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1. Commissioning and first results of the 174 GHz collective Thomson scattering diagnostic at Wendelstein 7-X

Author

Moseev, D., primary, Ponomarenko, S., additional, Laqua, H.P., additional, Stange, T., additional, Nielsen, S.K., additional, Braune, H., additional, Gantenbein, G., additional, Illy, S., additional, Jelonnek, J., additional, Kasparek, W., additional, Kuleshov, A., additional, Krier, L., additional, Lechte, C., additional, Marsen, S., additional, Nishiura, M., additional, Plaum, B., additional, Ragona, R., additional, Ruess, T., additional, Salewski, M., additional, Stordiau, P., additional, Thumm, M., additional, Wolf, R.C., additional, Zimmermann, J., additional, and W7-X Team, the, additional

Published
2024
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3. Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X

Author

Ponomarenko, S., Moseev, D., Stange, T., Krier, L., Stordiau, P., Braune, H., Gantenbein, G, Jelonnek, J., Kuleshov, A., Laqua, H. P., Lechte, C., Marsen, S., Nielsen, S. K., Oosterbeek, J. W., Plaum, B., Ragona, R., Rasmussen, J., Ruess, T., Salewski, M, Thumm, M., Zimmermann, J., Ponomarenko, S., Moseev, D., Stange, T., Krier, L., Stordiau, P., Braune, H., Gantenbein, G, Jelonnek, J., Kuleshov, A., Laqua, H. P., Lechte, C., Marsen, S., Nielsen, S. K., Oosterbeek, J. W., Plaum, B., Ragona, R., Rasmussen, J., Ruess, T., Salewski, M, Thumm, M., and Zimmermann, J.

Abstract

In this paper, we present the design and commissioning results of the upgraded collective Thomson scattering diagnostic at the Wendelstein 7-X stellarator. The diagnostic has a new radiometer designed to operate between the second and third harmonics of the electron cyclotron emission from the plasma at 171-177 GHz, where the emission background has a minimum and is of order 10-100 eV. It allows us to receive the scattered electromagnetic field with a significantly improved signal-to-noise ratio and extends the set of possible scattering geometries compared to the case of the original instrument operated at 140 GHz. The elements of the diagnostic are a narrowband notch filter and a frequency stabilized probing gyrotron that will allow measuring scattered radiation spectra very close to the probing frequency. Here, we characterize the microwave components applied to the radiometer and demonstrate the performance of the complete system that was achieved during the latest experimental campaign, OP2.1.

Published
2024

4. Commissioning and first results of the 174 GHz collective Thomson scattering diagnostic at Wendelstein 7-X

Author

Moseev, D., Ponomarenko, S., Laqua, H.P., Stange, T., Nielsen, S.K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Kasparek, W., Kuleshov, A., Krier, L., Lechte, C., Marsen, S., Nishiura, M., Plaum, B., Ragona, R., Ruess, T., Salewski, M., Stordiau, P., Thumm, M., Wolf, R.C., Zimmermann, J., Moseev, D., Ponomarenko, S., Laqua, H.P., Stange, T., Nielsen, S.K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Kasparek, W., Kuleshov, A., Krier, L., Lechte, C., Marsen, S., Nishiura, M., Plaum, B., Ragona, R., Ruess, T., Salewski, M., Stordiau, P., Thumm, M., Wolf, R.C., and Zimmermann, J.

Abstract

Collective Thomson Scattering (CTS) diagnostics measure the scattering spectrum of monochromatic incident radiation off collective fluctuations in the plasma. In this contribution, we present the first results from the upgraded CTS diagnostic at Wendelstein 7-X (W7-X) operating in the frequency range between 172 and 176 GHz. This frequency range allows for minimization of noise originating from the electron cyclotron emission in the plasma. Consequently, the good signal-to-noise ratio allows measurements of fast ions or bulk plasma parameters with higher temporal resolution compared with the previously used 140 GHz system.

Published
2024

5. The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator

Author

Laqua H. P., Avramidis K. A., Braune H., Chelis I., Gantenbein G., Illy S., Ioannidis Z., Jelonnek J., Jin J., Krier L., Lechte C., Leggieri A., Legrand F., Marsen S., Moseev D., Oosterbeek H., Rzesnicki T., Ruess T., Stange T., Thumm M., Tigelis I., and Wolf R. C.

Subjects
Physics, QC1-999
Abstract

The existing ECRH system at W7-X consists of 10 gyrotrons, with output power levels ranging from 0.6 MW up to 1.0 MW each at a frequency of 140 GHz, quasi-optical transmission lines and microwave launchers at the plasma vessel. Compared to other large fusion experiments, W7-X has a relatively low power-to-volume ratio. However high heating power is particularly necessary for achieving high plasma beta values, where the improved confinement of fast ions, one of the optimization criteria of W7-X, can be examined. It is therefore necessary to expand the ECRH systems in several consecutive steps. It is planned to increase the number of gyrotron positions from 10 to 12 and at the same time to evolve the gyrotron output power in several development steps from 1 MW to nominal 1.5 MW and, finally, up to 2 MW. At the same time, the transmission lines will also be upgraded for 2 MW operation. A special effort is also made to improve the reliability of the system by the fast control system.

Published
2023
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7. Recent experiments with the European 1MW, 170GHz industrial CW and short-pulse gyrotrons for ITER

Author

Ioannidis, Z. C., Albajar, F., Alberti, S., Avramidis, K. A., Bin, W., Bonicelli, T., Bruschi, A., Chelis, J., Fanale, F., Gantenbein, G., Genoud, J., Hogge, J.-P., Hermann, V., Illy, S., Jelonnek, J., Jin, J., Kasparek, W., Latsas, G. P., Legrand, F., Lechte, C., Pagonakis, I. Gr., Rzesnicki, T., Sánchez, F., Schlatter, C., Schmid, M., Tigelis, I. G., Thumm, M., Tran, M. Q., Zisis, A., and Zein, A.

Published
2019
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8. Experimental verification of the European 1 MW, 170 GHz industrial CW prototype gyrotron for ITER

Author

Rzesnicki, T., Albajar, F., Alberti, S., Avramidis, K.A., Bin, W., Bonicelli, T., Braunmueller, F., Bruschi, A., Chelis, J., Frigot, P.-E., Gantenbein, G., Hermann, V., Hogge, J.-P., Illy, S., Ioannidis, Z.C., Jin, J., Jelonnek, J., Kasparek, W., Latsas, G.P., Lechte, C., Lontano, M., Kobarg, T., Pagonakis, I.G., Rozier, Y., Schlatter, C., Schmid, M., Tigelis, I.G., Thumm, M., Tran, M.Q., Vomvoridis, J.L., and Zisis, A.

Published
2017
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10. The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator

Author

Laqua, H., Avramidis, K., Braune, H., Chelis, I., Gantenbein, G., Illy, S., Ioannidis, Z., Jelonnek, J., Jin, J., Krier, L., Lechte, C., Leggieri, A., Legrand, F., Marsen, S., Moseev, D., https://orcid.org/0000-0001-7955-8565, Oosterbeek, J., Rzesnicki, T., Ruess, T., Stange, T., https://orcid.org/0000-0003-4154-1455, Thumm, M., Tigelis, I., Wolf, R., https://orcid.org/0000-0002-2606-5289, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Published
2023

12. The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator

Author

W7-X Team, Laqua, H. P., Avramidis, K. A., Braune, H., Chelis, I., Gantenbein, G., Illy, S., Ioannidis, Z., Jelonnek, J., Jin, J., Krier, L., Lechte, C., Leggieri, A., Legrand, F., Marsen, S., Moseev, D., Oosterbeek, H., Rzesnicki, T., Ruess, T., Stange, T., Thumm, M., Tigelis, I., Wolf, R. C., Poli, E., Liu, Y., and Udintsev, V.

Subjects
Technology, ddc:600, W7-X, ECRH
Abstract

The existing ECRH system at W7-X consists of 10 gyrotrons, with output power levels ranging from 0.6 MW up to 1.0 MW each at a frequency of 140 GHz, quasi-optical transmission lines and microwave launchers at the plasma vessel. Compared to other large fusion experiments, W7-X has a relatively low power-to-volume ratio. However high heating power is particularly necessary for achieving high plasma beta values, where the improved confinement of fast ions, one of the optimization criteria of W7-X, can be examined. It is therefore necessary to expand the ECRH systems in several consecutive steps. It is planned to increase the number of gyrotron positions from 10 to 12 and at the same time to evolve the gyrotron output power in several development steps from 1 MW to nominal 1.5 MW and, finally, up to 2 MW. At the same time, the transmission lines will also be upgraded for 2 MW operation. A special effort is also made to improve the reliability of the system by the fast control system.

Published
2023

13. Status, Operation, and Extension of the ECRH System at ASDEX Upgrade

Author

Wagner, D., Stober, J., Leuterer, F., Monaco, F., Müller, S., Münich, M., Rapson, C. J., Reich, M., Schubert, M., Schütz, H., Treutterer, W., Zohm, H., Thumm, M., Scherer, T., Meier, A., Gantenbein, G., Jelonnek, J., Kasparek, W., Lechte, C., Plaum, B., Goodman, T., Litvak, A. G., Denisov, G. G., Chirkov, A., Zapevalov, V., Malygin, V., Popov, L. G., Nichiporenko, V. O., Myasnikov, V. E., Tai, E. M., Solyanova, E. A., Malygin, S. A., and ASDEX Upgrade Team

Published
2016
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19. Extension of the multi-frequency ECRH system at ASDEX upgrade

Author

Wagner D., Stober J., Kircher M., Leuterer F., Monaco F., Münich M., Schubert M., Zohm H., Gantenbein G., Jelonnek J., Thumm M., Meier A., Scherer T., Strauss D., Kasparek W., Lechte C., Plaum B., Zach A., Litvak A.G., Denisov G.G., Chirkov A., Malygin V., Popov L.G., Nichiporenko V.O., Myasnikov V.E., Tai E.M., Solyanova E.A., and Malygin S.A.

Subjects
Physics, QC1-999
Published
2017
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20. Remote-Steering Antennas for 140 GHz Electron Cyclotron Heating of the Stellarator W7-X

Author

Lechte C., Kasparek W., Plaum B., Zeitler A., Erckmann V., Laqua H., Schneider N., Weissgerber M., Bechtold A., Busch M., and Szepaniak B.

Subjects
Physics, QC1-999
Abstract

For electron cyclotron resonance heating of the stellarator W7-X at IPP Greifswald, a 140 GHz/10 MW cw millimeter wave system has been built. Two out of 12 launchers will employ a remote-steering design. This paper describes the overall design of the two launchers, and design issues like input coupling structures, manufacturing of corrugated waveguides, optimization of the steering range, integration of vacuum windows, mitrebends and vacuum valves into the launchers, as well as low power tests of the finished waveguides.

Published
2017
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21. Experimental Results of the EU ITER Prototype Gyrotrons

Author

Gantenbein G., Albajar F., Alberti S., Avramidis K., Bin W., Bonicelli T., Bruschi A., Chelis J., Fanale F., Legrand F., Hermann V., Hogge J.-P., Illy S., Ioannidis Z. C., Jin J., Jelonnek J., Kasparek W., Latsas G. P., Lechte C., Lontano M., Pagonakis I. G., Rzesnicki T., Schlatter C., Schmid M., Tigelis I. G., Thumm M., Tran M. Q., Vomvoridis J. L., Zein A., and Zisis A.

Subjects
Physics, QC1-999
Abstract

The European 1 MW, 170 GHz CW industrial prototype gyrotron for ECRH&CD on ITER was under test at the KIT test facility during 2016. In order to optimize the gyrotron operation, the tube was thoroughly tested in the short-pulse regime, with pulse lengths below 10 ms, for a wide range of operational parameters. The operation was extended to longer pulses with a duration of up to 180 s. In this work we present in detail the achievements and the challenges that were faced during the long-pulse experimental campaign.

Published
2017
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22. Thermographic reconstruction of heat load on the first wall of Wendelstein 7-X due to ECRH shine-through power

Author

W7-X Team, Corre, Y., Gaspar, J., Marsen, S., Moseev, D., Stange, T., Boscary, J., Drewelow, P., Gao, Y., Jakubowski, M., Hillairet, J., Laqua, H. P., Lechte, C., Moncada, V., Niemann, H., Preynas, M., Puig Sitjes, 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, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut universitaire des systèmes thermiques industriels (IUSTI), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Plasmaphysik [Garching] (IPP), University of Stuttgart, ITER organization (ITER), European Project: 633053,H2020,EURATOM-Adhoc-2014-20,EUROfusion(2014), and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Ir thermography, [PHYS]Physics [physics], Nuclear and High Energy Physics, Technology, Materials science, business.industry, heat flux calculation, Condensed Matter Physics, 01 natural sciences, Electron Cyclotron Resonance Heating, 010305 fluids & plasmas, Power (physics), Optics, 0103 physical sciences, infrared thermography, Wendelstein 7-X, Heat load, 010306 general physics, business, ddc:600
Abstract

Electron cyclotron resonance heating (ECRH) is a powerful and flexible plasma heating technique that serves as the main heater at Wendelstein 7-X (W7-X) and will be used at ITER for start-up, heating, current drive and mitigation of plasma instabilities. In the case of poor or degraded microwave absorption, which is expected in the O2-mode heating scenario, a significant part of the beam directly hits the wall, leading to local overheating and potential damage. The ECRH shine-through power is mostly reflected onto the targets; only a small fraction is really absorbed through ohmic losses (typically 3% for graphite at 140 GHz). The ohmic losses do not only depend on the material properties and the frequency, but also on the polarization of the wave and the angle of incidence. This paper presents a thermographic analysis of ECRH experiments at W7-X, including heat load and temperature simulations of the first wall that include ECRH shine through. Two O-mode ECRH experiments with both a high temperature rise of the first wall and different angles of beam incidence on the wall’s surface are depicted. One experiment has 775 kW of power modulation (5 Hz) with mixed polarization (45% O-mode, 55% X-mode) and an EC beam angle almost normal to the first wall. The second has 550 kW of steady EC power with O-mode polarization, a shallow beam angle and increased power absorption by the material. It is shown that infrared thermography is a useful tool for measuring shine-through power and protecting wall components.

Published
2021

24. 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

25. 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

26. Thermographic reconstruction of heat load on the first wall of Wendelstein 7-X due to ECRH shine-through power

Author

Corre, Y., primary, Gaspar, J., additional, Marsen, S., additional, Moseev, D., additional, Stange, T., additional, Boscary, J., additional, Drewelow, P., additional, Gao, Y., additional, Jakubowski, M., additional, Hillairet, J., additional, Laqua, H.P., additional, Lechte, C., additional, Moncada, V., additional, Niemann, H., additional, Preynas, M., additional, and Puig Sitjes, A., additional

Published
2021
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28. Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz

Author

Moseev, Dmitry, Laqua, H. P., Stange, T., Abramovic, I., Nielsen, S. K., Äkäslompolo, S., Avramidis, K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Jin, J., Kasparek, W., Krier, L., Korsholm, S.B., Lechte, C., Marek, Ales, Marsen, S., Nishiura, M., Pagonakis, I., Salewski, M., Rasmussen, J., Tancetti, A., Thumm, M., and Wolf, R. C.

Subjects
Physics::Plasma Physics, Physics::Accelerator Physics
Abstract

The Collective Thomson Scattering (CTS) diagnostic measures the scattering spectrum of incident radiation off collective fluctuations in plasmas. In Wendelstein 7-X (W7-X) the diagnostic uses a 140 GHz heating gyrotron as a source of the probing radiation. At this frequency, the CTS spectra are heavily affected by the electron cyclotron emission, and the microwave beam propagation is restricted at typical W7-X plasma parameters. The diagnostic was successfully commissioned in the last experimental campaign and demonstrated ion temperature measurements. However, the signal-to-noise ratio was too low for measuring other quantities such as the fast-ion velocity distribution function or the fuel ion ratio. Currently, the W7-X CTS diagnostic is undergoing an upgrade to a frequency of 175 GHz. This will increase the sensitivity of the diagnostic, since the noise due to electron cyclotron emission will be reduced, and it will relax the constraints on microwave beam propagation in W7-X. Here we present the salient features of the upgraded CTS system and discuss its prospects for both thermal-ion and fast-ion measurements.

Published
2020

29. Improvement of the Power Handling Capability of the Upgraded Multi-Frequency ECRH System at ASDEX Upgrade

Author

Wagner, D., primary, Stober, J., additional, Kircher, M., additional, Leuterer, F., additional, Monaco, F., additional, Munich, M., additional, Schubert, M., additional, Zohm, H., additional, Gantenbein, G., additional, Jelonnek, J., additional, Thumm, M., additional, Meier, A., additional, Scherer, T., additional, Strauss, D., additional, Kasparek, W., additional, Lechte, C., additional, Plaum, B., additional, Zach, A., additional, Litvak, A.G., additional, Denisov, G.G., additional, Chirkov, A., additional, Malygin, V., additional, Popov, L.G., additional, Nichiporenko, V.O., additional, Myasnikov, V.E., additional, Tai, E.M., additional, and Solyanova, E.A., additional

Published
2020
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30. Remote-Steering Launchers for the ECRH system on the Stellarator W7-X

Author

Kasparek W., Lechte C., Plaum B., Zeitler A., Erckmann V., Laqua H.P., Weißgerber M., Bechtold A., Busch M., and Szcepaniak B.

Subjects
Physics, QC1-999
Abstract

For electron cyclotron resonance heating of the stellarator W7-X at IPP Greifswald, a 140 GHz/10 MW cw millimeter wave system is in construction. Two out of 12 launchers will employ a remote-steering design. This paper describes the overall design of the two launchers, and design issues like input coupling structures, manufacturing of corrugated waveguides, optimization of the steering range, integration of vacuum windows, mitrebends and vacuum valves into the launchers, as well as tests of prototype parts.

Published
2015
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31. Development of Resonant Diplexers for high-power ECRH – Status, Applications, Plans

Author

Kasparek W., Plaum B., Lechte C., Wu Z., Wang H., Maraschek M., Stober J., Wagner D., Reich M., Schubert M., Grünwald G., Monaco F., Müller S., Schütz H., Erckmann V., Doelman N., van den Braber R., Klop W., van den Brand H., Bongers W., Krijger B., Petelin M., Koposova E., Lubyako L., Bruschi A., and Sakamoto K.

Subjects
Physics, QC1-999
Abstract

The development of diplexers for ECRH has been pursued at a number of institutes because of their attractive variety of applications: Power combination, non-mechanical, electrically controlled switching (of combined beams) between launchers with tens of kHz, and discrimination of low-power ECE signals from high-power ECRH is feasible. In a first part, this paper reports on plasma experiments with a ring resonator (Mk IIa) at ASDEX Upgrade. Commissioning experiments on fast switching between two launchers for synchronous stabilization of neoclassical tearing modes, as well as in-line ECE measurements have been performed, and experimental issues and first results are discussed. A clear influence of the switching phase on the amplitude of the 3/2 NTM mode was measured, complete stabilization could, however, not be demonstrated yet mainly due to imperfect resonator control. Concepts for improved tracking of the diplexers to the gyrotron frequency are presented. In a second part, the design of diplexers with ring resonators matched to HE11 fields is briefly discussed; these devices can be connected to corrugated waveguides without any mode converters. A compact version (MQ IV) is under investigation, which is compatible with the ITER ECRH system (170 GHz, 63.5 mm waveguide, vacuum tight casing), with the final goal of high-power tests at the 170 GHz gyrotron facility at JAEA in Naka, Japan. First low-power test results are presented.

Published
2015
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33. Validation of full-f global gyrokinetic modeling results against the FT-2 tokamak Doppler reflectometry data using synthetic diagnostics

Author

Gusakov, E, Altukhov, A, Gurchenko, A, Heuraux, Stéphane, Irzak, M, Esipov, L, Kiviniemi, T, Krutkin, O, Lechte, C, Leerink, S, Niskala, P, Zadvitskiy, G, Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and heuraux, stéphane

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph]
Abstract

International audience; Introduction The anomalous energy transport remains one of the main issues in magnetic confinement fusion research. According to the present day understanding [1, 2] the anomalous transport is determined by the multi-scale drift-wave turbulence and the nonlinear interaction of its components. The gyrokinetic (GK) simulations [3, 4] provide an efficient tool for studying the nonlinear turbulent plasma dynamics and in the recent papers [5, 6] such simulations of the electron and ion distribution functions from the first principles were performed for the small research limiter tokamak FT-2. The interplay of the multi-scale turbulence components was studied and successful quantitative comparison was presented with O-mode Doppler reflectometry (DR) and enhanced microwave scattering in the upper hybrid resonance [5, 6]. Unfortunately, the interpretation of DR data is complicated due to the contribution of the poorly localized small-angle scattering, which can lead to the overestimation of the turbulence radial correlation length in the linear scattering regime [7, 8], and to its underestimation in the strongly nonlinear regime [9]. In the latter case the turbulence wavenumber spectrum measurements are questionable, and only the plasma turbulence mean velocity could be determined [10]. Moreover the 2D propagation effects additionally complicate the experimental data interpretation and its comparison with the theory predictions. To overcome these issues, synthetic diagnostic can be used both for the interpretation of the experimental results and for the code benchmarking [11, 12]. In this paper two versions of the X-mode DR synthetic diagnostics are compared in the framework of the ELMFIRE global GK modeling of the FT-2 tokamak ohmic discharge [6]. The X-mode DR signal is computed both in the linear theory approximation using the reciprocity theorem [13] and by the full-wave code IPF-FD3D [14]. The temporal behavior of the DR signal frequency spectra and the dependence of its amplitude, frequency shift and shape on the probing antenna position are computed and compared to those measured in the experiment at the FT-2 tokamak. In the case of multi-frequency probing the radial correlation (RC) DR cross-correlation function (CCF) is also determined by both of the synthetic diagnostics and compared to that obtained in the experiment. The experimental approach The experiment was performed at the FT-2 tokamak (the major radius R = 0,55 m, the limiter radius a = 0,079 m) in the hydrogen ohmic discharge (with plasma current I p = 19 kA, central density n e (0) = 410 19 m-3 and electron temperature T e = 470 eV). The discharge is similar to that utilized for successful comprehensive benchmarking of the ELMFIRE GK code in [5, 6], expect for the toroidal magnetic field (B t (0) = 1.7 T instead of 2.1 T). The measured electron density and temperature profiles for this discharge used in the GK modelling, as well as the ion temperature profile are shown in Fig. 1. The vertically movable (by ±2 cm) X-mode double antenna set (shown in Fig.2) installed at high magnetic field side in the vicinity of equatorial plane allowed plasma probing at variable incidence angle with frequencies in the range f i = (50-75) GHz. It was used both in DR measurements utilizing the quadrature scheme and in the RCDR technique [15], as described in [16]. In the latter case the reference channel generator was tuned to the master frequency f 0 =70 GHz determining the measurement position in the vicinity of r = 5 cm, whereas another generator was used in the second, channel to determine the turbulence two-point CCF.

Published
2019

34. Full wave modeling of Doppler backscattering from filaments

Author

Bulanin, V, Gusakov, E, Heuraux, Stéphane, Lechte, C, Petrov, A, Teplova, N, Yashin, A, Zadvitskiy, G, da Silva, F, Team, Globus-M, Institut Jean Lamour (IJL), Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and heuraux, stéphane

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

35. Recent experiments with the European 1MW, 170GHz industrial CW and short-pulse gyrotrons for ITER

Author

Ioannidis, Z.C. Albajar, F. Alberti, S. Avramidis, K.A. Bin, W. Bonicelli, T. Bruschi, A. Chelis, J. Fanale, F. Gantenbein, G. Genoud, J. Hogge, J.-P. Hermann, V. Illy, S. Jelonnek, J. Jin, J. Kasparek, W. Latsas, G.P. Legrand, F. Lechte, C. Pagonakis, I.G. Rzesnicki, T. Sánchez, F. Schlatter, C. Schmid, M. Tigelis, I.G. Thumm, M. Tran, M.Q. Zisis, A. Zein, A.

Abstract

The European Gyrotron Consortium (EGYC) is developing the European 1 MW, 170 GHz Continuous Wave (CW) industrial prototype gyrotron for ITER in cooperation with Thales Electron Devices (TED) and Fusion for Energy (F4E). This conventional, hollow-cavity gyrotron, is based on the 1 MW, 170 GHz Short-Pulse (SP) modular gyrotron that has been designed and manufactured by the Karlsruhe Institute of Technology (KIT) in collaboration with TED. Both gyrotrons have been tested successfully in multiple experiments. In this work we briefly report on the results with the CW gyrotron at KIT and we focus at the experiments at the Swiss Plasma Center (SPC). In addition, we present preliminary results from various upgrades of the SP tube that are currently tested at KIT. © 2018

Published
2019

37. En Route to High-Performance Discharges: Insights and Guidance from High-Realism Gyrokinetics

Author

Görler, T., Di Siena, A., Doerk, H., Happel, T., Banon Navarro, A., Bilato, R., Bock, A., Conway, G., Jenko, F., Poli, E., Sonnendruecker, E., Stober, J., Farcas, I., Neckel, T., Citrin, J., Freethy, S., Creely, A., White, A., Hennequin, P., Johnson, T., Lechte, C., Schneider, M., ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, and JET Contributors

Published
2019

39. Electron-cyclotron-resonance heating in Wendelstein 7-X

Author

Wolf, R. C., Bozhenkov, S., Dinklage, A., Fuchert, G., Kazakov, Y. O., Laqua, H. P., Marsen, S., Marushchenko, N. B., Stange, T., Zanini, M., Abramovic, I., Alonso, A., Baldzuhn, J., Beurskens, M., Beidler, C. D., Braune, H., Brunner, K. J., Chaudhary, N., Damm, H., Drewelow, P., Gantenbein, G., Gao, Y., Geiger, J., Hirsch, M., Hofel, U., Jakubowski, M., Jelonnek, J., Jensen, T., Kasparek, W., Knauer, J., Korsholm, S. B., Langenberg, A., Lechte, C., Leipold, F., Mora, H. T., Neuner, U., Nielsen, S. K., Moseev, D., Oosterbeek, H., Pablant, N., Pasch, E., Plaum, B., Pedersen, T. S., Sitjes, A. P., Rahbarnia, K., Rasmussen, J., Salewski, M., Schilling, J., Scott, E., Stejner, M., Thomsen, H., Thumm, M., Turkin, Y., Wilde, F., Giannella, V., Citarella, R., W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society, and Science and Technology of Nuclear Fusion

Subjects
Physics, Technology, Cyclotron, Plasma, Collisionality, Fusion power, Condensed Matter Physics, 7. Clean energy, 01 natural sciences, Electron cyclotron resonance, Stellerator, 010305 fluids & plasmas, law.invention, Computational physics, Bootstrap current, stellarator, Nuclear Energy and Engineering, law, 0103 physical sciences, Electron temperature, Wendelstein 7-X, electron-cyclotron-resonance heating and current drive, 010306 general physics, ddc:600
Abstract

For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 ×1020 keV m-3 s), observed up to now in stellarators, was achieved (Sunn Pedersen et al 2018 Plasma Phys. Control. Fusion 61 014035). For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.

Published
2019

42. Simulation of Doppler backscattering off filaments in the Globus-M spherical tokamak

Author

Bulanin, V, Gusakov, E, Goussev, Vitali, Heuraux, Stéphane, Lechte, C, Minaev, V, Petrov, A, Petrov, Yu, Yashin, A, Sakharov, N, Da Silva, F, Teplova, N, Zadvitskiy, G, Team, Globus-M, heuraux, stéphane, Institut Jean Lamour (IJL), and Université de Lorraine (UL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Physics::Plasma Physics, [PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph]
Abstract

International audience; In this paper we present the results of two-dimensional full wave simulations of Doppler backscattering (DBS) from filaments in slab geometry. For simulation we have used a substitutional model of a filament of a Gaussian cross-section. The comparison of the simulation results and experimental data obtained at the tokamak Globus-M was performed.

Published
2019

43. Nuclear Fusion (FUSION): Plasma Heating Systems -Microwave Plasma Heating & Current Drive System

Author

Gantenbein, Gerd, Avramidis, K., Franck, J., Fuchs, M., Illy, S., Ioannidis, Z., Jelonnek, J., Jin, J., Kalaria, P., Kobarg, Th., Lang, R., Leonhardt, W., Marschall, M., Mellein, D., Meier, A., Pagonakis, I., Papenfuß, A., Ruess, S., Ruess, T., Rzesnicki, T., Scherer, Theo A., Schmid, M., Strauss, D., M. Thumm, M., Wadle, S., Weggen, J., Wu, Ch., Zein, A., Kasparek, W., Lechte, C., Munk, R., Plaum, B., Remppel, F., Röhlinger, H., Roth, B., Schlüter, K. H., Wolf, S., Zeitler, A., Berndt, B., Braune, H., Hollmann, F., Jonitz, L., Laqua, H., Marsen, S., Noke, F., Preynas, M., Purps, F., Reintrog, A., Schulz, T., Stange, T., Uhren, P., Weißgerber, M., and Wilde, F.

Subjects
Technology, ddc:600
Published
2019

44. Overview of first Wendelstein 7-X high-performance operation

Author

Klinger, T., Andreeva, T., Bozhenkov, S., Brandt, C., Burhenn, R., Buttenschön, B., Fuchert, G., Geiger, B., Grulke, O., Laqua, H., Pablant, N., Rahbarnia, K., Stange, T., von Stechow, A., Tamura, N., Thomsen, H., Turkin, Y., Wegner, T., Abramovic, I., Äkäslompolo, S., Alcuson, J., Aleynikov, P., Aleynikova, K., Ali, A., Alonso, A., Anda, G., Ascasibar, E., Bähner, J.P., Baek, S.G., Balden, M., Baldzuhn, J., Banduch, M., Barbui, T., Behr, W., Beidler, C., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Böckenhoff, D., Böswirth, B., Böttger, L.-G., Borchardt, M., Borsuk, V., Boscary, J., Bosch, H.-S., Beurskens, M., Brakel, R., Brand, H., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Bussiahn, R., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carralero, D., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M.J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., da Molin, A., da Silva, A., Damm, H., de la Pena, A., Degenkolbe, S., Dhard, C.P., Dibon, M., Dinklage, A., Dittmar, T., Drevlak, M., Drewelow, P., Drews, P., Durodie, F., Edlund, E., van Eeten, P., 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., Ford, O., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., García Regaña, J., Gates, D., Geiger, J., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Guerard, C., Hacker, P., Han, X., Harris, J.H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Helander, P., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hirsch, M., Hollfeld, K.P., Höfel, U., 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., Kazakov, Y.O., Kenmochi, N., Killer, C., Kirschner, A., Kleiber, R., 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., Krychowiak, M., Ksiazek, I., Kubkowska, M., Kühner, G., Kurki-Suonio, T., Kurz, P.A., Kwak, S., Landreman, M., Lang, P., Lang, R., Langenberg, A., Langish, S., 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., Neuner, U., 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., Pasch, E., Pavone, A., Pawelec, E., Pedersen, T.S., 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, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schilling, J., 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., Scott, E., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Smith, H., Spiess, W., Spong, D.A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Svensson, J., Szabó, V., Szabolics, T., Szepesi, T., Szökefalvi-Nagy, Z., 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., Vano, L., van Milligen, B., van Vuuren, A.J., Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Vorköper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Warmer, F., Wauters, T., Wegener, L., Weggen, J., 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., Wolf, R.C., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, D., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., Zuin, M., Klinger, T., Andreeva, T., Bozhenkov, S., Brandt, C., Burhenn, R., Buttenschön, B., Fuchert, G., Geiger, B., Grulke, O., Laqua, H., Pablant, N., Rahbarnia, K., Stange, T., von Stechow, A., Tamura, N., Thomsen, H., Turkin, Y., Wegner, T., Abramovic, I., Äkäslompolo, S., Alcuson, J., Aleynikov, P., Aleynikova, K., Ali, A., Alonso, A., Anda, G., Ascasibar, E., Bähner, J.P., Baek, S.G., Balden, M., Baldzuhn, J., Banduch, M., Barbui, T., Behr, W., Beidler, C., Benndorf, A., Biedermann, C., Biel, W., Blackwell, B., Blanco, E., Blatzheim, M., Ballinger, S., Bluhm, T., Böckenhoff, D., Böswirth, B., Böttger, L.-G., Borchardt, M., Borsuk, V., Boscary, J., Bosch, H.-S., Beurskens, M., Brakel, R., Brand, H., Bräuer, T., Braune, H., Brezinsek, S., Brunner, K.-J., Bussiahn, R., Bykov, V., Cai, J., Calvo, I., Cannas, B., Cappa, A., Carls, A., Carralero, D., Carraro, L., Carvalho, B., Castejon, F., Charl, A., Chaudhary, N., Chauvin, D., Chernyshev, F., Cianciosa, M., Citarella, R., Claps, G., Coenen, J., Cole, M.J., Cordella, F., Cseh, G., Czarnecka, A., Czerski, K., Czerwinski, M., Czymek, G., da Molin, A., da Silva, A., Damm, H., de la Pena, A., Degenkolbe, S., Dhard, C.P., Dibon, M., Dinklage, A., Dittmar, T., Drevlak, M., Drewelow, P., Drews, P., Durodie, F., Edlund, E., van Eeten, P., 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., Ford, O., Fornal, T., Frerichs, H., Freund, A., Funaba, T., Galkowski, A., Gantenbein, G., Gao, Y., García Regaña, J., Gates, D., Geiger, J., Giannella, V., Gogoleva, A., Goncalves, B., Goriaev, A., Gradic, D., Grahl, M., Green, J., Greuner, H., Grosman, A., Grote, H., Gruca, M., Guerard, C., Hacker, P., Han, X., Harris, J.H., Hartmann, D., Hathiramani, D., Hein, B., Heinemann, B., Helander, P., Henneberg, S., Henkel, M., Hernandez Sanchez, J., Hidalgo, C., Hirsch, M., Hollfeld, K.P., Höfel, U., 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., Kazakov, Y.O., Kenmochi, N., Killer, C., Kirschner, A., Kleiber, R., 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., Krychowiak, M., Ksiazek, I., Kubkowska, M., Kühner, G., Kurki-Suonio, T., Kurz, P.A., Kwak, S., Landreman, M., Lang, P., Lang, R., Langenberg, A., Langish, S., 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., Neuner, U., 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., Pasch, E., Pavone, A., Pawelec, E., Pedersen, T.S., 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, E., Sano, F., Satake, S., Schacht, J., Satheeswaran, G., Schauer, F., Scherer, T., Schilling, J., 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., Scott, E., Sereda, S., Shanahan, B., Sibilia, M., Sinha, P., Sipliä, S., Slaby, C., Sleczka, M., Smith, H., Spiess, W., Spong, D.A., Spring, A., Stadler, R., Stejner, M., Stephey, L., Stridde, U., Suzuki, C., Svensson, J., Szabó, V., Szabolics, T., Szepesi, T., Szökefalvi-Nagy, Z., 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., Vano, L., van Milligen, B., van Vuuren, A.J., Vela, L., Velasco, J.-L., Vergote, M., Vervier, M., Vianello, N., Viebke, H., Vilbrandt, R., Vorköper, A., Wadle, S., Wagner, F., Wang, E., Wang, N., Wang, Z., Warmer, F., Wauters, T., Wegener, L., Weggen, J., 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., Wolf, R.C., Wright, A., Wurden, G., Xanthopoulos, P., Yamada, H., Yamada, I., Yasuhara, R., Yokoyama, M., Zanini, M., Zarnstorff, M., Zeitler, A., Zhang, D., Zhang, H., Zhu, J., Zilker, M., Zocco, A., Zoletnik, S., and Zuin, M.

Abstract

The optimized superconducting stellarator device Wendelstein 7-X (with major radiusR = 5.5 m, minor radius a = 0.5 m, and 30 m3 plasma volume) restarted operation after the assembly of a graphite heat shield and 10 inertially cooled island divertor modules. This paper reports on the results from the first high-performance plasma operation. Glow discharge conditioning and ECRH conditioning discharges in helium turned out to be important for density and edge radiation control. Plasma densities of 1–4.5 × 1019 m−3 with central electron temperatures 5–10 keV were routinely achieved with hydrogen gas fueling, frequently terminated by a radiative collapse. In a first stage, plasma densities up to 1.4 × 1020 m−3 were reached with hydrogen pellet injection and helium gas fueling. Here, the ions are indirectly heated, and at a central density of 8 · 1019 m−3 a temperature of 3.4 keV with Te/Ti = 1 was transiently accomplished, which corresponds to nTi(0)τE = 6.4 × 1019 keV s m−3 with a peak diamagnetic energy of 1.1 MJ and volume-averaged normalized plasma pressure β = 1.2%. The routine access to high plasma densities was opened with boronization of the first wall. After boronization, the oxygen impurity content was reduced by a factor of 10, the carbon impurity content by a factor of 5. The reduced (edge) plasma radiation level gives routinely access to higher densities without radiation collapse, e.g. well above 1 × 1020 m−2 line integrated density and Te = Ti = 2 keV central temperatures at moderate ECRH power. Both X2 and O2 mode ECRH schemes were successfully applied. Core turbulence was measured with a phase contrast imaging diagnostic and suppression of turbulence during pellet injection was observed.

Published
2019

45. Collective Thomson scattering diagnostic at Wendelstein 7-X

Author

Moseev, D., Stejner, M., Stange, T., Abramovic, I., Laqua, H.P., Marsen, S., Schneider, N., Braune, H., Hoefel, U., Kasparek, W., Korsholm, S.B., Lechte, C., Leipold, F., Nielsen, S.K., Salewski, M., Rasmussen, J., Weißgerber, M., Wolf, R.C., Moseev, D., Stejner, M., Stange, T., Abramovic, I., Laqua, H.P., Marsen, S., Schneider, N., Braune, H., Hoefel, U., Kasparek, W., Korsholm, S.B., Lechte, C., Leipold, F., Nielsen, S.K., Salewski, M., Rasmussen, J., Weißgerber, M., and Wolf, R.C.

Abstract

A Collective Thomson Scattering (CTS) diagnostic is installed at Wendelstein 7-X for ion temperature measurements in the plasma core. The diagnostic utilizes 140 GHz gyrotrons usually used for electron cyclotron resonance heating (ECRH) as a source of probing radiation. The CTS diagnostic uses a quasi-optical transmission line covering a distance of over 40 m. The transmission line is shared between the ECRH system and the CTS diagnostic. Here we elaborate on the design, installation, and alignment of the CTS diagnostic and present the first measurements at Wendelstein 7-X.

Published
2019

46. Electron-cyclotron-resonance heating in Wendelstein 7-X: A versatile heating and current-drive method and a tool for in-depth physics studies:Paper

Author

Wolf, R C, Bozhenkov, S, Dinklage, A, Fuchert, G, Kazakov, Y O, Laqua, H P, Marsen, S, Marushchenko, N B, Stange, T, Zanini, M, Abramovic, I, Alonso, A, Baldzuhn, J, Beurskens, M, Beidler, C D, Braune, H, Brunner, K J, Chaudhary, N, Damm, H, Drewelow, P, Gantenbein, G, Gao, Yu, Geiger, J, Hirsch, M, Höfel, U, Jakubowski, M, Jelonnek, J, Jensen, T, Kasparek, W, Knauer, J, Korsholm, Søren Bang, Langenberg, A, Lechte, C, Leipold, F., Mora, H Trimino, Neuner, U, Nielsen, S. K., Moseev, D, Oosterbeek, H, Pablant, N, Pasch, E, Plaum, B, Pedersen, T Sunn, Sitjes, A Puig, Rahbarnia, K, Rasmussen, J., Salewski, M., Schilling, J, Scott, E, Stejner, M., Thomsen, H, Thumm, M, Turkin, Y, Wilde, F, Wolf, R C, Bozhenkov, S, Dinklage, A, Fuchert, G, Kazakov, Y O, Laqua, H P, Marsen, S, Marushchenko, N B, Stange, T, Zanini, M, Abramovic, I, Alonso, A, Baldzuhn, J, Beurskens, M, Beidler, C D, Braune, H, Brunner, K J, Chaudhary, N, Damm, H, Drewelow, P, Gantenbein, G, Gao, Yu, Geiger, J, Hirsch, M, Höfel, U, Jakubowski, M, Jelonnek, J, Jensen, T, Kasparek, W, Knauer, J, Korsholm, Søren Bang, Langenberg, A, Lechte, C, Leipold, F., Mora, H Trimino, Neuner, U, Nielsen, S. K., Moseev, D, Oosterbeek, H, Pablant, N, Pasch, E, Plaum, B, Pedersen, T Sunn, Sitjes, A Puig, Rahbarnia, K, Rasmussen, J., Salewski, M., Schilling, J, Scott, E, Stejner, M., Thomsen, H, Thumm, M, Turkin, Y, and Wilde, F

Abstract

For stellarators, which need no or only small amounts of current drive, electron-cyclotron-resonance heating (ECRH) is a promising heating method even for the envisaged application in a fusion power plant. Wendelstein 7-X (W7-X) is equipped with a steady-state capable ECRH system, operating at 140 GHz, which corresponds to the 2nd cyclotron harmonic of the electrons at a magnetic field of 2.5 T. Ten gyrotrons are operational and already delivered 7 MW to W7-X plasmas. Combined with pellet injection, the highest triple product (0.68 × 1020 keV m−3 s), observed up to now in stellarators, was achieved (Sunn Pedersen et al 2018 Plasma Phys. Control. Fusion 61 014035). For the first time, W7-X plasmas were sustained by 2nd harmonic O-mode heating, approaching the collisionality regime for which W7-X was optimized. Power deposition scans did not show any indication of electron temperature profile resilience. In low-density, low-power plasmas a compensation of the bootstrap current with electron-cyclotron current drive (ECCD) was demonstrated. Sufficiently strong ECCD close to the plasma centre produced periodic internal plasma-crash events, which coincide with the appearance of low order rationals of the rotational transform.

Published
2019

47. Experiments with the EU 1 MW, 170 GHz industrial prototype gyrotron for ITER at KIT

Author

Ioannidis, ZC (Ioannidis, Zisis C.)[ 1 ], Rzesnicki, T (Rzesnicki, Tomasz)[ 1 ], Albajar, F (Albajar, F.)[ 7 ], Alberti, S (Alberti, S.)[ 2 ], Avramidis, KA (Avramidis, Konstantinos A.)[ 1 ], Bin, W (Bin, William)[ 5 ], Bonicelli, T (Bonicelli, T.)[ 7 ], Bruschi, A (Bruschi, Alessandro)[ 5 ], Chelis, I (Chelis, Ioannis)[ 4 ], Frigot, PE (Frigot, P. -E.)[ 7 ], Gantenbein, G (Gantenbein, Gerd)[ 1 ], Hermann, V (Hermann, V.)[ 6 ], Hogge, JP (Hogge, J. -P.)[ 2 ], Illy, S (Illy, Stefan)[ 1 ], Jin, J (Jin, Jianbo)[ 1 ], Jelonnek, J (Jelonnek, John)[ 1 ], Kasparek, W (Kasparek, W.)[ 3 ], Latsas, G (Latsas, G.)[ 4 ], Lechte, C (Lechte, C.)[ 3 ], Legrand, F (Legrand, F.)[ 6 ], Kobarg, T (Kobarg, Thorsten)[ 1 ], Pagonakis, IG (Pagonakis, Ioannis Gr.)[ 1 ], Rozier, Y (Rozier, Y.)[ 6 ], Schlatter, C (Schlatter, C.)[ 2 ], Schmid, M (Schmid, Martin)[ 1 ], Tigelis, IG (Tigelis, Ioannis G.)[ 4 ], Thumm, M (Thumm, Manfred)[ 1 ], Tran, MQ (Tran, M. Q.)[ 2 ], Zein, A (Zein, Andy)[ 1 ], and Zisis, A (Zisis, A.)[ 4 ]

Subjects
Electron cyclotron resonance heating and current drive (ECRH&CD); gyrotron, international thermonuclear experimental reactor (ITER)
Abstract

The European 1-MW, 170-GHz continuous wave industrial prototype gyrotron for electron cyclotron resonance heating and current drive on international thermonuclear experimental reactor was during 2016 under test at the Karlsruhe Institute of Technology (KIT) test facility. In order to optimize the gyrotron operation, the tube was at first thoroughly tested in the short-pulse regime, with pulses that did not exceed 10 ms, for a wide range of operational parameters. Then, and after proper conditioning of the tube, the operation was extended to longer pulses with duration up to 180 s, which is the maximum pulselength possible at the KIT test facility. In this paper, we present in detail the achievements of the long-pulse experimental campaign.

Published
2017

48. Status of Resonant Diplexer Development for high-power ECRH Applications

Author

Bongers W., Fritz E., Doelman N., van den Braber R., Wagner D., Stober J., Schütz H., Schubert M, Purps F., Noke F., Müller S., Monaco F., Michel G., Maraschek M., Hollmann F., Grünwald G., Erckmann V., Filipovic E., Lechte C., Plaum B., Kasparek W., Krijger B., Petelin M., Lubyako L., Bruschi A., and Sakamoto K.

Subjects
Physics, QC1-999
Abstract

Characteristics of ring resonator diplexers for high-power ECRH are briefly reviewed. Commissioning experiments performed on ASDEX Upgrade with the diplexer Mk IIa are presented, which demonstrate slow and fast switching of the power between two launchers, and thus the capability for efficient suppression of neoclassical tearing modes and simultaneous central heating of the plasma. The development of the compact diplexer Mk IIIb is discussed, and test results are presented. Finally, an evacuated design for 170 GHz is shown.

Published
2012
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49. Large Scale CW ECRH Systems: Some considerations

Author

Turkin Y., Michel G., Marushchenko N. B., Lubiako L., Laqua H. P., Gantenbein G., Braune H., Petelin M.I., Lechte C., Plaum B., Kasparek W., Erckmann V., and Weissgerber M.

Subjects
Physics, QC1-999
Abstract

Electron Cyclotron Resonance Heating (ECRH) is a key component in the heating arsenal for the next step fusion devices like W7-X and ITER. These devices are equipped with superconducting coils and are designed to operate steady state. ECRH must thus operate in CW-mode with a large flexibility to comply with various physics demands such as plasma start-up, heating and current drive, as well as configurationand MHD - control. The request for many different sophisticated applications results in a growing complexity, which is in conflict with the request for high availability, reliability, and maintainability. ‘Advanced’ ECRH-systems must, therefore, comply with both the complex physics demands and operational robustness and reliability. The W7-X ECRH system is the first CW- facility of an ITER relevant size and is used as a test bed for advanced components. Proposals for future developments are presented together with improvements of gyrotrons, transmission components and launchers.

Published
2012
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50. In-situ characterization of spurious modes in HE11 transmission lines with a 5-port coupler

Author

Tretiak D., Ruiz J., Lechte C., Kasparek W., Plaum B., and Idei H.

Subjects
Physics, QC1-999
Abstract

Real-time in-situ measurement of spurious modes in HE11 transmission lines is becoming an important topic for the design of next-generation ECRH installations (e.g. ITER), because the acceptable tolerances for the alignment of the waveguides and coupling optics are small for oversized waveguides. Also, the effects of spurious modes (ohmic heating, wrong beam parameters at the launcher) become increasingly critical. We present a method for in-situ characterization of 4 dominant spurious modes by using a 5-port coupler, which is integrated into a miter bend. The coupler signals can be directly transformed into the mode spectrum by a matrix multiplication. A general formalism for obtaining the coefficients of the transformation matrix is presented along with a method for optimizing the coupler positions in order to obtain the maximum dynamic range for the diagnostics.

Published
2012
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