18 results on '"Beurskens, Marc"'
Number of results to display per page
Search Results
2. Large-scale drifts observed on electron temperature measurements on JET plasmas
- Author
-
Gerbaud, Thomas, Schmuck, Stefan, Alper, Barry, Beausang, Kieran, Beurskens, Marc, Flanagan, Joanne, Kempenaars, Mark, Sirinelli, Antoine, Maslov, Mikhail, Dif-Pradalier, Guilhem, and Contributors, JET EFDA
- Subjects
Physics - Plasma Physics ,Physics - Instrumentation and Detectors - Abstract
Between 1995 and 2009, electron temperature (Te) measurements of more than 15000 plasmas produced in the Joint European Torus (JET) have been carefully reviewed using the two main diagnostics available over this time period: Michelson interferometer and Thomson scattering systems. Long term stability of JET Te is experimentaly observed by defining the ECE TS ratio as the ratio of central Te measured by Michelson and LIDAR. This paper, based on a careful review of Te measurement from 15 years of JET plasmas, concludes that JET Te exhibits a 15-20% effective uncertainty mostly made of large-scale temporal drifts, and an overall uncertainty of 16-22%. Variations of 18 plasma parameters are checked in another data set, made of a "reference data set" made of ohmic pulses as similar as possible between 1998 and 2009. Time drifts of ECE TS ratios appear to be mostly disconnected from the variations observed on these 18 plasma parameters, except for the very low amplitude variations of the field which are well correlated with off-plasma variations of a 8-channel integrator module used for measuring many magnetic signals from JET. From mid-2002 to 2009, temporal drifts of ECE TS ratios are regarded as calibration drifts possibly caused by unexpected sensitivity to unknown parameters; the external temperature on JET site might be the best parameter suspected so far. Off-plasma monitoring of MI made of calibration performed in the laboratory are reported and do not appear to be clearly correlated with drifts of ECE TS ratio and variations of magnetics signals integrators. Comparison of estimations of plasma thermal energy for purely Ohmic and NBI-only plasmas does not provide any definite information on the accuracy of \mi or \lidar measurements. Whatever causes these Te drifts, this experimental issue is regarded as crucial for JET data quality., Comment: 15 pages, 15 figures
- Published
- 2012
3. Impact of Magnetic Field Configuration on Heat Transport in Stellarators and Heliotrons
- Author
-
WARMER, Felix, TANAKA, Kenji, XANTHOPOULOS, P., NUNAMI, Masanori, NAKATA, Motoki, BEIDLER, Craig, BOZHENKOV, Sergey, BEURSKENS, Marc, BRUNNER, K. J., FORD, O. P., FUCHERT, Golo, FUNABA, Hisamichi, GEIGER, J., GRADIC, D., IDA, Katsumi, IGAMI, Hiroe, KUBO, Shin, LANGENBERG, Andreas, LAQUA, Heinrich, LAZERSON, Samuel, MORISAKI, Tomohiro, OSAKABE, Masaki, PABLANT, Novimir, PASCH, E., PETERSON, Byron J., SATAKE, Shinsuke, SEKI, Ryosuke, SHIMOZUMA, Takashi, SMITH, H. M., STANGE, Torsten, STECHOW, A. von, SUGAMA, Hideo, SUZUKI, Yasuhiro, TAKAHASHI, Hiromi, TOKUZAWA, Tokihiko, TSUJIMURA, Toru, TURKIN, Yuri, WOLF, Robert, YAMADA, Ichihiro, YANAI, Ryoma, YASUHARA, Ryo, YOKOYAMA, Masayuki, YOSHIMURA, Yasuo, YOSHINUMA, Mikirou, ZHANG, Daihong, W7-X Team, LHD Experimental Group, WARMER, Felix, TANAKA, Kenji, XANTHOPOULOS, P., NUNAMI, Masanori, NAKATA, Motoki, BEIDLER, Craig, BOZHENKOV, Sergey, BEURSKENS, Marc, BRUNNER, K. J., FORD, O. P., FUCHERT, Golo, FUNABA, Hisamichi, GEIGER, J., GRADIC, D., IDA, Katsumi, IGAMI, Hiroe, KUBO, Shin, LANGENBERG, Andreas, LAQUA, Heinrich, LAZERSON, Samuel, MORISAKI, Tomohiro, OSAKABE, Masaki, PABLANT, Novimir, PASCH, E., PETERSON, Byron J., SATAKE, Shinsuke, SEKI, Ryosuke, SHIMOZUMA, Takashi, SMITH, H. M., STANGE, Torsten, STECHOW, A. von, SUGAMA, Hideo, SUZUKI, Yasuhiro, TAKAHASHI, Hiromi, TOKUZAWA, Tokihiko, TSUJIMURA, Toru, TURKIN, Yuri, WOLF, Robert, YAMADA, Ichihiro, YANAI, Ryoma, YASUHARA, Ryo, YOKOYAMA, Masayuki, YOSHIMURA, Yasuo, YOSHINUMA, Mikirou, ZHANG, Daihong, W7-X Team, and LHD Experimental Group
- Abstract
We assess the magnetic field configuration in modern fusion devices by comparing experiments with the same heating power, between a stellarator and a heliotron. The key role of turbulence is evident in the optimized stellarator, while neoclassical processes largely determine the transport in the heliotron device. Gyrokinetic simulations elucidate the underlying mechanisms promoting stronger ion scale turbulence in the stellarator. Similar plasma performances in these experiments suggests that neoclassical and turbulent transport should both be optimized in next step reactor designs., source:https://doi.org/10.1103/PhysRevLett.127.225001, identifier:0000-0001-9585-5201
- Published
- 2023
4. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X
- Author
-
BEIDLER, Craig, SMITH, H. M., ALONSO, Juan Arturo, ANDREEVA, T., BALDZUHN, J., BEURSKENS, Marc, BORCHARDT, Matthias, BOZHENKOV, Sergey, BRUNNER, Kai Jakob, DAMM, Hannes, DREVLAK, M., FORD, Oliver P., FUCHERT, Golo, GEIGER, Joachim, HELANDER, P., HERGENHAHN, Uwe, HIRSCH, M., Höfel, Udo, KAZAKOV, Yevgen, KLEIBER, Ralf, KRYCHOWIAK, Maciej, KWAK, Sehyun, LANGENBERG, Andreas, LAQUA, Heinrich, NEUNER, U., PABLANT, Novimir, PASCH, E., PAVONE, Andrea, PEDERSEN, Thomas Sunn, RAHBARNIA, Kian, SCHILLING, Jonathan, SCOTT, Evan, STANGE, Torsten, SVENSSON, J., THOMSEN, Henning, TURKIN, Yuriy, WARMER, Felix, WOLF, Robert, ZHANG, Daihong, the W7-X Team, BEIDLER, Craig, SMITH, H. M., ALONSO, Juan Arturo, ANDREEVA, T., BALDZUHN, J., BEURSKENS, Marc, BORCHARDT, Matthias, BOZHENKOV, Sergey, BRUNNER, Kai Jakob, DAMM, Hannes, DREVLAK, M., FORD, Oliver P., FUCHERT, Golo, GEIGER, Joachim, HELANDER, P., HERGENHAHN, Uwe, HIRSCH, M., Höfel, Udo, KAZAKOV, Yevgen, KLEIBER, Ralf, KRYCHOWIAK, Maciej, KWAK, Sehyun, LANGENBERG, Andreas, LAQUA, Heinrich, NEUNER, U., PABLANT, Novimir, PASCH, E., PAVONE, Andrea, PEDERSEN, Thomas Sunn, RAHBARNIA, Kian, SCHILLING, Jonathan, SCOTT, Evan, STANGE, Torsten, SVENSSON, J., THOMSEN, Henning, TURKIN, Yuriy, WARMER, Felix, WOLF, Robert, ZHANG, Daihong, and the W7-X Team
- 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 lackin, source:Beidler, C.D., Smith, H.M., Alonso, A. et al. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X. Nature 596, 221–226 (2021). https://doi.org/10.1038/s41586-021-03687-w, source:https://doi.org/10.1038/s41586-021-03687-w, identifier:0000-0002-4395-239X
- Published
- 2023
5. Core Diagnostics for WENDELSTEIN 7-X Steady-State Exploration Until 18 GJ
- Author
-
HIRSCH, Matthias W., BANNMANN, Sebastian, FUCHERT, Gole, Xiang, Han, HÖFEL, Udo, HUANG, Jia, KNAUER, Jens, KOSCHINSKY, Jean-Paul, KRÄMER-FLECKEN, Andreas, KURSINSKI, Beate, LANGENBERG, Andreas, LAZERSON, Samuel, BEURSKENS, Marc N. A., MEINEKE, Jens, MOSEEV, Dimitry, OOSTERBEEK, Johan, PABLANT, Novimir, PASCH, Eckehard, PAVONE, Andreas, PÖLÖSKEI, Peter, RICHERT, Torsten, STANGE, Torsten, STEFFEN, Matthias, BIEDERMANN, Christoph, STERN, Mathias, VANÓ, Lilla, WOLF, Robert C., XIANG, Haoming M., ZANINI, Marco, BOZHENKOV, Sergey, BRUNNER, Kai-Jakob, CHAUDHARY, Neha, DAMM, Hannes, FORD, Oliver, GUERRERO-ARNAIZ, Juan, and W7-X Team, Max Planck Institute for Plasma Physics, Max Planck Society
- Subjects
ddc:530 ,Condensed Matter Physics - Published
- 2022
6. On the role of density fluctuations in the core turbulent transport of Wendelstein 7-X
- Author
-
Carralero, Daniel, primary, Estrada, Teresa, additional, Maragkoudakis, Emmanouil, additional, Windisch, Thomas, additional, Alonso, J Arturo, additional, Velasco, Jose Luis, additional, Ford, Oliver P, additional, Jakubowski, Marcin, additional, Lazerson, Samuel A, additional, Beurskens, Marc N A, additional, Bozhenkov, Sergey A, additional, Calvo, Ivan, additional, Damm, Hannes, additional, Fuchert, Golo, additional, García Regaña, José Manuel, additional, Höfel, Udo, additional, Marushchenko, Nikolai B, additional, Pablant, Novimir Antoniuk, additional, Sanchez, Edilberto, additional, Smith, Hakan M, additional, Pasch, Ekkehard, additional, and Stange, Torsten, additional
- Published
- 2022
- Full Text
- View/download PDF
7. Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X
- Author
-
Stange Torsten, Laqua Heinrich Peter, Beurskens Marc, Bosch Hans-Stephan, Bozhenkov Sergey, Brakel Rudolf, Braune Harald, Brunner Kai Jakob, Cappa Alvaro, Dinklage Andreas, Erckmann Volker, Fuchert Golo, Gantenbein Gerd, Gellert Florian, Grulke Olaf, Hartmann Dirk, Hirsch Matthias, Höfel Udo, Kasparek Walter, Knauer Jens, Langenberg Andreas, Marsen Stefan, Marushchenko Nikolai, Moseev Dmitry, Pablant Novomir, Pasch Ekkehard, Rahbarnia Kian, Mora Humberto Trimino, Tsujimura Toru, Turkin Yuriy, Wauters Tom, and Wolf Robert
- Subjects
Physics ,QC1-999 - Abstract
During the first operational phase (OP 1.1) of Wendelstein 7-X (W7-X) electron cyclotron resonance heating (ECRH) was the exclusive heating method and provided plasma start-up, wall conditioning, heating and current drive. Six gyrotrons were commissioned for OP1.1 and used in parallel for plasma operation with a power of up to 4.3 MW. During standard X2-heating the spatially localized power deposition with high power density allowed controlling the radial profiles of the electron temperature and the rotational transform. Even though W7-X was not fully equipped with first wall tiles and operated with a graphite limiter instead of a divertor, electron densities of n e > 3·1019 m-3 could be achieved at electron temperatures of several keV and ion temperatures above 2 keV. These plasma parameters allowed the first demonstration of a multipath O2-heating scenario, which is envisaged for safe operation near the X-cutoff-density of 1.2·1020 m-3 after full commissioning of the ECRH system in the next operation phase OP1.2.
- Published
- 2017
- Full Text
- View/download PDF
8. First neutral beam experiments on Wendelstein 7-X
- Author
-
Lazerson, Samuel A., primary, Ford, Oliver, additional, Äkaslompolö, Simppa, additional, Bozhenkov, Sergey, additional, Slaby, Christoph, additional, Vanó, Lilla, additional, Spanier, Annabelle, additional, McNeely, Paul, additional, Rust, Norbert, additional, Hartmann, Dirk, additional, Poloskei, Peter, additional, Buttenschoゆ, Birger, additional, Burhenn, Rainer, additional, Tamura, Naoki, additional, Bussiahn, Rene, additional, Wegner, Thomas, additional, Drevlak, Michael, additional, Turkin, Yuriy, additional, Ogawa, Kunihiro, additional, Knauer, Jens, additional, Brunner, Kai Jakob, additional, Pasch, Ekkehard, additional, Beurskens, Marc, additional, Damm, Hannes, additional, Fuchert, Golo, additional, Nelde, Philipp, additional, Scott, Evan, additional, Pablant, Novimir, additional, Langenberg, Andreas, additional, Traverso, Peter, additional, Valson, Pranay, additional, Hergenhahn, Uwe, additional, Pavone, Andrea, additional, Rahbarnia, Kian, additional, Andreeva, Tamara, additional, Schilling, Jonathan, additional, Brandt, Christian, additional, Neuner, Ulrich, additional, Thomsen, Henning, additional, Chaudhary, Neha, additional, Höefel, Udo, additional, Stange, Torsten, additional, Weir, Gavin, additional, Marushchenko, Nikolai, additional, Jakubowski, Marcin, additional, Ali, Adnan, additional, Gao, Yu, additional, Niemann, Holger, additional, Puig Sitjes, Aleix, additional, Koenig, Ralf, additional, Schroeder, Ralf, additional, den Harder, Niek, additional, Heinemann, Bernd, additional, Hopf, Christian, additional, Riedl, Rudolf, additional, Wolf, Robert C., additional, and W7-X Team, the, additional
- Published
- 2021
- Full Text
- View/download PDF
9. Demonstration of reduced neoclassical energy transport in Wendelstein 7-X
- Author
-
BEIDLER, Craig, SMITH, H. M., ALONSO, Juan Arturo, ANDREEVA, T., BALDZUHN, J., BEURSKENS, Marc, BORCHARDT, Matthias, BOZHENKOV, Sergey, BRUNNER, Kai Jakob, DAMM, Hannes, DREVLAK, M., FORD, Oliver P., FUCHERT, Golo, GEIGER, Joachim, HELANDER, P., HERGENHAHN, Uwe, HIRSCH, M., Höfel, Udo, KAZAKOV, Yevgen, KAZAKOV, Yevgen O., KLEIBER, Ralf, KRYCHOWIAK, Maciej, KWAK, Sehyun, LANGENBERG, Andreas, LAQUA, Heinrich, NEUNER, U., PABLANT, Novimir, PASCH, E., PAVONE, Andrea, PEDERSEN, Thomas Sunn, RAHBARNIA, Kian, SCHILLING, Jonathan, SCOTT, Evan, STANGE, Torsten, SVENSSON, J., THOMSEN, Henning, TURKIN, Yuriy, WARMER, Felix, WOLF, Robert, ZHANG, Daihong, the W7-X Team, BEIDLER, Craig, SMITH, H. M., ALONSO, Juan Arturo, ANDREEVA, T., BALDZUHN, J., BEURSKENS, Marc, BORCHARDT, Matthias, BOZHENKOV, Sergey, BRUNNER, Kai Jakob, DAMM, Hannes, DREVLAK, M., FORD, Oliver P., FUCHERT, Golo, GEIGER, Joachim, HELANDER, P., HERGENHAHN, Uwe, HIRSCH, M., Höfel, Udo, KAZAKOV, Yevgen, KAZAKOV, Yevgen O., KLEIBER, Ralf, KRYCHOWIAK, Maciej, KWAK, Sehyun, LANGENBERG, Andreas, LAQUA, Heinrich, NEUNER, U., PABLANT, Novimir, PASCH, E., PAVONE, Andrea, PEDERSEN, Thomas Sunn, RAHBARNIA, Kian, SCHILLING, Jonathan, SCOTT, Evan, STANGE, Torsten, SVENSSON, J., THOMSEN, Henning, TURKIN, Yuriy, WARMER, Felix, WOLF, Robert, ZHANG, Daihong, and the W7-X Team
- Abstract
0000-0002-4395-239X, 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 lackin
- Published
- 2021
10. Impact of Magnetic Field Configuration on Heat Transport in Stellarators and Heliotrons
- Author
-
WARMER, Felix, TANAKA, Kenji, XANTHOPOULOS, P., NUNAMI, Masanori, NAKATA, Motoki, BEIDLER, Craig, BOZHENKOV, Sergey, BEURSKENS, Marc, BRUNNER, K. J., FORD, O. P., FUCHERT, Golo, FUNABA, Hisamichi, GEIGER, J., GRADIC, D., IDA, Katsumi, IGAMI, Hiroe, KUBO, Shin, LANGENBERG, Andreas, LAQUA, Heinrich, LAZERSON, Samuel, MORISAKI, Tomohiro, OSAKABE, Masaki, PABLANT, Novimir, PASCH, E., PETERSON, Byron, PETERSON, Byron J., SATAKE, Shinsuke, SEKI, Ryosuke, SHIMOZUMA, Takashi, SMITH, H. M., STANGE, Torsten, STECHOW, A. von, SUGAMA, Hideo, SUZUKI, Yasuhiro, TAKAHASHI, Hiromi, TOKUZAWA, Tokihiko, TSUJIMURA, Toru, TURKIN, Yuri, WOLF, Robert, YAMADA, Ichihiro, YANAI, Ryoma, YANAI, Ryohma, YASUHARA, Ryo, YOKOYAMA, Masayuki, YOSHIMURA, Yasuo, YOSHINUMA, Mikirou, ZHANG, Daihong, W7-X Team, LHD Experimental Group, WARMER, Felix, TANAKA, Kenji, XANTHOPOULOS, P., NUNAMI, Masanori, NAKATA, Motoki, BEIDLER, Craig, BOZHENKOV, Sergey, BEURSKENS, Marc, BRUNNER, K. J., FORD, O. P., FUCHERT, Golo, FUNABA, Hisamichi, GEIGER, J., GRADIC, D., IDA, Katsumi, IGAMI, Hiroe, KUBO, Shin, LANGENBERG, Andreas, LAQUA, Heinrich, LAZERSON, Samuel, MORISAKI, Tomohiro, OSAKABE, Masaki, PABLANT, Novimir, PASCH, E., PETERSON, Byron, PETERSON, Byron J., SATAKE, Shinsuke, SEKI, Ryosuke, SHIMOZUMA, Takashi, SMITH, H. M., STANGE, Torsten, STECHOW, A. von, SUGAMA, Hideo, SUZUKI, Yasuhiro, TAKAHASHI, Hiromi, TOKUZAWA, Tokihiko, TSUJIMURA, Toru, TURKIN, Yuri, WOLF, Robert, YAMADA, Ichihiro, YANAI, Ryoma, YANAI, Ryohma, YASUHARA, Ryo, YOKOYAMA, Masayuki, YOSHIMURA, Yasuo, YOSHINUMA, Mikirou, ZHANG, Daihong, W7-X Team, and LHD Experimental Group
- Abstract
0000-0001-9585-5201, We assess the magnetic field configuration in modern fusion devices by comparing experiments with the same heating power, between a stellarator and a heliotron. The key role of turbulence is evident in the optimized stellarator, while neoclassical processes largely determine the transport in the heliotron device. Gyrokinetic simulations elucidate the underlying mechanisms promoting stronger ion scale turbulence in the stellarator. Similar plasma performances in these experiments suggests that neoclassical and turbulent transport should both be optimized in next step reactor designs.
- Published
- 2021
11. Impact of the temperature ratio on turbulent impurity transport in Wendelstein 7-X
- Author
-
Wegner, Thomas, primary, Alcuson, Jorge Alberto, additional, Geiger, Benedikt, additional, von Stechow, Adrian, additional, Xanthopoulos, Pavlos, additional, Angioni, Clemente, additional, Beurskens, Marc N A, additional, Böttger, Lukas, additional, Bozhenkov, Sergey A, additional, Brunner, Kai Jakob, additional, Burhenn, Rainer, additional, Buttenschön, Birger, additional, Damm, Hannes, additional, Edlund, Eric M, additional, Ford, Oliver P, additional, Fuchert, Golo, additional, Grulke, Olaf, additional, Huang, Zhouji, additional, Knauer, Jens P, additional, Kunkel, Falk, additional, Langenberg, Andreas, additional, Pablant, Novimir Antoniuk, additional, Pasch, Ekkehard, additional, Rahbarnia, Kian, additional, Schilling, Jonathan, additional, Thomsen, H, additional, and Vano, Lilla, additional
- Published
- 2020
- Full Text
- View/download PDF
12. Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited)
- Author
-
Krychowiak, M., Adnan, A., Alonso, A., Andreeva, T., Baldzuhn, J., Barbui, T., Beurskens, Marc N.A., Biel, W., Biedermann, C., Blackwell, B.D., Bosch, H.S., Bozhenkov, S., Brakel, R., Bräuer, T., Brotas de Carvalho, B., Burhenn, R., Buttenschön, B., Cappa, A., Cseh, G., Czarnecka, A., Dinklage, A., Drews, P., Dzikowicka, A., Effenberg, F., Endler, M., Erckmann, V., Estrada, T., Ford, O., Fornal, T., Frerichs, H., Fuchert, G., Geiger, J., Grulke, O., Harris, J.H., Hartfuß, H.J., Hartmann, D., Hathiramani, D., Hirsch, M., Höfel, U., Jabłoński, S., Jakubowski, M.W., Kaczmarczyk, J., Klinger, T., Klose, S., Knauer, J., Kocsis, G., König, R., Kornejew, P., Krämer-Flecken, A., Krawczyk, N., Kremeyer, T., Ksiazek, I., Kubkowska, M., Langenberg, A., Laqua, H.P., Laux, M., Lazerson, S., Liang, Y., Liu, S.C., Lorenz, A., Marchuk, A.O., Marsen, S., Moncada, V., Naujoks, D., Neilson, H., Neubauer, O., Neuner, U., Niemann, H., Oosterbeek, J.W., Otte, M., Pablant, N., Pasch, E., Sunn Pedersen, T., Pisano, F., Rahbarnia, K., Ryć, L., Schmitz, O., Schmuck, S., Schneider, W., Schröder, T., Schuhmacher, H., Schweer, B., Standley, B., Stange, T., Stephey, L., Svensson, J., Szabolics, T., Szepesi, T., Thomsen, H., Travère, J.M., Trimino Mora, H., Tsuchiya, H., Weir, G.M., Wenzel, U., Werner, A., Wiegel, B., Windisch, T., Wolf, R., Wurden, G.A., Zhang, D., Zimbal, A., Zoletnik, S., Krychowiak, M., Adnan, A., Alonso, A., Andreeva, T., Baldzuhn, J., Barbui, T., Beurskens, Marc N.A., Biel, W., Biedermann, C., Blackwell, B.D., Bosch, H.S., Bozhenkov, S., Brakel, R., Bräuer, T., Brotas de Carvalho, B., Burhenn, R., Buttenschön, B., Cappa, A., Cseh, G., Czarnecka, A., Dinklage, A., Drews, P., Dzikowicka, A., Effenberg, F., Endler, M., Erckmann, V., Estrada, T., Ford, O., Fornal, T., Frerichs, H., Fuchert, G., Geiger, J., Grulke, O., Harris, J.H., Hartfuß, H.J., Hartmann, D., Hathiramani, D., Hirsch, M., Höfel, U., Jabłoński, S., Jakubowski, M.W., Kaczmarczyk, J., Klinger, T., Klose, S., Knauer, J., Kocsis, G., König, R., Kornejew, P., Krämer-Flecken, A., Krawczyk, N., Kremeyer, T., Ksiazek, I., Kubkowska, M., Langenberg, A., Laqua, H.P., Laux, M., Lazerson, S., Liang, Y., Liu, S.C., Lorenz, A., Marchuk, A.O., Marsen, S., Moncada, V., Naujoks, D., Neilson, H., Neubauer, O., Neuner, U., Niemann, H., Oosterbeek, J.W., Otte, M., Pablant, N., Pasch, E., Sunn Pedersen, T., Pisano, F., Rahbarnia, K., Ryć, L., Schmitz, O., Schmuck, S., Schneider, W., Schröder, T., Schuhmacher, H., Schweer, B., Standley, B., Stange, T., Stephey, L., Svensson, J., Szabolics, T., Szepesi, T., Thomsen, H., Travère, J.M., Trimino Mora, H., Tsuchiya, H., Weir, G.M., Wenzel, U., Werner, A., Wiegel, B., Windisch, T., Wolf, R., Wurden, G.A., Zhang, D., Zimbal, A., and Zoletnik, S.
- Abstract
Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.
- Published
- 2016
13. The ASDEX Upgrade Program Targeting Gaps to Fusion Energy
- Author
-
Neu, Rudolf, primary, Bobkov, Volodymyr, additional, Bock, Alexander, additional, Bernert, Matthias, additional, Beurskens, Marc, additional, Herrmann, Albrecht, additional, Kallenbach, Arne, additional, Lang, Peter Thomas, additional, Noterdaeme, Jean-Marie, additional, Pautasso, Gabriella, additional, Reich, Matthias, additional, Schweinzer, Josef, additional, Stober, Jorg, additional, Suttrop, Wolfgang, additional, Zohm, Hartmut, additional, and Kirk, Andrew, additional
- Published
- 2016
- Full Text
- View/download PDF
14. Fine scale structures in the RTP tokamak plasma, measured with high resolution Thomson scattering
- Author
-
LOPES CARDOZO Niek, DE BAAR Marco, BARTH Rolie, BEURSKENS Marc, GORINI GIUSEPPE, HOGEWEIJ Dick, KARELSE Frank, MANTICA Paola, VAN DER MEIDEN Hennie, and SCHILHAM Arnold
- Subjects
Electron Cyclotron Heating ,RTp ,JET ,electron transport barrier ,plasma structure ,Thomson scattering - Abstract
The Rijnhuizen Tokamak RTP, closed in Sept.1998, was unique for its combination of domi nant 2nd harmonic ECH (4-7 times the Ohmic power, deposited within 10% of the minor radius) and highresolution electron diagnostics. By scanning the ECH deposition through the plasma, electron transporr barriers associated with the rational q-values l,4/3,3/2,2, 5/2, and 3 were experimentally demonstrated. Modulated ECH showed that the transport barriers are layers of strong inward convection. The ECH power is deposited just outside the barriers. A conceptual model was developed in which transporr barriers are linked to rational q-values. The model reproduces all of the essential features of the RTp data sets, and was also tested against data from JET and TEXTOR.
- Published
- 2001
15. Experiences With Tungsten Plasma Facing Components in ASDEX Upgrade and JET.
- Author
-
Neu, Rudolf Ludwig, Brezinsek, Sebastijan, Beurskens, Marc, Bobkov, Volodymyr, de Vries, Peter, Giroud, Carine, Joffrin, Emmanuel, Kallenbach, Arne, Matthews, Guy F., Mayoral, Marie-Line, Pautasso, Gabriella, Putterich, Thomas, Ryter, Francois, Schweinzer, Josef, ASDEX Upgrade Team, and JET EFDA Contributors
- Subjects
PLASMA gas research ,TUNGSTEN ,DIVERTERS (Electronics) ,NUCLEAR reactors - Abstract
ASDEX Upgrade (AUG) has been converted to all W plasma facing components (PFCs) in 2007 and JET has implemented the ITER like wall (ILW) project (2011) using the same PFC configuration as ITER during its active phase, namely Be in the main chamber and tungsten in the divertor. As a result of the all metal PFCs in both devices much less surface conditioning is needed to arrive at reproducible wall conditions. Specifically, the Be PFCs of JET led to a very small low-Z content (reduction of C and O by at least a factor of 10), reducing the edge radiation in steady-state operation as well as during disruptions. Both devices successfully employ massive gas injection to mitigate disruption forces and power loads to PFCs by radiating up to 100% of the available energy. Hydrogen retention is strongly reduced (AUG: factor 5, JET: factor 10) and the remaining retention is still dominated by codeposition with residual C in AUG and intrinsic Be in JET. The very low edge and divertor radiation could be compensated by impurity seeding either by a single gas species (N2) (AUG and JET) or by combining N2 and Ar (AUG) injection for divertor and main chamber radiation, respectively. The W sputtering in the divertor increases when seeding small amounts of N2, but decreases for higher fluxes due to the plasma cooling provided by the nitrogen radiation. The tungsten content is controlled by the source as well as by its edge and central transport. It could be kept sufficiently small by using a minimum gas fueling to reduce the W erosion and to diminish the W penetration. The control of the central W transport by central (wave) heating had been well established in AUG, however, in both devices the W content is increased during ICRH operation most probably due to increased W sputtering caused by rectified sheaths. The H-Mode threshold is reduced by 20%–30% in AUG and JET, but on average the confinement is lower in JET-ILW than with C PFCs. To date it is not yet clear, whether the reduced H-Mode confinement has to be attributed to the use of W PFCs, since such a clear trend as in JET was not found in AUG. The increase of confinement with N2 seeding observed in both devices hints to the fact, that low-Z impurities like carbon or nitrogen play a beneficial role for the pedestal confinement. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
16. Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X
- Author
-
Stange, Torsten, Laqua, Heinrich Peter, Beurskens, Marc, Bosch, Hans-Stephan, Bozhenkov, Sergey, Brakel, Rudolf, Braune, Harald, Brunner, Kai Jakob, Cappa, Alvaro, Dinklage, Andreas, Erckmann, Volker, Fuchert, Golo, Gantenbein, Gerd, Gellert, Florian, Grulke, Olaf, Hartmann, Dirk, Hirsch, Matthias, Höfel, Udo, Kasparek, Walter, Knauer, Jens, Langenberg, Andreas, Marsen, Stefan, Marushchenko, Nikolai, Moseev, Dmitry, Pablant, Novomir, Pasch, Ekkehard, Rahbarnia, Kian, Mora, Humberto Trimino, Tsujimura, Toru, Turkin, Yuriy, Wauters, Tom, and Wolf, Robert
- Subjects
7. Clean energy
17. Letter
- Author
-
W7-X Team, Wegner, Thomas, Alcuson, Jorge Alberto, Geiger, Benedikt, Stechow, Adrian von, Xanthopoulos, Pavlos, Angioni, Clemente, Beurskens, Marc N. A., Böttger, Lukas, Bozhenkov, Sergey A., Brunner, Kai Jakob, Burhenn, Rainer, Buttenschön, Birger, Damm, Hannes, Edlund, Eric M., Ford, Oliver P., Fuchert, Golo, Grulke, Olaf, Huang, Zhouji, Knauer, Jens P., Kunkel, Falk, Langenberg, Andreas, Pablant, Novimir Antoniuk, Pasch, Ekkehard, Rahbarnia, Kian, Schilling, Jonathan, Thomsen, H., Vano, Lilla, 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
Nuclear and High Energy Physics ,Electron density ,Technology ,Materials science ,Condensed matter physics ,Plasma ,Condensed Matter Physics ,7. Clean energy ,01 natural sciences ,Instability ,010305 fluids & plasmas ,law.invention ,Ion ,Impurity ,law ,Physics::Plasma Physics ,0103 physical sciences ,Electron temperature ,Wendelstein 7-X ,010306 general physics ,ddc:600 ,Stellarator - Abstract
First experimental observations in the Wendelstein 7-X stellarator indicate that the impurity confinement can be explained by turbulent processes. In particular, plasma discharges with increased ion to electron temperature ratio are accompanied by reduced electron density fluctuation amplitudes and anomalous impurity diffusion, suggesting a lower turbulent transport. Employing gyro-kinetic numerical simulations, we argue that the temperature Ratio plays a key role for reducing the ion temperature gradient instability in Wendelstein 7-X, leading to an enhanced impurity confinement.
- Full Text
- View/download PDF
18. The pedestal structure in high performance JET plasmas
- Author
-
Leyland, Matthew J., Gibson, Kieran J., and Beurskens, Marc N. A.
- Subjects
530 - Abstract
The ITER baseline scenario is foreseen to be a type I ELMy H-mode. This mode of operation is characterised by a steep pressure gradient at the plasma edge termed the pedestal. Quantifying the pedestal structure and its role on confinement for current Tokamaks, such as JET, is key to gaining an insight into the operation of future devices. Furthermore, to identify the physical mechanism(s) governing the pedestal structure, it is essential to compare measurements to modelling results. This thesis focuses on the JET high resolution Thomson scattering (HRTS) system, a key diagnostic, as it provides radial electron temperature and density profiles. This thesis first presents how the performance of the HRTS system polychromators was improved by performing a realignment and optimisation. Consequently, all the electron temperature profile data after the installation of the JET ITER-Like-Wall are independently calibrated (instead of cross-calibrated via the ECE diagnostic). The JET pedestal structure is quantified by performing a modified hyperbolic tangent fit to the HRTS profiles. The JET pedestal fitting tool incorporates the diagnostic measurement accuracy (the instrument function) resulting in a deconvolved fit. This is necessary in order to accurately determine the pedestal width. It has previously been shown that the systematic error in the fit parameters due to the deconvolution technique is negligible in comparison to the statistical error, as long as the pedestal is wider than the instrument function. Furthermore, this thesis shows that the systematic error due to ELM synchronisation is also negligible by replicating the fitting process and performing a Monte-Carlo simulation using synthetic HRTS-like profiles. The JET pedestal fitting tool has been used to quantify the variation in pedestal structure for a database of JET baseline type I ELMy H-mode deuterium fuelling and nitrogen seeding plasmas before and after the installation of the ITER-like wall. Across a high triangularity deuterium fuelling scan for JET plasmas with a carbon wall there is a widening of the pedestal and an increase in the pedestal height, which accounts for the improvement in edge performance. After the installation of the ITER-like-wall, the energy confinement of equivalent JET plasmas was degraded by up to 40% due to a reduction in pedestal performance and a strong pedestal-core coupling. However, this performance could be partially recovered with nitrogen seeding. Measurements of the pedestal structure show that with increasing nitrogen seeding there is an increase in both the pedestal height and width, which is not yet captured by the EPED model. A key result of this thesis is, with increasing deuterium fuelling, the pedestal now widens whilst the pedestal height remains constant. These measurements pose the biggest challenge for the EPED model as they deviate from the square root relation between the pedestal width and normalised pedestal height acting as the kinetic ballooning.
- Published
- 2014
Catalog
Books, media, physical & digital resources
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.