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51. 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

52. Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator

Author: Killer, C., Aleynikov, P., Biedermann, C., Dhard, C. P., Drews, P., Gao, Y., Grulke, O., Jakubowski, M., Knieps, A., Kocsis, G., Naujoks, D., Puig Sitjes, A., Spolaore, M., Stange, T., Szepesi, T., Tancetti, A., Thomsen, H., Killer, C., Aleynikov, P., Biedermann, C., Dhard, C. P., Drews, P., Gao, Y., Grulke, O., Jakubowski, M., Knieps, A., Kocsis, G., Naujoks, D., Puig Sitjes, A., Spolaore, M., Stange, T., Szepesi, T., Tancetti, A., and Thomsen, H.
Abstract: Hot spots and bright patterns on plasma-facing components (PFC) in visible light are observed in electron cyclotron resonance heated (ECRH) plasmas at low densities in the stellarator Wendelstein 7-X. The events are often located far outside of any convective plasma loads and led in some cases to damages of diagnostic components, where the interaction zones qualitatively agree with fast particle loss simulations. Reciprocating electric probes indicate that this phenomenon is related to a non-thermal electron population that can have a beam like character, being directed in one parallel direction. Further, the electrons can be trapped on rational flux surfaces and be used to map magnetic islands.
Published: 2022

53. Conceptual design of a heavy ion beam probe diagnostic for the Wendelstein 7-X Stellarator

Author: Mora, H. Trimino, Crowley, T. P., Demers, D. R., Fimognari, P. J., Grulke, O., Laube, R., Mora, H. Trimino, Crowley, T. P., Demers, D. R., Fimognari, P. J., Grulke, O., and Laube, R.
Abstract: This article describes the current state of the design of the heavy ion beam probe (HIBP) for Wendelstein 7-X (W7-X). It will be the first HIBP diagnostic on an optimized stellarator and is designed to study electric fields and ion scale turbulence in all W7-X reference magnetic configurations. The use of an existing 2 MV accelerator, located outside of the torus hall, results in the need for a circuitous primary beamline. This increases the complexity of the ion optics design to deliver a focused beam to the plasma. To access most of the magnetic configuration space of W7-X, the secondary beamline and an energy analyzer are designed to pivot, thereby redirecting a wider range of secondary beam trajectories. Signal level estimates indicate that the equilibrium potential can be measured at all radii and that the radial coverage for potential and density fluctuations measurements depends on the plasma density.
Published: 2022

54. Development of a synthetic phase contrast imaging diagnostic for turbulence studies at Wendelstein 7-X

Author: Hansen, S. K., Porkolab, M., Bähner, J. P., Huang, Z., von Stechow, A., Grulke, O., Edlund, E. M., Wilms, F., Bañón Navarro, A., Jenko, F., Sánchez, E., Hansen, S. K., Porkolab, M., Bähner, J. P., Huang, Z., von Stechow, A., Grulke, O., Edlund, E. M., Wilms, F., Bañón Navarro, A., Jenko, F., and Sánchez, E.
Abstract: We present a synthetic phase contrast imaging (PCI) diagnostic for studying turbulence at the Wendelstein 7-X (W7-X) stellarator. We first describe the implemented instrument response model, which captures diffraction effects, detector noise, and the long-wavelength cutoff due to the phase plate of the PCI system. To verify the instrument response model, we show that it is capable of reproducing the PCI signal generated by the sound wave speaker used for calibration at W7-X. Next, we discuss the calculation of synthetic PCI signals based on the global, nonlinear gyrokinetic codes GENE-3D and EUTERPE, including results from some of the first stellarator simulations of this type with kinetic electrons (KEs) in GENE-3D. While the simulations used in this work lack a neoclassical radial electric field, which is crucial for reproducing experimental PCI signals, they do indicate that the dominant rotation direction and velocities of the turbulent fluctuations can be inferred from the wave number-frequency spectra of the PCI signals, as expected. The synthetic PCI wave number spectra are further shown to be similar to those of the line-integrated fluctuating electron density, with distinct differences between adiabatic and KE simulations, explainable by previously published turbulence models. For example, the wave number spectra of all adiabatic electron simulations analyzed here follow a power law with an exponent close to −5 for sufficiently large wave numbers. This indicates that universal features of electron density turbulence at W7-X may be studied using the PCI system.
Published: 2022

55. Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

Author: Beurskens, M. N. A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcuson, J. A., Baehner, J. P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H. P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E. R., Stange, T., von Stechow, A., Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R. C., Zohm, H., Beurskens, M. N. A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcuson, J. A., Baehner, J. P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H. P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E. R., Stange, T., von Stechow, A., Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R. C., and Zohm, H.
Abstract: In electron (cyclotron) heated plasmas, in both ASDEX Upgrade (L-mode) and Wendelstein 7-X, clamping of the ion temperature occurs at Ti ∼ 1.5 keV independent of magnetic configuration. The ions in such plasmas are heated through the energy exchange power as ne2(Te-Ti)/Te3/2, which offers a broad ion heating profile, similar to that offered by alpha heating in future thermonuclear fusion reactors. However, the predominant electron heating may put an additional constraint on the ion heat transport, as the ratio Te/Ti > 1 can exacerbates ITG/TEM core turbulence. Therefore, in practical terms the strongly 'stiff' core transport translates into Ti-clamping in electron heated plasmas. Due to this clamping, electron heated L-mode scenarios, with standard gas fueling, in either tokamaks or stellarators may struggle to reach high normalized ion temperature gradients required in a compact fusion reactor. The comparison shows that core heat transport in neoclassically optimized stellarators is driven by the same mechanisms as in tokamaks. The absence of a strong H-mode temperature edge pedestal in stellarators, sofar (which, like in tokamaks, could lift the clamped temperature-gradients in the core), puts a strong requirement on reliable and sustainable core turbulence suppression techniques in stellarators.
Published: 2022

56. Estimate of convective radial transport due to SOL turbulence as measured by GPI in Alcator C-Mod

Author: Zweben, S.J., Terry, J.L., LaBombard, B., Agostini, M., Greenwald, M., Grulke, O., Hughes, J.W., D’Ippolito, D.A., Krasheninnikov, S.I., Myra, J.R., Russell, D.A., Stotler, D.P., and Umansky, M.
Published: 2011
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57. First Thomson Scattering Results in the Helicon Plasma Source for Awake

Author: Stollberg, C., primary, Sublet, A., additional, Buttenschon, B., additional, Furno, I., additional, Vincent, B., additional, Guittienne, P., additional, Andrebe, Y., additional, Agnello, R., additional, and Grulke, O., additional
Published: 2022
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58. 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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59. Reciprocating probe measurements in the test divertor operation phase of Wendelstein 7-X

Author: Killer, C., primary, Drews, P., additional, Grulke, O., additional, Knieps, A., additional, Nicolai, D., additional, and Satheeswaran, G., additional
Published: 2022
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60. Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

Author: Beurskens, M.N.A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcus��n, J.A., Baehner, J.P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H.P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E.R., Stange, T., Von Stechow, A., Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R.C., Zohm, H., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfu��, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, J��rg
Published: 2022
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61. Letter

Author: Li, Y., Xu, G., Dudson, B., Liu, X., Huang, Z., Killer, C., Feng, Y., Liu, S., Yan, N., Morales, J., Tsitrone, E., Brezinsek, S., Liang, Y., Eldon, D., Xiao, C., Geiger, J., Grulke, O., Otte, M., the WEST Team, the W7-X Team, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, WEST Team, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Nuclear and High Energy Physics, Technology, ddc:620, Condensed Matter Physics, ddc:600
Abstract: A universal energy partition mechanism between ions and electrons has been confirmed to exist in the scrape-off layer of both the WEST tokamak and the W7-X stellarator. A peaked plasma density structure induced by an infinite magnetic connection length structure is observed to destroy this dependence and enhance the local ion and electron temperature ratio in the stellarator. A theoretical analysis reveals that the ratio of ion and electron parallel heat conduction is predominant in determining this universality, while electrons would further be cooled in the density-peaked region.
Published: 2022
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62. Magnetic configuration scans during divertor operation of Wendelstein 7-X

Author: Team, The W7-X, Andreeva, T., Geiger, J., Dinklage, A., Wurden, G., Thomsen, H., Rahbarnia, K., Schmitt, J. C., Hirsch, M., Fuchert, G., Nührenberg, C., Alonso, A., Beidler, C. D., Beurskens, M. N. A., Bozhenkov, S., Brakel, R., Brandt, C., Bykov, V., Grahl, M., Grulke, O., Killer, C., Kocsis, G., Klinger, T., Krämer-Flecken, A., Lazerson, S., Otte, M., Pablant, N., Schilling, J., Windisch, T., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, and Weggen, Jörg
Subjects: Technology, ddc:600
Published: 2022

63. Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

Author: W7-X Team, Beurskens, M. N. A., Angioni, C., Bozhenkov, S. A., Ford, O., Kiefer, C., Xanthopoulos, P., Turkin, Y., Alcusón, J. A., Baehner, J. P., Beidler, C., Birkenmeier, G., Fable, E., Fuchert, G., Geiger, B., Grulke, O., Hirsch, M., Jakubowski, M., Laqua, H. P., Langenberg, A., Lazerson, S., Pablant, N., Reisner, M., Schneider, P., Scott, E. R., Stange, T., Stechow, A. von, Stober, J., Stroth, U., Wegner, Th., Weir, G., Zhang, D., Zocco, A., Wolf, R. C., Zohm, H., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, and EUROfusion MST1 Team
Subjects: Technology, Nuclear and High Energy Physics, Turbulent transport, Materials science, Turbulence, Ion temperature clamping, Plasma, Electron, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Nuclear physics, Electron heating, ASDEX Upgrade, Physics::Plasma Physics, 0103 physical sciences, Stellarator transport, Wendelstein 7-X, ddc:620, 010306 general physics, ddc:600
Abstract: In electron (cyclotron) heated plasmas, in both ASDEX Upgrade (L-mode) and Wendelstein 7-X, clamping of the ion temperature occurs at T i ∼ 1.5 keV independent of magnetic configuration. The ions in such plasmas are heated through the energy exchange power as n e 2 ( T e − T i ) / T e 3 / 2 , which offers a broad ion heating profile, similar to that offered by alpha heating in future thermonuclear fusion reactors. However, the predominant electron heating may put an additional constraint on the ion heat transport, as the ratio T e/T i > 1 can exacerbates ITG/TEM core turbulence. Therefore, in practical terms the strongly ‘stiff’ core transport translates into T i-clamping in electron heated plasmas. Due to this clamping, electron heated L-mode scenarios, with standard gas fueling, in either tokamaks or stellarators may struggle to reach high normalized ion temperature gradients required in a compact fusion reactor. The comparison shows that core heat transport in neoclassically optimized stellarators is driven by the same mechanisms as in tokamaks. The absence of a strong H-mode temperature edge pedestal in stellarators, sofar (which, like in tokamaks, could lift the clamped temperature-gradients in the core), puts a strong requirement on reliable and sustainable core turbulence suppression techniques in stellarators.
Published: 2021
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64. Experimental investigations of turbulent structure propagation across a [formula omitted]-velocity shear

Author: Windisch, T., Grulke, O., and Klinger, T.
Published: 2009
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65. Nonlinear control of transport in drift wave turbulence

Author: Brandt, C., Grulke, O., and Klinger, T.
Published: 2009
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66. Spatial structure of scrape-off-layer filaments near the midplane and X-point regions of Alcator-C-Mod

Author: Terry, J.L., Zweben, S.J., Umansky, M.V., Cziegler, I., Grulke, O., LaBombard, B., and Stotler, D.P.
Published: 2009
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67. Analysis of proton bunch parameters in the AWAKE experiment

Author: Hafych, V., additional, Caldwell, A., additional, Agnello, R., additional, Ahdida, C.C., additional, Aladi, M., additional, Amoedo Goncalves, M.C., additional, Andrebe, Y., additional, Apsimon, O., additional, Apsimon, R., additional, Bachmann, A.-M., additional, Baistrukov, M.A., additional, Batsch, F., additional, Bergamaschi, M., additional, Blanchard, P., additional, Burrows, P.N., additional, Buttenschön, B., additional, Chappell, J., additional, Chevallay, E., additional, Chung, M., additional, Cooke, D.A., additional, Damerau, H., additional, Davut, C., additional, Demeter, G., additional, Dexter, A., additional, Doebert, S., additional, Farmer, J., additional, Fasoli, A., additional, Fedosseev, V.N., additional, Fiorito, R., additional, Fonseca, R.A., additional, Furno, I., additional, Gessner, S., additional, Gorn, A.A., additional, Granados, E., additional, Granetzny, M., additional, Graubner, T., additional, Grulke, O., additional, Gschwendtner, E., additional, Guran, E.D., additional, Henderson, J.R., additional, Hüther, M., additional, Kedves, M.Á., additional, Khudyakov, V., additional, Kim, S.-Y., additional, Kraus, F., additional, Krupa, M., additional, Lefevre, T., additional, Liang, L., additional, Lopes, N., additional, Lotov, K.V., additional, Mazzoni, S., additional, Medina Godoy, D., additional, Moody, J.T., additional, Moon, K., additional, Morales Guzmán, P.I., additional, Moreira, M., additional, Nechaeva, T., additional, Nowak, E., additional, Pakuza, C., additional, Panuganti, H., additional, Pardons, A., additional, Perera, A., additional, Pucek, J., additional, Pukhov, A., additional, Ráczkevi, B., additional, Ramjiawan, R.L., additional, Rey, S., additional, Schmitz, O., additional, Senes, E., additional, Silva, L.O., additional, Stollberg, C., additional, Sublet, A., additional, Topaloudis, A., additional, Torrado, N., additional, Tuev, P.V., additional, Turner, M., additional, Velotti, F., additional, Verra, L., additional, Vieira, J., additional, Vincke, H., additional, Welsch, C.P., additional, Wendt, M., additional, Wing, M., additional, Wolfenden, J., additional, Woolley, B., additional, Xia, G., additional, Zepp, M., additional, and Zevi Della Porta, G., additional
Published: 2021
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68. Ion temperature clamping in Wendelstein 7-X electron cyclotron heated plasmas

Author: Beurskens, M.N.A., primary, Bozhenkov, S.A., additional, Ford, O., additional, Xanthopoulos, P., additional, Zocco, A., additional, Turkin, Y., additional, Alonso, A., additional, Beidler, C., additional, Calvo, I., additional, Carralero, D., additional, Estrada, T., additional, Fuchert, G., additional, Grulke, O., additional, Hirsch, M., additional, Ida, K., additional, Jakubowski, M., additional, Killer, C., additional, Krychowiak, M., additional, Kwak, S., additional, Lazerson, S., additional, Langenberg, A., additional, Lunsford, R., additional, Pablant, N., additional, Pasch, E., additional, Pavone, A., additional, Reimold, F., additional, Romba, Th., additional, von Stechow, A., additional, Smith, H.M., additional, Windisch, T., additional, Yoshinuma, M., additional, Zhang, D., additional, Wolf, R.C., additional, and W7-X Team, the, additional
Published: 2021
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69. Characterization of neutral loop discharges in the VINETA device

Author: von Stechow, A., Grulke, O., and Klinger, T.
Published: 2012
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70. High Resolution Probe for filament transport and current density study at the edge region of W7-X

Author: Spolaore, M, Agostinetti, P, Killer, C, Moresco, M, Brombin, M, Cavazzana, R, Ghirardelli, R, Grenfell, G, Grulke, O, Lazerson, S, Martines, E, Neubauer, O, Nicolai, D, Satheeswaran, G, Schweer, B, Vianello, N, Visentin, M, Spolaore M, Agostinetti P, Killer C, Moresco M, Brombin M, Cavazzana R, Ghirardelli R, Grenfell G, Grulke O, Lazerson SA, Martines E, Neubauer O, Nicolai D, Satheeswaran G, Schweer B, Vianello N, Visentin M, Spolaore, M, Agostinetti, P, Killer, C, Moresco, M, Brombin, M, Cavazzana, R, Ghirardelli, R, Grenfell, G, Grulke, O, Lazerson, S, Martines, E, Neubauer, O, Nicolai, D, Satheeswaran, G, Schweer, B, Vianello, N, Visentin, M, Spolaore M, Agostinetti P, Killer C, Moresco M, Brombin M, Cavazzana R, Ghirardelli R, Grenfell G, Grulke O, Lazerson SA, Martines E, Neubauer O, Nicolai D, Satheeswaran G, Schweer B, Vianello N, and Visentin M
Abstract: For the study of electrostatic and magnetic properties of filaments characterizing the edge region of the stellarator experiment W7-X, a specifically designed insertable probe head was constructed within the framework of EUROfusion WP.S1 work package in collaboration between Consorzio RFX, IPP Greifswald and Forschungszentrum Mich. The probe head, named High Resolution Probe (HRP), was conceived to be installed on the mid-plane multi-purpose fast reciprocating manipulator on W7-X. Electromagnetic filamentary turbulent structures are found to characterize the edge region of different magnetic configurations including Reversed Field Pinch, stellarator and tokamak, where strong currents are associated also to ELM filamentary structures. The study of those phenomena in W7-X stellarator is of particular interest as the electromagnetic features of filaments are expected to become more relevant with the increase of the local plasma beta. In particular the aim is to provide information about the presence and the features of parallel current density associated to filamentary turbulent or ELM-like structures. Furthermore, the possibility to measure the time evolution of the flow radial profiles using the Mach probe array was considered as a further interesting part of the study, given the strong interplay expected between the turbulent fluctuations and the average flows. Further important information provided is the radial propagation of turbulent flux. The contribution will present the design development, the R&D studies and the applied solutions for the sensors embedded in the probe head. In particular, the presence of 140 GHz ECRH plasma environment represents one of the main challenges for reliable magnetic fluctuation measurements. First measurements were performed during the W7-X experimental campaign OP1.2b, where electromagnetic features of turbulence were measured with the probe, at different magnetic configurations.
Published: 2019

71. Ion temperature clamping in Wendelstein 7-X electron cyclotron heated plasmas

Author: W7-X Team, Beurskens, M. N. A., Bozhenkov, S. A., Ford, O., Xanthopoulos, P., Zocco, A., Turkin, Y., Alonso, A., Beidler, C., Calvo, I., Carralero, D., Estrada, T., Fuchert, G., Grulke, O., Hirsch, M., Ida, K., Jakubowski, M., Killer, C., Krychowiak, M., Kwak, S., Lazerson, S., Langenberg, A., Lunsford, R., Pablant, N., Pasch, E., Pavone, A., Reimold, F., Romba, Th., Stechow, A. von, Smith, H. M., Windisch, T., Yoshinuma, M., Zhang, D., 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: Technology, ddc:600
Published: 2021

72. Characterization of injection and confinement improvement through impurity induced profile modifications on the Wendelstein 7-X stellarato

Author: W7-X Team, Lunsford, R., Killer, C., Nagy, A., Gates, D. A., Klinger, T., Dinklage, A., Satheeswaran, G., Kocsis, G., Lazerson, S. A., Nespoli, F., Pablant, N. A., Stechow, A. von, Alonso, A., Andreeva, T., Beurskens, M., Biedermann, C., Brezinsek, S., Brunner, K. J., Buttenschön, B., Carralero, D., Cseh, G., Drewelow, P., Effenberg, F., Estrada, T., Ford, O. P., Grulke, O., Hergenhahn, U., Höefel, U., Knauer, J., Krause, M., Krychowiak, M., Kwak, S., Langenberg, A., Neuner, U., Nicolai, D., Pavone, A., Puig Sitjes, A., Rahbarnia, K., Schilling, J., Svensson, J., Szepesi, T., Thomsen, H., Wauters, T., Windisch, T., Winters, V., Zhang, D., Zsuga, 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, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Physics, Technology, Electron density, Plasma, Boron carbide, Condensed Matter Physics, 01 natural sciences, Electron cyclotron resonance, 010305 fluids & plasmas, law.invention, Ion, chemistry.chemical_compound, chemistry, law, Electric field, 0103 physical sciences, ddc:530, Wendelstein 7-X, Atomic physics, 010306 general physics, ddc:600, Stellarator
Abstract: Pulsed injections of boron carbide granules into Wendelstein 7-X stellarator (W7-X) plasmas transiently increase the plasma stored energy and core ion temperatures above the reference W7-X experimental programs by up to 30%. In a series of 4 MW electron cyclotron resonance heating experiments, the PPPL Probe Mounted Powder Injector provided 50 ms bursts of 100 μm granules every 350 ms at estimated quantities ranging from approximately 1 mg/pulse to over 30 mg/pulse. For each injection, the stored energy was observed to initially drop and the radiated power transiently increased, while the radial electron density profile rose at the edge as material was assimilated. Once the injected boron carbide was fully absorbed, the density rise transitioned to the core while the stored energy increased above the previous baseline level by an amount linearly correlated with the injection quantity. During the injection, the ion temperature gradient steepened with peak core ion temperatures observed to increase from a nominal 1.7 keV to over 2.6 keV for the largest injection amounts. Enhanced performance is accompanied by a reversal of the radial electric field at ρ < 0.3, indicating that the core transport has switched to the ion root. These observations are suggestive of a change in transport and provide further evidence that externally induced profile modifications provide a possible path to enhanced W7-X performance metrics.I. INTRODUCTIO
Published: 2021
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73. Synthetic Phase Contrast Imaging Diagnostic for Wendelstein 7-X

Author: Hansen, S., Porkolab, M., Huang, Z., Bähner, J., Stechow, A., Grulke, O., Edlund, E., Banon Navarro, A., Sanchez, E., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Published: 2021

74. Current effect on the edge profiles in the island at W7-X

Author: Drews, P., Killer, C., Knieps, A., Reimold, F., Zhang, D., Brezinsek, S., Jakubowski, M., Cosfeld, J., Endler, M., Hammond, K., Henkel, M., Geiger, J., Grulke, O., König, R., Krämer-Flecken, A., Liang, Y., Liu, S., Nicolai, D., Satheeswaran, G., Neubauer, O., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Published: 2021

75. Magnetic and Electrostatic Turbulence Island Modulation in the W7-X Boundary

Author: Spolaore M., Killer C., Agostinetti P., Cavazzana R., Ghiraldelli R., Grenfell G., Grulke O., Knieps A., Lazerson S.A., Moresco M., Martines E., Neubauer O., Nocolai D., Satheeswaran G., Schweer B., Vianello N., and W7-X Team
Subjects: magnetic and electrostatic turbulence island modulation, magnetic island in the boundary of nuclear fusion, stellarator experiment W7-X
Abstract: The presence of magnetic island in the boundary of fusion devices is expected to strongly affect the local plasma properties, inducing local flow velocity patterns and perturbing the edge profiles as well as the transport properties. In particular the proximity to the island Xpoint or O-point is found to induce both electrostatic and magnetic turbulence modulation, with experimental evidences in different magnetic configurations. The boundary of the W7-X stellarator experiment is characterized by the presence of a poloidal chain of magnetic islands, whose features depend on the magnetic configuration as defined by the rotational transform, ?/2?. These islands intercept the divertor plates and provide a poloidal series of X-points constituting the island divertor, the concept exploited in the W7-X for the particle and energy exhaust. In this contribution the presence and features of turbulent fluctuations in both electrostatic and magnetic quantities, including the parallel current density fluctuations will be investigated in the Scrape-Off-Layer region of W7-X experiment. To this end a specifically designed insertable probe head was constructed within the framework of EUROfusion WP.S1 work package in collaboration between Consorzio RFX, IPP Greifswald and Forschungszentrum Jülich. The probe head, named High Resolution Probe (HRP) [1,2], was conceived to be installed on the mid-plane multi-purpose fast reciprocating manipulator on W7-X and is suitable for the study of electrostatic and magnetic properties of filaments emerging from turbulence background and characterizing the edge region. In particular the magnetic island related turbulence modulation and the filamentary structure population distribution will be analysed by applying advanced statistical tools First measurements were performed during the W7-X experimental campaign OP1.2b, where in particular the probe was exploring different magnetic configurations. The respective features of the electromagnetic turbulence will be compared.
Published: 2021

76. Heat pulse propagation and anomalous electron heat transport measurements on the optimized stellarator W7-X

Author: W7-X Team, Weir, G. M., Xanthopoulos, P., Hirsch, M., Höfel, U., Stange, T., Pablant, N., Grulke, O., Äkäslompolo, S., Alcusón, J., Bozhenkov, S., Beurskens, M., Dinklage, A., Fuchert, G., Geiger, J., Landreman, M., Langenberg, A., Lazerson, S., Marushchenko, N., Pasch, E., Schilling, J., Scott, E. R., Turkin, Y., Klinger, 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, Nuclear and High Energy Physics, Technology, Heat pulse, Electron, Collisionality, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, Atomic physics, Wendelstein 7-X, 010306 general physics, ddc:600, Stellarator
Abstract: The optimized stellarator Wendelstein 7-X (W7-X) is designed to have an approximately quasi-isodynamic magnetic configuration with reduced neoclassical transport in comparison to a classical stellarator, and turbulent transport is expected to be a significant source of anomalous heat transport across the plasma minor radius. The ion temperature gradient driven mode and the trapped electron mode (TEM) are thought to be responsible for the ion-scale turbulence in W7-X plasmas with volume averaged pressure below 1%. In this work, the electron temperature gradient driven turbulence is shown to be a good candidate for the explanation of the observed electron heat flux, in the inner plasma region where the density gradient is weak (in the outer region, a relatively stronger density gradient would drive additional TEM turbulence). The experimental electron heat transport measured during electron cyclotron resonant heating power and plasma density scans is compared to neoclassical predictions, and the stiffness in the electron heat transport measured during transient transport experiments is presented in three common magnetic configurations of W7-X. In low-⟨β⟩ plasma discharges, the stiffness in the electron heat flux, quantified by the ratio of the heat pulse to power balance diffusivity, χ e H P / χ e P B , is measured to be less than 2, and trend downwards with increasing collisionality.
Published: 2021
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77. Core plasma density fluctuations in Wendelstein 7-X ECRH plasmas

Author: Bähner, J., Alcuson, J., Hansen, S., Stechow, A., Grulke, O., Windisch, T., Smith, H., Huang, Z., Edlund, E., Porkolab, M., Beurskens, M., Bozhenkov, S., Ford, O., Vano, L., Langenberg, A., Pablant, N., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Published: 2021

78. 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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79. Heat pulse propagation and anomalous electron heat transport measurements on the optimized stellarator W7-X

Author: Weir, G.M., Xanthopoulos, P., Hirsch, M., Höfel, U., Stange, T., Pablant, N., Grulke, O., Äkäslompolo, S., Alcusón, J., Bozhenkov, S., Beurskens, M., Dinklage, A., Fuchert, G., Geiger, J., Landreman, M., Langenberg, A., Lazerson, S., Marushchenko, N., Pasch, E., Schilling, J., Scott, E.R., Turkin, Y., Klinger, 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, and Weggen, Jörg
Published: 2021
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80. 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., Hirsch, M., H��fel, 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., ��k��slompolo, S., Alcus��n, J., Aleynikov, P., Aleynikova, K., Ali, A., Anda, G., Ascasibar, E., B��hner, 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., B��ckenhoff, D., B��swirth, B., B��ttger, L.-G., Borsuk, V., Boscary, J., Bosch, H.-S., Brakel, R., Brand, H., Brandt, C., Br��uer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Burhenn, R., Bussiahn, R., Buttensch��n, 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., Da Molin, A., Da Silva, A., De La Pena, A., 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., Garc��a Rega��a, 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., H��lting, A., H��schen, 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., K��chl, F., Kolesnichenko, Y., K��nies, A., K��nig, R., Kornejew, P., Koschinsky, J.-P., K��ster, F., Kr��mer, M., Krampitz, R., Kr��mer-Flecken, A., Krawczyk, N., Kremeyer, T., Krom, J., Ksiazek, I., Kubkowska, M., K��hner, 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., L��cke, A., Lumsdaine, A., Lutsenko, V., Maa��berg, 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., M��nnich, T., Morisaki, T., Moseev, D., Murakami, S., N��fr��di, G., Nagel, M., Naujoks, D., Neilson, H., Neu, R., Neubauer, O., Ngo, T., Nicolai, D., Nielsen, S. K., Niemann, H., Nishizawa, T., Nocentini, R., N��hrenberg, C., N��hrenberg, J., Obermayer, S., Offermanns, G., Ogawa, K., ��lmanns, J., Ongena, J., Oosterbeek, J. W., Orozco, G., Otte, M., Pacios Rodriguez, L., Panadero, N., Panadero Alvarez, N., Papenfu��, D., Paqay, S., Pawelec, E., Pelka, G., Perseo, V., Peterson, B., Pilopp, D., Pingel, S., Pisano, F., Plaum, B., Plunk, G., P��l��skei, P., Porkolab, M., Proll, J., Puiatti, M.-E., Puig Sitjes, A., Purps, F., Rack, M., R��csei, S., Reiman, A., Reimold, F., Reiter, D., Remppel, F., Renard, S., Riedl, R., Riemann, J., Risse, K., Rohde, V., R��hlinger, H., Rom��, 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., S��nchez, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schlaich, A., Schlisio, G., Schluck, F., Schl��ter, K.-H., Schmitt, J., Schmitz, H., Schmitz, O., Schmuck, S., Schneider, M., Schneider, W., Scholz, P., Schrittwieser, R., Schr��der, M., Schr��der, T., Schroeder, R., Schumacher, H., Schweer, B., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipli��, S., Slaby, C., Sleczka, M., Spiess, W., Spong, D. A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Szab��, V., Szabolics, T., Szepesi, T., Sz��kefalvi-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., Tulip��n, S., Unterberg, B., Vakulchyk, I., Valet, S., Van��, L., Van Eeten, P., Van Milligen, B., Van Vuuren, A. J., Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Von Stechow, A., Vork��per, 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., and Zuin, M.
Subjects: Chemical engineering, ddc:660
Published: 2021

81. Changes in the edge magnetic field of Wendelstein 7-X in high-beta plasmas

Author: Knieps, A., Liang, Y., Suzuki, Y., Andreeva, T., Drews, P., Gao, Y., Geiger, J., Grulke, O., Hollfeld, K., Jakubowski, M., Killer, C., Neubauer, O., Nicolai, D., Neuner, U., Niemann, H., Huang, Z., Rahbarnia, K., Satheeswaran, G., Schilling, J., Thomsen, H., Zhou, S., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Published: 2021

82. High-performance ECRH at W7-X: experience and perspectives

Author: W7-X Team, Laqua, H. P., Baldzuhn, J., Braune, H., Bozhenkov, S., Brunner, K., Hirsch, M., Hoefel, U., Knauer, J., Langenberg, A., Marsen, S., Moseev, D., Pasch, E., Rahbarnia, K., Stange, T., Wolf, R. C., Pablant, N., Grulke, O., 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: Technology, ddc:600
Published: 2021

83. Turbulence studies in NBI heated discharges by the Phase Contrast Imaging diagnostic in the Wendelstein 7-X stellarator

Author: Huang, Z., Edlund, E., Porkolab, M., Stechow, A., Bähner, J., Hansen, S., Grulke, O., Ford, O., Beurskens, M., Bozhenkov, S., Lazerson, S., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Published: 2021

84. Dynamics and dependencies of the configuration-dependent 1–2 kHz fluctuation in W7-X

Author: Ballinger, S.B., primary, Terry, J.L., additional, Baek, S.G., additional, Beurskens, M., additional, Brunner, K.J., additional, Fuchert, G., additional, Knauer, J., additional, Killer, C., additional, Pasch, E., additional, Rahbarnia, K., additional, Schilling, J., additional, Scott, E., additional, von Stechow, A., additional, Thomsen, H., additional, Grulke, O., additional, Wurden, G., additional, Kocsis, G., additional, Szepesi, T., additional, and Zsuga, L., additional
Published: 2021
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85. Evolution of a plasma column measured through modulation of a high-energy proton beam

Author: Gessner, S., Adli, E., Apsimon, O., Apsimon, R., Bachmann, A.-M., Batsch, F., Bracco, C., Braunmuller, F., Burger, S., Burt, G., Buttenschon, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Demeter, G., Deubner, L.H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V.N., Fiorito, R., Fonseca, R.A., Friebel, F., Garolfi, L., Goddard, B., Gorgisyan, I., Gorn, A.A., Granados, E., Grulke, O., Gschwendtner, E., Hartin, A., Helm, A., Henderson, J.R., Huther, M., Ibison, M., Jolly, S., Keeble, F., Kelisani, M.D., Khudyakov, V.K., Kim, S.-Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liu, S., Lopes, N., Lotov, K.V., Martyanov, M., Mazzoni, S., Minakov, V.A., Molendijk, J.C., Moody, J.T., Moreira, M., Panuganti, H., Pardons, A., Pena Asmus, F., Perera, A., Petrenko, A., Pukhov, A., Rey, S., Ruhl, H., Saberi, H., Sherwood, P., Silva, L.O., Sosedkin, A.P., Sublet, A., Tuev, P.V., Turner, M., Velotti, F., Verra, L., Verzilov, V.A., Vieira, J., Welsch, C.P., Wendt, M., Williamson, B., Wing, M., Woolley, B., Xia, G., and Zevi Della Porta, G.
Subjects: Accelerator Physics (physics.acc-ph), Plasma Physics (physics.plasm-ph), Physics::Plasma Physics, physics.plasm-ph, Other Fields of Physics, FOS: Physical sciences, Physics::Accelerator Physics, Physics - Accelerator Physics, Accelerators and Storage Rings, Physics - Plasma Physics, physics.acc-ph
Abstract: Plasma wakefield acceleration is a method for accelerating particle beams using electromagnetic fields that are orders of magnitude larger than those found in conventional radio frequency cavities. The core component of a plasma wakefield accelerator is the plasma source, which ranges from millimeter-scale gas jets used in laser-driven experiments, to the ten-meter-long rubidium cell used in the AWAKE experiment. The density of the neutral gas is a controlled input to the experiment, but the density of the plasma after ionization depends on many factors. AWAKE uses a high-energy proton beam to drive the plasma wakefield, and the wakefield acts back on the proton bunch by modulating it at the plasma frequency. We infer the plasma density by measuring the frequency of modulation of the proton bunch, and we measure the evolution of the density versus time by varying the arrival of the proton beam with respect to the ionizing laser pulse. Using this technique, we uncover a microsecond-long period of a stable plasma density followed by a rapid decay in density. The stability of the plasma after ionization has implications for the design of much longer vapor cells that could be used to accelerate particle beams to extremely high energies.
Published: 2020

86. Energy-and-pitch-angle-resolved escaping beam ion measurements by Faraday-cup-based fast-ion loss detector in Wendelstein 7-X

Author: OGAWA, Kunihoro, Bozhenkov, S.A., Äkäslompolo, S., Killer, C., Grulke, O., Nicolai, D., Satheewaran, G., ISOBE, Mitsutaka, OSAKABE, Masaki, YOKOYAMA, Masayuki, OGAWA, Kunihoro, Bozhenkov, S.A., Äkäslompolo, S., Killer, C., Grulke, O., Nicolai, D., Satheewaran, G., ISOBE, Mitsutaka, OSAKABE, Masaki, and YOKOYAMA, Masayuki
Abstract: With the objective of understanding the energetic-particle loss mechanism in three-dimensional plasmas, a Faraday-cup-based fast-ion loss detector (FILD) was developed and installed in OP1.2b in Wendelstein 7-X (W7-X) as a collaboration between the National Institute for Fusion Science and Max-Planck-Institute for Plasma Physics. The FILD, which consists of double apertures and thin aluminum foils, was based on a magnetic spectrometer using the magnetic field of the fusion device. The double aperture limits the thermal ion, but allows the energetic ion to enter the FILD box. The thin aluminum foils serve as the ion collector. Orbit-following calculations were performed in order to find a suitable position for the FILD. The results indicated that barely co- and counter-going transit ions reached the FILD position mounted on the multi-purpose manipulator installed on W7-X. Moreover, because the injection angle of neutral beams injector installed on W7-X was relatively perpendicular, the target range of pitch angle was set to from 91 degrees to 150 degrees. An energy-and-pitch-angle map was created using a grid calculation code in order to decide on the position/size of aperture and aluminum foil. The grid calculation code indicates the position where the energetic ion would strike on the aluminum foil. Here, the map was used as the basis for designing an aluminum foil pattern with two energies and four pitch angle ranges. Also, note that the lower energy range was designed so that it accommodates a neutral beam injection energy of 55 kV. Measurements of beam ion losses were performed in neutral beam (NB) blip experiments, where concurrent increases and decreases of barely co-going transit beam ion losses due to NB injections were observed. Furthermore, this study validated that the FILD installed on a midplane manipulator probe is capable of probing a range of radii spanning 1.0–1.5 cm, over which the beam ion loss current would vary significantly., source:https://doi.org/10.1088/1748-0221/14/09/C09021, identifier:0000-0003-4555-1837
Published: 2021

87. The Wendelstein 7-X phase contrast imaging diagnostic

Author: Huang, Z., Edlund, E., Porkolab, M., Bähner, J. P., Böttger, L. G., Sehren, C. V., von Stechow, A., Grulke, O., Huang, Z., Edlund, E., Porkolab, M., Bähner, J. P., Böttger, L. G., Sehren, C. V., von Stechow, A., and Grulke, O.
Abstract: A phase contrast imaging (PCI) diagnostic has been developed for the Wendelstein 7-X (W7-X) stellarator. The PCI diagnostic provides a line-integrated measurement of turbulent electron density fluctuations, which is essential for understanding high performance scenarios that can lead to improved confinement at fusion-relevant temperatures and densities. The PCI system is also sensitive to coherent fluctuations, which arise from Alfvén eigenmodes or other MHD activity. This paper provides an overview of the hardware and the optical system and presents an example PCI measurement from the W7-X OP1.2b experimental campaign.
Published: 2021

88. Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Author: Chappell, J., Adli, E., Agnello, R., Aladi, M., Andrebe, Y., Apsimon, O., Apsimon, R., Bachmann, A. M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Blanchard, P., Burrows, P. N., Buttenschön, B., Caldwell, A., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Deubner, L. H., Dexter, A., Djotyan, G. P., Doebert, S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Furno, I., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Granetzny, M., Grulke, O., Gschwendtner, E., Hafych, V., Hartin, A., Helm, A., Henderson, J. R., Howling, A., Hüther, M., Jacquier, R., Jolly, S., Kargapolov, I. Yu, Kedves, M. A., Keeble, F., Kelisani, M. D., Kim, S. Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liang, L., Liu, S., Lopes, N., Lotov, K. V., Martyanov, M., Mazzoni, S., Medina Godoy, D., Minakov, V. A., Moody, J. T., Morales Guzmán, P. I., Moreira, M., Panuganti, H., Pardons, A., Peña Asmus, F., Perera, A., Petrenko, A., Pucek, J., Pukhov, A., Ráczkevi, B., Ramjiawan, R. L., Rey, S., Ruhl, H., Saberi, H., Schmitz, O., Senes, E., Sherwood, P., Silva, L. O., Spitsyn, R. I., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Williamson, B., Wing, M., Wolfenden, J., Woolley, B., Xia, G., Zepp, M., Zevi Della Porta, G., Chappell, J., Adli, E., Agnello, R., Aladi, M., Andrebe, Y., Apsimon, O., Apsimon, R., Bachmann, A. M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Blanchard, P., Burrows, P. N., Buttenschön, B., Caldwell, A., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Deubner, L. H., Dexter, A., Djotyan, G. P., Doebert, S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Furno, I., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Granetzny, M., Grulke, O., Gschwendtner, E., Hafych, V., Hartin, A., Helm, A., Henderson, J. R., Howling, A., Hüther, M., Jacquier, R., Jolly, S., Kargapolov, I. Yu, Kedves, M. A., Keeble, F., Kelisani, M. D., Kim, S. Y., Kraus, F., Krupa, M., Lefevre, T., Li, Y., Liang, L., Liu, S., Lopes, N., Lotov, K. V., Martyanov, M., Mazzoni, S., Medina Godoy, D., Minakov, V. A., Moody, J. T., Morales Guzmán, P. I., Moreira, M., Panuganti, H., Pardons, A., Peña Asmus, F., Perera, A., Petrenko, A., Pucek, J., Pukhov, A., Ráczkevi, B., Ramjiawan, R. L., Rey, S., Ruhl, H., Saberi, H., Schmitz, O., Senes, E., Sherwood, P., Silva, L. O., Spitsyn, R. I., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Williamson, B., Wing, M., Wolfenden, J., Woolley, B., Xia, G., Zepp, M., and Zevi Della Porta, G.
Abstract: Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scans.
Published: 2021

89. Simulation and experimental study of proton bunch self-modulation in plasma with linear density gradients

Author: Morales Guzmán, P. I., Muggli, P., Agnello, R., Ahdida, C. C., Aladi, M., Amoedo Goncalves, M. C., Andrebe, Y., Apsimon, O., Apsimon, R., Bachmann, A. M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Blanchard, P., Braunmüller, F., Burrows, P. N., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Dexter, A., Doebert, S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Furno, I., Gessner, S., Gorn, A. A., Granados, E., Granetzny, M., Graubner, T., Grulke, O., Gschwendtner, E., Guran, E. D., Hafych, V., Henderson, J. R., Hüther, M., Kedves, M., Khudyakov, V., Kim, S. Y., Kraus, F., Krupa, M., Lefevre, T., Morales Guzmán, P. I., Muggli, P., Agnello, R., Ahdida, C. C., Aladi, M., Amoedo Goncalves, M. C., Andrebe, Y., Apsimon, O., Apsimon, R., Bachmann, A. M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Blanchard, P., Braunmüller, F., Burrows, P. N., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Dexter, A., Doebert, S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Furno, I., Gessner, S., Gorn, A. A., Granados, E., Granetzny, M., Graubner, T., Grulke, O., Gschwendtner, E., Guran, E. D., Hafych, V., Henderson, J. R., Hüther, M., Kedves, M., Khudyakov, V., Kim, S. Y., Kraus, F., Krupa, M., and Lefevre, T.
Abstract: We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.264801]: with negative gradients, the charge of the modulated bunch is lower than with positive gradients. In addition, the bunch modulation frequency varies with gradient. Simulation results show that dephasing of the wakefields with respect to the relativistic protons along the plasma is the main cause for the loss of charge. The study of the modulation frequency reveals details about the evolution of the self-modulation process along the plasma. In particular for negative gradients, the modulation frequency across time-resolved images of the bunch indicates the position along the plasma where protons leave the wakefields. Simulations and experimental results are in excellent agreement.
Published: 2021

90. Phase contrast imaging measurements and numerical simulations of turbulent density fluctuations in gas-fuelled ECRH discharges in Wendelstein 7-X

Author: Baehner, J. -P., Alcuson, J. K., Hansen, S. K., von Stechow, A., Grulke, O., Windisch, T., Smith, H. M., Huang, Z., Edlund, E. M., Porkolab, M., Beurskens, M. N. A., Bozhenkov, S. A., Ford, O. P., Vano, L., Langenberg, A., Pablant, N., Plunk, G. G., Banon Navarro, A., Jenko, F., Baehner, J. -P., Alcuson, J. K., Hansen, S. K., von Stechow, A., Grulke, O., Windisch, T., Smith, H. M., Huang, Z., Edlund, E. M., Porkolab, M., Beurskens, M. N. A., Bozhenkov, S. A., Ford, O. P., Vano, L., Langenberg, A., Pablant, N., Plunk, G. G., Banon Navarro, A., and Jenko, F.
Abstract: The fundamental nature of turbulent density fluctuations in standard Wendelstein 7-X (W7-X) stellarator discharges is investigated experimentally via phase contrast imaging (PCI) in combination with gyrokinetic simulations with the code GENE. We find that density fluctuations are ion-temperature-gradient-driven and radially localised in the outer half of the plasma. It is shown that the line-integrated PCI measurements cover the right range of wavenumbers and a favourable toroidal and poloidal location to capture some of the strongest density fluctuations in W7-X. Due to the radial localisation of fluctuations, measured wavenumber-frequency spectra exhibit a dominant phase velocity, which can be related to the E X B rotation velocity at the radial position of a well in the neoclassical radial electric field. The match is robust against variations of heating power and line-integrated density, which is partly due to the localisation of fluctuations and partly due to effects of the radial gradient in the E X B velocity profile on the wavenumber-frequency spectrum. The latter effect is studied with a newly built synthetic PCI diagnostic and global gyrokinetic simulations with GENE-3D.
Published: 2021

91. Ion temperature clamping in Wendelstein 7-X electron cyclotron heated plasmas

Author: Beurskens, M. N.A., Bozhenkov, S. A., Ford, O., Xanthopoulos, P., Zocco, A., Turkin, Y., Alonso, A., Beidler, C., Calvo, I., Carralero, D., Estrada, T., Fuchert, G., Grulke, O., Hirsch, M., Ida, K., Jakubowski, M., Killer, C., Krychowiak, M., Kwak, S., Lazerson, S., Langenberg, A., Lunsford, R., Pablant, N., Pasch, E., Pavone, A., Reimold, F., Romba, Th, Von Stechow, A., Smith, H. M., Windisch, T., Yoshinuma, M., Zhang, D., Wolf, R. C., Beurskens, M. N.A., Bozhenkov, S. A., Ford, O., Xanthopoulos, P., Zocco, A., Turkin, Y., Alonso, A., Beidler, C., Calvo, I., Carralero, D., Estrada, T., Fuchert, G., Grulke, O., Hirsch, M., Ida, K., Jakubowski, M., Killer, C., Krychowiak, M., Kwak, S., Lazerson, S., Langenberg, A., Lunsford, R., Pablant, N., Pasch, E., Pavone, A., Reimold, F., Romba, Th, Von Stechow, A., Smith, H. M., Windisch, T., Yoshinuma, M., Zhang, D., and Wolf, R. C.
Published: 2021

92. High-performance ECRH at W7-X:Experience and perspectives

Author: Laqua, H. P., Baldzuhn, J., Braune, H., Bozhenkov, S., Brunner, K., Hirsch, M., Hoefel, U., Knauer, J., Langenberg, A., Marsen, S., Moseev, D., Pasch, E., Rahbarnia, K., Stange, T., Wolf, R. C., Pablant, N., Grulke, O., Laqua, H. P., Baldzuhn, J., Braune, H., Bozhenkov, S., Brunner, K., Hirsch, M., Hoefel, U., Knauer, J., Langenberg, A., Marsen, S., Moseev, D., Pasch, E., Rahbarnia, K., Stange, T., Wolf, R. C., Pablant, N., and Grulke, O.
Abstract: The second operation phase of W7-X (OP1.2) showed the potential of exclusively electron cyclotron resonance heating (ECRH)-sustained plasma operations in stellarators. Employing multi-pass ECRH scenario in the second harmonic O-mode (O2-ECRH), stationary densities of up to 1.4 × 1020 m-3 could be achieved. This scenario also made stationary divertor detachment possible, which is a reactor-relevant scenario for power and particle exhaust. At high densities and with sufficiently high density gradients for an improved ion confinement, the coupling between the electrons and ions was strong enough to bring the ion temperature to values above 3 keV and to the neoclassical limit for some magnetic configurations, thus enabling to test the W7-X neoclassical optimization. The planned enhancement of the ECRH performance will enable to advance towards reactor-relevant beta values and to investigate their stability and confinement of fast particles, which is a priority goal of W7-X.
Published: 2021

93. Dynamics and dependencies of the configuration-dependent 1–2 kHz fluctuation in W7-X

Author: Ballinger, S. B., Terry, J. L., Baek, S. G., Beurskens, M., Brunner, K. J., Fuchert, G., Knauer, J., Killer, C., Pasch, E., Rahbarnia, K., Schilling, J., Scott, E., von Stechow, A., Thomsen, H., Grulke, O., Wurden, G., Kocsis, G., Szepesi, T., Zsuga, L., Ballinger, S. B., Terry, J. L., Baek, S. G., Beurskens, M., Brunner, K. J., Fuchert, G., Knauer, J., Killer, C., Pasch, E., Rahbarnia, K., Schilling, J., Scott, E., von Stechow, A., Thomsen, H., Grulke, O., Wurden, G., Kocsis, G., Szepesi, T., and Zsuga, L.
Abstract: A 1–2 kHz electromagnetic mode is present in a large fraction of W7-X discharges in the standard magnetic field configurations with 5/5 edge island structure. The power in the mode is significantly reduced in other magnetic configurations. The mode can appear spontaneously and persist for the full duration of a discharge. Its full width at half maximum is typically 100–300 Hz. The 1–2 kHz mode was first observed in visible light emissions from the divertor [1]. Matching spectral peaks were found in measurements of both global and edge plasma parameters, including line-integrated density, diamagnetic energy, and edge floating potential and ion saturation current [2]. An infrared camera recording shows a temperature modulation of ~ 2.5 K due to this mode on a divertor tile where the average temperature was 600 °C. Separate correlation analyses of the high-speed camera recordings, Langmuir probe signals, and Mirnov coil signals all indicate a poloidal velocity of 0.5–10 km/s and m = 2 as a likely poloidal mode number. Langmuir probes mounted on the Multi-Purpose Manipulator show that the fluctuation is present in one of the magnetic islands over a radial distance of at least 5 mm. A database of various diagnostic measurements and dB/dt signals from a Mirnov coil was created using a majority of the discharges from the 2018 campaign on W7-X, in order to shed light on the plasma parameters that are correlated with the existence of the 1–2 kHz mode. The power in the mode is positively correlated to the toroidal current, total external heating power, and core electron temperature. It is negatively correlated with plasma density.
Published: 2021

94. Reciprocating probe measurements in the test divertor operation phase of Wendelstein 7-X

Author: W7-X Team, Killer, C., Drews, P., Grulke, O., Knieps, A., Nicolai, D., Satheeswaran, G., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
Subjects: Plasma Physics (physics.plasm-ph), Technology, Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)), FOS: Physical sciences, Plasma diagnostics - probes, ddc:610, ddc:600, Instrumentation, Physics - Plasma Physics, Mathematical Physics
Abstract: Reciprocating probes are a classic and widespread tool for the investigation of the edge and Scrape-Off Layer of magnetic fusion plasmas. In the Wendelstein 7-X (W7-X) stellarator, the Multi-Purpose Manipulator serves as a multi-user platform for probe measurements of various kinds. This paper presents a review on reciprocating probe operation during the first operation phase of W7-X with a test divertor (2017–2018). It gives an overview of the diverse zoo of probe heads and presents lessons learned about probe operation in complex magnetic geometries, operation safety, and probe head design. A few examples of probe measurements with a focus on unexpected observations are presented, e.g. indications for supra-thermal electrons and the propagation of plasma perturbations due to biased probes.
Published: 2022
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95. Radially propagating turbulent structures in a linear helicon plasma device

Author: Windisch, T., Grulke, O., and Klinger, T.
Published: 2007
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96. Heat pulse propagation and anomalous electron heat transport measurements on the optimized stellarator W7-X

Author: Weir, G.M., primary, Xanthopoulos, P., additional, Hirsch, M., additional, Höfel, U., additional, Stange, T., additional, Pablant, N., additional, Grulke, O., additional, Äkäslompolo, S., additional, Alcusón, J., additional, Bozhenkov, S., additional, Beurskens, M., additional, Dinklage, A., additional, Fuchert, G., additional, Geiger, J., additional, Landreman, M., additional, Langenberg, A., additional, Lazerson, S., additional, Marushchenko, N., additional, Pasch, E., additional, Schilling, J., additional, Scott, E.R., additional, Turkin, Y., additional, and Klinger, T., additional
Published: 2021
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97. Spectra of highly ionized xenon (6–30 nm) excited in W7-AS plasmas

Author: Hacker, H.H., Burhenn, R., Kondo, K., Anton, M., Assmus, D., Baeumel, S., Beidler, C., Bindemann, T., Brakel, R., Cattanei, G., Dinklage, A., Dodhy, A., Dorst, D., Ehmler, H., Elsner, A., Endler, M., Engelhardt, K., Erckmann, V., Feng, Y., Fuchs, C., Gadelmeier, F., Geiger, J., Giannone, L., Grigull, P., Gruenwald, G., Grulke, O., Harmeyer, E., Hartfuss, H.J., Herrnegger, F., Hirsch, M., Hofner, J., Hollmann, F., Holzhauer, E., Igitkhanov, Y., Jaenicke, R., Karger, F., Kick, M., Kisslinger, J., Klose, S., Knauer, J., Kroiss, H., Kühner, G., Kus, A., Laqua, H., Liu, R., Maassberg, H., Marushchenko, N., McCormick, K., Michel, G., Noke, F., Ott, W., Otte, M., Pacco-Duechs, M.G., Penningsfeld, F.P., Polunovsky, E., Probst, F., Purps, F., Ruhs, N., Rust, N., Saffert, N.J., Salat, A., Sallander, J., Sardei, F., Schneider, F., Schubert, M., Sidorenko, I., Speth, E., Suess, R., Thomsen, H., Volpe, F., Wagner, F., Weller, A., Wendland, C., Werner, A., Wobig, H., Wuersching, E., and Zimmermann, D.
Published: 2001
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98. The Wendelstein 7-X phase contrast imaging diagnostic

Author: Huang, Z., primary, Edlund, E., additional, Porkolab, M., additional, Bähner, J-P., additional, Böttger, L.-G., additional, Sehren, C. v., additional, Stechow, A. von, additional, and Grulke, O., additional
Published: 2021
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99. Proton beam defocusing in AWAKE: comparison of simulations and measurements

Author: Gorn, A A, primary, Turner, M, additional, Adli, E, additional, Agnello, R, additional, Aladi, M, additional, Andrebe, Y, additional, Apsimon, O, additional, Apsimon, R, additional, Bachmann, A-M, additional, Baistrukov, M A, additional, Batsch, F, additional, Bergamaschi, M, additional, Blanchard, P, additional, Burrows, P N, additional, Buttenschön, B, additional, Caldwell, A, additional, Chappell, J, additional, Chevallay, E, additional, Chung, M, additional, Cooke, D A, additional, Damerau, H, additional, Davut, C, additional, Demeter, G, additional, Deubner, L H, additional, Dexter, A, additional, Djotyan, G P, additional, Doebert, S, additional, Farmer, J, additional, Fasoli, A, additional, Fedosseev, V N, additional, Fiorito, R, additional, Fonseca, R A, additional, Friebel, F, additional, Furno, I, additional, Garolfi, L, additional, Gessner, S, additional, Goddard, B, additional, Gorgisyan, I, additional, Granados, E, additional, Granetzny, M, additional, Grulke, O, additional, Gschwendtner, E, additional, Hafych, V, additional, Hartin, A, additional, Helm, A, additional, Henderson, J R, additional, Howling, A, additional, Hüther, M, additional, Jacquier, R, additional, Kargapolov, I Yu, additional, Kedves, M Á, additional, Keeble, F, additional, Kelisani, M D, additional, Kim, S-Y, additional, Kraus, F, additional, Krupa, M, additional, Lefevre, T, additional, Liang, L, additional, Liu, S, additional, Lopes, N, additional, Lotov, K V, additional, Martyanov, M, additional, Mazzoni, S, additional, Medina Godoy, D, additional, Minakov, V A, additional, Moody, J T, additional, Morales Guzmán, P I, additional, Moreira, M, additional, Nechaeva, T, additional, Panuganti, H, additional, Pardons, A, additional, Peña Asmus, F, additional, Perera, A, additional, Petrenko, A, additional, Pucek, J, additional, Pukhov, A, additional, Ráczkevi, B, additional, Ramjiawan, R L, additional, Rey, S, additional, Ruhl, H, additional, Saberi, H, additional, Schmitz, O, additional, Senes, E, additional, Sherwood, P, additional, Silva, L O, additional, Spitsyn, R I, additional, Tuev, P V, additional, Velotti, F, additional, Verra, L, additional, Verzilov, V A, additional, Vieira, J, additional, Welsch, C P, additional, Williamson, B, additional, Wing, M, additional, Wolfenden, J, additional, Woolley, B, additional, Xia, G, additional, Zepp, M, additional, and Zevi Della Porta, G, additional
Published: 2020
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100. 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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