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15 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. Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma

Author

Batsch, F, Muggli, P, Agnello, R, Ahdida, CC, Amoedo Goncalves, MC, Andrebe, Y, Apsimon, O, Apsimon, R, Bachmann, A-M, Baistrukov, MA, Blanchard, P, Braunmüller, F, Burrows, PN, Buttenschön, B, Caldwell, A, Chappell, J, Chevallay, E, Chung, M, Cooke, DA, Damerau, H, Davut, C, Demeter, G, Deubner, HL, Doebert, S, Farmer, J, Fasoli, A, Fedosseev, VN, Fiorito, R, Fonseca, RA, Friebel, F, Furno, I, Garolfi, L, Gessner, S, Gorgisyan, I, Gorn, AA, Granados, E, Granetzny, M, Graubner, T, Grulke, O, Gschwendtner, E, Hafych, V, Helm, A, Henderson, JR, Hüther, M, Kargapolov, I Yu, Kim, S-Y, Kraus, F, Krupa, M, Lefevre, T, Liang, L, Liu, S, Lopes, N, Lotov, KV, Martyanov, M, Mazzoni, S, Medina Godoy, D, Minakov, VA, Moody, JT, Moon, K, Morales Guzmán, PI, Moreira, M, Nechaeva, T, Nowak, E, Pakuza, C, Panuganti, H, Pardons, A, Perera, A, Pucek, J, Pukhov, A, Ramjiawan, RL, Rey, S, Rieger, K, Schmitz, O, Senes, E, Silva, LO, Speroni, R, Spitsyn, RI, Stollberg, C, Sublet, A, Topaloudis, A, Torrado, N, Tuev, PV, Turner, M, Velotti, F, Verra, L, Verzilov, VA, Vieira, J, Vincke, H, Welsch, CP, Wendt, M, Wing, M, Wiwattananon, P, Wolfenden, J, Woolley, B, Xia, G, Zepp, M, Zevi Della Porta, G, AWAKE Collaboration, and Collaboration, AWAKE

Subjects
Accelerator Physics (physics.acc-ph), Proton, Other Fields of Physics, Phase (waves), FOS: Physical sciences, General Physics and Astronomy, Ciências Naturais::Ciências Físicas [Domínio/Área Científica], 01 natural sciences, Instability, Relativistic particle, physics.plasm-ph, 0103 physical sciences, 010306 general physics, physics.acc-ph, Physics, acceleration, Plasma, electron-beam, Accelerators and Storage Rings, Physics - Plasma Physics, ddc, Plasma Physics (physics.plasm-ph), Transverse plane, Amplitude, Physics::Accelerator Physics, Physics - Accelerator Physics, Atomic physics, Event (particle physics)
Abstract

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude ($\ge(4.1\pm0.4)$ MV/m), the phase of the modulation along the bunch is reproducible from event to event, with 3 to 7% (of 2$\pi$) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated., Comment: Letter and Supplemental Material, 6 figures, 8 pages

Published
2021
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3. 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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4. 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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5. 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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6. Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Author

Chappell, J., Adli, E., Agnello, R., Aladi, M., Andrebe, Y, Apsimon, O., Apsimon, R., Bachmann, A.-M., Baistrukov, M. A., Batsch, F., Bergamaschi, M., Della Porta, G. Z., Blanchard, P., Burrows, P. N., Buttenschön, B., Caldwell, A., Chevallay, E., Chung, M., Cooke, D. A., Damerau, H., Davut, C., Demeter, G., Deubner, L. H., Dexter, A., Djotyan, G. P., Doebert. S., Farmer, J., Fasoli, A., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Friebel, F., Furno, I., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Granetzny, M., Grulke, O., Gschwendtner, E., Hafych, V., Hartin, A., Helm, A, Henderson, J. R., Howling, A., Hüther, M ., Jacquier, R., Jolly, S. W., Kargapolov, I. Y., Kedves, M. Á., Keeble, F., Kelisani, M. D., Kim, S.-Y, Krausz, F., Krupa, M., Lefevre, T ., Li, Y., Liang, L., Liu, S., Lopes, N. C., Lotov, K. V., Martyanov, M., Mazzoni, S., Medina Godoy, D., Militsyn, B. L., Minakov, V. A., Moody, J. T., Morales Guzmán, P. I., Moreira, M. 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., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Williamson, B., Wing, M., Wolfenden, J., Woolley, B., Xia, G. X., and Zepp, M.

Subjects
Accelerator Physics (physics.acc-ph), Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Proton, Other Fields of Physics, FOS: Physical sciences, Electron, 01 natural sciences, law.invention, law, Electron injection, Physics::Plasma Physics, physics.plasm-ph, 0103 physical sciences, 010306 general physics, physics.acc-ph, Physics, 010308 nuclear & particles physics, Dynamics (mechanics), Surfaces and Interfaces, Plasma, Laser, Accelerators and Storage Rings, Physics - Plasma Physics, ddc, Plasma Physics (physics.plasm-ph), Amplitude, Physics::Accelerator Physics, Physics - Accelerator Physics, Atomic physics, Excitation
Abstract

Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scans., 11 pages, 8 figures

Published
2021
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7. Preparation, analysis, and application of coated glass targets for the Wendelstein 7-X laser blow-off system

Author

W7-X Team, Wegner, Th., Geiger, B., Foest, R., Jansen van Vuuren, A., Winters, V. R., Biedermann, C., Burhenn, R., Buttenschön, B., Cseh, G., Joda, I., Kocsis, G., Kunkel, F., Quade, A., Schäfer, J., Schmitz, O., Szepesi, 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

Subjects
010302 applied physics, Technology, Materials science, Laser ablation, business.industry, Plasma, engineering.material, Laser, 01 natural sciences, 010305 fluids & plasmas, law.invention, Stress (mechanics), Coating, Impurity, law, Physical vapor deposition, 0103 physical sciences, engineering, Optoelectronics, Wendelstein 7-X, business, Instrumentation, ddc:600
Abstract

Coated glass targets are a key component of the Wendelstein 7-X laser blow-off system that is used for impurity transport studies. The preparation and analysis of these glass targets as well as their performance is examined in this paper. The glass targets have a high laser damage threshold and are coated via physical vapor deposition with µm thick films. In addition, nm-thin layers of Ti are used as an interface layer for improved ablation efficiency and reduced coating stress. Hence, the metallic or ceramic coating has a lateral homogeneity within 2% and contaminants less than 5%, being optimal for laser ablation processing. With this method, a short (few ms) and well defined pulse of impurities with about 1017 particles can be injected close to the last closed flux surface of Wendelstein 7-X. In particular, a significant amount of atoms with a velocity of about 1 km/s enters the plasma within 1 ms. The atoms are followed by a negligible concentration of slower clusters and macro-particles. This qualifies the use of the targets and applied laser settings for impurity transport studies with the laser blow-off system in Wendelstein 7-X.

Published
2020

8. 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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9. Correction to 'Proton-driven plasma wakefield acceleration in AWAKE' (vol 377, 20180418, 2019)

Author

Gschwendtner, E., Turner, M., Adli, E., Ahuja, A., Apsimon, O., Apsimon, R., Bachmann, A.-M., Batsch, F., Bracco, C., Braunmüller, F., Burger, S., Burt, G., Buttenschön, B., Caldwell, A., Chappell, J., Chevallay, E., Chung, M., Cooke, D., Damerau, H., Deubner, L. H., Dexter, A., Doebert, S., Farmer, J., Fedosseev, V. N., Fiorito, R., Fonseca, R. A., Garolfi, L., Gessner, S., Goddard, B., Gorgisyan, I., Gorn, A. A., Granados, E., Grulke, O., Hartin, A., Helm, A, Henderson, J. R., Hüther, M., Ibison, M., Jolly, S., Keeble, F., Kelisani, M. D., Kim, S.-Y., Krausz, F., Krupa, M., Lefevre, T., Liu, S., Lopes, N., Lotov, K., Martyanov, M., Mazzoni, S., Minakov, V., Molendijk, J. C., Moody, J. T., Moreira, M. T., Muggli, P., Panuganti, H., Pardons, A., Peña Asmus, F., Perera, A., Petrenko, A., Pukhov, A., Rey, S., Ruhl, H., Saberi, H., Sublet, A., Sherwood, P., Silva, L. O., Sosedkin, A. P., Tuev, P. V., Velotti, F., Verra, L., Verzilov, V. A., Vieira, J., Welsch, C. P., Wendt, M., Williamson, B., Wing, M., Woolley, B., Xia, G., and AWAKE Collaboration Team

Subjects
Accelerator Physics (physics.acc-ph), AWAKE Collaboration, Proton, General Science & Technology, General Mathematics, Engenharia e Tecnologia::Engenharia Civil [Domínio/Área Científica], FOS: Physical sciences, General Physics and Astronomy, Electron, plasma wakefield acceleration, Ciências Naturais::Ciências Físicas [Domínio/Área Científica], 01 natural sciences, 010305 fluids & plasmas, Nuclear physics, Ciências Naturais::Matemáticas [Domínio/Área Científica], Physics::Plasma Physics, AWAKE, 0103 physical sciences, 010306 general physics, Nuclear Experiment, physics.acc-ph, Physics, Large Hadron Collider, General Engineering, Plasma, Plasma acceleration, Accelerators and Storage Rings, Ciências Naturais::Outras Ciências Naturais [Domínio/Área Científica], seeded self modulation, Physics::Accelerator Physics, Physics - Accelerator Physics
Abstract

In this article, we briefly summarize the experiments performed during the first run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013–2018) was to demonstrate that 10– 20 MeV electrons can be accelerated to GeV energies in a plasma wakefield driven by a highly relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future. This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration'. In this article, we briefly summarize the experiments performed during the first Run of the Advanced Wakefield Experiment, AWAKE, at CERN (European Organization for Nuclear Research). The final goal of AWAKE Run 1 (2013 - 2018) was to demonstrate that 10-20 MeV electrons can be accelerated to GeV-energies in a plasma wakefield driven by a highly-relativistic self-modulated proton bunch. We describe the experiment, outline the measurement concept and present first results. Last, we outline our plans for the future.

Published
2019
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10. Wendelstein 7-X on the path to long-pulse high-performance operation

Author

W7-X Team, Endler, M., Baldzuhn, J., Beidler, C. D., Bosch, H.-S., Bozhenkov, S., Buttenschön, B., Dinklage, A., Fellinger, J., Feng, Y., Fuchert, G., Gao, Y., Geiger, J., Grulke, O., Hartmann, D., Jakubowski, M., König, R., Laqua, H. P., Lazerson, S., McNeely, P., Naujoks, D., Neuner, U., Otte, M., Pasch, E., Sunn Pedersen, T., Perseo, V., Puig Sitjes, A., Rahbarnia, K., Rust, N., Schmitz, O., Spring, A., Stange, T., Stechow, A. von, Turkin, Y., Wang, E., Wolf, R. C., Gantenbein, Gerd, Huber, Martina, Illy, Stefan, Jelonnek, John, Kobarg, Thorsten, Lang, Rouven, Leonhardt, Wolfgang, Mellein, Daniel, Papenfuß, Daniel, Scherer, Theo, Thumm, Manfred, Wadle, Simone, Weggen, Jörg, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Technology, Optimisation, Steady-state, Stellarator, Wendelstein 7-X, Nuclear engineering, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, law.invention, Data acquisition, law, Range (aeronautics), 0103 physical sciences, Water cooling, General Materials Science, 010306 general physics, Civil and Structural Engineering, Steady state, Mechanical Engineering, Fusion power, Nuclear Energy and Engineering, Path (graph theory), ddc:600
Abstract

The Wendelstein 7-X project is aimed at demonstrating that an optimised stellarator is an attractive candidate for a fusion reactor. This requires the achievement of a number of technical and physics goals. Several of these goals have already been achieved in the first three experimental campaigns. We shall exemplify this by a number of results. One important goal is the demonstration of quasi-steady-state operation at high plasma density and temperature for half an hour, which encompasses the physical and technical requirements of stable operation with density and impurity control, cw heating, water-cooled targets, particle exhaust, and an appropriate control and data acquisition system for long-pulse operation. In the previous experimental campaigns, with uncooled targets, stationary discharges for up to 25 s with 5 MW heating power and up to 100 s with 2 MW heating power were achieved. For the next operational phase, to start in 2022, water-cooled targets are being installed, water cooling will be provided for all first-wall components, and a number of further upgrades to plasma heating, vacuum and fuelling systems as well as diagnostics will become available. With this equipment, the further goals of the project will be tackled, including the stepwise extension of discharge intervals to the multi-minute range. The experimental results so far have confirmed the neoclassical theory underlying several of the optimisation goals. At the same time, they showed that an optimisation is also required with respect to anomalous transport. In the future operational phases we aim at building a solid theoretical, experimental and technical foundation for the design of a next-step stellarator device.

Published
2021
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11. 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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12. 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

13. 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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14. 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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15. 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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