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1. On the role of density fluctuations in the core turbulent transport of Wendelstein 7-X

Author

Carralero, D., Estrada, T., Maragkoudakis, E., Windisch, T., Alonso, J. A., Velasco, J. L., Ford, O., Jakubowski, M., Lazerson, S., Beurskens, M., Bozhenkov, S., Calvo, I., Damm, H., Fuchert, G., García-Regaña, J. M., Höfel, U., Marushchenko, N., Pablant, N., Sánchez, E., Smith, H. M., Pasch, E., and Stange, T.

Subjects
Physics - Plasma Physics
Abstract

A recent characterization of core turbulence carried out with a Doppler reflectometer in the optimized stellarator Wendelstein 7-X (W7-X) found that discharges achieving high ion temperatures at the core featured an ITG-like suppression of density fluctuations driven by a reduction of the gradient ratio $\eta_i = L_n/L_{T_i}$ [D. Carralero et al., Nucl. Fusion, 2021]. In order to confirm the role of ITG turbulence in this process, we set out to establish experimentally the relation between core density fluctuations, turbulent heat flux and global confinement. With this aim, we consider the scenarios found in the previous work and carry out power balance analysis for a number of representative ones, including some featuring high ion temperature. As well, we evaluate the global energy confinement time and discuss it in the context of the ISS04 inter-stellarator scaling. We find that, when turbulence is suppressed as a result of a reduction of $\eta_i$, there is a reduction of ion turbulent transport, and global performance is improved as a result. This is consistent with ITG turbulence limiting the ion temperature at the core of W7-X. In contrast, when turbulence is reduced following a decrease in collisionality, no changes are observed in transport or confinement. This could be explained by ITG modes being combined with TEM turbulence when the later is destabilized at low collisionalities., Comment: Submitted to PPCF, 47th EPS special issue

Published
2021
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2. An experimental characterization of core turbulence regimes in Wendelstein 7-X

Author

Carralero, D., Estrada, T., Maragkoudakis, E., Windisch, T., Alonso, J. A., Beurskens, M., Bozhenkov, S., Calvo, I., Damm, H., Ford, O., Fuchert, G., García-Regaña, J. M., Pablant, N., Sánchez, E., Pasch, E., Velasco, J. L., and team, the Wendelstein 7-X

Subjects
Physics - Plasma Physics
Abstract

First results from the optimized helias Wendelstein 7-X stellarator (W7-X) have shown that core transport is no longer mostly neoclassical, as is the case in previous kinds of stellarators. Instead, turbulent transport poses a serious limitation to the global performance of the machine. Several studies have found this particularly relevant for ion transport, with core ion temperatures becoming clamped at relatively low values of $T_{i} \simeq 1.7$ keV, except in the few scenarios in which turbulence can be suppressed. In order to understand turbulent mechanisms at play, it is important to have a clear understanding of the parametric dependencies of turbulent fluctuations, and the relation between them and turbulent transport. In this work we use Doppler reflectometry measurements carried out during a number of relevant operational scenarios to provide a systematic characterization of ion-scale ($k_\perp\rho_i\simeq 1$) density fluctuations in the core of W7-X. Then, we study the relation between fluctuation amplitude and plasma profiles and show how distinct regimes can be defined for the former, depending on normalized gradients $a/L_{ne}$ and $a/L_{Ti}$. Furthermore, we discuss the importance of other potentially relevant parameters such as $T_e/T_i$, $E_r$ or collisionality. Comparing the different regimes, we find that turbulence amplitude depends generally on the gradient ratio $\eta_i=L_{ne}/L_{Ti}$, as would be expected for ITG modes, with the exception of a range of discharges, for which turbulence suppression may be better explained by an ITG to TEM transition triggered by a drop in collisionality. Finally, we show a number of scenarios under which $T_{i,core} > 1.7$ keV is achieved and how core fluctuations are suppressed in all of them, thus providing experimental evidence of microturbulence being the main responsible for the limited ion confinement in W7-X., Comment: Manuscript submitted to Nuclear Fusion in May 2021

Published
2021
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3. Characterization of the radial electric field and edge velocity shear in Wendelstein 7-X

Author

Carralero, D., Estrada, T., Windisch, T., Velasco, J. L., Alonso, J. A., Beurskens, M., Bozhenkov, S., Damm, H., Fuchert, G., Gao, Y., Jakubowski, M., Nieman, H., Pablant, N., Pasch, E., Weir, G., and team, the Wendelstein 7-X

Subjects
Physics - Plasma Physics
Abstract

In this work we present the first measurements obtained by the V-band Doppler reflectometer during the second operation phase of Wendelstein 7-X to discuss the influence in the velocity shear layer and the radial electric field, E$_r$, of several plasma parameters such as magnetic configuration, rotational transform or degree of detachment. In the first place, we carry out a systematic characterization of the turbulence rotation velocity profile in order to describe the influence of density and heating power on E$_r$ under the four most frequent magnetic configurations. The $|$E$_r|$ value in the edge is found to increase with configurations featuring higher $\iota$, although this does not apply for the high mirror configuration, KJM. As well, the E$_r$ value in the SOL and the velocity shear near the separatrix are found to display a clear dependence on heating power and density for all configurations. For a number of relevant cases, these results are assessed by comparing them to neoclassical predictions obtained from the codes DKES and KNOSOS, finding generally good agreement with experimental results. Finally, the evolution of E$_r$ at the edge is evaluated throughout the island-divertor detachment regime achieved for the first time in the 2018 campaign. After detachment, $|$E$_r|$ is reduced both at the SOL and edge, and the plasma column shrinks, with the shear layer seemingly moving radially inwards from the separatrix., Comment: Sent for publication to Nuclear Fusion

Published
2020

4. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author

Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S.A., Brunner, K.J., Damm, H., Drevlak, M., Ford, O.P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., and Hirsch, M.

Subjects
Energy transformation -- Research, Stellarators -- Usage, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak.sup.1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X).sup.2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator's non-turbulent 'neoclassical' energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas.sup.3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible.sup.1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization. Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device., Author(s): C. D. Beidler [sup.1] , H. M. Smith [sup.1] , A. Alonso [sup.2] , T. Andreeva [sup.1] , J. Baldzuhn [sup.1] , M. N. A. Beurskens [sup.1] , M. [...]

Published
2021
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5. Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Author

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, Pedersen T. S., Abramovic I., Agostinetti P., Torres M. A., Akaslompolo S., Belloso J. A., 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. -H., Avramidis K., Aymerich E., Baek S. -G., Bahner J., Baillod A., Balden M., Baldzuhn J., Ballinger S., Banduch M., Bannmann S., Navarro A. B., 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. C., 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. W., 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. A., Escoto F. J., 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. M. G., Garcia-Cortes I., Gaspar J., Gates D. A., Geiger J., Geiger B., Giudicotti L., Gonzalez A., Goriaev A., Gradic D., Grahl M., Graves J. P., Green J., Grelier E., Greuner H., Gross S., Grote H., Groth M., Gruca M., Grulke O., Grun M., Arnaiz J. G., Gunter S., Haak V., Haas M., Hacker P., Hakola A., Hallenbert A., Hammond K., Han X., Hansen S. K., Harris J. H., 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. P., 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. J., 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 Ya. I., Konies A., Konig R., Kontula J., Kornejew P., Koschinsky J., Kozulia M. M., Kramer-Flecken A., Krampitz R., Krause M., Krawczyk N., Kremeyer T., Krier L., Kriete D. M., Krychowiak M., Ksiazek I., Kubkowska M., Kuczynski M., Kuhner G., Kumar A., Kurki-Suonio T., Kwak S., Landreman M., Lang P. T., Langenberg A., Laqua H. P., Laqua H., Laube R., Lazerson S., Lewerentz M., Li C., Liang Y., Linsmeier Ch., 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. J., McCormack O., McNeely P., Meister H., Mendelevitch B., Mendes S., Merlo A., Messian A., Mielczarek A., Mishchenko O., Missal B., Mitteau R., Moiseenko V. E., 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. K., 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. P., 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. J., Puiatti M. -E., Sitjes A. P., 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. L., Tamura N., Tancetti A., Tantos C., Terry J., Thienpondt H., Thomsen H., Thumm M., Travere J. M., Traverso P., Tretter J., Trier E., Mora H. T., Tsujimura T., Turkin Y., Tykhyi A., Unterberg B., van Eeten P., van Milligen B. Ph., van Schoor M., Vano L., Varoutis S., Vecsei M., Vela L., Velasco J. L., 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. M., Wurden G. A., 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., 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, 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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, 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S., Abramovic I., Agostinetti P., Torres M. A., Akaslompolo S., Belloso J. A., 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. -H., Avramidis K., Aymerich E., Baek S. -G., Bahner J., Baillod A., Balden M., Baldzuhn J., Ballinger S., Banduch M., Bannmann S., Navarro A. B., 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. C., 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. W., 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. A., Escoto F. J., 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. M. G., Garcia-Cortes I., Gaspar J., Gates D. A., Geiger J., Geiger B., Giudicotti L., Gonzalez A., Goriaev A., Gradic D., Grahl M., Graves J. P., Green J., Grelier E., Greuner H., Gross S., Grote H., Groth M., Gruca M., Grulke O., Grun M., Arnaiz J. G., Gunter S., Haak V., Haas M., Hacker P., Hakola A., Hallenbert A., Hammond K., Han X., Hansen S. K., Harris J. H., 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. P., 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. J., 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 Ya. I., Konies A., Konig R., Kontula J., Kornejew P., Koschinsky J., Kozulia M. 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P., 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. L., Tamura N., Tancetti A., Tantos C., Terry J., Thienpondt H., Thomsen H., Thumm M., Travere J. M., Traverso P., Tretter J., Trier E., Mora H. T., Tsujimura T., Turkin Y., Tykhyi A., Unterberg B., van Eeten P., van Milligen B. Ph., van Schoor M., Vano L., Varoutis S., Vecsei M., Vela L., Velasco J. L., 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. M., Wurden G. A., 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., and Zsuga L.

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.

Published
2022

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

Author

Pedersen, Thomas Sunn, Abramovic, I., Agostinetti, P., Torres, M. Agredano, Äkäslompolo, S., Belloso, J. Alcuson, 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. H., Avramidis, K., Aymerich, E., Baek, S. G., Bähner, J., Baillod, A., Balden, M., Baldzuhn, J., Ballinger, S., Banduch, M., Bannmann, S., Navarro, A. Bañón, Barbui, T., Beidler, C., Belafdil, C., Bencze, A., Benndorf, A., Beurskens, M., Biedermann, C., Biletskyi, O., Blackwell, B., Blatzheim, M., Bluhm, T., Böckenhoff, D., Bongiovi, G., Borchardt, M., Borodin, D., Boscary, J., Bosch, H., Bosmann, T., Böswirth, B., Böttger, L., Bottino, A., Bozhenkov, S., Brakel, R., Brandt, C., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K., Buller, S., Burhenn, R., Bussiahn, R., Buttenschön, B., Buzás, A., Bykov, V., Calvo, I., Mata, K. Camacho, 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. W., 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. A., Escoto, F. J., 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., Füllenbach, F., Gantenbein, G., Gao, Y., Garcia, K., Regaña, J. M.García, García-Cortés, I., Gaspar, J., Gates, D. A., Geiger, J., Geiger, B., Giudicotti, L., González, A., Goriaev, A., Gradic, D., Grahl, M., Graves, J. P., Green, J., Grelier, E., Greuner, H., Groß, S., Grote, H., Groth, M., Gruca, M., Grulke, O., Grün, M., Arnaiz, J. Guerrero, Günter, S., Haak, V., Haas, M., Hacker, P., Hakola, A., Hallenbert, A., Hammond, K., Han, X., Hansen, S. K., Harris, J. H., 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., Höfel, U., Hollfeld, K. P., Holtz, A., Hopf, D., Höschen, D., Houry, M., Howard, J., Huang, X., Hubeny, M., Hudson, S., Ida, K., Igitkhanov, Y., Igochine, V., Illy, S., Ionita-Schrittwieser, C., Isobe, M., Jabłczynska, M., Jablonski, S., Jagielski, B., Jakubowski, M., van Vuuren, A. Jansen, 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., Köchl, F., Kocsis, G., Kolesnichenko, Ya I., Könies, A., König, R., Kontula, J., Kornejew, P., Koschinsky, J., Kozulia, M. M., Krämer-Flecken, A., Krampitz, R., Krause, M., Krawczyk, N., Kremeyer, T., Krier, L., Kriete, D. M., Krychowiak, M., Ksiazek, I., Kubkowska, M., Kuczynski, M., Kühner, G., Kumar, A., Kurki-Suonio, T., Kwak, S., Landreman, M., Lang, P. T., Langenberg, A., Laqua, H., Laube, R., Lazerson, S., Lewerentz, M., Li, C., Liang, Y., Linsmeier, Ch, 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. J., McCormack, O., McNeely, P., Meister, H., Mendelevitch, B., Mendes, S., Merlo, A., Messian, A., Mielczarek, A., Mishchenko, O., Missal, B., Mitteau, R., Moiseenko, V. E., Mollen, A., Moncada, V., Mönnich, 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. K., Niemann, H., Nishiza, T., Nishizawa, T., Nührenberg, C., Ochoukov, R., Oelmann, J., Offermanns, G., Ogawa, K., Okamura, S., Ölmanns, J., Ongena, J., Oosterbeek, J., Otte, M., Pablant, N., Alvarez, N. Panadero, Pandey, A., Pasch, E., Pavlichenko, R., Pavone, A., Pawelec, E., Pechstein, G., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plöckl, B., Plunk, G., Pölöskei, P., Pompe, B., Popov, A., Porkolab, M., Proll, J., Pueschel, M. J., Puiatti, M. E., Sitjes, A. Puig, 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., Schröder, T., Schröder, M., Schroeder, R., Schweer, B., Schwörer, D., Scott, E., Shanahan, B., Sias, G., Sichta, P., Singer, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Smith, H., Smoniewski, J., Sonnendrücker, 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., Szücs, M., Tabarés, F. L., Tamura, N., Tancetti, A., Tantos, C., Terry, J., Thienpondt, H., Thomsen, H., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trier, E., Mora, H. Trimino, Tsujimura, T., Turkin, Y., Tykhyi, A., Unterberg, B., van Eeten, P., van Milligen, B. Ph, van Schoor, M., Vano, L., Varoutis, S., Vecsei, M., Vela, L., Velasco, J. L., 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. M., Wurden, G. A., 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., Pedersen, Thomas Sunn, Abramovic, I., Agostinetti, P., Torres, M. Agredano, Äkäslompolo, S., Belloso, J. Alcuson, 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. H., Avramidis, K., Aymerich, E., Baek, S. G., Bähner, J., Baillod, A., Balden, M., Baldzuhn, J., Ballinger, S., Banduch, M., Bannmann, S., Navarro, A. Bañón, Barbui, T., Beidler, C., Belafdil, C., Bencze, A., Benndorf, A., Beurskens, M., Biedermann, C., Biletskyi, O., Blackwell, B., Blatzheim, M., Bluhm, T., Böckenhoff, D., Bongiovi, G., Borchardt, M., Borodin, D., Boscary, J., Bosch, H., Bosmann, T., Böswirth, B., Böttger, L., Bottino, A., Bozhenkov, S., Brakel, R., Brandt, C., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K., Buller, S., Burhenn, R., Bussiahn, R., Buttenschön, B., Buzás, A., Bykov, V., Calvo, I., Mata, K. Camacho, 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. W., 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. A., Escoto, F. J., 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., Füllenbach, F., Gantenbein, G., Gao, Y., Garcia, K., Regaña, J. M.García, García-Cortés, I., Gaspar, J., Gates, D. A., Geiger, J., Geiger, B., Giudicotti, L., González, A., Goriaev, A., Gradic, D., Grahl, M., Graves, J. P., Green, J., Grelier, E., Greuner, H., Groß, S., Grote, H., Groth, M., Gruca, M., Grulke, O., Grün, M., Arnaiz, J. Guerrero, Günter, S., Haak, V., Haas, M., Hacker, P., Hakola, A., Hallenbert, A., Hammond, K., Han, X., Hansen, S. K., Harris, J. H., 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., Höfel, U., Hollfeld, K. P., Holtz, A., Hopf, D., Höschen, D., Houry, M., Howard, J., Huang, X., Hubeny, M., Hudson, S., Ida, K., Igitkhanov, Y., Igochine, V., Illy, S., Ionita-Schrittwieser, C., Isobe, M., Jabłczynska, M., Jablonski, S., Jagielski, B., Jakubowski, M., van Vuuren, A. Jansen, 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., Köchl, F., Kocsis, G., Kolesnichenko, Ya I., Könies, A., König, R., Kontula, J., Kornejew, P., Koschinsky, J., Kozulia, M. M., Krämer-Flecken, A., Krampitz, R., Krause, M., Krawczyk, N., Kremeyer, T., Krier, L., Kriete, D. M., Krychowiak, M., Ksiazek, I., Kubkowska, M., Kuczynski, M., Kühner, G., Kumar, A., Kurki-Suonio, T., Kwak, S., Landreman, M., Lang, P. T., Langenberg, A., Laqua, H., Laube, R., Lazerson, S., Lewerentz, M., Li, C., Liang, Y., Linsmeier, Ch, 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. J., McCormack, O., McNeely, P., Meister, H., Mendelevitch, B., Mendes, S., Merlo, A., Messian, A., Mielczarek, A., Mishchenko, O., Missal, B., Mitteau, R., Moiseenko, V. E., Mollen, A., Moncada, V., Mönnich, 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. K., Niemann, H., Nishiza, T., Nishizawa, T., Nührenberg, C., Ochoukov, R., Oelmann, J., Offermanns, G., Ogawa, K., Okamura, S., Ölmanns, J., Ongena, J., Oosterbeek, J., Otte, M., Pablant, N., Alvarez, N. Panadero, Pandey, A., Pasch, E., Pavlichenko, R., Pavone, A., Pawelec, E., Pechstein, G., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plöckl, B., Plunk, G., Pölöskei, P., Pompe, B., Popov, A., Porkolab, M., Proll, J., Pueschel, M. J., Puiatti, M. E., Sitjes, A. Puig, 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., Schröder, T., Schröder, M., Schroeder, R., Schweer, B., Schwörer, D., Scott, E., Shanahan, B., Sias, G., Sichta, P., Singer, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Smith, H., Smoniewski, J., Sonnendrücker, 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., Szücs, M., Tabarés, F. L., Tamura, N., Tancetti, A., Tantos, C., Terry, J., Thienpondt, H., Thomsen, H., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trier, E., Mora, H. Trimino, Tsujimura, T., Turkin, Y., Tykhyi, A., Unterberg, B., van Eeten, P., van Milligen, B. Ph, van Schoor, M., Vano, L., Varoutis, S., Vecsei, M., Vela, L., Velasco, J. L., 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. M., Wurden, G. A., 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., and Zsuga, L.

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.

Published
2022

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

Author

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

Published
2022
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9. Publisher Correction: Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author

Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S.A., Brunner, K.J., Damm, H., Drevlak, M., Ford, O.P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., and Hirsch, M.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): C. D. Beidler [sup.1] , H. M. Smith [sup.1] , A. Alonso [sup.2] , T. Andreeva [sup.1] , J. Baldzuhn [sup.1] , M. N. A. Beurskens [sup.1] , M. [...]

Published
2021
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10. Bolometer tomography on Wendelstein 7-X for study of radiation asymmetry

Author

Zhang, D., primary, Burhenn, R., additional, Beidler, C.D., additional, Feng, Y., additional, Thomsen, H., additional, Brandt, C., additional, Buller, S., additional, Reimold, F., additional, Hacker, P., additional, Laube, R., additional, Geiger, J., additional, Regaña, J.M.García, additional, Smith, H.M., additional, König, R., additional, Giannone, L., additional, Penzel, F., additional, Klinger, T., additional, Baldzuhn, J., additional, Bozhenkov, S., additional, Bräuer, T., additional, Brunner, J.K., additional, Buttenschön, B., additional, Damm, H., additional, Endler, M., additional, Effenberg, F., additional, Fuchert, G., additional, Gao, Y., additional, Jakubowski, M., additional, Knauer, J., additional, Kremeyer, T., additional, Krychowiak, M., additional, Kwak, S., additional, Laqua, H.P., additional, Langenberg, A., additional, Otte, M., additional, Pablant, N., additional, Pasch, E., additional, Rahbarnia, K., additional, Pavone, A., additional, Rudischhauser, L., additional, Svensson, J., additional, Killer, C., additional, Windisch, T., additional, and W7-X Team, the, additional

Published
2021
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11. Impurity transport in ion- and electron-root confinement scenarios at Wendelstein 7-X

Author

Langenberg, A., primary, Wegner, Th., additional, Marchuk, O., additional, García-Regaña, J.M., additional, Pablant, N.A., additional, Fuchert, G., additional, Bozhenkov, S., additional, Damm, H., additional, Pasch, E., additional, Brunner, K.-J., additional, Knauer, J., additional, Beurskens, M., additional, Reimold, F., additional, Wolf, R.C., additional, and W7-X Team, the, additional

Published
2021
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12. An experimental characterization of core turbulence regimes in Wendelstein 7-X

Author

Carralero, D., primary, Estrada, T., additional, Maragkoudakis, E., additional, Windisch, T., additional, Alonso, J.A., additional, Beurskens, M., additional, Bozhenkov, S., additional, Calvo, I., additional, Damm, H., additional, Ford, O., additional, Fuchert, G., additional, García-Regaña, J.M., additional, Pablant, N., additional, Sánchez, E., additional, Pasch, E., additional, Velasco, J.L., additional, and Wendelstein 7-X team, the, additional

Published
2021
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14. Impact of magnetic islands on plasma flow and turbulence in W7-X

Author

W7-X Team, Estrada, T., Maragkoudakis, E., Carralero, D., Windisch, T., Velasco, J. L., Killer, C., Andreeva, T., Geiger, J., Dinklage, A., Krämer-Flecken, A., Wurden, G. A., Beurskens, M., Bozhenkov, S., Damm, H., Fuchert, G., Pasch, E., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Technology, Nuclear and High Energy Physics, Plasma flow, Turbulence, 0103 physical sciences, Mechanics, ddc:620, 010306 general physics, Condensed Matter Physics, ddc:600, 01 natural sciences, 010305 fluids & plasmas
Abstract

The effect of magnetic islands on plasma flow and turbulence has been experimentally investigated in the stellarator W7-X. Magnetic configurations with the 5/5 magnetic island positioned at the plasma edge, inside the last closed flux surface, are studied. The main diagnostic used in the present work is a V-band Doppler reflectometer that allows the measurement of the perpendicular plasma flow and density fluctuations with good spatial resolution. A characteristic signature of the 5/5 magnetic island is clearly detected in the perpendicular flow profile. The comparison of the experimental flow and the neoclassically driven E × B flow indicates that the island contribution to the flow is maximum at the island boundaries and close to zero at the island O-point. Besides, a reduction in the density fluctuation level is found nearby the island O-point. The similarities between these observations and those found in other devices and in gyrokinetic simulations are discussed.

Published
2021
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15. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Author

W7-X Team, Beidler, C. D., Smith, H. M., Alonso, A., Andreeva, T., Baldzuhn, J., Beurskens, M. N. A., Borchardt, M., Bozhenkov, S. A., Brunner, K. J., Damm, H., Drevlak, M., Ford, O. P., Fuchert, G., Geiger, J., Helander, P., Hergenhahn, U., Hirsch, M., Höfel, U., Kazakov, Ye. O., Kleiber, R., Krychowiak, M., Kwak, S., Langenberg, A., Laqua, H. P., Neuner, U., Pablant, N. A., Pasch, E., Pavone, A., Pedersen, T. S., Rahbarnia, K., Schilling, J., Scott, E. R., Stange, T., Svensson, J., Thomsen, H., Turkin, Y., Warmer, F., Wolf, R. C., Zhang, D., Abramovic, I., Äkäslompolo, S., Alcusón, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., Bähner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Böckenhoff, D., Böswirth, B., Böttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttenschön, B., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M., Cole, M. J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., Molin, A. da, Silva, A. da, Pena, A. de la, Degenkolbe, S., Dhard, C. P., Dibon, M., Dinklage, A., Dittmar, T., Drewelow, P., Drews, P., Durodie, F., Edlund, E., Effenberg, F., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Feng, Y., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., García Regaña, J., Gates, D., Geiger, B., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Grulke, O., Guerard, C., Hacker, P., Han, X., Harris, J. H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., Hölting, A., Höschen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ida, K., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J.-P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Killer, C., Kirschner, A., Klinger, T., Knauer, J., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., Köchl, F., Kolesnichenko, Y., Könies, A., König, R., Kornejew, P., Koschinsky, J.-P., Köster, F., Krämer, M., Krampitz, R., Krämer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., Kühner, G., Kurki-Suonio, T., Kurz, P. A., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lazerson, S., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J.-F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., Lücke, A., Lumsdaine, A., Lutsenko, V., Maaßberg, H., Marchuk, O., Matthew, J. H., Marsen, S., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., McCarthy, K., McNeely, P., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., Mönnich, T., Morisaki, T., Moseev, D., Murakami, S., Náfrádi, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., Nührenberg, C., Nührenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., Ölmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfuß, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., Pölöskei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., Récsei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., Röhlinger, H., Romé, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Rust, N., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., Sanchez, M., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schlüter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schröder, M., Schröder, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szabó, V., Szabolics, T., Szepesi, T., Szökefalvi-Nagy, Z., Tamura, N., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulipán, S., Unterberg, B., Vakulchyk, I., Valet, S., Vanó, L., Eeten, P. van, Milligen, B. van, Vuuren, A. J. van, Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Stechow, A. von, Vorköper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Wauters, T., Wegener, L., Weggen, J., Wegner, T., Wei, Y., Weir, G., Wendorf, J., Wenzel, U., Werner, A., White, A., Wiegel, B., Wilde, F., Windisch, T., Winkler, M., Winter, A., Winters, V., Wolf, S., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., Zuin, M., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, Applied Physics and Science Education, Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and European Commission

Subjects
Magnetically Confined Plasmas, Tokamak, Design, Helias, Nuclear engineering, Magnetically confined plasmas, 01 natural sciences, 7. Clean energy, Article, Plasma physics, 010305 fluids & plasmas, law.invention, law, Physics::Plasma Physics, 0103 physical sciences, Nuclear fusion, 010306 general physics, Engineering & allied operations, Stellarator, Physics, Plasma fusion, Multidisciplinary, Toroid, biology, Plasma Physics, Física, Magnetic confinement fusion, Plasma, biology.organism_classification, Energía Nuclear, ddc:620, Wendelstein 7-X
Abstract

Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak1 is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)2, a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator’s non-turbulent ‘neoclassical’ energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas3,4. The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible1,5. Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization., Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device.

Published
2021
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16. Impurity transport in ion- and electron-root confinement scenarios at Wendelstein 7-X

Author

W7-X Team, Langenberg, A., Wegner, Th., Marchuk, O., García-Regaña, J. M., Pablant, N. A., Fuchert, G., Bozhenkov, S., Damm, H., Pasch, E., Brunner, K.-J., Knauer, J., Beurskens, M., Reimold, F., Wolf, R. C., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
ddc:620, Engineering & allied operations
Published
2021
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17. Charge-state independent anomalous transport for a wide range of different impurity species observed at Wendelstein 7-X

Author

W7-X Team, Langenberg, A., Wegner, Th., Pablant, N. A., Marchuk, O., Geiger, B., Tamura, N., Bussiahn, R., Kubkowska, M., Mollén, A., Traverso, P., Smith, H. M., Fuchert, G., Bozhenkov, S., Damm, H., Pasch, E., Brunner, K.-J., Knauer, J., Beurskens, M., Burhenn, R., Wolf, R. C., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Range (particle radiation), Technology, Turbulence, Charge (physics), State (functional analysis), Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Atomic mass, 010305 fluids & plasmas, law.invention, Impurity, law, 0103 physical sciences, Wendelstein 7-X, Atomic physics, 010306 general physics, ddc:600, Stellarator
Abstract

In this paper, the plasma volume averaged impurity confinement of selected charge states and impurity species has been characterized for the Stellarator Wendelstein 7-X (W7-X), covering a wide range of atomic charges ( Z = 12–44) and atomic masses ( M = 28–184). A comparison of the experimental findings to theoretical neoclassical and turbulent transport expectations suggests, aside from/in addition to the neoclassical transport, an additional significant anomalous transport mechanism, which is not inconsistent with the predictions of a turbulence dominated impurity transport and is in agreement with the experimental results from recent transport studies based on the direct measurements of impurity diffusion profiles, performed at W7-X.

Published
2020

18. Increasing the density in Wendelstein 7-X: benefits and limitations

Author

W7-X Team, Fuchert, G., Brunner, K. J., Rahbarnia, K., Stange, T., Zhang, D., Baldzuhn, J., Bozhenkov, S. A., Beidler, C. D., Beurskens, M. N. A., Brezinsek, S., Burhenn, R., Damm, H., Dinklage, A., Feng, Y., Hacker, P., Hirsch, M., Kazakov, Y., Knauer, J., Langenberg, A., Laqua, H. P., Lazerson, S., Pablant, N. A., Pasch, E., Reimold, F., Sunn Pedersen, T., Scott, E. R., Warmer, F., Winters, V. R., Wolf, R. C., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Technology, Nuclear and High Energy Physics, Range (particle radiation), Divertor, Plasma, Radiation, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, Computational physics, law, 0103 physical sciences, Radiative transfer, ddc:620, Wendelstein 7-X, 010306 general physics, ddc:600, Energy (signal processing), Stellarator
Abstract

In stellarators, increasing the density is beneficial for the energy confinement. While there is no single reason for this observation, it is still very robust across different devices and this is reflected in the empirical energy confinement time scaling for stellarators, ISS04. In order to study whether this is also true for Wendelstein 7-X, the density scaling of the energy confinement time is analyzed and compared to ISS04 for the first divertor experiments. When the density is increased beyond a critical density, however, radiative collapses are frequently observed. Existing analytical models for the critical density are revisited to assess whether they can predict the accessible density range. Furthermore, since close to the collapse the radiation losses increase substantially, the impact on the global energy confinement is investigated. It is found that in plasmas with high radiation the density scaling of the energy confinement time becomes weaker, the reason for this observation is not yet clear. In the second half of the first divertor campaign, boronization was applied to W7-X for the first time. This broadened the operational window, allowing for operation at higher density and, hence, higher stored energy.

Published
2020
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19. Enhanced energy confinement after series of pellets in Wendelstein 7-X

Author

W7-X Team, Baldzuhn, J., Damm, H., Beidler, C. D., McCarthy, K., Panadero, N., Biedermann, C., Bozhenkov, S. A., Dinklage, A., Brunner, K. J., Fuchert, G., Kazakov, Y., Beurskens, M., Dibon, M., Geiger, J., Grulke, O., Höfel, U., Klinger, T., Köchl, F., Knauer, J., Kocsis, G., Kornejew, P., Lang, P. T., Langenberg, A., Laqua, H., Pablant, N. A., Pasch, E., Pedersen, T. S., Ploeckl, B., Rahbarnia, K., Schlisio, G., Scott, E. R., Stange, T., Von Stechow, A., Szepesi, T., Turkin, Y., Wagner, F., Winters, V., Wurden, G., Zhang, D., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Materials science, Series (mathematics), Pellets, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Nuclear Energy and Engineering, Impurity, 0103 physical sciences, Wendelstein 7-X, Atomic physics, 010306 general physics, ddc:600, Energy (signal processing)
Abstract

A series of ice pellets was injected into the advanced stellarator Wendelstein 7-X (W7-X). Although the pellets were small and slow, deep and efficient particle fueling could be observed experimentally. The most striking feature appearing after the injection of the pellets, however, was a transient increase in the energy confinement time. This transient phase resembled in several aspects modes of enhanced confinement after gas-puff or pellet injection, as observed in other fusion experiments. All experimental attempts, to prolong this phase, failed. In this paper, discharges are described that show the enhanced energy confinement, and some conditions are summarized which seem to be essential in order to generate it. The focus here is on deep particle fueling by pellets, and shaping of the density profiles during and after the series of pellets. During this time, neutral gas particle re-fueling at the plasma edge is reduced, while density profile peaking and low impurity radiation losses are present.

Published
2020

20. Enhanced energy confinement after series of pellets in Wendelstein 7-X

Author

Baldzuhn, J, Damm, H, Beidler, C D, McCarthy, K, Panadero, N, Biedermann, C, Bozhenkov, S A, Dinklage, A, Brunner, K J, Fuchert, G, Kazakov, Y, Beurskens, M, Dibon, M, Geiger, J, Grulke, O, Höfel, U, Klinger, T, Köchl, F, Knauer, J, Kocsis, G, Kornejew, P, Lang, P T, Langenberg, A, Laqua, H, Pablant, N A, Pasch, E, Pedersen, T S, Ploeckl, B, Rahbarnia, K, Schlisio, G, Scott, E R, Stange, T, Von Stechow, A, Szepesi, T, Turkin, Y, Wagner, F, Winters, V, Wurden, G, Zhang, D., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Published
2020
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22. Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

Author

Estrada, T., primary, Carralero, D., additional, Windisch, T., additional, Sánchez, E., additional, García-Regaña, J.M., additional, Martínez-Fernández, J., additional, de la Peña, A., additional, Velasco, J.L., additional, Alonso, J.A., additional, Beurskens, M., additional, Bozhenkov, S., additional, Damm, H., additional, Fuchert, G., additional, Kleiber, R., additional, Pablant, N., additional, Pasch, E., additional, and W7-X team, the, additional

Published
2021
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23. Bolometer tomography on Wendelstein 7-X for study of radiation asymmetry

Author

W7-X Team, Zhang, D., Burhenn, R., Beidler, C. D., Feng, Y., Thomsen, H., Brandt, C., Buller, S., Reimold, F., Hacker, P., Laube, R., Geiger, J., Regaña, J. M. García, Smith, H. M., König, R., Giannone, L., Penzel, F., Klinger, T., Baldzuhn, J., Bozhenkov, S., Bräuer, T., Brunner, J. K., Buttenschön, B., Damm, H., Endler, M., Effenberg, F., Fuchert, G., Gao, Y., Jakubowski, M., Knauer, J., Kremeyer, T., Krychowiak, M., Kwak, S., Laqua, H. P., Langenberg, A., Otte, M., Pablant, N., Pasch, E., Rahbarnia, K., Pavone, A., Rudischhauser, L., Svensson, J., Killer, C., Windisch, T., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Technology, Nuclear and High Energy Physics, business.industry, media_common.quotation_subject, Bolometer, Radiation, Condensed Matter Physics, 01 natural sciences, Asymmetry, 010305 fluids & plasmas, law.invention, Optics, law, 0103 physical sciences, Tomography, Wendelstein 7-X, 010306 general physics, business, ddc:600, media_common
Published
2021
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24. Enhanced energy confinement after series of pellets in Wendelstein 7-X

Author

Baldzuhn, J, primary, Damm, H, additional, Beidler, C D, additional, McCarthy, K, additional, Panadero, N, additional, Biedermann, C, additional, Bozhenkov, S A, additional, Dinklage, A, additional, Brunner, K J, additional, Fuchert, G, additional, Kazakov, Y, additional, Beurskens, M, additional, Dibon, M, additional, Geiger, J, additional, Grulke, O, additional, Höfel, U, additional, Klinger, T, additional, Köchl, F, additional, Knauer, J, additional, Kocsis, G, additional, Kornejew, P, additional, Lang, P T, additional, Langenberg, A, additional, Laqua, H, additional, Pablant, N A, additional, Pasch, E, additional, Pedersen, T S, additional, Ploeckl, B, additional, Rahbarnia, K, additional, Schlisio, G, additional, Scott, E R, additional, Stange, T, additional, Von Stechow, A, additional, Szepesi, T, additional, Turkin, Y, additional, Wagner, F, additional, Winters, V, additional, Wurden, G, additional, and Zhang, D., additional

Published
2020
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25. Soft x-ray tomography measurements in the Wendelstein 7-X stellarator

Author

Brandt, C, primary, Schilling, J, additional, Thomsen, H, additional, Broszat, T, additional, Laube, R, additional, Schröder, T, additional, Andreeva, T, additional, Beurskens, M N A, additional, Bozhenkov, S A, additional, Brunner, K J, additional, Card, A, additional, Cordes, C, additional, Damm, H, additional, Fuchert, G, additional, Gallowski, K, additional, Gutzmann, R, additional, Knauer, J, additional, Laqua, H P, additional, Marquardt, M, additional, Nelde, Ph, additional, Neuner, U, additional, Pasch, E, additional, Rahbarnia, K, additional, Recknagel, J, additional, Schülke, M, additional, Scott, E R, additional, and Sieber, T, additional

Published
2020
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26. An experimental characterization of core turbulence regimes in Wendelstein 7-X

Author

W7-X Team, Carralero, D., Estrada, T., Maragkoudakis, E., Windisch, T., Alonso, J. A., Beurskens, M., Bozhenkov, S., Calvo, I., Damm, H., Ford, O., Fuchert, G., García-Regaña, J. M., Pablant, N., Sánchez, E., Pasch, E., Velasco, J. L., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
Physics, Technology, Nuclear and High Energy Physics, Turbulence, FOS: Physical sciences, Condensed Matter Physics, 01 natural sciences, Physics - Plasma Physics, 010305 fluids & plasmas, law.invention, Characterization (materials science), Computational physics, Plasma Physics (physics.plasm-ph), Core (optical fiber), Physics::Plasma Physics, law, 0103 physical sciences, Wendelstein 7-X, 010306 general physics, ddc:600, Stellarator
Abstract

First results from the optimized helias Wendelstein 7-X stellarator (W7-X) have shown that core transport is no longer mostly neoclassical, as is the case in previous kinds of stellarators. Instead, turbulent transport poses a serious limitation to the global performance of the machine. Several studies have found this particularly relevant for ion transport, with core ion temperatures becoming clamped at relatively low values of $T_{i} \simeq 1.7$ keV, except in the few scenarios in which turbulence can be suppressed. In order to understand turbulent mechanisms at play, it is important to have a clear understanding of the parametric dependencies of turbulent fluctuations, and the relation between them and turbulent transport. In this work we use Doppler reflectometry measurements carried out during a number of relevant operational scenarios to provide a systematic characterization of ion-scale ($k_\perp\rho_i\simeq 1$) density fluctuations in the core of W7-X. Then, we study the relation between fluctuation amplitude and plasma profiles and show how distinct regimes can be defined for the former, depending on normalized gradients $a/L_{ne}$ and $a/L_{Ti}$. Furthermore, we discuss the importance of other potentially relevant parameters such as $T_e/T_i$, $E_r$ or collisionality. Comparing the different regimes, we find that turbulence amplitude depends generally on the gradient ratio $\eta_i=L_{ne}/L_{Ti}$, as would be expected for ITG modes, with the exception of a range of discharges, for which turbulence suppression may be better explained by an ITG to TEM transition triggered by a drop in collisionality. Finally, we show a number of scenarios under which $T_{i,core} > 1.7$ keV is achieved and how core fluctuations are suppressed in all of them, thus providing experimental evidence of microturbulence being the main responsible for the limited ion confinement in W7-X., Comment: Manuscript submitted to Nuclear Fusion in May 2021

Published
2021
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27. Plasma Termination by Excess Pellet Fueling and Impurities in TJ-II, LHD and Wendelstein 7-X

Author

Dinklage, A., McCarthy, K., Suzuki, C., Tamura, N., Wegner, T., Yamada, H., Baldzuhn, J., Buttenschön, B., Damm, H., Drewelow, P., Fuchert, G., Kasahara, H., Maier, D., Miyazawa, J., Motojima, G., Oishi, T., Pedersen, T., Sakamoto, R., Wolf, R., Zhang, D., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, LHD Experiment Group, and TJ-II Team

Published
2019

28. Increasing the Density in W7-X: Benefits and Limitations

Author

Fuchert, G., Brunner, K., Rahbarnia, K., Stange, T., Zhang, D., Baldzuhn, J., Bozhenkov, S., Beidler, C., Brezinsek, S., Burhenn, R., Damm, H., Dinklage, A., Hirsch, M., Kazakov, Y., Knauer, J., Feng, Y., Langenberg, A., Laqua, H., Lazerson, S., Pablant, N., Pasch, E., Pedersen, T., Scott, E., Warmer, F., Winters, V., Wolf, R., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2019

29. Plasma termination by excess pellet fueling and impurity injection in TJ-II, the Large Helical Device and Wendelstein 7-X

Author

Dinklage, A., McCarthy, K. J., Suzuki, C., Tamura, N., Wegner, Th., Yamada, H., Baldzuhn, J., Brunner, K. J., Buttenschön, B., Damm, H., Drewelow, P., Fuchert, G., Hirsch, M., Hoefel, U., Kasahara, H., Knauer, J., Maier, D., Miyazawa, J., Motojima, G., Oishi, T., Rahbarnia, K., Sunn Pedersen, T., Sakamoto, R., Wolf, R. C., Zhang, D., Gantenbein, Gerd, Huber, Martina, Hunger, Hermann, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Losert, M., Meier, A., Mellein, Daniel, Papenfuß, Daniel, Samartsev, Andrey, Scherer, Theo, Schlaich, A., Spiess, W., Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Nuclear and High Energy Physics, Materials science, Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Large Helical Device, Impurity, law, 0103 physical sciences, Pellet, Atomic physics, Wendelstein 7-X, 010306 general physics, ddc:600, Stellarator
Published
2019

30. High density and high performance operation with pellet injection in W7-X

Author

Bozhenkov, S., Kazakov, Y., Baldzuhn, J., Laqua, H., Alonso, J., Beurskens, M., Brandt, C., Brunner, K., Damm, H., Fuchert, G., Hirsch, M., Höfel, U., Jakubowski, M., Knauer, J., Kocsis, G., König, R., Langenberg, A., Lazerson, S., Marushchenko, N., McCarthy, K., Pasch, E., Pablant, N., Panadero Alvarez, N., Rahbarnia, K., Schmitt, J., Thomsen, H., Turkin, Y., Warmer, F., Wurden, G., Zhang, D., Pedersen, T., Wolf, R., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2019

32. Electron-cyclotron-resonance heating in Wendelstein 7-X

Author

Wolf, R. C., Bozhenkov, S., Dinklage, A., Fuchert, G., Kazakov, Y. O., Laqua, H. P., Marsen, S., Marushchenko, N. B., Stange, T., Zanini, M., Abramovic, I., Alonso, A., Baldzuhn, J., Beurskens, M., Beidler, C. D., Braune, H., Brunner, K. J., Chaudhary, N., Damm, H., Drewelow, P., Gantenbein, G., Gao, Y., Geiger, J., Hirsch, M., Hofel, U., Jakubowski, M., Jelonnek, J., Jensen, T., Kasparek, W., Knauer, J., Korsholm, S. B., Langenberg, A., Lechte, C., Leipold, F., Mora, H. T., Neuner, U., Nielsen, S. K., Moseev, D., Oosterbeek, H., Pablant, N., Pasch, E., Plaum, B., Pedersen, T. S., Sitjes, A. P., Rahbarnia, K., Rasmussen, J., Salewski, M., Schilling, J., Scott, E., Stejner, M., Thomsen, H., Thumm, M., Turkin, Y., Wilde, F., Giannella, V., Citarella, R., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, and Science and Technology of Nuclear Fusion

Subjects
Physics, Technology, Cyclotron, Plasma, Collisionality, Fusion power, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Electron cyclotron resonance, Stellerator, 010305 fluids & plasmas, law.invention, Computational physics, Bootstrap current, stellarator, Nuclear Energy and Engineering, law, 0103 physical sciences, Electron temperature, Wendelstein 7-X, electron-cyclotron-resonance heating and current drive, 010306 general physics, ddc:600
Abstract

For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 ×1020 keV m-3 s), observed up to now in stellarators, was achieved (Sunn Pedersen et al 2018 Plasma Phys. Control. Fusion 61 014035). For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.

Published
2019
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33. Pellet fueling experiments in Wendelstein 7-X

Author

W7-X Team, Baldzuhn, J., Damm, H., Beidler, C. D., McCarthy, K., Panadero, N., Biedermann, C., Bozhenkov, S. A., Brunner, K. J., Fuchert, G., Kazakov, Y., Beurskens, M., Dibon, M., Geiger, J., Grulke, O., Höfel, U., Klinger, T., Köchl, F., Knauer, J., Kocsis, G., Kornejew, P., Lang, P. T., Langenberg, A., Laqua, H., Pablant, N. A., Pasch, E., Pedersen, T. S., Ploeckl, B., Rahbarnia, K., Schlisio, G., Scott, E. R., Stange, T., Stechow, A. von, Szepesi, T., Turkin, Y., Wagner, F., Winters, V., Wurden, G., Zhang, D., Gantenbein, Gerd, Huber, Martina, Hunger, Hermann, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Losert, M., Meier, A., Mellein, Daniel, Papenfuß, Daniel, Samartsev, Andrey, Scherer, Theo, Schlaich, A., Spiess, W., Thumm, Manfred, Wadle, Simone, and Weggen, Jörg

Subjects
Technology, ddc:600
Published
2019

34. Structure of island localized modes in Wendelstein 7-X1

Author

Wurden, G. A., Andreeva, T., Hammond, K., Hirsch, M., H öfel, U., Killer, C., Kocsis, G., Kornejew, P., Krämer-Flecken, A., Krychowiak, M., Lazerson, S., Rahbarnia, K., Ballinger, S., Schilling, J., Szepesi, T., Thomsen, H., Winters, V., Zoletnik, S., the W7-X Team, Bozhenkov, S., Brandt, C., Buttenschoen, B., Damm, H., Endler, M., Freundt, S., and Geiger, J.

Published
2019

37. Overview of first Wendelstein 7-X high-performance operation

Author

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, 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., 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, 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., and Zuin, M.

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

38. Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies:Paper

Author

Wolf, R C, Bozhenkov, S, Dinklage, A, Fuchert, G, Kazakov, Y O, Laqua, H P, Marsen, S, Marushchenko, N B, Stange, T, Zanini, M, Abramovic, I, Alonso, A, Baldzuhn, J, Beurskens, M, Beidler, C D, Braune, H, Brunner, K J, Chaudhary, N, Damm, H, Drewelow, P, Gantenbein, G, Gao, Yu, Geiger, J, Hirsch, M, Höfel, U, Jakubowski, M, Jelonnek, J, Jensen, T, Kasparek, W, Knauer, J, Korsholm, Søren Bang, Langenberg, A, Lechte, C, Leipold, F., Mora, H Trimino, Neuner, U, Nielsen, S. K., Moseev, D, Oosterbeek, H, Pablant, N, Pasch, E, Plaum, B, Pedersen, T Sunn, Sitjes, A Puig, Rahbarnia, K, Rasmussen, J., Salewski, M., Schilling, J, Scott, E, Stejner, M., Thomsen, H, Thumm, M, Turkin, Y, Wilde, F, Wolf, R C, Bozhenkov, S, Dinklage, A, Fuchert, G, Kazakov, Y O, Laqua, H P, Marsen, S, Marushchenko, N B, Stange, T, Zanini, M, Abramovic, I, Alonso, A, Baldzuhn, J, Beurskens, M, Beidler, C D, Braune, H, Brunner, K J, Chaudhary, N, Damm, H, Drewelow, P, Gantenbein, G, Gao, Yu, Geiger, J, Hirsch, M, Höfel, U, Jakubowski, M, Jelonnek, J, Jensen, T, Kasparek, W, Knauer, J, Korsholm, Søren Bang, Langenberg, A, Lechte, C, Leipold, F., Mora, H Trimino, Neuner, U, Nielsen, S. K., Moseev, D, Oosterbeek, H, Pablant, N, Pasch, E, Plaum, B, Pedersen, T Sunn, Sitjes, A Puig, Rahbarnia, K, Rasmussen, J., Salewski, M., Schilling, J, Scott, E, Stejner, M., Thomsen, H, Thumm, M, Turkin, Y, and Wilde, F

Abstract

For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 × 1020 keV m−3 s), observed up to now in stellarators, was achieved (Sunn Pedersen et al 2018 Plasma Phys. Control. Fusion 61 014035). For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.

Published
2019

39. Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

Author

W7-X Team, Estrada, T., Carralero, D., Windisch, T., Sánchez, E., García-Regaña, J. M., Martínez-Fernández, J., Peña, A. de la, Velasco, J. L., Alonso, J. A., Beurskens, M., Bozhenkov, S., Damm, H., Fuchert, G., Kleiber, R., Pablant, N., Pasch, E., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Nuclear and High Energy Physics, Materials science, Plasma turbulence, Magnetic confinement fusion, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, symbols.namesake, Electric field, Phase (matter), 0103 physical sciences, Pellet, symbols, Atomic physics, 010306 general physics, Reflectometry, ddc:600, Doppler effect
Abstract

Radial profiles of density fluctuations and the radial electric field, E r, have been measured using Doppler reflectometry during the post-pellet enhanced confinement phase achieved, under different heating power levels and magnetic configurations, during the 2018 W7-X experimental campaign. A pronounced E r-well is measured with local values as high as −40 kV m−1 in the radial range ρ ∼ 0.7–0.8 during the post-pellet enhanced confinement phase. The maximum E r intensity scales with both the plasma density and electron cyclotron heating power level, following a similar trend to the plasma energy content. A good agreement is found when the experimental E r profiles are compared to simulations carried out using the neoclassical codes, the drift kinetic equation solver (DKES) and kinetic orbit-averaging solver for stellarators (KNOSOS). The density fluctuation level decreases from the plasma edge toward the plasma core and the drop is more pronounced in the post-pellet enhanced confinement phase than in reference gas-fuelled plasmas. Besides, in the post-pellet phase, the density fluctuation level is lower in the high iota magnetic configuration than in the standard one. To determine whether this difference is related to the differences in the plasma profiles or to the stability properties of the two configurations, gyrokinetic simulations have been carried out using the codes stella and EUTERPE. The simulation results point to the plasma profile evolution after the pellet injection and the stabilization effect of the radial electric field profile as the dominant players in the stabilization of the plasma turbulence.

Published
2021
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40. Impact of magnetic islands on plasma flow and turbulence in W7-X.

Author

Estrada, T., Maragkoudakis, E., Carralero, D., Windisch, T., Velasco, J.L, Killer, C., Andreeva, T., Geiger, J., Dinklage, A., Krämer-Flecken, A., Wurden, G.A., Beurskens, M., Bozhenkov, S., Damm, H., Fuchert, G., Pasch, E., and Team, the W7-X

Subjects
PLASMA turbulence, PLASMA flow, SPATIAL resolution, ISLANDS, PLASMA boundary layers, PLASMA density
Abstract

The effect of magnetic islands on plasma flow and turbulence has been experimentally investigated in the stellarator W7-X. Magnetic configurations with the 5/5 magnetic island positioned at the plasma edge, inside the last closed flux surface, are studied. The main diagnostic used in the present work is a V-band Doppler reflectometer that allows the measurement of the perpendicular plasma flow and density fluctuations with good spatial resolution. A characteristic signature of the 5/5 magnetic island is clearly detected in the perpendicular flow profile. The comparison of the experimental flow and the neoclassically driven E × B flow indicates that the island contribution to the flow is maximum at the island boundaries and close to zero at the island O-point. Besides, a reduction in the density fluctuation level is found nearby the island O-point. The similarities between these observations and those found in other devices and in gyrokinetic simulations are discussed. [ABSTRACT FROM AUTHOR]

Published
2021
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41. First results from an event synchronized—high repetition Thomson scattering system at Wendelstein 7-X

Author

Damm, H., primary, Pasch, E., additional, Dinklage, A., additional, Baldzuhn, J., additional, Bozhenkov, S.A., additional, Brunner, K.J., additional, Effenberg, F., additional, Fuchert, G., additional, Geiger, J., additional, Harris, J.H., additional, Knauer, J., additional, Kornejew, P., additional, Kremeyer, T., additional, Krychowiak, M., additional, Schilling, J., additional, Schmitz, O., additional, Scott, E.R., additional, Winters, V., additional, and Team, The Wendelstein, additional

Published
2019
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42. Pellet fueling experiments in Wendelstein 7-X

Author

Baldzuhn, J, primary, Damm, H, additional, Beidler, C D, additional, McCarthy, K, additional, Panadero, N, additional, Biedermann, C, additional, Bozhenkov, S A, additional, Brunner, K J, additional, Fuchert, G, additional, Kazakov, Y, additional, Beurskens, M, additional, Dibon, M, additional, Geiger, J, additional, Grulke, O, additional, Höfel, U, additional, Klinger, T, additional, Köchl, F, additional, Knauer, J, additional, Kocsis, G, additional, Kornejew, P, additional, Lang, P T, additional, Langenberg, A, additional, Laqua, H, additional, Pablant, N A, additional, Pasch, E, additional, Pedersen, T S, additional, Ploeckl, B, additional, Rahbarnia, K, additional, Schlisio, G, additional, Scott, E R, additional, Stange, T, additional, von Stechow, A, additional, Szepesi, T, additional, Turkin, Y, additional, Wagner, F, additional, Winters, V, additional, Wurden, G, additional, and Zhang, D, additional

Published
2019
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43. First Observation of a Stable Highly Dissipative Divertor Plasma Regime on the Wendelstein 7-X Stellarator

Author

Zhang, D., primary, König, R., additional, Feng, Y., additional, Burhenn, R., additional, Brezinsek, S., additional, Jakubowski, M., additional, Buttenschön, B., additional, Niemann, H., additional, Pavone, A., additional, Krychowiak, M., additional, Kwak, S., additional, Svensson, J., additional, Gao, Y., additional, Pedersen, T. S., additional, Alonso, A., additional, Baldzuhn, J., additional, Beidler, C. D., additional, Biedermann, C., additional, Bozhenkov, S., additional, Brunner, K. J., additional, Damm, H., additional, Hirsch, M., additional, Giannone, L., additional, Drewelow, P., additional, Effenberg, F., additional, Fuchert, G., additional, Hammond, K. C., additional, Höfel, U., additional, Killer, C., additional, Knauer, J., additional, Laqua, H. P., additional, Laube, R., additional, Pablant, N., additional, Pasch, E., additional, Penzel, F., additional, Rahbarnia, K., additional, Reimold, F., additional, Thomsen, H., additional, Winters, V., additional, Wagner, F., additional, and Klinger, T., additional

Published
2019
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44. Overview of first Wendelstein 7-X high-performance operation

Author

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

Published
2019
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45. Phased array Doppler reflectometry at Wendelstein 7-X

Author

Windisch, T., Wolf, S., Weir, G. M., Bozhenkov, S. A., Damm, H., Fuchert, G., Grulke, Olaf, Hirsch, M., Kasparek, W., Klinger, T., Lechte, C., Pasch, E., Plaum, B., Scott, E. A., Team, W7-X, Windisch, T., Wolf, S., Weir, G. M., Bozhenkov, S. A., Damm, H., Fuchert, G., Grulke, Olaf, Hirsch, M., Kasparek, W., Klinger, T., Lechte, C., Pasch, E., Plaum, B., Scott, E. A., and Team, W7-X

Abstract

A passive phased array Doppler reflectometry system has recently been installed in the Wendelstein-7X stellarator. In contrast to conventional Doppler reflectometry systems, the microwave beam can be steered on short time scales in the measurement plane perpendicular to the magnetic field in the range of ±25 degrees without mechanical steering components. This paper characterizes the design and properties of the phased array antenna system and presents the first measurement results from the latest OP1.2a campaign.

Published
2018

46. Measurements of the parameter dependencies of the bootstrap current in the W7-X stellarator.

Author

Neuner, U., Rahbarnia, K., Beidler, C.D., Dinklage, A., Turkin, Y., Stange, T., Andreeva, T., Schilling, J., Thomsen, H., Beurskens, M., Bozhenkov, S., Brunner, K.J., Damm, H., Fuchert, G., Geiger, J., Hergenhahn, U., Höfel, U., Knauer, J., Krychowiak, M., and Kwak, S.

Subjects
STELLARATORS, PLASMA density, MAGNETIC traps, ABSOLUTE value, TOROIDAL plasma
Abstract

Intrinsic, diffusion-driven toroidal (bootstrap) currents between −7 and 17 kA were measured in the optimised stellarator Wendelstein 7-X (W7-X) for several magnetic configurations at line-integrated plasma densities between 2 × 1019 and 1.6 × 1020 m−2 and heating powers between 0.5 and 6 MW. The sign of the bootstrap current changes with field reversal, and its magnitude decreases with the mirror term and the rotational transform of the magnetic configuration as well as the line-integrated plasma density, and increases with the heating power. Both the absolute values and the dependencies agree with neoclassical calculations within their respective uncertainties, confirming the neoclassical optimisation of W7-X for small bootstrap currents. [ABSTRACT FROM AUTHOR]

Published
2021
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47. Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase

Author

Wolf, R. C., Alonso, A., Akaslompolo, S., Baldzuhn, J., Beurskens, M., Beidler, C. D., Biedermann, C., Bosch, H. -S., Bozhenkov, S., Brakel, R., Braune, H., Brezinsek, S., Brunner, K. -J., Damm, H., Dinklage, A., Drewelow, P., Effenberg, F., Feng, Y., Ford, O., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Harder, N., Hartmann, D., Helander, P., Heinemann, B., Hirsch, M., Hofel, U., Hopf, C., Ida, K., Isobe, M., Jakubowski, M. W., Kazakov, Y. O., Killer, C., Klinger, T., Knauer, J., Konig, R., Krychowiak, M., Langenberg, A., Laqua, H. P., Lazerson, S., Mcneely, P., Marsen, S., Marushchenko, N., Nocentini, R., Ogawa, K., Orozco, G., Osakabe, M., Otte, M., Pablant, N., Pasch, E., Pavone, A., Porkolab, M., Puig Sitjes, A., Rahbarnia, K., Riedl, R., Rust, N., Scott, E., Schilling, J., Schroeder, R., Stange, T., Von Stechow, A., Strumberger, E., Sunn Pedersen, T., Svensson, J., Thomson, H., Turkin, Y., Vano, L., Wauters, T., Wurden, G., Yoshinuma, M., Zanini, M., Zhang, D., Andreeva, T., Brandt, C., Burhenn, R., Buttenschon, B., Geiger, B., Tamura, N., Thomsen, H., Wegner, T., Abramovic, I., Alcuson, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., Bahner, J. P., Baek, S. G., Balden, M., Banduch, M., Barbui, T., Behr, W., Beidler, C., Benndorf, A., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Bockenhoff, D., Boswirth, B., Bottger, L. -G., Borchardt, M., Borsuk, V., Boscary, J., Brand, H., Brauer, T., 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., De La Pena, A., Degenkolbe, S., Dhard, C. P., Dibon, M., Dittmar, T., Drevlak, M., Drews, P., Durodie, F., Edlund, E., Van Eeten, P., Ehrke, G., Elgeti, S., Endler, M., Ennis, D., Esteban, H., Estrada, T., Fellinger, J., Flom, E., Fernandes, H., Fietz, W. H., Figacz, W., Fontdecaba, J., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Garcia Regana, J., Gates, D., 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., Hathiramani, D., Hein, B., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hollfeld, K. P., Holting, A., Hoschen, D., Houry, M., Howard, J., Huang, X., Huang, Z., Hubeny, M., Huber, M., Hunger, H., Ilkei, T., Illy, S., Israeli, B., Jablonski, S., Jakubowski, M., Jelonnek, J., Jenzsch, H., Jesche, T., Jia, M., Junghanns, P., Kacmarczyk, J., Kallmeyer, J. -P., Kamionka, U., Kasahara, H., Kasparek, W., Kenmochi, N., Kirschner, A., Kleiber, R., Knaup, M., Knieps, A., Kobarg, T., Kocsis, G., Kochl, F., Kolesnichenko, Y., Konies, A., Kornejew, P., Koschinsky, J. -P., Koster, F., Kramer, M., Krampitz, R., Kramer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., Kuhner, G., Kurki-Suonio, T., Kurz, P. A., Kwak, S., Landreman, M., Lang, P., Lang, R., Langish, S., Laqua, H., Laube, R., Lechte, C., Lennartz, M., Leonhardt, W., Li, C., Li, Y., Liang, Y., Linsmeier, C., Liu, S., Lobsien, J. -F., Loesser, D., Loizu Cisquella, J., Lore, J., Lorenz, A., Losert, M., Lucke, A., Lumsdaine, A., Lutsenko, V., Maassberg, H., Marchuk, O., Matthew, J. H., Marushchenko, M., Masuzaki, S., Maurer, D., Mayer, M., Mccarthy, K., Meier, A., Mellein, D., Mendelevitch, B., Mertens, P., Mikkelsen, D., Mishchenko, A., Missal, B., Mittelstaedt, J., Mizuuchi, T., Mollen, A., Moncada, V., Monnich, T., Morisaki, T., Moseev, D., Murakami, S., Nafradi, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Neuner, U., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nuhrenberg, C., Nuhrenberg, J., Obermayer, S., Offermanns, G., Olmanns, J., Ongena, J., Oosterbeek, J. W., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfuss, D., Paqay, S., Pawelec, E., Pedersen, T. S., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., Poloskei, P., Proll, J., Puiatti, M. -E., Purps, F., Rack, M., Recsei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riemann, J., Risse, K., Rohde, V., Rohlinger, H., Rome, M., Rondeshagen, D., Rong, P., Roth, B., Rudischhauser, L., Rummel, K., Rummel, T., Runov, A., Ryc, L., Ryosuke, S., Sakamoto, R., Salewski, M., Samartsev, A., Sanchez, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schluter, K. -H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schroder, M., Schroder, T., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Siplia, S., Slaby, C., Sleczka, M., Smith, H., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szabo, V., Szabolics, T., Szepesi, T., Szokefalvi-Nagy, Z., Tancetti, A., Terry, J., Thomas, J., Thumm, M., Travere, J. M., Traverso, P., Tretter, J., Trimino Mora, H., Tsuchiya, H., Tsujimura, T., Tulipan, S., Unterberg, B., Vakulchyk, I., Valet, S., Van Milligen, B., Van Vuuren, A. J., Vela, L., Velasco, J. -L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Vorkoper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Warmer, F., 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., Wright, A., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zarnstorff, M., Zeitler, A., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., Zuin, M., Science and Technology of Nuclear Fusion, Turbulence in Fusion Plasmas, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Technology, Plasma parameters, Divertor, Nuclear engineering, Plasma, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, Magnetic field, law, 0103 physical sciences, Limiter, Wendelstein 7-X, 010306 general physics, ddc:600, Stellarator
Abstract

Wendelstein 7-X is the first comprehensively optimized stellarator aiming at good confinement with plasma parameters relevant to a future stellarator power plant. Plasma operation started in 2015 using a limiter configuration. After installing an uncooled magnetic island divertor, extending the energy limit from 4 to 80 MJ, operation continued in 2017. For this phase, the electron cyclotron resonance heating (ECRH) capability was extended to 7 MW, and hydrogen pellet injection was implemented. The enhancements resulted in the highest triple product (6.5 × 1019 keV m-3 s) achieved in a stellarator until now. Plasma conditions [Te(0) ≈ Ti(0) ≈ 3.8 keV, τE > 200 ms] already were in the stellarator reactor-relevant ion-root plasma transport regime. Stable operation above the 2nd harmonic ECRH X-mode cutoff was demonstrated, which is instrumental for achieving high plasma densities in Wendelstein 7-X. Further important developments include the confirmation of low intrinsic error fields, the observation of current-drive induced instabilities, and first fast ion heating and confinement experiments. The efficacy of the magnetic island divertor was instrumental in achieving high performance in Wendelstein 7-X. Symmetrization of the heat loads between the ten divertor modules could be achieved by external resonant magnetic fields. Full divertor power detachment facilitated the extension of high power plasmas significantly beyond the energy limit of 80 MJ.

Published
2019
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48. Observation of anomalous impurity transport during low-density experiments in W7-X with laser blow-off injections of iron

Author

W7-X Team, Geiger, B., Wegner, Th., Beidler, C. D., Burhenn, R., Buttenschön, B., Dux, R., Langenberg, A., Pablant, N. A., Pütterich, T., Turkin, Y., Windisch, T., Winters, V., Beurskens, M., Biedermann, C., Brunner, K. J., Cseh, G., Damm, H., Effenberg, F., Fuchert, G., Grulke, O., Harris, J. H., Killer, C., Knauer, J., Kocsis, G., Krämer-Flecken, A., Kremeyer, T., Krychowiak, M., Marchuk, O., Nicolai, D., Rahbarnia, K., Satheeswaran, G., Schilling, J., Schmitz, O., Schröder, T., Szepesi, T., Thomsen, H., Trimino Mora, H., Traverso, P., Zhang, D., Baumann, Klaus, Dammertz, Günter, Gantenbein, Gerd, Huber, Martina, Hunger, Hermann, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Losert, M., Mellein, Daniel, Papenfuß, Daniel, Smartsev, A., Scherer, Theo, Schlaich, Andreas, Spieß, W., Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Nuclear and High Energy Physics, Materials science, Turbulence, Condensed Matter Physics, Laser, 01 natural sciences, 010305 fluids & plasmas, law.invention, Strahl, Impurity, law, 0103 physical sciences, Low density, Atomic physics, 010306 general physics, ddc:600, Stellarator
Published
2019
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49. Impact of the temperature ratio on turbulent impurity transport in Wendelstein 7-X.

Author

Wegner, Th., Alcusón, J.A., Geiger, B., Stechow, A. v., Xanthopoulos, P., Angioni, C., Beurskens, M.N.A., Böttger, L.-G., Bozhenkov, S.A., Brunner, K.J., Burhenn, R., Buttenschön, B., Damm, H., Edlund, E., Ford, O.P., Fuchert, G., Grulke, O., Huang, Z., Knauer, J., and Kunkel, F.

Subjects
ELECTRON temperature, ION temperature, PLASMA flow, ELECTRON density, TEMPERATURE, DIFFUSION
Abstract

First experimental observations in the Wendelstein 7-X stellarator indicate that the impurity confinement can be explained by turbulent processes. In particular, plasma discharges with increased ion to electron temperature ratio are accompanied by reduced electron density fluctuation amplitudes and anomalous impurity diffusion, suggesting a lower turbulent transport. Employing gyro-kinetic numerical simulations, we argue that the temperature ratio plays a key role for reducing the ion temperature gradient instability in Wendelstein 7-X, leading to an enhanced impurity confinement. [ABSTRACT FROM AUTHOR]

Published
2020
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50. High-performance plasmas after pellet injections in Wendelstein 7-X.

Author

Bozhenkov, S.A., Kazakov, Y., Ford, O.P., Beurskens, M.N.A., Alcusón, J., Alonso, J.A., Baldzuhn, J., Brandt, C., Brunner, K.J., Damm, H., Fuchert, G., Geiger, J., Grulke, O., Hirsch, M., Höfel, U., Huang, Z., Knauer, J., Krychowiak, M., Langenberg, A., and Laqua, H.P.

Subjects
PELLETIZING, ION temperature, ION channels, PLASMA turbulence, TURBULENCE
Abstract

A significant improvement of plasma parameters in the optimized stellarator W7-X is found after injections of frozen hydrogen pellets. The ion temperature in the post-pellet phase exceeds 3 keV with 5 MW of electron heating and the global energy confinement time surpasses the empirical ISS04-scaling. The plasma parameters realized in such experiments are significantly above those in comparable gas-fuelled discharges. In this paper, we present details of these pellet experiments and discuss the main plasma properties during the enhanced confinement phases. Local power balance is applied to show that the heat transport in post-pellet phases is close to the neoclassical level for the ion channel and is about a factor of two above that level for the combined losses. In comparable gas-fuelled discharges, the heat transport is by about ten times larger than the neoclassical level, and thus is largely anomalous. It is further observed that the improvement in the transport is related to the peaked density profiles that lead to a stabilization of the ion-scale turbulence. [ABSTRACT FROM AUTHOR]

Published
2020
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