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Your search keyword '"Buttenschön B"' showing total 9 results
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9 results on '"Buttenschön B"'

1. Confinement degradation and plasma loss induced by strong sawtooth crashes at W7-X

Author

W7-X Team, Zanini, M., Buttenschön, B., Laqua, H. P., Thomsen, H., Stange, T., Brandt, C., Braune, H., Brunner, K. J., Dinklage, A., Gao, Y., Hirsch, M., Höfel, U., Knauer, J., Marsen, S., Marushchenko, N., Pavone, A., Rahbarnia, K., Schilling, J., Turkin, Y., Wolf, R. C., Zocco, A., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Nuclear and High Energy Physics, Materials science, Plasma, Sawtooth wave, Condensed Matter Physics, 01 natural sciences, Molecular physics, 010305 fluids & plasmas, 0103 physical sciences, ddc:530, 010306 general physics, ddc:600, Degradation (telecommunications)
Abstract

Sawtooth-like crashes were observed during electron cyclotron current drive experiments for strikeline controls at the optimised superconducting stellarator Wendelstein 7-X (W7-X). The majority of the crashes did not have a relevant impact on plasma performance. However, a limited number of events, characterised by a large plasma volume affected by the instability, have been related to a strong deterioration performance and even to the premature termination of the plasma. The hot plasma core expelled during these sawtooth crashes can reach the plasma edge, where plasma surface interaction can occur and impurities can be released. The x-ray tomography shows a strong radiation increase starting from the edge and moving towards the inner plasma regions. This results in the cooling down and shrinking of the plasma, which eventually leads to a poor coupling of the ECRH to the electrons, that can in turn result in a plasma loss. A relation between the size and amplitude of the sawtooth crashes and the impurity increase is reported.

Published
2021

2. 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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3. Plasma radiation behavior approaching high-radiation scenarios in W7-X

Author

W7-X Team, Zhang, D., Burhenn, R., Feng, Y., König, R., Buttenschön, B., Beidler, C. D., Hacker, P., Reimold, F., Thomsen, H., Laube, R., Klinger, T., Giannone, L., Penzel, F., Pavone, A., Krychowiak, M., Beurskens, M., Bozhenkov, S., Brunner, J. K., Effenberg, F., Fuchert, G., Gao, Y., Geiger, J., Hirsch, M., Höfel, U., Jakubowski, M., Knauer, J., Kwak, S., Laqua, H. P., Niemann, H., Otte, M., Pedersen, T. Sunn, Pasch, E., Pablant, N., Rahbarnia, K., Svensson, J., Blackwell, B., Drews, P., Endler, M., Rudischhauser, L., Wang, E., Weir, G., Winters, V., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, Nuclear and High Energy Physics, Technology, business.industry, High radiation, Plasma radiation, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Optics, 0103 physical sciences, ddc:620, 010306 general physics, business, ddc:600
Abstract

The W7-X stellarator has so far performed experiments under both limiter and divertor conditions. The plasma is mostly generated by ECR-heating with powers up to 6.5 MW, and the plasma density is usually limited by the radiation losses from low-Z impurities (such as carbon and oxygen) released mainly from the graphite targets. The present work first summarizes the radiation loss fractions f rad achieved in quasi-stationary hydrogen plasmas in both operational phases, and then shows how impurity radiation behaves differently with the two different boundary conditions as the plasma density increases. The divertor operation is emphasized and some beneficial effects (with respect to impurity radiation) are highlighted: (1) intensive radiation is located at the edge (r/a > 0.8) even at high radiation loss fractions, (2) the plasma remains stable up to f rad approaching unity, (3) the reduction in the stored energy is about 10% for high f rad scenarios. Moreover, effects of wall boronisation on impurity radiation profiles are also presented.

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

Author

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

Subjects
Physics, Technology, Nuclear and High Energy Physics, business.industry, media_common.quotation_subject, Bolometer, Radiation, Condensed Matter Physics, 01 natural sciences, Asymmetry, 010305 fluids & plasmas, law.invention, Optics, law, 0103 physical sciences, Tomography, Wendelstein 7-X, 010306 general physics, business, ddc:600, media_common
Published
2021
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5. Proton beam defocusing in AWAKE: comparison of simulations and measurements

Author

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

Subjects
Accelerator Physics (physics.acc-ph), Physics, Proton, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Other Fields of Physics, FOS: Physical sciences, Condensed Matter Physics, Accelerators and Storage Rings, 01 natural sciences, 7. Clean energy, Physics - Plasma Physics, 010305 fluids & plasmas, 3. Good health, Plasma Physics (physics.plasm-ph), Nuclear Energy and Engineering, physics.plasm-ph, 0103 physical sciences, Physics::Accelerator Physics, Physics - Accelerator Physics, Atomic physics, Nuclear Experiment, Beam (structure), physics.acc-ph
Abstract

In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from the Super Proton Synchrotron (SPS) at CERN. The angular distribution of the protons deflected due to SSM is a quantitative measure of the process, which agrees with simulations by the two-dimensional (axisymmetric) particle-in-cell code LCODE. Agreement is achieved for beam populations between $10^{11}$ and $3 \times 10^{11}$ particles, various plasma density gradients ($-20 \div 20\%$) and two plasma densities ($2\times 10^{14} \text{cm}^{-3}$ and $7 \times 10^{14} \text{cm}^{-3}$). The agreement is reached only in the case of a wide enough simulation box (at least five plasma wavelengths)., Comment: 8 pages, 9 figures, 1 table

Published
2020
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6. Plasma termination by excess pellet fueling and impurity injection in TJ-II, the Large Helical Device and Wendelstein 7-X

Author

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

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

7. AWAKE readiness for the study of the seeded self-modulation of a 400\,GeV proton bunch

Author

Muggli, P., Adli, E., Apsimon, R., Asmus, F., Baartman, R., Bachmann, A.-M., Barros Marin, M., Batsch, F., Bauche, J., Berglyd Olsen, V. K., Bernardini, M., Turner, M., Verzilov, V., Vieira, J., Vincke, H., Welsch, C. P., Williamson, B., Wing, M., Xia, G. X., Zhang, H., The AWAKE collaboration, Biskup, B., Blanco Vinuela, E., Boccardi, A., Bogey, T., Bohl, T., Bracco, C., Braunmuller, F., Burger, S., Burt, G., Bustamante, S., Buttenschön, B., Butterworth, A., Caldwell, A., Cascella, M., Chevallay, E., Chung, M., Damerau, H., Deacon, L., Dexter, A., Dirksen, P., Doebert, S., Farmer, J., Fedosseev, V., Feniet, T., Fior, G., Fiorito, R., Fonseca, R. A., Friebel, F., Gander, P., Gessner, S., Gorgisyan, I., Gorn, A. A., Grulke, O., Gschwendtner, E., Guerrero, A., Hansen, J., Hessler, C., Hofle, W., Holloway, J., Hüther, M., Ibison, M., Islam, M. R., Jensen, L., Jolly, S. W., Kasim, M., Keeble, F., Kim, S.-Y., Krausz, F., Lasheen, A., Lefevre, T., LeGodec, G., Li, Y., Liu, S., Lopes, N. C., Lotov, K., Martyanov, M., Mazzoni, S., Medina Godoy, D., Mete, O., Minakov, V. A., Mompo, R., Moody, J. T., Moreira, M. T., Mitchell, J., Mutin, C., Norreys, P., Öz, E., Ozturk, E., Pauw, W., Pardons, A., Pasquino, C., Pepitone, K., Petrenko, A., Pitmann, S., Plyushchev, G., Pukhov, A., Rieger, K., Ruhl, H., Schmidt, J., Shalimova, I. A., Shaposhnikova, E., Sherwood, P., Silva, L., Sosedkin, A. P., Speroni, R., Spitsyn, R. I., Szczurek, K., Thomas, J., Tuev, P. V., and AWAKE Collaboration

Subjects
Accelerator Physics (physics.acc-ph), Proton, Particle acceleration, Other Fields of Physics, chemistry.chemical_element, FOS: Physical sciences, 01 natural sciences, Ciências Naturais::Ciências Físicas [Domínio/Área Científica], 010305 fluids & plasmas, law.invention, Rubidium, law, Physics::Plasma Physics, Seeded self-modulation, Ionization, physics.plasm-ph, Plasma wakefields driven by protons, 0103 physical sciences, Physics::Atomic Physics, 010306 general physics, Nuclear Experiment, physics.acc-ph, Physics, Plasma, Plasma-based accelerator, Condensed Matter Physics, Plasma acceleration, Laser, Accelerators and Storage Rings, Physics - Plasma Physics, Pulse (physics), Plasma Physics (physics.plasm-ph), Nuclear Energy and Engineering, chemistry, Physics::Accelerator Physics, Seeding, Physics - Accelerator Physics, Plasma wakefields seeding, Atomic physics
Abstract

AWAKE is a proton-driven plasma wakefield acceleration experiment. % We show that the experimental setup briefly described here is ready for systematic study of the seeded self-modulation of the 400\,GeV proton bunch in the 10\,m-long rubidium plasma with density adjustable from 1 to 10$\times10^{14}$\,cm$^{-3}$. % We show that the short laser pulse used for ionization of the rubidium vapor propagates all the way along the column, suggesting full ionization of the vapor. % We show that ionization occurs along the proton bunch, at the laser time and that the plasma that follows affects the proton bunch. %, Comment: Presented as an invited talk at the EPS=Plasma Physics Conference 2017

Published
2017
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8. Observation of anomalous impurity transport during low-density experiments in W7-X with laser blow-off injections of iron

Author

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

Subjects
Technology, Nuclear and High Energy Physics, Materials science, Turbulence, Condensed Matter Physics, Laser, 01 natural sciences, 010305 fluids & plasmas, law.invention, Strahl, Impurity, law, 0103 physical sciences, Low density, Atomic physics, 010306 general physics, ddc:600, Stellarator
Published
2019
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9. Impurity sources and fluxes in W7-X: from the plasma-facing components to the edge layer

Author

W7-X Team, Wang, E., Brezinsek, S., Sereda, S., Buttenschön, B., Barbui, T., Dhard, C. P., Endler, M., Ford, O., Flom, E., Hammond, K. C., Jakubowski, M., Krychowiak, M., Kornejew, P., König, R., Liang, Y., Mayer, M., Naujoks, D., Neubauer, O., Oelmann, J., Rasinski, M., Winters, V. R., Goriaev, A., Wauters, T., Wei, Y., Zhang, D., Baumann, Klaus, Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Materials science, Hydrogen, Proton, Divertor, Analytical chemistry, chemistry.chemical_element, Order (ring theory), Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, chemistry, Impurity, Sputtering, 0103 physical sciences, ddc:530, 010306 general physics, ddc:600, Mathematical Physics, Helium, Order of magnitude
Abstract

Wendelstein 7-X (W7-X) is a nearly full-carbon machine with graphite divertors, baffles and shields in Operation Phase 1.2b (OP 1.2b). Divertor spectrometer measurements showed that an amount of helium and oxygen impurities existed in the predominately hydrogen plasma, which resulted in a high carbon impurity level by enhanced physical and chemical sputtering by these impurities in comparison with the pure impinging proton yields. In order to improve the wall conditions, especially to reduce the oxygen content, boronizations were applied in OP1.2b. After the boronization, an oxygen decrease by more than an order of magnitude was observed. Helium disappeared in comparison with OP1.2a due to reduced application of helium wall conditioning after introduction of boronizations. The overall radiation normalized to line integrated density was reduced by a factor of six. In addition, local CH4 injection was applied in the divertor in order to quantify the chemical sputtering by hydrogen on divertor plates. The experimentally determined effective D/XB of the A–X band of CH resulting from CH4 was ${\left[\tfrac{{D}}{{X}{B}}\right]}_{{{A}}^{2}{\rm{\Delta }}\to {{X}}^{2}{\rm{\Pi }}}^{{\rm{C}}{{\rm{H}}}_{4}\to {\rm{C}}{\rm{H}}}=16$ at T e ≈ 20 eV and n e ≈ 5 × 1018 m−3. It was applied to determine the hydrocarbon fluxes and further to deduce the particle flux ratio ГCH4/ГH on divertor plates.

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