Overview of first Wendelstein 7-X high-performance operation
Klinger, T.;Andreeva, T.;Bozhenkov, S.;Brandt, C.;Burhenn, R.;Buttenschön, B.;Fuchert, G.;Geiger, B.;Grulke, O.;Laqua, H. P.;Pablant, N.;Rahbarnia, K.;Stange, T.;von Stechow, A.;Tamura, N.;Thomsen, H.;Turkin, Y.;Wegner, T.;Abramovic, I.;Äkäslompolo, S.;Alcuson, J.;Aleynikov, P.;Aleynikova, K.;Ali, A.;Alonso, A.;Anda, G.;Ascasibar, E.;Bähner, J. P.;Baek, S. G.;Balden, M.;Baldzuhn, J.;Banduch, M.;Barbui, T.;Behr, W.;Beidler, C.;Benndorf, A.;Biedermann, C.;Biel, W.;Blackwell, B.;Blanco, E.;Blatzheim, M.;Ballinger, S.;Bluhm, T.;Böckenhoff, D.;Böswirth, B.;Böttger, L. -G.;Borchardt, M.;Borsuk, V.;Boscary, J.;Bosch, H. -S.;Beurskens, M.;Brakel, R.;Brand, H.;Bräuer, T.;Braune, H.;Brezinsek, S.;Brunner, K. -J.;Bussiahn, R.;Bykov, V.;Cai, J.;Calvo, I.;Cannas, B.;Cappa, A.;Carls, A.;Carralero, D.;Carraro, L.;Carvalho, B.;Castejon, F.;Charl, A.;Chaudhary, N.;Chauvin, D.;Chernyshev, F.;Cianciosa, M.;Citarella, R.;Claps, G.;Coenen, J.;Cole, M.;Cole, M. J.;Cordella, F.;Cseh, G.;Czarnecka, A.;Czerski, K.;Czerwinski, M.;Czymek, G.;da Molin, A.;da Silva, A.;Damm, H.;de la Pena, A.;Degenkolbe, S.;Dhard, C. P.;Dibon, M.;Dinklage, A.;Dittmar, T.;Drevlak, M.;Drewelow, P.;Drews, P.;Durodie, F.;Edlund, E.;van Eeten, P.;Effenberg, F.;Ehrke, G.;Elgeti, S.;Endler, M.;Ennis, D.;Esteban, H.;Estrada, T.;Fellinger, J.;Feng, Y.;Flom, E.;Fernandes, H.;Fietz, W. H.;Figacz, W.;Fontdecaba, J.;Ford, O.;Fornal, T.;Frerichs, H.;Freund, A.;Funaba, T.;Galkowski, A.;Gantenbein, G.;Gao, Y.;García Regaña, J.;Gates, D.;Geiger, J.;Giannella, V.;Gogoleva, A.;Goncalves, B.;Goriaev, A.;Gradic, D.;Grahl, M.;Green, J.;Greuner, H.;Grosman, A.;Grote, H.;Gruca, M.;Guerard, C.;Hacker, P.;Han, X.;Harris, J. H.;Hartmann, D.;Hathiramani, D.;Hein, B.;Heinemann, B.;Helander, P.;Henneberg, S.;Henkel, M.;Hernandez Sanchez, J.;Hidalgo, C.;Hirsch, M.;Hollfeld, K. P.;Höfel, U.;Hölting, A.;Höschen, D.;Houry, M.;Howard, J.;Huang, X.;Huang, Z.;Hubeny, M.;Huber, M.;Hunger, H.;Ida, K.;Ilkei, T.;Illy, S.;Israeli, B.;Jablonski, S.;Jakubowski, M.;Jelonnek, J.;Jenzsch, H.;Jesche, T.;Jia, M.;Junghanns, P.;Kacmarczyk, J.;Kallmeyer, J. -P.;Kamionka, U.;Kasahara, H.;Kasparek, W.;Kazakov, Y. O.;Kenmochi, N.;Killer, C.;Kirschner, A.;Kleiber, R.;Knauer, J.;Knaup, M.;Knieps, A.;Kobarg, T.;Kocsis, G.;Köchl, F.;Kolesnichenko, Y.;Könies, A.;König, R.;Kornejew, P.;Koschinsky, J. -P.;Köster, F.;Krämer, M.;Krampitz, R.;Krämer-Flecken, A.;Krawczyk, N.;Kremeyer, T.;Krom, J.;Krychowiak, M.;Ksiazek, I.;Kubkowska, M.;Kühner, G.;Kurki-Suonio, T.;Kurz, P. A.;Kwak, S.;Landreman, M.;Lang, P.;Lang, R.;Langenberg, A.;Langish, S.;Laqua, H.;Laube, R.;Lazerson, S.;Lechte, C.;Lennartz, M.;Leonhardt, W.;Li, C.;Li, C.;Li, Y.;Liang, Y.;Linsmeier, C.;Liu, S.;Lobsien, J. -F.;Loesser, D.;Loizu Cisquella, J.;Lore, J.;Lorenz, A.;Losert, M.;Lücke, A.;Lumsdaine, A.;Lutsenko, V.;Maaßberg, H.;Marchuk, O.;Matthew, J. H.;Marsen, S.;Marushchenko, M.;Masuzaki, S.;Maurer, D.;Mayer, M.;McCarthy, K.;McNeely, P.;Meier, A.;Mellein, D.;Mendelevitch, B.;Mertens, P.;Mikkelsen, D.;Mishchenko, A.;Missal, B.;Mittelstaedt, J.;Mizuuchi, T.;Mollen, A.;Moncada, V.;Mönnich, T.;Morisaki, T.;Moseev, D.;Murakami, S.;Náfrádi, G.;Nagel, M.;Naujoks, D.;Neilson, H.;Neu, R.;Neubauer, O.;Neuner, U.;Ngo, T.;Nicolai, D.;Nielsen, S. K.;Niemann, H.;Nishizawa, T.;Nocentini, R.;Nührenberg, C.;Nührenberg, J.;Obermayer, S.;Offermanns, G.;Ogawa, K.;Ölmanns, J.;Ongena, J.;Oosterbeek, J. W.;Orozco, G.;Otte, M.;Pacios Rodriguez, L.;Panadero, N.;Panadero Alvarez, N.;Papenfuß, D.;Paqay, S.;Pasch, E.;Pavone, A.;Pawelec, E.;Pedersen, T. S.;Pelka, G.;Perseo, V.;Peterson, B.;Pilopp, D.;Pingel, S.;Pisano, F.;Plaum, B.;Plunk, G.;Pölöskei, P.;Porkolab, M.;Proll, J.;Puiatti, M. -E.;Puig Sitjes, A.;Purps, F.;Rack, M.;Récsei, S.;Reiman, A.;Reimold, F.;Reiter, D.;Remppel, F.;Renard, S.;Riedl, R.;Riemann, J.;Risse, K.;Rohde, V.;Röhlinger, H.;Romé, M.;Rondeshagen, D.;Rong, P.;Roth, B.;Rudischhauser, L.;Rummel, K.;Rummel, T.;Runov, A.;Rust, N.;Ryc, L.;Ryosuke, S.;Sakamoto, R.;Salewski, M.;Samartsev, A.;Sanchez, E.;Sano, F.;Satake, S.;Schacht, J.;Satheeswaran, G.;Schauer, F.;Scherer, T.;Schilling, J.;Schlaich, A.;Schlisio, G.;Schluck, F.;Schlüter, K. -H.;Schmitt, J.;Schmitz, H.;Schmitz, O.;Schmuck, S.;Schneider, M.;Schneider, W.;Scholz, P.;Schrittwieser, R.;Schröder, M.;Schröder, T.;Schroeder, R.;Schumacher, H.;Schweer, B.;Scott, E.;Sereda, S.;Shanahan, B.;Sibilia, M.;Sinha, P.;Sipliä, S.;Slaby, C.;Sleczka, M.;Smith, H.;Spiess, W.;Spong, D. A.;Spring, A.;Stadler, R.;Stejner, M.;Stephey, L.;Stridde, U.;Suzuki, C.;Svensson, J.;Szabó, V.;Szabolics, T.;Szepesi, T.;Szökefalvi-Nagy, Z.;Tancetti, A.;Terry, J.;Thomas, J.;Thumm, M.;Travere, J. M.;Traverso, P.;Tretter, J.;Trimino Mora, H.;Tsuchiya, H.;Tsujimura, T.;Tulipán, S.;Unterberg, B.;Vakulchyk, I.;Valet, S.;Vano, L.;van Milligen, B.;van Vuuren, A. J.;Vela, L.;Velasco, J. -L.;Vergote, M.;Vervier, M.;Vianello, N.;Viebke, H.;Vilbrandt, R.;Vorköper, A.;Wadle, S.;Wagner, F.;Wang, E.;Wang, N.;Wang, Z.;Warmer, F.;Wauters, T.;Wegener, L.;Weggen, J.;Wei, Y.;Weir, G.;Wendorf, J.;Wenzel, U.;Werner, A.;White, A.;Wiegel, B.;Wilde, F.;Windisch, T.;Winkler, M.;Winter, A.;Winters, V.;Wolf, S.;Wolf, R. C.;Wright, A.;Wurden, G.;Xanthopoulos, P.;Yamada, H.;Yamada, I.;Yasuhara, R.;Yokoyama, M.;Zanini, M.;Zarnstorff, M.;Zeitler, A.;Zhang, D.;Zhang, H.;Zhu, J.;Zilker, M.;Zocco, A.;Zoletnik, S.;Zuin, M.
2019-01-01
Abstract
The optimized superconducting stellarator device Wendelstein 7-X (with major radius R = 5.5 m, minor radius a = 0.5 m, and 30 m(3) 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 x 10(19) 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 x 10(20) 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 . 10(19) m(-3) a temperature of 3.4 keV with T-e/T-i = 1 was transiently accomplished, which corresponds to nT(i)(0)tau(E) = 6.4 x 10(19) keV s m(-3) with a peak diamagnetic energy of 1.1 MJ and volume-averaged normalized plasma pressure = 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 x 10(20) m(-2) line integrated density and T-e = T-i = 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.