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697 results on '"Stroth, U"'

252. Poloidal asymmetric flow and current relaxation of ballooned transport during I-phase in ASDEX Upgrade.

Author

Manz, P., Birkenmeier, G., Fuchert, G., Cavedon, M., Conway, G. D., Maraschek, M., Medvedeva, A., Mink, F., Scott, B. D., Shao, L. M., and Stroth, U.

Subjects
CONFORMAL geometry, EQUILIBRIUM, DIFFERENTIABLE dynamical systems, MATHEMATICS, EXPONENTIAL dichotomy
Abstract

Turbulence driven poloidal asymmetric parallel flow and current perturbations are studied for tokamak plasmas of circular geometry. Whereas zonal flows can lead to in-out asymmetry of parallel flows and currents via the Pfirsch-Schlüter mechanism, ballooned transport can result in an up-down asymmetry due to the Stringer spin-up mechanism. Measurements of up-down asymmetric parallel current fluctuations occurring during the I-phase in ASDEX Upgrade are not responses to the equilibrium by the Pfirsch-Schlüter current, but can be interpreted as a response to strongly ballooned plasma transport coupled with the Stringer spin-up mechanism. A good agreement of the experimental measured limit-cycle frequencies during I-phase with the Stringer spin-up relaxation frequency is found. [ABSTRACT FROM AUTHOR]

Published
2016
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256. High-Confinment NBI Discharges in W7-AS

Author

Stroth, U., Anton, M., Baldzuhn, J., Burhenn, R., Geiger, J., Geist, T., Giannone, L., Hartfuss, H., Hirsch, M., Jaenecke, R., Koponen, J., Kick, M., Kuehner, G., Penningsfeld, F., Wagner, F., and Weller, A.

Published
1997

258. Schemes of microwave heating of overdense plasmas in the stellarator TJ-K

Author

Köhn, A, primary, Birkenmeier, G, additional, Chusov, A, additional, Diez, P, additional, Feuer, A, additional, Höfel, U, additional, Höhnle, H, additional, Holzhauer, E, additional, Kasparek, W, additional, Merli, S, additional, Ramisch, M, additional, Seifert, J, additional, Wolf, S, additional, and Stroth, U, additional

Published
2012
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259. Intermittent transport across the scrape-off layer: latest results from ASDEX Upgrade

Author

Kocan, M., Müller, H. W., Nold, B., Lunt, T., Adamek, J., Allan, S. Y., Bernert, M., Conway, G. D., Marne, P. de, Eich, T., Elmore, S., Gennrich, F. P., Herrmann, A., Horacek, J., Huang, Z., Kallenbach, A., Komm, M., Maraschek, M., Mehlmann, F., Müller, S., Ribeiro, T. T., Rohde, V., Schrittwieser, R., Scott, B., Stroth, U., Suttrop, W., Wolfrum, E., ASDEX Upgrade Team, and ASDEX Upgrade Team

Subjects
Nuclear and High Energy Physics, Materials science, Infrared, Turbulence, Divertor, Perturbation (astronomy), Plasma, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Ion, ASDEX Upgrade, Saturation current, 0103 physical sciences, Atomic physics, 010306 general physics
Abstract

We report the latest results of turbulence and transport studies in the ASDEX Upgrade scrape-off layer (SOL). Dissimilarity between the plasma and the floating potential fluctuations is studied experimentally and by gyrofluid simulations. Measurements by a retarding field analyser reveal that both, edge-localized mode (ELM) and turbulent filaments, convey hot ions over large radial distances in the SOL. The measured far SOL ELM ion temperature increases with the ELM energy, consistent with earlier observations that large ELMs deposit a large fraction of their energy outside the divertor. In the SOL, the ELM suppression by magnetic perturbations (MPs) results in lower ELM ion energy in the far SOL. At the same time, large filaments of ion saturation current are replaced by more continuous bursts. Splitting of the divertor strike zones observed by the infrared imaging in H-mode with MPs agree with predictions from the EMC3-Eirene simulations. This suggests that the ‘lobe’ structures due to perturbation fields observed near the X-point are not significantly affected by plasma screening, and can be described by a vacuum approach, as in the EMC3-Eirene. Finally, some effects of the MPs on the L-mode SOL are addressed.

Published
2013

262. Characterization of Energy Confinement in Net-current Free Plasmas using the Extended International Stellarator Database

Author

Yamada, Y, Harris, Jeffrey, Dinklage, Andreas, Ascasibar, E, Sano, F, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, C, Tribaldos, V, Watanabe, K, Suzuki, Y, Okamura, S, Yamada, Y, Harris, Jeffrey, Dinklage, Andreas, Ascasibar, E, Sano, F, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, C, Tribaldos, V, Watanabe, K, Suzuki, Y, and Okamura, S

Abstract

International collaboration on development of a stellarator confinement database has progressed. More than 3000 data points from nine major stellarator experiments have been compiled. Robust dependences of the energy confinement time on the density and the heating power have been confirmed. Dependences on other operational parameters, i.e. the major and minor radii, magnetic field and the rotational transform , have been evaluated using inter-machine analyses. In order to express the energy confinement in a unified scaling law, systematic differences in each subgroup are quantified. An a posteriori approach using a confinement enhancement factor on ISS95 as a renormalizing configuration- dependent parameter yields a new scaling expression ISS04; . Gyro-Bohm characteristic similar to ISS95 has been confirmed for the extended database with a wider range of plasma parameters and magnetic configurations than in the study of ISS95. It has also been discovered that there is a systematic offset of energy confinement between magnetic configurations, and its measure correlates with the effective helical ripple of the external stellarator field. Full documentation of the International Stellarator Confinement Database is available at http://iscdb.nifs.ac.jp/ and http://www.ipp.mpg.de/ISS.

Published
2005

263. Characterization of energy confinement in net-current free plasmas using the extended International Stellarator Database

Author

Yamada, H, Harris, JH, Dinklage, A, Ascasibar, E, Sano, F, Okamura, S, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, CD, Tribaldos, V, Watanabe, KY, Suzuki, Y, Yamada, H, Harris, JH, Dinklage, A, Ascasibar, E, Sano, F, Okamura, S, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, CD, Tribaldos, V, Watanabe, KY, and Suzuki, Y

Published
2005

264. Characterization of energy confinement in net-current free plasmas using the extended International Stellarator Database

Author

70115856, 40249967, Yamada, H, Harris, JH, Dinklage, A, Ascasibar, E, Sano, F, Okamura, S, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, CD, Tribaldos, V, Watanabe, KY, Suzuki, Y, 70115856, 40249967, Yamada, H, Harris, JH, Dinklage, A, Ascasibar, E, Sano, F, Okamura, S, Talmadge, J, Stroth, U, Kus, A, Murakami, S, Yokoyama, M, Beidler, CD, Tribaldos, V, Watanabe, KY, and Suzuki, Y

Published
2005

266. Scalable Microwave Plasma Sources From Low to Atmospheric Pressure

Author

Schulz, A., primary, Büchele, P., additional, Ramisch, E., additional, Janzen, O., additional, Jimenez, F., additional, Kamm, C., additional, Kopecki, J., additional, Leins, M., additional, Merli, S., additional, Petto, H., additional, Mendez, F.R., additional, Schneider, J., additional, Schumacher, U., additional, Walker, M., additional, and Stroth, U., additional

Published
2012
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269. ECRH on ASDEX Upgrade - System Status, Feed-Back Control, Plasma Physics Results -

Author

Stober, J., primary, Bock, A., additional, Höhnle, H., additional, Reich, M., additional, Sommer, F., additional, Treutterer, W., additional, Wagner, D., additional, Gianone, L., additional, Herrmann, A., additional, Leuterer, F., additional, Monaco, F., additional, Marascheck, M., additional, Mlynek, A., additional, Müller, S., additional, Münich, M., additional, Poli, E., additional, Schubert, M., additional, Schütz, H., additional, Zohm, H., additional, Kasparek, W., additional, Stroth, U., additional, Meier, A., additional, Scherer, Th., additional, Strauβ, D., additional, Vaccaro, A., additional, Flamm, J., additional, Thumm, M., additional, Litvak, A., additional, Denisov, G.G., additional, Chirkov, A.V., additional, Tai, E.M., additional, Popov, L.G., additional, Nichiporenko, V.O., additional, Myasnikov, V.E., additional, Soluyanova, E.A., additional, and Malygin, S.A., additional

Published
2012
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270. Configuration effect on energy confinement and local transport in LHD and contribution to the International Stellarator Database

Author

Yamada, Hiroshi, Ida, K, Murakami, S, Watanabe, K, Ascasibar, E, Brakel, R, Dinklage, Andreas, Harris, Jeffrey, Okamura, Satoshi, Sano, F, Stroth, U, Inagaki, S, Tanaka, K, Goto, M, Nishimura, K, Narihara, K, Morita, S, Sakakibara, Satoru, Peterson, Byron, Sakamoto, R, Miyazawa, Junichu, Morisaki, Tomohiro, Osakabe, M, Toi, K, Tamura, N, Ikeda, Kyoko, Yamazaki, K, Kawahata, K, Kaneko, Osamu, Ohyabu, N, Komori, Akio, Motojima, Osamu, Yamada, Hiroshi, Ida, K, Murakami, S, Watanabe, K, Ascasibar, E, Brakel, R, Dinklage, Andreas, Harris, Jeffrey, Okamura, Satoshi, Sano, F, Stroth, U, Inagaki, S, Tanaka, K, Goto, M, Nishimura, K, Narihara, K, Morita, S, Sakakibara, Satoru, Peterson, Byron, Sakamoto, R, Miyazawa, Junichu, Morisaki, Tomohiro, Osakabe, M, Toi, K, Tamura, N, Ikeda, Kyoko, Yamazaki, K, Kawahata, K, Kaneko, Osamu, Ohyabu, N, Komori, Akio, and Motojima, Osamu

Abstract

New stellarator experiments have been launched since the last compilation of the international stellarator database in 1995. Parameter regimes have been extended by Large Helical Device (LHD), and a variety of improved modes have been found since then. The revision of the international stellarator database has been initiated, driven by these emerging interests and by the requirements for a reactor assessment. Some provisional issues are discussed. An understanding of configurational ef fects is a prerequisite to the derivation of a unified scaling. Differences in magnetic geometry are influential in characterizing energy confinement. The results from the magnetic axis and elongation scans in LHD are high-lighted. Comparison with tokamak confinement is also addressed. The revision of the database is in progress, and this paper is an interim report.

Published
2004

274. Extension of the ECRH operational space with O2 and X3 heating schemes to control tungsten accumulation in ASDEX Upgrade

Author

Höhnle, H., primary, Stober, J., additional, Herrmann, A., additional, Kasparek, W., additional, Leuterer, F., additional, Monaco, F., additional, Neu, R., additional, Schmid-Lorch, D., additional, Schütz, H., additional, Schweinzer, J., additional, Stroth, U., additional, Wagner, D., additional, Vorbrugg, S., additional, and Wolfrum, E., additional

Published
2011
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276. Long-range correlations and edge transport bifurcation in fusion plasmas

Author

Xu, Y., primary, Carralero, D., additional, Hidalgo, C., additional, Jachmich, S., additional, Manz, P., additional, Martines, E., additional, van Milligen, B., additional, Pedrosa, M.A., additional, Ramisch, M., additional, Shesterikov, I., additional, Silva, C., additional, Spolaore, M., additional, Stroth, U., additional, and Vianello, N., additional

Published
2011
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277. ECRH ON ASDEX UPGRADE - SYSTEM EXTENSION, NEW MODES OF OPERATION, PLASMA PHYSICS RESULTS

Author

STOBER, J., primary, WAGNER, D., additional, GIANNONE, L., additional, LEUTERER, F., additional, MARASCHECK, M., additional, MLYNEK, A., additional, MONACO, F., additional, MÜNICH, M., additional, POLI, E., additional, REICH, M., additional, SCHMID-LORCH, D., additional, SCHÜTZ, H., additional, SCHWEINZER, J., additional, TREUTTERER, W., additional, ZOHM, H., additional, MEIER, A., additional, SCHERER, TH., additional, FLAMM, J., additional, THUMM, M., additional, HÖHNLE, H., additional, KASPAREK, W., additional, STROTH, U., additional, CHIRKOV, A.V., additional, DENISOV, G.G., additional, LITVAK, A., additional, MALYGIN, S.A., additional, MYASNIKOV, V.E., additional, NICHIPORENKO, V.O., additional, POPOV, L.G., additional, SOLUYANOVA, E.A., additional, and TAI, E.M., additional

Published
2011
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299. Cluster Analysis of the International Stellarator Confinement Database

Author

Kus, A., primary, Dinklage, A., additional, Preuss, R., additional, Ascasibar, E., additional, Harris, J. H., additional, Okamura, S., additional, Sano, F., additional, Stroth, U., additional, Talmadge, J., additional, Yamada, H., additional, Hartfuss, Hans-Jürgen, additional, Dudeck, Michel, additional, Musielok, Jozef, additional, and Sadowski, Marek J., additional

Published
2008
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300. ECRH of overdense plasmas in TJ-K

Author

Köhn, A., primary, Höhnle, H., additional, Holzhauer, E., additional, Kasparek, W., additional, Ramisch, M., additional, Stroth, U., additional, Hartfuss, Hans-Jürgen, additional, Dudeck, Michel, additional, Musielok, Jozef, additional, and Sadowski, Marek J., additional

Published
2008
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