. If present in the core, their radial location can be determined from the light emission profile produced by an ablating pellet as it traverses the plasma and confirmed from the power spectral distribution spectrograph of the total secondary beam current collected by a scanning heavy ion beam probe system. Moreover, it is found that if a pellet is subject to excess ablation due to core fast electron impacts, the resultant pellet efficiency (deposited particles/delivered particles) increases by up to 50% with respect to injections into similar, fast-electron free, plasmas. This is consistently found for microwave-heated plasmas, where pellet penetration is shallower than the magnetic axis in TJ-II, when such a population is present, as well as for neutral beam created and heated plasmas in which fast-electrons, generated during magnetic field ramp-up, persist in the core along a discharge. Similarly, when polystyrene pellets (TESPEL) are injected into the same machine sector, an analogous increase in post-injection particle deposition is seen. It is postulated that vaporization of the pellet through heating by fast electrons modifies normal neutral cloud and plasmoid development and hence affects outwards drifting that is inherent to magnetic fusion devices. [ABSTRACT FROM AUTHOR]

Published
2019
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42. On-surface potential and radial electric field variations in electron root stellarator plasmas.

Author

J M García-Regaña, T Estrada, I Calvo, J L Velasco, J A Alonso, D Carralero, R Kleiber, M Landreman, A Mollén, E Sánchez, C Slaby, and Team, TJ-II Team and W7-X

Subjects
*ELECTRIC fields, *ELECTRONS, *STELLARATORS, *PLASMA devices, *PLASMA physics, *CONTROLLED fusion
Abstract

In the present work we report recent radial electric field measurements carried out with the Doppler reflectometry (DR) system in the TJ-II stellarator. The study focuses on the fact that, under some conditions, the radial electric field measured at different points over the same flux surface shows significantly different values. A numerical analysis is carried out considering the contribution arising from the radial dependence of Φ1 as a possible correction term to the total radial electric field. Here Φ1 is the neoclassical electrostatic potential variation over the surface. The comparison shows good agreement in some aspects, like the conditions under which this correction is large (electron-root conditions) or negligible (ion-root conditions). But it disagrees in others like the sign of the correction. The results are discussed together with the underlying reasons of this partial disagreement. In addition, motivated by the recent installation of the dual DR system in Wendelstein 7-X (W7-X), Φ1 estimations for W7-X are revisited considering core electron-root confinement plasmas from its first experimental campaign. The simulations show larger values of Φ1 under electron-root conditions than under ion root. The contribution from the kinetic electron response is shown to become important at some radii. All this results in a potential variation size in W7-X noticeably larger than estimated in our previous work (García-Regaña et al 2017 Nucl. Fusion57 056004), for other plasma parameters and another configuration. [ABSTRACT FROM AUTHOR]

Published
2018
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43. Role of isotope mass and evidence of fluctuating zonal flows during the L–H transition in the TJ-II stellarator.

Author

U Losada, T Estrada, B Liu, B van Milligen, J Cheng, C Silva, I Pastor, J M Fontdecaba, C Hidalgo, and team1, the TJ-II

Subjects
*HYDROGEN, *ELECTRIC fields, *ELECTROMAGNETIC theory, *DEUTERIUM ions, *MONOVALENT cations
Abstract

Mean radial electric fields as well as low frequency Zonal Flow-like global oscillations in radial electric field have been identified during the low to high (L–H) transition in Hydrogen and Deuterium dominated plasmas in the stellarator TJ-II. No evidence of isotope effect on the L–H transition dynamics was observed in the investigated TJ-II plasma scenarios. These observations emphasize the critical role of both zero frequency (equilibrium) and low frequency varying large-scale flows for stabilizing turbulence during the triggering of the L–H transition in magnetically confined toroidal plasmas. [ABSTRACT FROM AUTHOR]

Published
2018
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44. HVOF-sprayed HAp/S53P4 BG composite coatings on an AZ31 alloy for potential applications in temporary implants

Author

Carlos A. Poblano-Salas, John Henao, Astrid L. Giraldo-Betancur, Paola Forero-Sossa, Diego German Espinosa-Arbelaez, Jorge A. González-Sánchez, Luis R. Dzib-Pérez, Susana T. Estrada-Moo, and Idelfonso E. Pech-Pech

Subjects
Coatings, Composites, Thermal spray, Temporary implants, Hydrogen evolution, Mining engineering. Metallurgy, TN1-997
Abstract

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray (HVOF) from hydroxyapatite (HAp) and bioactive glasses (BG) have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration, considering that both phases have different reaction and dissolution rates under in-vitro conditions. In the present work, 75% wt. HAp - 25% wt. S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 alloy. The study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those coatings. Different characterization techniques, such as scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy, were employed to characterize relevant structural and microstructural properties of the composite coatings. The results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved (max 550 °C) and the differences in coefficients of thermal expansion. It was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the coatings. In addition, in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 alloy. The results showed a significant decrease in hydrogen evolution (at least 98%) when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid (SBF).

Published
2024
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45. Influence of magnetic well on electromagnetic turbulence in the TJ-II stellarator

Author

M de Aguilera, L. I. Krupnik, Francisco Castejón, A.V. Melnikov, A. López-Fraguas, T. Estrada, L.G. Eliseev, M. A. Ochando, E. Ascasíbar, C. Hidalgo, and Shoji Yamamoto

Subjects
Physics, business.industry, Turbulence, Oscillation, Mode (statistics), Plasma, Edge (geometry), Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Computational physics, law.invention, Amplitude, Optics, Nuclear Energy and Engineering, law, 0103 physical sciences, 010306 general physics, business, Stellarator
Abstract

A magnetic well scan has been performed in the TJ-II stellarator to investigate the confinement properties with different values of the well, or even of the hill, and to explore the properties of electromagnetic turbulence. Stable plasmas have been obtained in theoretically Mercier-unstable configurations, and the electrostatic turbulence levels in the edge are increased. Three families of modes appear during the experiments: (1) a family of modes of Alfvenic nature with high frequencies; (2) a second set of modes of middle frequencies (tens of kHz) and (3) an oscillation at f ≈ 10–20 kHz happens in several cases. In spite of the fact that the vacuum rotational transform is very similar in all of the cases, the Alfvenic mode family changes drastically when decreasing the magnetic well, showing a non-monotonic behaviour of the amplitude, and a decrease of the typical frequencies. This behaviour cannot be explained only by current or density variations, so the effect of the modification of the configuration is playing a key role. Regarding the intermediate frequencies, a coherent mode appears with decreasing frequency as the magnetic well decreases. This mode is a candidate for a GAM, which can survive in these TJ-II plasmas, despite of the strong damping these modes should suffer in this device.

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

Author

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

Subjects
Magnetic confinement, Nuclear and High Energy Physics, Technology and Engineering, Plasma heating, Cyclotron resonance, CONFINEMENT, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, PHYSICS, Nuclear physics, stellarator, current drive, magnetic confinement, plasma heating, Condensed Matter Physics, law, 0103 physical sciences, ddc:530, 010306 general physics, tellarator, Stellarator, Physics, Magnetic confinement fusion, Plasma, 530 Physik, TRANSPORT, Current drive, Electron temperature, Plasma diagnostics, Atomic physics, Wendelstein 7-X, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 × 1019 m−3 , central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre. EURATOM 633053

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48. Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma

Author

M.V. Navarro, J.M. Hernández Sánchez, N. Panadero, I. Pastor, A. López Fraguas, Naoki Tamura, A. Soleto, Regina Garcia, T. Estrada, Tj-Ii Team, K. J. McCarthy, S.K. Combs, and E. Ascabíbar

Subjects
Hydrogen, digestive, oral, and skin physiology, Analytical chemistry, Pellets, General Physics and Astronomy, chemistry.chemical_element, Injector, Plasma, 01 natural sciences, 010305 fluids & plasmas, law.invention, chemistry, law, Solid hydrogen, 0103 physical sciences, Pellet, 010306 general physics, Stellarator, Particle deposition
Abstract

A cryogenic pellet injector (PI) and tracer encapsulated solid pellet (TESPEL) injector system has been operated in combination on the stellarator TJ-II. This unique arrangement has been created by piggy-backing a TESPEL injector onto the backend of a pipe-gun–type PI. The combined injector provides a powerful new tool for comparing ablation and penetration of polystyrene TESPEL pellets and solid hydrogen pellets, as well as for contrasting subsequent pellet particle deposition and plasma perturbation under analogous plasma conditions. For instance, a significantly larger increase in plasma line-averaged electron density, and electron content, is observed after a TESPEL pellet injection compared with an equivalent cryogenic pellet injection. Moreover, for these injections from the low-magnetic-field side of the plasma cross-section, TESPEL pellets deposit electrons deeper into the plasma core than cryogenic pellets. Finally, the physics behind these observations and possible implications for pellet injection studies are discussed.

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49. On the interplay between turbulent forces and neoclassical particle losses in zonal flow dynamics

Author

Francisco Castejón, S. Mulas, B. Liu, R. Gerrú, T. Estrada, U. Losada, B. Ph. van Milligen, and C. Hidalgo

Subjects
Physics, Nuclear and High Energy Physics, Turbulence, Monte Carlo method, FOS: Physical sciences, Plasma, Mechanics, Reynolds stress, Condensed Matter Physics, 01 natural sciences, Physics - Plasma Physics, 010305 fluids & plasmas, Plasma Physics (physics.plasm-ph), Physics::Fluid Dynamics, Amplitude, Physics::Plasma Physics, Electric field, 0103 physical sciences, Physics::Space Physics, Perpendicular, 010306 general physics, Order of magnitude
Abstract

This study presents the investigation of the connection between radial electric field, gradient of Reynolds stress and Long Range Correlation (LRC), as a proxy for Zonal Flows (ZF), in different plasma scenarios in the TJ-II stellarator. Monte Carlo simulations were made showing that radial electric fields in the range of those experimentally measured have an effect on the neoclassical orbit losses. The results indicate that, despite the order of magnitude of turbulent acceleration is comparable to the neoclassical damping of perpendicular flows, its dependence with radial electric field is not correlated with the evolution of LRC amplitude, indicating that turbulent acceleration alone cannot explain the dynamics of Zonal Flows. These results are in line with the expectation that the interplay between turbulent and neoclassical mechanisms is a crucial ingredient of the dynamics of edge Zonal Flows., 6 pages, 15 figures, results presented in 19th Coordinated working group meeting of IPP

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50. Causal impact of magnetic fluctuations in slow and fast L–H transitions at TJ-II

Author

Tj-Ii Team, T. Estrada, B.A. Carreras, J. M. Fontdecaba, C. Hidalgo, I. Pastor, R. Balbín, B. Ph. van Milligen, and E. Ascasíbar

Subjects
Physics, Work (thermodynamics), Condensed matter physics, Rational surface, Flow (psychology), digestive, oral, and skin physiology, FOS: Physical sciences, Zonal flow (plasma), Condensed Matter Physics, equipment and supplies, 01 natural sciences, Physics - Plasma Physics, 010305 fluids & plasmas, law.invention, Shear (sheet metal), Causality (physics), Plasma Physics (physics.plasm-ph), law, 0103 physical sciences, Magnetohydrodynamics, 010306 general physics, human activities, Stellarator
Abstract

This work focuses on the relationship between L-H (or L-I) transitions and MHD activity in the low magnetic shear TJ-II stellarator. It is shown that the presence of a low order rational surface in the plasma edge (gradient) region lowers the threshold density for H-mode access. MHD activity is systematically suppressed near the confinement transition. We apply a causality detection technique (based on the Transfer Entropy) to study the relation between magnetic oscillations and locally measured plasma rotation velocity (related to Zonal Flows). For this purpose, we study a large number of discharges in two magnetic configurations, corresponding to 'fast' and 'slow' transitions. With the 'slow' transitions, the developing Zonal Flow prior to the transition is associated with the gradual reduction of magnetic oscillations. The transition itself is marked by a strong spike of 'information transfer' from magnetic to velocity oscillations, suggesting that the magnetic drive may play a role in setting up the final sheared flow responsible for the H-mode transport barrier. Similar observations were made for the 'fast' transitions. Thus, it is shown that magnetic oscillations associated with rational surfaces play an important and active role in confinement transitions, so that electromagnetic effects should be included in any complete transition model., Comment: 38 pages, 15 figures

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