Overview of first Wendelstein 7-X high-performance operation

T. Klinger*, T. Andreeva, S. Bozhenkov, C. Brandt, R. Burhenn, B. Buttenschön, G. Fuchert, B. Geiger, O. Grulke, H. Laqua, N. Pablant, K. Rahbarnia, T. Stange, A. von Stechow, N. Tamura, H. Thomsen, Y. Turkin, T. Wegner, I. Abramovic, S. ÄkäslompoloJ. Alcuson, P. Aleynikov, K. Aleynikova, A. Ali, A. Alonso, G. Anda, E. Ascasibar, J.P. Bähner, S.G. Baek, M. Balden, J. Baldzuhn, M. Banduch, T. Barbui, W. Behr, C. Beidler, A. Benndorf, C. Biedermann, W. Biel, B. Blackwell, E. Blanco, M. Blatzheim, S. Ballinger, T. Bluhm, D. Böckenhoff, B. Böswirth, L.-G. Böttger, M. Borchardt, V. Borsuk, J. Boscary, H.-S. Bosch, M. Beurskens, R. Brakel, H. Brand, T. Bräuer, H. Braune, S. Brezinsek, K.-J. Brunner, R. Bussiahn, V. Bykov, J. Cai, I. Calvo, B. Cannas, A. Cappa, A. Carls, D. Carralero, L. Carraro, B. Carvalho, F. Castejon, A. Charl, N. Chaudhary, D. Chauvin, F. Chernyshev, M. Cianciosa, R. Citarella, G. Claps, J. Coenen, M.J. Cole, M.J. Cole, F. Cordella, G. Cseh, A. Czarnecka, K. Czerski, M. Czerwinski, G. Czymek, A. da Molin, A. da Silva, H. Damm, A. de la Pena, S. Degenkolbe, C.P. Dhard, M. Dibon, A. Dinklage, T. Dittmar, M. Drevlak, P. Drewelow, P. Drews, F. Durodie, E. Edlund, P. van Eeten, F. Effenberg, G. Ehrke, S. Elgeti, M. Endler, D. Ennis, H. Esteban, T. Estrada, J. Fellinger, Y. Feng, E. Flom, H. Fernandes, W.H. Fietz, W. Figacz, J. Fontdecaba, O. Ford, T. Fornal, H. Frerichs, A. Freund, T. Funaba, A. Galkowski, G. Gantenbein, Y. Gao, J. García Regaña, D. Gates, J. Geiger, V. Giannella, A. Gogoleva, B. Goncalves, A. Goriaev, D. Gradic, M. Grahl, J. Green, H. Greuner, A. Grosman, H. Grote, M. Gruca, C. Guerard, P. Hacker, X. Han, J.H. Harris, D. Hartmann, D. Hathiramani, B. Hein, B. Heinemann, P. Helander, S. Henneberg, M. Henkel, J. Hernandez Sanchez, C. Hidalgo, M. Hirsch, K.P. Hollfeld, U. Höfel, A. Hölting, D. Höschen, M. Houry, J. Howard, X. Huang, Z. Huang, M. Hubeny, M. Huber, H. Hunger, K. Ida, T. Ilkei, S. Illy, B. Israeli, S. Jablonski, M. Jakubowski, J. Jelonnek, H. Jenzsch, T. Jesche, M. Jia, P. Junghanns, J. Kacmarczyk, J.-P. Kallmeyer, U. Kamionka, H. Kasahara, W. Kasparek, Y.O. Kazakov, N. Kenmochi, C. Killer, A. Kirschner, R. Kleiber, J. Knauer, M. Knaup, A. Knieps, T. Kobarg, G. Kocsis, F. Köchl, Y. Kolesnichenko, A. Könies, R. König, P. Kornejew, J.-P. Koschinsky, F. Köster, M. Krämer, R. Krampitz, A. Krämer-Flecken, N. Krawczyk, T. Kremeyer, J. Krom, M. Krychowiak, I. Ksiazek, M. Kubkowska, G. Kühner, T. Kurki-Suonio, P.A. Kurz, S. Kwak, M. Landreman, P. Lang, R. Lang, A. Langenberg, S. Langish, H. Laqua, R. Laube, S. Lazerson, C. Lechte, M. Lennartz, W. Leonhardt, C. Li, Y. Li, Y. Liang, C. Linsmeier, S. Liu, J.-F. Lobsien, D. Loesser, J. Loizu Cisquella, J. Lore, A. Lorenz, M. Losert, A. Lücke, A. Lumsdaine, V. Lutsenko, H. Maaßberg, O. Marchuk, J.H. Matthew, S. Marsen, M. Marushchenko, S. Masuzaki, D. Maurer, M. Mayer, K. McCarthy, P. McNeely, A. Meier, D. Mellein, B. Mendelevitch, P. Mertens, D. Mikkelsen, A. Mishchenko, B. Missal, J. Mittelstaedt, T. Mizuuchi, A. Mollen, V. Moncada, T. Mönnich, T. Morisaki, D. Moseev, S. Murakami, G. Náfrádi, M. Nagel, D. Naujoks, H. Neilson, R. Neu, O. Neubauer, U. Neuner, T. Ngo, D. Nicolai, S.K. Nielsen, H. Niemann, T. Nishizawa, R. Nocentini, C. Nührenberg, J. Nührenberg, S. Obermayer, G. Offermanns, K. Ogawa, J. Ölmanns, J. Ongena, J.W. Oosterbeek, G. Orozco, M. Otte, L. Pacios Rodriguez, N. Panadero, N. Panadero Alvarez, D. Papenfuß, S. Paqay, E. Pasch, A. Pavone, E. Pawelec, T.S. Pedersen, G. Pelka, V. Perseo, B. Peterson, D. Pilopp, S. Pingel, F. Pisano, B. Plaum, G. Plunk, P. Pölöskei, M. Porkolab, J. Proll, M.-E. Puiatti, A. Puig Sitjes, F. Purps, M. Rack, S. Récsei, A. Reiman, F. Reimold, D. Reiter, F. Remppel, S. Renard, R. Riedl, J. Riemann, K. Risse, V. Rohde, H. Röhlinger, M. Romé, D. Rondeshagen, P. Rong, B. Roth, L. Rudischhauser, K. Rummel, T. Rummel, A. Runov, N. Rust, L. Ryc, S. Ryosuke, R. Sakamoto, M. Salewski, A. Samartsev, E. Sanchez, F. Sano, S. Satake, J. Schacht, G. Satheeswaran, F. Schauer, T. Scherer, J. Schilling, A. Schlaich, G. Schlisio, F. Schluck, K.-H. Schlüter, J. Schmitt, H. Schmitz, O. Schmitz, S. Schmuck, M. Schneider, W. Schneider, P. Scholz, R. Schrittwieser, M. Schröder, T. Schröder, R. Schroeder, H. Schumacher, B. Schweer, E. Scott, S. Sereda, B. Shanahan, M. Sibilia, P. Sinha, S. Sipliä, C. Slaby, M. Sleczka, H. Smith, W. Spiess, D.A. Spong, A. Spring, R. Stadler, M. Stejner, L. Stephey, U. Stridde, C. Suzuki, J. Svensson, V. Szabó, T. Szabolics, T. Szepesi, Z. Szökefalvi-Nagy, A. Tancetti, J. Terry, J. Thomas, M. Thumm, J.M. Travere, P. Traverso, J. Tretter, H. Trimino Mora, H. Tsuchiya, T. Tsujimura, S. Tulipán, B. Unterberg, I. Vakulchyk, S. Valet, L. Vano, B. van Milligen, A.J. van Vuuren, L. Vela, J.-L. Velasco, M. Vergote, M. Vervier, N. Vianello, H. Viebke, R. Vilbrandt, A. Vorköper, S. Wadle, F. Wagner, E. Wang, N. Wang, Z. Wang, F. Warmer, T. Wauters, L. Wegener, J. Weggen, Y. Wei, G. Weir, J. Wendorf, U. Wenzel, A. Werner, A. White, B. Wiegel, F. Wilde, T. Windisch, M. Winkler, A. Winter, V. Winters, S. Wolf, R.C. Wolf, A. Wright, G. Wurden, P. Xanthopoulos, H. Yamada, I. Yamada, R. Yasuhara, M. Yokoyama, M. Zanini, M. Zarnstorff, A. Zeitler, D. Zhang, H. Zhang, J. Zhu, M. Zilker, A. Zocco, S. Zoletnik, M. Zuin

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Abstract

The optimized superconducting stellarator device Wendelstein 7-X (with major radiusR = 5.5 m, minor radius a = 0.5 m, and 30 m3 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 1–4.5 × 1019 m−3 with central electron temperatures 5–10 keV were routinely achieved with hydrogen gas fueling, frequently terminated by a radiative collapse. In a first stage, plasma densities up to 1.4 × 1020 m−3 were reached with hydrogen pellet injection and helium gas fueling. Here, the ions are indirectly heated, and at a central density of 8 · 1019 m−3 a temperature of 3.4 keV with Te/Ti = 1 was transiently accomplished, which corresponds to nTi(0)τE = 6.4 × 1019 keV s m−3 with a peak diamagnetic energy of 1.1 MJ and volume-averaged normalized plasma pressure β = 1.2%. 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 1 × 1020 m−2 line integrated density and Te = Ti = 2 keV 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.
Original languageEnglish
Article number112004
JournalNuclear Fusion
Volume59
Issue number11
Number of pages11
ISSN0029-5515
DOIs
Publication statusPublished - 2019

Keywords

  • Stellarator
  • Divertor
  • ECR heating
  • NBI heating
  • Plasma performance
  • Turbulence
  • Impurities

Cite this

Klinger, T., Andreeva, T., Bozhenkov, S., Brandt, C., Burhenn, R., Buttenschön, B., Fuchert, G., Geiger, B., Grulke, O., Laqua, H., Pablant, N., Rahbarnia, K., Stange, T., von Stechow, A., Tamura, N., Thomsen, H., Turkin, Y., Wegner, T., Abramovic, I., ... Zuin, M. (2019). Overview of first Wendelstein 7-X high-performance operation. Nuclear Fusion, 59(11), [112004]. https://doi.org/10.1088/1741-4326/ab03a7