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152 results on '"Killer C."'

1. Gas puff imaging of plasma turbulence in the magnetic island scrape-off layer of W7-X

Author

Baek, S. G., Ballinger, S., Grulke, O., Killer, C., von Stechow, A., Terry, J. L., Scharmer, F., and Shanahan, B.

Subjects
Physics - Plasma Physics
Abstract

The turbulence characteristics of the scrape-off-layer (SOL) plasma in the W7-X stellarator are investigated using a gas-puff-imaging (GPI) diagnostic, newly installed and operated during the OP 2.1 campaign. The SOL plasma on W7-X features a chain of magnetic islands intersected by discrete divertor plates at five separate toroidal locations, forming a set of island divertors for heat and particle exhaust. GPI measures 2D emission fluctuations in the magnetic island plasma. A dedicated experiment was conducted to characterize the broadband turbulence and filament dynamics in the island divertor SOL in the standard magnetic configuration. This involves shifting the poloidal location of the magnetic island with respect to the GPI field of view. Overall, initial analyses confirm minimal intermittent type fluctuations, compared to tokamaks. A relationship between the radial profile of the connection length and the sheared poloidal flow structure is discussed. Turbulence statistical analyses reveal poloidal asymmetry of the fluctuation properties and a birth region of intermittent fluctuations indicated by skewness reversal. Their birth locations appear sensitive to plasma conditions. Finally, 2D cross-correlation analysis is presented to study turbulence propagation in the presence of multiple shear layers in the poloidal flows, showing a dominant poloidal motion and evidencing a shear effect.

Published
2024

2. The Realization of a Gas Puff Imaging System on the Wendelstein 7-X Stellarator

Author

Terry, J. L., von Stechow, A., Baek, S. G., Ballinger, S. B., Grulke, O., von Sehren, C., Laube, R., Killer, C., Scharmer, F., Brunner, K. J., Knauer, J., Bois, S., and Team, the W7-X

Subjects
Physics - Plasma Physics
Abstract

A system for studying the spatio-temporal dynamics of fluctuations in the boundary of the W7-X plasma using the Gas-Puff Imaging (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number of challenges specific to long-pulse superconducting devices like W7-X, including the long distance between the plasma and the vacuum vessel wall, the long distance between the plasma and diagnostic ports, the range of last closed flux surface locations for different magnetic configurations in W7-X, and management of heat loads on the system's plasma-facing components. The system features a pair of "converging-diverging" nozzles for partially collimating the gas puffed locally $\approx$135 mm radially outboard of the plasma boundary, a pop-up turning mirror for viewing the gas puff emission from the side (also acting as a shutter for the re-entrant vacuum window), and a high-throughput optical system that collects visible emission resulting from the interaction between the puffed gas and the plasma and directs it along a water-cooled re-entrant tube directly onto the 8 x 16 pixel detector array of the fast camera. The DEGAS 2 neutrals code was used to simulate the H$_\alpha$ (656 nm) and the HeI (587 nm) line emission expected from well-characterized gas-puffs of H$_2$ and He and excited within typical edge plasma profiles in W7-X, thereby predicting line brightnesses used to reduce the risks associated with system sensitivity and placement of the field of view. Operation of GPI on W7-X shows excellent signal to noise ratios (>100) over the field of view for minimally perturbing gas puffs. The GPI system provides detailed measurements of the 2-dimensional (radial and poloidal) dynamics of plasma fluctuations in the W7-X edge, scrape-off layer, and in and around the magnetic islands that make up the island divertor configuration employed on W7-X., Comment: 30 pages, 23 figures, submitted to Review of Scientific Instruments

Published
2024

3. On the interaction between the island divertor heat fluxes, the scrape-off layer radial electric field and the edge turbulence in Wendelstein 7-X plasmas

Author

Maragkoudakis, E., Carralero, D., Estrada, T., Windisch, T., Gao, Y., Killer, C., Jakubowski, M., Sitjes, A. Puig, Pisano, F., Sándor, H., Vecsei, M., Zoletnik, S., Cappa, A., and team, the Wendelstein 7-X

Subjects
Physics - Plasma Physics
Abstract

The formation of the radial electric field, $E_{\rm r}$ in the SOL has been experimentally studied for attached divertor conditions in stellarator W7-X. The main objective of this study is to test the validity in a complex 3D island divertor of simple models, typically developed in tokamaks, relating $E_{\rm r}$ to the sheath potential drop gradient at the target. Additionally, we investigate the effect of the edge $E_{\rm r}$ shear on the reduction of density fluctuation amplitude, a well-established phenomenon according to the existing bibliography. The main diagnostic for measurements in the SOL is a V-band Doppler reflectometer that can provide the measurement of the $E_{\rm r}$ and density fluctuations with good spatial resolution. Three-dimensional measurements of divertor parameters has been carried out using infrared cameras, with $\lambda_{\rm q}$ resulting a suitable proxy for the model-relevant $\lambda_{\rm T}$. In the investigated attached regimes, it is shown for the first time that the formation of the $E_{\rm r}$ in the SOL depends on parameters at the divertor, following a $E_{\rm r} \propto T_{\rm e} /\lambda_q$ qualitatively similar to that found in a tokamak. Then, from the analyzed plasmas, the observed $E_{\rm r}$ shear at the edge is linked to a moderate local reduction of the amplitude of density fluctuations.

Published
2022
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6. WeTrace -- A Privacy-preserving Mobile COVID-19 Tracing Approach and Application

Author

De Carli, A., Franco, M., Gassmann, A., Killer, C., Rodrigues, B., Scheid, E., Schoenbaechler, D., and Stiller, B.

Subjects
Computer Science - Cryptography and Security
Abstract

For the protection of people and society against harm and health threats -- especially for the COVID-19 pandemic -- a variety of different disciplines needs to be involved. The data collection of very basic and health-related data of individuals in today's highly mobile society does help to plan, protect, and identify next steps health authorities and governments can, shall, or need to plan for or even implement. Thus, every individual, every human, and every inhabitant of the world is the key player -- very different to many past crises'. And since the individual is involved -- all individuals -- his/her (a) health and (b) privacy shall be considered in a very carefully crafted balance, not overruling one aspect with another one or even prioritizing certain aspects. Privacy remains the key. Thus, the solution of the current pandemic's data collection can be based on a fully privacy-preserving application, which can be used by individuals on their mobile devices, such as smartphones, while maintaining at the same time their privacy. Additionally, respective data collected in such a fully distributed setting does help to confine the pandemic and can be achieved in a democratic and very open, but still and especially privacy-protecting world. Therefore, the WeTrace approach and application as described in this paper utilizes the Bluetooth Low Energy (BTE) communication channel, many modern mobile devices offer, where asymmetric cryptography is being applied to allows for the decyphering of a message for that destination it had been intended for. Since literally every other potential participant only listens to random data, even a brute force attack will not succeed. WeTrace and its Open Source implementation is the only known approach so far, which ensures that any receiver of a message knows that this is for him/her, but does not know who the original sender was.

Published
2020

7. Validating the ASCOT modelling of NBI fast ions in Wendelstein 7-X stellarator

Author

Äkäslompolo, S., Drewelow, P., Gao, Y., Ali, A., Biedermann, C., Bozhenkov, S., Dhard, C. P., Endler, M., Fellinger, J., Ford, O. P., Geiger, B., Geiger, J., Harderd, N. den, Hartmann, D., Hathiramani, D., Isobe, M., Jakubowski, M., Kazakov, Y., Killer, C., Lazerson, S., Mayerd, M., McNeely, P., Naujoks, D., Neelis, T. W. C., Kontula, J., Kurki-Suonio, T., Niemann, H., Ogawa, K., Pisano, F., Poloskei, P. Zs., Sitjes, A. Puig, Rahbarnia, K., Rust, N., Schmitt, J. C., Sleczka, M., Vano, L., van Vuuren, A., Wurden, G., Wolf, R. C., and Team, the W7-X

Subjects
Physics - Plasma Physics, Physics - Computational Physics
Abstract

The first fast ion experiments in Wendelstein 7-X were performed in 2018. They are one of the first steps in demonstrating the optimised fast ion confinement of the stellarator. The fast ions were produced with a neutral beam injection (NBI) system and detected with infrared cameras (IR), a fast ion loss detector (FILD), fast ion charge exchange spectroscopy (FIDA), and post-mortem analysis of plasma facing components. The fast ion distribution function in the plasma and at the wall is being modelled with the ASCOT suite of codes. They calculate the ionisation of the injected neutrals and the consecutive slowing down process of the fast ions. The primary output of the code is the multidimensional fast ion distribution function within the plasma and the distribution of particle hit locations and velocities on the wall. Synthetic measurements based on ASCOT output are compared to experimental results to assess the validity of the modelling. This contribution presents an overview of the various fast ion measurements in 2018 and the current modelling status. The validation and data-analysis is on-going, but the wall load IR modelling already yield results that match with the experiments., Comment: Presented in the 3rd European Conference on Plasma Diagnostics; 6th to 9th of May 2019; Lisbon, Portugal

Published
2019
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9. Realization of a gas puff imaging system on the Wendelstein 7-X stellarator.

Author

Terry, J. L., von Stechow, A., Baek, S. G., Ballinger, S. B., Grulke, O., von Sehren, C., Laube, R., Killer, C., Scharmer, F., Brunner, K. J., Knauer, J., and Bois, S.

Subjects
PLASMA boundary layers, HEATING load, PLASMA dynamics, PLASMA gases, IMAGING systems
Abstract

A system for studying the spatiotemporal dynamics of fluctuations in the boundary of the W7-X plasma using the "Gas-Puff Imaging" (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number of challenges specific to long-pulse superconducting devices, such as W7-X, including the long distance between the plasma and the vacuum vessel wall, the long distance between the plasma and diagnostic ports, the range of last closed flux surface (LCFS) locations for different magnetic configurations in W7-X, and management of heat loads on the system's plasma-facing components. The system features a pair of "converging–diverging" nozzles for partially collimating the gas puffed locally ≈135 mm radially outboard of the plasma boundary, a pop-up turning mirror for viewing the gas puff emission from the side (which also acts as a shutter for the re-entrant vacuum window), and a high-throughput optical system that collects visible emission resulting from the interaction between the puffed gas and the plasma and directs it along a water-cooled re-entrant tube directly onto the 8 × 16 pixel detector array of the fast camera. The DEGAS 2 neutral code was used to simulate the Hα (656 nm) and HeI (587 nm) line emission expected from well-characterized gas-puffs of H2 and He and excited within typical edge plasma profiles in W7-X, thereby predicting line brightnesses used to reduce the risks associated with system sensitivity and placement of the field of view. Operation of GPI on W7-X shows excellent signal-to-noise ratios (> 100 at 2 Mframes/s) over the field of view for minimally perturbing gas puffs. The GPI system provides detailed measurements of the two-dimensional (radial and poloidal) dynamics of plasma fluctuations in the W7-X edge and scrape-off layer and in and around the magnetic islands outside the LCFS that make up the island divertor configuration employed on W7-X. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Edge plasma measurements on the OP 1.2a divertor plasmas at W7-X using the combined probe

Author

Drews, P., Killer, C., Cosfeld, J., Knieps, A., Brezinsek, S., Jakubowski, M., Brandt, C., Bozhenkov, S., Dinklage, A., Cai, J., Endler, M., Hammond, K., Henkel, M., Gao, Y., Geiger, J., Grulke, O., Höschen, D., König, R., Krämer-Flecken, A., Liang, Y., Li, Y., Liu, S., Niemann, H., Nicolai, D., Neubauer, O., Neuner, U., Rack, M., Rahbarnia, K., Rudischhauser, L., Sandri, N., Satheeswaran, G., Schilling, S., Thomsen, H., Windisch, T., and Sereda, S.

Published
2019
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15. Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

Author

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

16. Inhibition of parametric decay in heating microwave beams during fluctuations of the density profile in the edge island of Wendelstein 7-X

Author

Tancetti, A., Nielsen, S. K., Rasmussen, J., Moseev, D., Stange, T., Marsen, S., Vecséi, M., Killer, C., Wurden, G. A., Jensen, T., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., Rahbarnia, K., Brandt, C., Thomsen, H., Hirsch, M., Hoefel, U., Chaudhary, N., Winters, V., Kornejew, P., Harris, J., Laqua, H. P., Tancetti, A., Nielsen, S. K., Rasmussen, J., Moseev, D., Stange, T., Marsen, S., Vecséi, M., Killer, C., Wurden, G. A., Jensen, T., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., Rahbarnia, K., Brandt, C., Thomsen, H., Hirsch, M., Hoefel, U., Chaudhary, N., Winters, V., Kornejew, P., Harris, J., and Laqua, H. P.

Abstract

Experimental evidence of parametric decay instability (PDI) is observed in the Wendelstein 7-X stellarator, when high-power microwave beams cross a stationary magnetic island at the plasma edge. Here, trapping and build-up of upper hybrid waves within a density bump (measured within the island by alkali beam emission spectroscopy) is responsible for the reduction of the instability power threshold below the maximum gyrotron power. In this paper, we provide the first experimental evidence of the connection between the trapping mechanism in the island density bump and excitation of PDI-related signals. We show correlations of periodic crashes in the PDI-related signals with quasi-continuous fluctuations at the plasma edge, which, additionally, cause a flattening of the density profile in the island. We demonstrate that flattening of the experimental density profiles can suppress the trapping mechanism and inhibit the low-threshold PDI. PDI on the edge island could alter the power deposition profile and reduce the efficiency of the electron cyclotron resonance heating system, simultaneously posing a serious threat to the optimal operation of microwave-based diagnostics and plasma-facing components.

Published
2023

17. Effects of drifts on scrape-off layer transport in W7-X

Author

Kriete, D. M., Pandey, A., Perseo, V., Schmitt, J. C., Ennis, D. A., Gradic, D., Hammond, K. C., Jakubowski, M., Killer, C., König, R., Maurer, D. A., Reimold, F., Winters, V., Beurskens, M. N. A., Bozhenkov, S. A., Brunner, K. J., Fuchert, G., Knauer, J., Pasch, E., Scott, E. R., Gantenbein, Gerd, Illy, Stefan, Jelonnek, John, Krier, Laurent, Thumm, Manfred, Team, the W-X., and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Nuclear and High Energy Physics, Technology, Condensed Matter Physics, ddc:600
Abstract

Drifts affect particle, momentum, and energy transport in the scrape-off layer (SOL) of tokamaks and stellarators, altering plasma flows and creating asymmetries between divertors. To understand how drifts affect SOL transport in the W7-X island divertor, an experiment was performed to compare plasmas with matched core parameters but opposite magnetic field directions, and therefore opposite drift transport directions. Parallel flow measurements made with coherence imaging spectroscopy are interpreted with the aid of a diagnostic forward model and a 1D simple SOL model that includes the E × B drift. In low-density plasmas ( n ‾ e < 2 × 10 19 m−3), the poloidal E × B drift induces a large poloidal density asymmetry within the island SOL, as measured by divertor Langmuir probes. This in turn causes the parallel flow stagnation point to shift from the position halfway between targets to the X-point in the drift direction, leading to near-unidirectional flow throughout the SOL. As density increases, the effects of the poloidal E × B drift decrease substantially, resulting in a smaller density asymmetry and the development of a counter-streaming flow pattern. For the entire density range probed in this experiment ( n ‾ e = 1.5 − 6 × 10 19 m−3), the experimental observations are more consistent with the effects of the poloidal E × B drift than the radial E × B drift.

Published
2023

18. On the interaction between the island divertor heat fluxes, the scrape-off layer radial electric field and the edge turbulence in Wendelstein 7-X plasmas

Author

Maragkoudakis, E., primary, Carralero, D., additional, Estrada, T., additional, Windisch, T., additional, Gao, Y., additional, Killer, C., additional, Jakubowski, M., additional, Puig Sitjes, A., additional, Pisano, F., additional, Sándor, H., additional, Vecsei, M., additional, Zoletnik, S., additional, and Cappa, A., additional

Published
2022
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19. Inhibition of parametric decay in heating microwave beams during fluctuations of the density profile in the edge island of Wendelstein 7-X

Author

Tancetti, A, primary, Nielsen, S K, additional, Rasmussen, J, additional, Moseev, D, additional, Stange, T, additional, Marsen, S, additional, Vecséi, M, additional, Killer, C, additional, Wurden, G A, additional, Jensen, T, additional, Stejner, M, additional, Anda, G, additional, Dunai, D, additional, Zoletnik, S, additional, Rahbarnia, K, additional, Brandt, C, additional, Thomsen, H, additional, Hirsch, M, additional, Hoefel, U, additional, Chaudhary, N, additional, Winters, V, additional, Kornejew, P, additional, Harris, J, additional, and Laqua, H P, additional

Published
2022
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20. Radiation characteristics of detached divertor plasmas in W7-X

Author

Wang, E., primary, König, R., additional, Krychowiak, M., additional, Brezinsek, S., additional, Drews, P., additional, Gradic, D., additional, Jakubowski, M., additional, Kornejew, P., additional, Kremeyer, T., additional, Killer, C., additional, Liang, Y., additional, Neubauer, O., additional, Pandey, A., additional, Rudischhauser, L., additional, Sereda, S., additional, Schlisio, G., additional, and Xu, S., additional

Published
2022
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21. Observation of non-thermal electrons outside the SOL in the Wendelstein 7-X stellarator

Author

Killer, C., primary, Aleynikov, P., additional, Biedermann, C., additional, Dhard, C.P., additional, Drews, P., additional, Gao, Y., additional, Grulke, O., additional, Jakubowski, M., additional, Knieps, A., additional, Kocsis, G., additional, Naujoks, D., additional, Puig Sitjes, A., additional, Spolaore, M., additional, Stange, T., additional, Szepesi, T., additional, Tancetti, A., additional, and Thomsen, H., additional

Published
2022
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22. Nonlinear decay of high-power microwaves into trapped modes in inhomogeneous plasma

Author

The Wendelstein 7-X Team, Tancetti, A., Nielsen, S.K., Rasmussen, J., Gusakov, E.Z., Popov, A. Yu, Moseev, D., Stange, T., Senstius, M.G., Killer, C., Vecséi, M., Jensen, T., Zanini, M., Abramovic, I., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., Laqua, H.P., The Wendelstein 7-X Team, Tancetti, A., Nielsen, S.K., Rasmussen, J., Gusakov, E.Z., Popov, A. Yu, Moseev, D., Stange, T., Senstius, M.G., Killer, C., Vecséi, M., Jensen, T., Zanini, M., Abramovic, I., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., and Laqua, H.P.

Abstract

We present novel experimental evidence of parametric decay instability of microwave beams in the plasma edge of the Wendelstein 7-X stellarator. We propose that the instability is sustained by trapping of only one daughter wave in the non-monotonic density profile measured with high spatial resolution within a stationary magnetic island. The power levels and spectral shapes of the detected microwave signal are reproduced by numerical modelling and a theoretical power threshold is predicted around 300 kW, comparable with observations. We predict a fraction of power drained by daughter waves around 4% in the experiments, potentially increasing above 50% for more hollow edge density profiles. Such absorption levels could significantly reduce the efficiency of the microwave heating and current-drive system in tokamaks and stellarators.

Published
2022

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

Author

Killer, C., Drews, P., Grulke, O., Knieps, A., Nicolai, D., Satheeswaran, G., Killer, C., Drews, P., Grulke, O., Knieps, A., Nicolai, D., and Satheeswaran, G.

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

24. 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

26. 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

27. Nonlinear decay of high-power microwaves into trapped modes in inhomogeneous plasma

Author

Tancetti, A., Nielsen, S. K., Rasmussen, J., Gusakov, E. Z., Popov, A. Yu, Moseev, D., Stange, T., Senstius, M. G., Killer, C., Vecséi, M., Jensen, T., Zanini, M., Abramovic, I., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., Laqua, H. P., Tancetti, A., Nielsen, S. K., Rasmussen, J., Gusakov, E. Z., Popov, A. Yu, Moseev, D., Stange, T., Senstius, M. G., Killer, C., Vecséi, M., Jensen, T., Zanini, M., Abramovic, I., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., and Laqua, H. P.

Abstract

We present novel experimental evidence of parametric decay instability of microwave beams in the plasma edge of the Wendelstein 7-X stellarator. We propose that the instability is sustained by trapping of only one daughter wave in the non-monotonic density profile measured with high spatial resolution within a stationary magnetic island. The power levels and spectral shapes of the detected microwave signal are reproduced by numerical modelling and a theoretical power threshold is predicted around 300 kW, comparable with observations. We predict a fraction of power drained by daughter waves around 4% in the experiments, potentially increasing above 50% for more hollow edge density profiles. Such absorption levels could significantly reduce the efficiency of the microwave heating and current-drive system in tokamaks and stellarators.

Published
2022

28. 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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30. Analysis of hydrogen fueling, recycling, and confinement at Wendelstein 7-X via a single-reservoir particle balance

Author

Kremeyer, Thierry, König, R., Brezinsek, S., Schmitz, O., Feng, Y., Winters, V., Rudischhauser, L., Buttenschön, B., Brunner, K. J., Drewelow, P., Flom, E., Fuchert, G., Gao, Y., Geiger, J., Jakubowski, M., Killer, C., Knauer, J., Krychowiak, M., Lazerson, S., Reimold, F., Schlisio, G., Viebke, H., 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, and Weggen, Jörg

Subjects
Technology, ddc:600
Published
2022
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31. 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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32. 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

33. Inhibition of parametric decay in heating microwave beams during fluctuations of the density profile in the edge island of Wendelstein 7-X

Author

W7-X Team, Tancetti, A., Nielsen, S. K., Rasmussen, J., Moseev, D., Stange, T., Marsen, S., Vecséi, M., Killer, C., Wurden, G. A., Jensen, T., Stejner, M., Anda, G., Dunai, D., Zoletnik, S., Rahbarnia, K., Brandt, C., Thomsen, H., Hirsch, M., Hoefel, U., Chaudhary, N., Winters, V., Kornejew, P., Harris, J., Laqua, H. P., Gantenbein, Gerd, Illy, Stefan, Jelonnek, John, Krier, Laurent, and Thumm, Manfred

Subjects
Technology, Nuclear Energy and Engineering, Condensed Matter Physics, ddc:600
Abstract

Experimental evidence of parametric decay instability (PDI) is observed in the Wendelstein 7-X stellarator, when high-power microwave beams cross a stationary magnetic island at the plasma edge. Here, trapping and build-up of upper hybrid waves within a density bump (measured within the island by alkali beam emission spectroscopy) is responsible for the reduction of the instability power threshold below the maximum gyrotron power. In this paper, we provide the first experimental evidence of the connection between the trapping mechanism in the island density bump and excitation of PDI-related signals. We show correlations of periodic crashes in the PDI-related signals with quasi-continuous fluctuations at the plasma edge, which, additionally, cause a flattening of the density profile in the island. We demonstrate that flattening of the experimental density profiles can suppress the trapping mechanism and inhibit the low-threshold PDI. PDI on the edge island could alter the power deposition profile and reduce the efficiency of the electron cyclotron resonance heating system, simultaneously posing a serious threat to the optimal operation of microwave-based diagnostics and plasma-facing components.

Published
2022
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34. Inhibition of parametric decay in heating microwave beams during fluctuations of the density profile in the edge island of Wendelstein 7-X.

Author

Tancetti, A, Nielsen, S K, Rasmussen, J, Moseev, D, Stange, T, Marsen, S, Vecséi, M, Killer, C, Wurden, G A, Jensen, T, Stejner, M, Anda, G, Dunai, D, Zoletnik, S, Rahbarnia, K, Brandt, C, Thomsen, H, Hirsch, M, Hoefel, U, and Chaudhary, N

Subjects
MICROWAVE plasmas, CYCLOTRON resonance, ELECTRON cyclotron resonance heating, EMISSION spectroscopy, PLASMA beam injection heating
Abstract

Experimental evidence of parametric decay instability (PDI) is observed in the Wendelstein 7-X stellarator, when high-power microwave beams cross a stationary magnetic island at the plasma edge. Here, trapping and build-up of upper hybrid waves within a density bump (measured within the island by alkali beam emission spectroscopy) is responsible for the reduction of the instability power threshold below the maximum gyrotron power. In this paper, we provide the first experimental evidence of the connection between the trapping mechanism in the island density bump and excitation of PDI-related signals. We show correlations of periodic crashes in the PDI-related signals with quasi-continuous fluctuations at the plasma edge, which, additionally, cause a flattening of the density profile in the island. We demonstrate that flattening of the experimental density profiles can suppress the trapping mechanism and inhibit the low-threshold PDI. PDI on the edge island could alter the power deposition profile and reduce the efficiency of the electron cyclotron resonance heating system, simultaneously posing a serious threat to the optimal operation of microwave-based diagnostics and plasma-facing components. [ABSTRACT FROM AUTHOR]

Published
2023
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35. 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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36. Bolometer tomography on Wendelstein 7-X for study of radiation asymmetry

Author

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

Published
2021
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37. 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

38. 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

39. 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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41. 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

42. 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

43. Impact of magnetic islands on plasma flow and turbulence in W7-X

Author

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

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

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

Published
2021
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44. 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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45. 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

47. 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

48. 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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49. 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

50. Validating the ASCOT modelling of NBI fast ions in Wendelstein 7-X stellarator

Author

Äkäslompolo, S., Drewelow, P., Gao, Y., Ali, A., Bellinger, J., Ford, O.P., Geiger, J., Hartmann, D.A., Hathiraman, D., ISOBE, Mitsutaka, JAKUBOWSKI, Marcin, Kazakov, Y., Killer, C., Lazerson, S., Mayer, M., McNeely, P., Naujoks, D., Neelis, T.W.C., Kontula, J., Kurki-Suonio, T., Niemann, H., OGAWA, Kunihoro, Pisano, F., Poloskei, P. Zs., Puig Sitjes, A., Rohbarnia, K., Rust, N., Schmitt, J.C., Sleczka, M., Vano, L., Vuurer, A. van, Wurden, G., Wolf, R.C., Äkäslompolo, S., Drewelow, P., Gao, Y., Ali, A., Bellinger, J., Ford, O.P., Geiger, J., Hartmann, D.A., Hathiraman, D., ISOBE, Mitsutaka, JAKUBOWSKI, Marcin, Kazakov, Y., Killer, C., Lazerson, S., Mayer, M., McNeely, P., Naujoks, D., Neelis, T.W.C., Kontula, J., Kurki-Suonio, T., Niemann, H., OGAWA, Kunihoro, Pisano, F., Poloskei, P. Zs., Puig Sitjes, A., Rohbarnia, K., Rust, N., Schmitt, J.C., Sleczka, M., Vano, L., Vuurer, A. van, Wurden, G., and Wolf, R.C.

Abstract

The first fast ion experiments in Wendelstein 7-X were performed in 2018. They are one of the first steps in demonstrating the optimised fast ion confinement of the stellarator. The fast ions were produced with a neutral beam injection (NBI) system and detected with infrared cameras (IR), a fast ion loss detector (FILD), fast ion charge exchange spectroscopy (FIDA), and post-mortem analysis of plasma facing components. The fast ion distribution function in the plasma and at the wall is being modelled with the ASCOT suite of codes. They calculate the ionisation of the injected neutrals and the consecutive slowing down process of the fast ions. The primary output of the code is the multidimensional fast ion distribution function within the plasma and the distribution of particle hit locations and velocities on the wall. Synthetic measurements based on ASCOT output are compared to experimental results to assess the validity of the modelling. This contribution presents an overview of the various fast ion measurements in 2018 and the current modelling status. The validation and data-analysis is on-going, but the wall load IR modelling already yield results that match with the experiments., source:Citation S. Äkäslompolo et al 2019 JINST 14 C10012, source:https://doi.org/10.1088/1748-0221/14/10/C10012

Published
2021

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