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2. Physics of tearing mode rotation and slow-down in the RFX-mod tokamak.

Author

Cordaro, L., Zanca, P., Zuin, M., Auriemma, F., Fassina, A., Martines, E., Zaniol, B., Cavazzana, R., De Masi, G., Grenfell, G., Momo, B., Spagnolo, S., Spolaore, M., and Vianello, N.

Subjects
TOKAMAKS, PHYSICS, FUSION reactors, ROTATIONAL motion, FLOW measurement
Abstract

We present a study of the fast, spontaneous rotation regime of tearing modes (TM) in the RFX-mod circular tokamak discharges. Integrated analyses of magnetic, flow and kinetic measurements, are discussed. This analysis of rotation frequency components related to the ion flow and diamagnetic drift shows that the TM fast rotation is mainly driven by the diamagnetic drift. The global decrease of the temperature profile, induced by a growing mode amplitude, can explain the slowing-down of the rotation, which in turn can trigger a potentially disruptive sequence. We show that in RFX-mod the slowing-down cannot be explained solely on the basis of the electromagnetic torque with the external conductive structures, as often reported in literature from other experiments. This analysis, indeed, suggests a strong relationship between the TM dynamics and the transport physics. Statistical analysis of disruptions with slowing down of island rotation shows that TMs take a part in the disruption, even without a locking to the wall. [ABSTRACT FROM AUTHOR]

Published
2022
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9. 3D filamentary transport and the role of edge sheared radial electric fields in the RFX-mod tokamak

Author

Grenfell G., Spolaore M., Abate D., Carraro L., Marrelli L., van Milligen B., Predebon I., Spagnolo S., Veranda M., Agostini M., Cavazzana R., Cordaro L., De Masi G., Franz P., Martines E., Momo B., Puiatti M.E., Scarin P., Vianello N., Zaniol B., Zuin M., and RFX-mod Team

Subjects
3D filamentary transport, RFX-Mod, Physics::Plasma Physics, tokamak
Abstract

Sheared radial electric field is an important parameter in regulating cross-field transport in fusiondevices. The edge and scrape-off layer (SOL) turbulence coupling, as well as the parallel dissipation,are responsible for the SOL width maintenance, which, in turn, is a critical parameter for particle andenergy exhaustion in tokamaks \cite{Grenfell:2019}. This coupling is usually attributed to the trans-port of streamers or blobs (also called filaments). They are mostly created in the plasma edge, in highgradient free energy regions, and transported radially by ExB drift. The turbulent filaments prop-erties, e.g. velocity and size, and ultimately their penetration into the SOL, are defined by the typeof instability that generates them as well as how they interact with the background \cite{Myra:2013}.High beta filaments, on the other hand, tend to be more resilient to the background. This is thecase of the Edge-Localized Mode filaments in H-mode regimes, one of the current threats for thefeasibility of future fusion reactors. In this work, we study the filament or blob cross-field transportin the RFX-mod operating as tokamak in different plasma regimes by using a set of electrostatic andmagnetic probes \cite{Grenfell:2018}. It has been shown recently that H-mode ELM-free and ELMyare induced in the RFX-mod tokamak by electrode biasing technique \cite{Spolaore:2017}. We showthat the properties of filaments in these regimes, as well as in L-mode, are distinct. While in L-modeblobs propagate almost freely into the SOL scaling as sheath-connected filaments \cite{Manz:2013},in the ELM-free H-mode, filaments are trapped (their cross-field velocity approaches to zero) and dis-sipated around the plasma boundary, where the ExB shearing rate is marginally comparable to theireffective convective time \cite{Grenfell:2018}. ELMs filaments propagate further into the SOL carry-ing a larger parallel current density associated with the edge transport barrier relaxation.

Published
2019

10. Self-organized helical equilibria as a new paradigm for ohmically heated fusion plasmas

Author

Lorenzini, R., Martines, E., Piovesan, P., Terranova, D., Zanca, P., Zuin, M., Alfier, A., Bonfiglio, D., Bonomo, F., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Escande, D. F., Fassina, A., Franz, P., Gobbin, M., Innocente, P., Marrelli, L., Pasqualotto, R., Puiatti, M. E., Spolaore, M., Valisa, M., Vianello, N., Martin, P., Apolloni, L., Adamek, J., Agostini, M., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, P., Bolzonella, T., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Cavinato, M., Chapman, B. E., Chitarin, G., Bello, S. D., Lorenzi, A. D., Masi, G. D., Ferro, A., Gaio, E., Gazza, E., Giudicotti, L., Gnesotto, F., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Liu, Y. Q., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Martini, S., McCollam, K., Milani, F., Moresco, M., Novello, L., Ortolani, S., Paccagnella, R., Peruzzo, S., Piovan, R., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, G., Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spizzo, G., Taliercio, C., Toigo, V., Villone, F., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., Zuin, M. Z., Lorenzini, R., Martines, E., Piovesan, P., Terranova, D., Zanca, P., Zuin, M., Alfier, A., Bonfiglio, D., Bonomo, F., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Escande, D. F., Fassina, A., Franz, P., Gobbin, M., Innocente, P., Marrelli, L., Pasqualotto, R., Puiatti, M. E., Spolaore, M., Valisa, M., Vianello, N., Martin, P., Apolloni, L., Adamek, J., Agostini, M., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, P., Bolzonella, T., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Cavinato, M., Chapman, B. E., Chitarin, G., Bello, S. D., Lorenzi, A. D., Masi, G. D., Ferro, A., Gaio, E., Gazza, E., Giudicotti, L., Gnesotto, F., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Liu, Y. Q., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Martini, S., Mccollam, K., Milani, F., Moresco, M., Novello, L., Ortolani, S., Paccagnella, R., Peruzzo, S., Piovan, R., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, G., Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spizzo, G., Taliercio, C., Toigo, V., Villone, F., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., Zuin, M. Z., Lorenzini, R, Martines, E, Piovesan, P, Terranova, D, Zanca, P, Zuin, M, Alfier, A, Bonfiglio, D, Bonomo, F, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Escande, D, Fassina, A, Franz, P, Gobbin, M, Innocente, P, Marrelli, L, Pasqualotto, R, Puiatti, M, Spolaore, M, Valisa, M, Vianello, N, and Martin, P

Subjects
Physics, quasi-single-helicity, Toroid, Tokamak, Fusion plasma, General Physics and Astronomy, Magnetic confinement fusion, reversed field pinch, Mechanics, Plasma, Fusion power, Instability, law.invention, Physics::Plasma Physics, law, RFP, Pinch, QSH, Atomic physics
Abstract

In the quest for new energy sources, the research on controlled thermonuclear fusion has been boosted by the start of the construction phase of the International Thermonuclear Experimental Reactor (ITER). ITER is based on the tokamak magnetic configuration, which is the best performing one in terms of energy confinement. Alternative concepts are however actively researched, which in the long term could be considered for a second generation of reactors. Here, we show results concerning one of these configurations, the reversed-field pinch (RFP). By increasing the plasma current, a spontaneous transition to a helical equilibrium occurs, with a change of magnetic topology. Partially conserved magnetic flux surfaces emerge within residual magnetic chaos, resulting in the onset of a transport barrier. This is a structural change and sheds new light on the potential of the RFP as the basis for a low-magnetic-field ohmic fusion reactor. © 2009 Macmillan Publishers Limited.

Published
2009

11. Magnetic perturbations as a viable tool for edge turbulence modification

Author

Vianello N., Rea C., Agostini M., Cavazzana R., Ciaccio G., De Masi G., Martines E., Mazzi A., Momo B., Spizzo G., Scarin P., Spolaore M., Zanca P., Zuin M., Carraro L., Innocente P., Marrelli L., Puiatti M. E., Terranova D., the RFX-mod Team, Vianello, N, Rea, C, Agostini, M, Cavazzana, R, Ciaccio, G, De Masi, G, Martines, E, Mazzi, A, Momo, B, Spizzo, G, Scarin, P, Spolaore, M, Zanca, P, Zuin, M, Carraro, L, Innocente, P, Marrelli, L, Puiatti, M, and Terranova, D

Subjects
Physics, Safety factor, Tokamak, Reversed field pinch, Turbulence, business.industry, turbulence, Perturbation (astronomy), RMP, Condensed Matter Physics, 01 natural sciences, 010305 fluids & plasmas, Computational physics, Magnetic field, law.invention, electric field, Optics, Nuclear Energy and Engineering, law, Physics::Plasma Physics, 0103 physical sciences, Magnetohydrodynamics, 010306 general physics, business, Phenomenology (particle physics)
Abstract

A complete description of the effects of magnetic perturbation on the edge region of RFX-mod is here reported. The flexibility of the RFX-mod device [1] allows for the operation of the machine both as a reversed field pinch (RFP, with maximum current 2 MA) and as a low-current, circular ohmic tokamak (I-p,I-max = 0.15 MA). The present paper summarizes the most recent results obtained in both configurations with either spontaneous or induced edge radial magnetic perturbation. Emphasis will be devoted to the experimental characterization of the edge flow, focusing on the phase relation between flow and perturbed magnetic field. These informations are provided for natural and stimulated helical discharges in RFPs, and for tokamak safely operated, thanks to the unique RFX-mod MHD control system, in a wide range of edge safety factor 1.9 less than or similar to q(a)

Published
2015
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12. Edge effects of dynamically shaped tokamak configuration in RFX-mod experiment

Author

Spolaore M, Cavazzana R, De Masi G, Finotti C, Kudlacek O, Marchiori G, Martines E, Momo B, Rea C, Spagnolo S, Vianello N, Zuin M, Spolaore, M, Cavazzana, R, De Masi, G, Finotti, C, Kudlacek, O, Marchiori, G, Martines, E, Momo, B, Rea, C, Spagnolo, S, Vianello, N, and Zuin, M

Subjects
RFX-mod, edge plasma, tokamak
Published
2014

13. Answers to the RFX-Mod evaluation panel questions

Author

Bonfiglio D., Canton A., Cavazzana R., Marchiori G., Marrelli L., Martines E., Puiatti M.E., Spizzo G., Terranova D., and Zanca P.

Subjects
RFX-mod, Tokamak, RFP, Stellarator
Abstract

Answers to the RFX-Mod evaluation panel questions

Published
2016

14. Feedback control of the m=2,n=1 mode in RFX-mod tokamak plasmas with qcyl(a)=2

Author

Baruzzo M, Bolzonella T, Cavazzana R, In Y, Marchiori G, Marrelli L, Martin P, Martines E, Okabayashi M, Paccagnella R, Piovesan P, Piron L, Soppelsa A, Terranova D, Zanca P, Baruzzo, M, Bolzonella, T, Cavazzana, R, In, Y, Marchiori, G, Marrelli, L, Martin, P, Martines, E, Okabayashi, M, Paccagnella, R, Piovesan, P, Piron, L, Soppelsa, A, Terranova, D, and Zanca, P

Subjects
feedback control, RFX-mod, MHD, tokamak
Published
2011

15. Direct plasma potential measurements by a novel probe

Author

Adamek J, Balan P, Hron M, Ionita C, Martines E, Ryszawy J, Schrittwieser R, Stöckel J, Tichy M, Van Oost G, Adamek, J, Balan, P, Hron, M, Ionita, C, Martines, E, Ryszawy, J, Schrittwieser, R, Stöckel, J, Tichy, M, and Van Oost, G

Subjects
ball-pen probe, plasma potential, tokamak, CASTOR
Published
2004

18. Probe array diagnostics for spatially resolved fluctuation measurements

Author

Hron, M, Martines, E, Devynck, P, Bonhomme, G, Gravier, E, Adamek, J, Doveil, F, Voitsekhovitch, I, Stöckel, J, Azeroual, A, Duran, I, Van Oost, G, Zacek, F, Hron, M, Martines, E, Devynck, P, Bonhomme, G, Gravier, E, Adamek, J, Doveil, F, Voitsekhovitch, I, Stöckel, J, Azeroual, A, Duran, I, Van Oost, G, and Zacek, F

Subjects
plasma turbulence, probe array, tokamak, CASTOR
Published
2002

19. ELM-related high frequency MHD activity in ASDEX Upgrade

Author

Bolzonella, T., Martines, E., Maraschek, M., Zohm, H., Günter, S., Saarelma, S., Bolzonella, T, Martines, E, Maraschek, M, Zohm, H, Günter, S, Saarelma, S, and ASDEX Upgrade Team

Subjects
MHD, spectrogram, ASDEX Upgrade, tokamak
Published
2002

20. Fluctuation measurements with emissive probes in tokamaks

Author

Adamek J, Duran I, Hron M, Stockel J, Balan P, Schrittwieser R, Ionita C, Martines E, Tichy M, Van Oost G, Adamek, J, Duran, I, Hron, M, Stockel, J, Balan, P, Schrittwieser, R, Ionita, C, Martines, E, Tichy, M, and Van Oost, G

Subjects
Edge plasma, Tokamak, Emissive probe, Plasma fluctuation
Abstract

A new probe head, composed of two electro-emissive probes and two Langmuir probes has been designed to measure edge fluctuations in the CASTOR tokamak. In this contribution, only one Langmuir and one electron-emissive probe are used to measure the temperature and potential fluctuations and the phase angle between them.

Published
2002

21. Measurements of the plasma potential with an emissive probe in the CASTOR tokamak

Author

Schrittwieser, R, Adámek, J, Balan, P, Ionita, C, Jakubka, K, Kriska, L, Martines, E, Pohoata, V, Stöckel, J, Tichy, M, Van Oost, G, Schrittwieser, R, Adámek, J, Balan, P, Ionita, C, Jakubka, K, Kriska, L, Martines, E, Pohoata, V, Stöckel, J, Tichy, M, and Van Oost, G

Subjects
plasma potential, emissive probes, tokamak, CASTOR
Published
2001

22. Plasma potential measurements with emissive probes in the Castor tokamak

Author

Schrittwieser R, Adámek J, Balan P, Hron M, Ionita C, Jakubka K, Kryska L, Martines E, Pohoata V, Stöckel J, Tichy M, Van Oost G, Schrittwieser, R, Adámek, J, Balan, P, Hron, M, Ionita, C, Jakubka, K, Kryska, L, Martines, E, Pohoata, V, Stöckel, J, Tichy, M, and Van Oost, G

Subjects
plasma potential, tokamak, CASTOR, emissive probe
Published
2001

24. Plasma polarization of the separatrix on the CASTOR tokamak

Author

Stöckel J, Hron M, Duran I, Dyabilin K, Horácek J, Jakubka K, Kryska L, Martines E, Nanobashvili S, Van Oost G, Tendler M, Zácek F, Szegö, K, Todd, TN, Zoletnik, S, Stöckel, J, Hron, M, Duran, I, Dyabilin, K, Horácek, J, Jakubka, K, Kryska, L, Martines, E, Nanobashvili, S, Van Oost, G, Tendler, M, and Zácek, F

Subjects
edge biasing, tokamak, CASTOR
Published
2000

25. Formation of convective cells in the scrape-off layer of the CASTOR tokamak

Author

Stöckel, J., Devynck, P., Gunn, J., Martines, E., Bonhomme, Gildas, Van Oost, G., Hron, M., Adamek, J., Brotánková, J., Dejarnac, R., Duran, I., Görler, T., Hansen, T., Panek, R., Stejskal, P., Svoboda, V., Zacek, F., Institute of Plasma Physics, Association Euratom/IPP.CR (IPP PRAGUE), Czech Academy of Sciences [Prague] (CAS), Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Consorzio RFX, Associazione Euratom/ENEA sulla Fusione (RFX), Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratoire de physique des milieux ionisés et applications (LPMIA), Université Henri Poincaré - Nancy 1 (UHP)-Centre National de la Recherche Scientifique (CNRS), Department of Applied physics [Ghent], Universiteit Gent = Ghent University [Belgium] (UGENT), Universität Ulm - Ulm University [Ulm, Allemagne], Agenzia Nazionale per le nuove Tecnologie, l’energia e lo sviluppo economico sostenibile = Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), and Universiteit Gent = Ghent University (UGENT)

Subjects
Plasma Physics (physics.plasm-ph), convective cells, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Physics::Plasma Physics, FOS: Physical sciences, edge plasma, tokamak, Physics - Plasma Physics, probe arrays
Abstract

Understanding of the scrape-off layer (SOL) physics in tokamaks requires diagnostics with sufficient temporal and spatial resolution. This contribution describes results of experiments performed in the SOL of the CASTOR tokamak (R=40 cm, a = 6 cm) by means of a ring of 124 Langmuir probes surrounding the whole poloidal cross section. The individual probes measure either the ion saturation current of the floating potential with the spatial resolution up to 3 mm. Experiments are performed in a particular magnetic configuration, characterized by a long parallel connection length in the SOL, L_par ~q2piR. We report on measurements in discharges, where the edge electric field is modified by inserting a biased electrode into the edge plasma. In particular, a complex picture is observed, if the biased electrode is located inside the SOL. The poloidal distribution of the floating potential appears to be strongly non-uniform at biasing. The peaks of potential are observed at particular poloidal angles. This is interpreted as formation of a biased flux tube, which emanates from the electrode along the magnetic field lines and snakes q times around the torus. The resulting electric field in the SOL is 2-dimensional, having the radial as well as the poloidal component. It is demonstrated that the poloidal electric field E_pol convects the edge plasma radially due to the E_pol x B_T drift either inward or outward depending on its sign. The convective particle flux is by two orders of magnitude larger than the fluctuation-induced one and consequently dominates., 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France)

Published
2004

26. Edge Plasma Studies and Related Diagnostics on CASTOR Tokamak.

Author

Hron, M., Stockel, J., Devynck, P., Martines, E., Van Oost, G., Duran, I., Panek, R., Adamek, J., and Weinzettl, V.

Subjects
TOKAMAKS, FUSION reactors, NUCLEAR reactors, TURBULENCE, FLUID dynamics, LANGMUIR probes
Abstract

In this contribution, two sets of measurements using a full poloidal array of Langmuir probes in the scrape-off layer of the CASTOR tokamak are described. First, results obtained with edge plasma biasing show creation of convective cells that cause radial transport due to ExB drift. Next, the analysis of the turbulence behaviour in standard ohmic discharges shows the presence of a spatially periodical mode with mode number equal to the edge safety factor q. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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27. Tokamak experiments in RFX-mod with polarized insertable electrode

Author

Lorella Carraro, Cavazzana, R., Del Bello, S., Masi, G., Ferro, A., Finotti, C., Franz, P., Grando, L., Innocente, P., Kudlacek, O., Marchiori, G., Marrelli, L., Martines, E., Paccagnella, R., Piovesan, P., Piron, C., Puiatti, M. E., Recchia, M., Scarin, P., Spagnolo, S., Spolaore, M., Taliercio, C., Zaniol, B., Zanotto, L., Zuin, M., Poedts, S, Fajardo, M, Giruzzi, G, Gans, T, Vennekens, N, Mantica, P, Carraro, L, Cavazzana, R, Dal Bello, S, De Masi, G, Ferro, A, Finotti, C, Franz, P, Grando, L, Innocente, P, Kudlacek, O, Marchiori, G, Marrelli, L, Martines, E, Paccagnella, R, Piovesan, P, Piron, C, Puiatti, M, Recchia, M, Scarin, P, Spagnolo, S, Spolaore, M, Taliercio, C, Zaniol, B, Zanotto, L, and Zuin, M

Subjects
RFX-mod, edge biasing, Physics::Plasma Physics, tokamak
Abstract

The RFX-mod device (R=2m, a=0.459m) can be operated as an ohmic tokamak with a toroidal field up to 0.55T for 1 sec. Thanks to its MHD control system and to the close fitting vacuum vessel, it can systematically operate circular cross section discharges up to very low q, q(a)

28. Survey of results on plasma biasing in the CASTOR tokamak

Author

Stockel, J., Adamek, J., Brotánková, J., Dejarnac, R., Devynck, P., Duran, I., Gunn, J., Horacek, J., Hron, M., Kocan, M., Martines, E., Radomir Panek, Spolaore, M., Oost, G., Stockel, J, Adamek, J, Brotánková, J, Dejarnac, R, Devynck, P, Duran, I, Gunn, J, Horacek, J, Hron, M, Kocan, M, Martines, E, Panek, R, Spolaore, M, and Van Oost, G

Subjects
tokamak, CASTOR, edge biasing
Abstract

Experimental observations on edge plasma biasing on the CASTOR tokamak are summarized. Three regimes differing in the electrode position and in the biasing voltage are identified. Characteristic features observed at the plasma edge are studied by a set of electric probes and impact of biasing on the edge plasma as well as on global confinement is described.

29. Diagnostics, data acquisition and control of the divertor test tokamak experiment

Author

Alfredo Pironti, Lorella Carraro, G. Ramogida, M. Spolaore, Raffaele Albanese, Alessandro Fassina, Paolo Innocente, Roberto Cavazzana, Massimo Nocente, Simone Peruzzo, Mario Cavinato, Carlo Sozzi, Emilio Martines, Roberto Ranz, L. Gabellieri, L. Marrelli, Adriano Luchetta, M.L. Apicella, Paolo Franz, Alessandra Canton, M. E. Puiatti, Giuseppe Gorini, Roberto Ambrosino, F. Piccolo, Marco Ariola, Gianluca Spizzo, Giorgio Maddaluno, G. De Tommasi, M. Valisa, Filippo Sartori, Paolo Scarin, Gabriele Manduchi, Andre Neto, Albanese, R, Ambrosino, R, Ariola, M, De Tommasi, G, Pironti, A, Cavinato, M, Neto, A, Piccolo, F, Sartori, F, Ranz, R, Carraro, L, Canton, A, Cavazzana, R, Fassina, A, Franz, P, Innocente, P, Luchetta, A, Manduchi, G, Marrelli, L, Martines, E, Peruzzo, S, Puiatti, M, Scarin, P, Spizzo, G, Spolaore, M, Valisa, M, Gorini, G, Nocente, M, Sozzi, C, Apicella, M, Gabellieri, L, Maddaluno, G, Ramogida, G, Albanese, R., Ambrosino, R., Ariola, M., De Tommasi, G., Pironti, A., Cavinato, M., Neto, A., Piccolo, F., Sartori, F., Ranz, R., Carraro, L., Canton, A., Cavazzana, R., Fassina, A., Franz, P., Innocente, P., Luchetta, A., Manduchi, G., Marrelli, L., Martines, E., Peruzzo, S., Puiatti, M. E., Scarin, P., Spizzo, G., Spolaore, M., Valisa, M., Gorini, G., Nocente, M., Sozzi, C., Apicella, M. L., Gabellieri, L., Maddaluno, G., and Ramogida, G.

Subjects
Tokamak, Computer science, Data acquisition, Diagnostics, Plasma control, Power exhaust, Civil and Structural Engineering, Materials Science (all), Nuclear Energy and Engineering, Mechanical Engineering, Nuclear engineering, Control (management), 01 natural sciences, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, General Materials Science, Diagnostic, 010306 general physics, Divertor, Power (physics), Data flow diagram, Control system, Control methods
Abstract

The system of diagnostics, data acquisition and control foreseen on the Divertor Test Tokamak experiment (DTT) is presented. Conceived in an integrated way, the control system meets the specifications of a fusion experiment devoted to the study of the power exhaust problem in view of DEMO. Diagnostics and feedback control are particularly functional to the need of maintaining the plasma close to equilibrium in situations prone to instabilities where the plasma wall interaction is optimized. Strongly oriented to the exploration of control methods suitable for DEMO, DTT will specifically experiment on physics and engineering model based control systems. Control and data flow schemes are inspired by those of ITER.

Published
2017

30. Overview of the RFX fusion science program

Author

M. Gobbin, Roberto Pasqualotto, D. Bonfiglio, Enrico Zilli, Giuseppe Marchiori, Piero Martin, S. Martini, Fulvio Auriemma, E. Gazza, D.K. Mansfield, P. Zaccaria, Piergiorgio Sonato, S. Ortolani, Wolf-Dieter Schneider, D. Yadikin, Stefano Munaretto, L. Piron, M. Valisa, Fabio Sattin, Susanna Cappello, G. V. Perverezev, F. Milani, Roberto Paccagnella, Paolo Bettini, S. Fiameni, Roscoe White, A. Ruzzon, V. Antoni, Leonardo Giudicotti, Yueqiang Liu, Lionello Marrelli, Nicola Vianello, S. Dal Bello, A. Scaggion, V. Rigato, Fabio Villone, A. Zamengo, Federica Bonomo, R. Cavazzana, M. Baruzzo, L. Carraro, F. Fantini, Giuseppe Zollino, Barbara Zaniol, Rita Lorenzini, Luis Chacon, X. Garbet, C. Angioni, Andrea Rizzolo, G. De Masi, G. Rostagni, W. A. Cooper, Manabu Takechi, Piero Agostinetti, Paolo Scarin, A. Pizzimenti, Yongkyoon In, Sheena Menmuir, Silvia Spagnolo, M. Moresco, Satoru Kiyama, S. P. Hirshman, M. Okabayashi, Giuseppe Chitarin, S. C. Guo, Gabriele Manduchi, Dominique Escande, Gianluigi Serianni, Alessandro Fassina, Luca Grando, Simona Barison, Allen H. Boozer, Michael Drevlak, Diego Marcuzzi, M. Pavei, J.Q. Dong, Anton Soppelsa, B. Momo, Gianluca Spizzo, Hajime Sakakita, Neil Pomphrey, Shunsuke Ide, Donald A. Spong, J. S. Sarff, Alessandra Canton, D. Lopez Bruna, M. Brombin, Matteo Zuin, T. Bolzonella, R. Piovan, Songfen Liu, Alberto Ferro, Italo Predebon, V. Igochine, L. Zanotto, Simone Peruzzo, Elena Gaio, P. Piovesan, Cesare Taliercio, J. Adamek, Go Matsunaga, P. Zanca, A. Buffa, M. Veranda, N. Pomaro, M. Spolaore, Oliviero Barana, Francesco Gnesotto, Emilio Martines, M. Dalla Palma, Paolo Franz, David Terranova, Yoichi Hirano, Matteo Agostini, G. Mazzitelli, Alberto Alfier, L. Novello, Vanni Toigo, M. Boldrin, R. Delogu, Guglielmo Rubinacci, Maria Ester Puiatti, A. Fiorentin, Karsten McCollam, E. Spada, M. Cavinato, A. De Lorenzi, L. Apolloni, J. Brotankova, F. Fellin, P. Innocente, Raul Sanchez, Zhirui Wang, Adriano Luchetta, Martin, P, Adamek, J, Agostinetti, P, Agostini, M, Alfier, A, Angioni, C, Antoni, V, Apolloni, L, Auriemma, F, Barana, O, Barison, S, Baruzzo, M, Bettini, P, Boldrin, M, Bolzonella, T, Bonfiglio, D, Bonomo, F, Boozer, A, Brombin, M, Brotankova, J, Buffa, A, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cavinato, M, Chacon, L, Chitarin, G, Cooper, W, Dal Bello, S, Dalla Palma, M, Delogu, R, De Lorenzi, A, De Masi, G, Dong, J, Drevlak, M, Escande, D, Fantini, F, Fassina, A, Fellin, F, Ferro, A, Fiameni, S, Fiorentin, A, Franz, P, Gaio, E, Garbet, X, Gazza, E, Giudicotti, L, Gnesotto, F, Gobbin, M, Grando, L, Guo, S, Hirano, Y, Hirshman, S, Ide, S, Igochine, V, In, Y, Innocente, P, Kiyama, S, Liu, S, Liu, Y, Bruna, D, Lorenzini, R, Luchetta, A, Manduchi, G, Mansfield, D, Marchiori, G, Marcuzzi, D, Marrelli, L, Martini, S, Matsunaga, G, Martines, E, Mazzitelli, G, Mccollam, K, Menmuir, S, Milani, F, Momo, B, Moresco, M, Munaretto, S, Novello, L, Okabayashi, M, Ortolani, S, Paccagnella, R, Pasqualotto, R, Pavei, M, Perverezev, G, Peruzzo, S, Piovan, R, Piovesan, P, Piron, L, Pizzimenti, A, Pomaro, N, Pomphrey, N, Predebon, I, Puiatti, M, Rigato, V, Rizzolo, A, Rostagni, G, Rubinacci, G, Ruzzon, A, Sakakita, H, Sanchez, R, Sarff, J, Sattin, F, Scaggion, A, Scarin, P, Schneider, W, Serianni, G, Sonato, P, Spada, E, Soppelsa, A, Spagnolo, S, Spolaore, M, Spong, D, Spizzo, G, Takechi, M, Taliercio, C, Terranova, D, Toigo, V, Valisa, M, Veranda, M, Vianello, N, Villone, F, Wang, Z, White, R, Yadikin, D, Zaccaria, P, Zamengo, A, Zanca, P, Zaniol, B, Zanotto, L, Zilli, E, Zollino, G, Zuin, M, Martin, P., Adamek, J., Agostinetti, P., Agostini, M., Alfier, A., Angioni, C., Antoni, V., Apolloni, L., Auriemma, F., Barana, O., Barison, S., Baruzzo, M., Bettini, P., Boldrin, M., Bolzonella, T., Bonfiglio, D., Bonomo, F., Boozer, A. H., Brombin, M., Brotankova, J., Buffa, A., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Chacon, L., Chitarin, G., Cooper, W. A., Bello, S. D., Palma, M. D., Delogu, R., Lorenzi, A. D., Masi, G. D., Dong, J. Q., Drevlak, M., Escande, D. F., Fantini, F., Fassina, A., Fellin, F., Ferro, A., Fiameni, S., Fiorentin, A., Franz, P., Gaio, E., Garbet, X., Gazza, E., Giudicotti, L., Gnesotto, F., Gobbin, M., Grando, L., Guo, S. C., Hirano, Y., Hirshman, S. P., Ide, S., Igochine, V., In, Y., Innocente, P., Kiyama, S., Liu, S. F., Liu, Y. Q., Bruna, D. L., Lorenzini, R., Luchetta, A., Manduchi, G., Mansfield, D. K., Marchiori, G., Marcuzzi, D., Marrelli, L., Martini, S., Matsunaga, G., Martines, E., Mazzitelli, G., Mccollam, K., Menmuir, S., Milani, F., Momo, B., Moresco, M., Munaretto, S., Novello, L., Okabayashi, M., Ortolani, S., Paccagnella, R., Pasqualotto, R., Pavei, M., Perverezev, G. V., Peruzzo, S., Piovan, R., Piovesan, P., Piron, L., Pizzimenti, A., Pomaro, N., Pomphrey, N., Predebon, I., Puiatti, M. E., Rigato, V., Rizzolo, A., Rostagni, G., Rubinacci, Guglielmo, Ruzzon, A., Sakakita, H., Sanchez, R., Sarff, J. S., Sattin, F., Scaggion, A., Scarin, P., Schneider, W., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spolaore, M., Spong, D. A., Spizzo, G., Takechi, M., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Veranda, M., Vianello, N., Villone, F., Wang, Z., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zollino, G., and Zuin, M.

Subjects
Nuclear and High Energy Physics, RFX-mod, Tokamak, Nuclear engineering, PLASMAS, CONFINEMENT, reversed field pinch, magnetic confinement, law.invention, law, Physics::Plasma Physics, RFP, Scaling, Mod, Physics, Reversed field pinch, STABILITY, Magnetic confinement fusion, INTERNAL TRANSPORT BARRIER, Plasma, Fusion power, Condensed Matter Physics, REVERSED-FIELD-PINCH, Atomic physics, Magnetohydrodynamics, Stellarator
Abstract

This paper summarizes the main achievements of the RFX fusion science program in the period between the 2008 and 2010 IAEA Fusion Energy Conferences. RFX-mod is the largest reversed field pinch in the world, equipped with a system of 192 coils for active control of MHD stability. The discovery and understanding of helical states with electron internal transport barriers and core electron temperature >1.5 keV significantly advances the perspectives of the configuration. Optimized experiments with plasma current up to 1.8 MA have been realized, confirming positive scaling. The first evidence of edge transport barriers is presented. Progress has been made also in the control of first-wall properties and of density profiles, with initial first-wall lithization experiments. Micro-turbulence mechanisms such as ion temperature gradient and micro-tearing are discussed in the framework of understanding gradient-driven transport in low magnetic chaos helical regimes. Both tearing mode and resistive wall mode active control have been optimized and experimental data have been used to benchmark numerical codes. The RFX programme also provides important results for the fusion community and in particular for tokamaks and stellarators on feedback control of MHD stability and on three-dimensional physics. On the latter topic, the result of the application of stellarator codes to describe three-dimensional reversed field pinch physics will be presented. © 2011 IAEA, Vienna.

Published
2011

31. Overview of RFX-mod results

Author

R. Paccagnella, Cesare Taliercio, J. Adamek, V. Antoni, A. Pizzimenti, Gianluca Spizzo, Gabriele Manduchi, E. Spada, Vanni Toigo, D. Terranova, Alberto Ferro, N. Pomaro, P. Zaccaria, Rita Lorenzini, B. E. Chapman, Piero Martin, L. Guazzotto, A. Zamengo, Simone Peruzzo, Elena Gaio, Italo Predebon, V. Igochine, F. Milani, M. Spolaore, Oliviero Barana, Francesco Gnesotto, Alessandro Fassina, Giuseppe Marchiori, E. Gazza, G. Serianni, L. Zanotto, Piergiorgio Sonato, L. Piron, A. De Lorenzi, Diego Marcuzzi, Alessandra Canton, Matteo Zuin, T. Bolzonella, Federica Bonomo, Fabio Villone, M. Valisa, S. Cappello, H. Zohm, R. Cavazzana, J. Brotankova, Maria Ester Puiatti, M. Gobbin, P. Scarin, P. Zanca, Silvia Spagnolo, M. Baruzzo, Lionello Marrelli, Fabio Sattin, A. Buffa, Nicola Vianello, Fulvio Auriemma, Karsten McCollam, S. Ortolani, J. S. Sarff, S. Dal Bello, M. Cavinato, Paolo Bettini, P. Piovesan, G. Rostagni, P. Innocente, P. Buratti, M. Moresco, Roscoe White, Leonardo Giudicotti, Anton Soppelsa, Guglielmo Rubinacci, Sheena Menmuir, Emilio Martines, Paolo Franz, L. Carraro, D. Bonfiglio, Enrico Zilli, S. Martini, G. De Masi, L. Apolloni, Giuseppe Chitarin, M. Brombin, R. Piovan, Matteo Agostini, J.A. Reusch, Barbara Zaniol, Yueqiang Liu, S. C. Guo, Dominique Escande, S.V. Annibaldi, Alberto Alfier, L. Novello, Luca Grando, Adriano Luchetta, Roberto Pasqualotto, D. Yadikin, Martin, P, Apolloni, L, Puiatti, M, Adamek, J, Agostini, M, Alfier, A, Annibaldi, S, Antoni, V, Auriemma, F, Barana, O, Baruzzo, M, Bettini, P, Bolzonella, T, Bonfiglio, D, Bonomo, F, Brombin, M, Brotankova, J, Buffa, A, Buratti, P, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cavinato, M, Chapman, B, Chitarin, G, Dal Bello, S, De Lorenzi, A, De Masi, G, Escande, D, Fassina, A, Ferro, A, Franz, P, Gaio, E, Gazza, E, Giudicotti, L, Gnesotto, F, Gobbin, M, Grando, L, Guazzotto, L, Guo, S, Igochine, V, Innocente, P, Liu, Y, Lorenzini, R, Luchetta, A, Manduchi, G, Marchiori, G, Marcuzzi, D, Marrelli, L, Martini, S, Martines, E, Mccollam, K, Menmuir, S, Milani, F, Moresco, M, Novello, L, Ortolani, S, Paccagnella, R, Pasqualotto, R, Peruzzo, S, Piovan, R, Piovesan, P, Piron, L, Pizzimenti, A, Pomaro, N, Predebon, I, Reusch, J, Rostagni, G, Rubinacci, G, Sarff, J, Sattin, F, Scarin, P, Serianni, G, Sonato, P, Spada, E, Soppelsa, A, Spagnolo, S, Spolaore, M, Spizzo, G, Taliercio, C, Terranova, D, Toigo, V, Valisa, M, Vianello, N, Villone, F, White, R, Yadikin, D, Zaccaria, P, Zamengo, A, Zanca, P, Zaniol, B, Zanotto, L, Zilli, E, Zohm, H, Zuin, M, Martin, P., Apolloni, L., Puiatti, M. E., Adamek, J., Agostini, M., Alfier, A., Annibaldi, S. V., Antoni, V., Auriemma, F., Barana, O., Baruzzo, M., Bettini, P., Bolzonella, T., Bonfiglio, D., Bonomo, F., Brombin, M., Brotankova, J., Buffa, A., Buratti, P., Canton, A., Cappello, S., Carraro, L., Cavazzana, R., Cavinato, M., Chapman, B. E., Chitarin, G., Dal Bello, S., De Lorenzi, A., De Masi, G., Escande, D. F., Fassina, A., Ferro, A., Franz, P., Gaio, E., Gazza, E., Giudicotti, L., Gnesotto, F., Gobbin, M., Grando, L., Guazzotto, L., Guo, S. C., Igochine, V., Innocente, P., Liu, Y. Q., Lorenzini, R., Luchetta, A., Manduchi, G., Marchiori, G., Marcuzzi, D., Marrelli, L., Martini, S., Martines, E., Mccollam, K., Menmuir, S., Milani, F., Moresco, M., Novello, L., Ortolani, S., Paccagnella, R., Pasqualotto, R., Peruzzo, S., Piovan, R., Piovesan, P., Piron, L., Pizzimenti, A., Pomaro, N., Predebon, I., Reusch, J. A., Rostagni, G., Rubinacci, Guglielmo, Sarff, J. S., Sattin, F., Scarin, P., Serianni, G., Sonato, P., Spada, E., Soppelsa, A., Spagnolo, S., Spolaore, M., Spizzo, G., Taliercio, C., Terranova, D., Toigo, V., Valisa, M., Vianello, N., Villone, F., White, R. B., Yadikin, D., Zaccaria, P., Zamengo, A., Zanca, P., Zaniol, B., Zanotto, L., Zilli, E., Zohm, H., and Zuin, M.

Subjects
Physics, Nuclear and High Energy Physics, Leading edge, Tokamak, RFX-mod, Reversed field pinch, MHD, magnetic confinement, Magnetic confinement fusion, reversed field pinch, Fusion power, Condensed Matter Physics, TRANSPORT, law.invention, LUNDQUIST NUMBER, Nuclear physics, REVERSED-FIELD-PINCH, EDGE, law, RFP, Electron temperature, Magnetohydrodynamics, Plasma stability
Abstract

With the exploration of the MA plasma current regime in up to 0.5 s long discharges, RFX-mod has opened new and very promising perspectives for the reversed field pinch (RFP) magnetic configuration, and has made significant progress in understanding and improving confinement and in controlling plasma stability. A big leap with respect to previous knowledge and expectations on RFP physics and performance has been made by RFX-mod since the last 2006 IAEA Fusion Energy Conference. A new self-organized helical equilibrium has been experimentally achieved (the Single Helical Axis - SHAx - state), which is the preferred state at high current. Strong core electron transport barriers characterize this regime, with electron temperature gradients comparable to those achieved in tokamaks, and by a factor of 4 improvement in confinement time with respect to the standard RFP. RFX-mod is also providing leading edge results on real-time feedback control of MHD instabilities, of general interest for the fusion community. © 2009 IAEA, Vienna.

Published
2009

32. Physics of tearing mode rotation and slow-down in the RFX-mod tokamak

Author

L. Cordaro, P. Zanca, M. Zuin, F. Auriemma, A. Fassina, E. Martines, B. Zaniol, R. Cavazzana, G. De Masi, G. Grenfell, B. Momo, S. Spagnolo, M. Spolaore, N. Vianello, Cordaro, L, Zanca, P, Zuin, M, Auriemma, F, Fassina, A, Martines, E, Zaniol, B, Cavazzana, R, De Masi, G, Grenfell, G, Momo, B, Spagnolo, S, Spolaore, M, and Vianello, N

Subjects
Nuclear and High Energy Physics, diamagnetic drift, tearing mode, mode rotation, Condensed Matter Physics, tokamak
Abstract

We present a study of the fast, spontaneous rotation regime of tearing modes (TM) in the RFX-mod circular tokamak discharges. Integrated analyses of magnetic, flow and kinetic measurements, are discussed. This analysis of rotation frequency components related to the ion flow and diamagnetic drift shows that the TM fast rotation is mainly driven by the diamagnetic drift. The global decrease of the temperature profile, induced by a growing mode amplitude, can explain the slowing-down of the rotation, which in turn can trigger a potentially disruptive sequence. We show that in RFX-mod the slowing-down cannot be explained solely on the basis of the electromagnetic torque with the external conductive structures, as often reported in literature from other experiments. This analysis, indeed, suggests a strong relationship between the TM dynamics and the transport physics. Statistical analysis of disruptions with slowing down of island rotation shows that TMs take a part in the disruption, even without a locking to the wall.

Published
2022

33. On the road to ITER NBIs: SPIDER improvement after first operation and MITICA construction progress

Author

M. Tardocchi, G. Mico, Hitesh Patel, V. Antoni, A. Garbuglia, A. Masiello, Emanuele Sartori, L. Giacomelli, M. Brombin, F. Geli, A. De Lorenzi, Pierluigi Veltri, Piero Agostinetti, Gabriele Manduchi, S. Cristofaro, T. Maejima, D. Bruno, F. Paolucci, Marica Rebai, L. Cordaro, M. Zaupa, B. Pouradier-Duteil, S. Denizeau, M. Vignando, R. Lorenzini, Y. Yamashita, M. Dan, R. Casagrande, D. Lopez-Bruna, Federica Bonomo, R. Zagorski, M. Siragusa, M. Zuin, A. Rigoni-Garola, V. Candeloro, Daniel Gutierrez, H. Decamps, C. Taliercio, Loris Zanotto, F. Fellin, C. Rotti, M. Fadone, R. Delogu, M. Valente, M. Bigi, A. Canton, Gabriele Croci, R. Agnello, A. Pimazzoni, Bernd Heinemann, Emilio Martines, O. McCormack, M. Dalla Palma, Kazuhiro Watanabe, J. Graceffa, Nicola Pilan, Simone Peruzzo, Vanni Toigo, E. Oshita, A. Rizzolo, Elena Gaio, D. Aprile, M. Dremel, M. De Muri, B. Zaniol, R. Milazzo, C. Cavallini, Silvia Spagnolo, Gianluigi Serianni, N. Cruz, A. Sottocornola, Claudia Gasparrini, Hiroyuki Tobari, L. Trevisan, Namita Singh, P. Tomsic, T. Patton, F. Gasparini, F. Taccogna, Diego Marcuzzi, Atsushi Kojima, E. Spada, A. Muraro, Ursel Fantz, M. Pavei, A.K. Chakraborty, Francesco Gnesotto, A. Ferro, S. Konno, Tullio Bonicelli, Roberto Cavazzana, Giuseppe Chitarin, Nicolò Marconato, Giuseppe Gorini, Adriano Luchetta, A. Maistrello, A. Zamengo, C. Poggi, Marco D’Arienzo, N. Pomaro, F. Panin, A. Rousseau, Monica Spolaore, G. Berton, J.F. Moreno, W. Kraus, S. Dal Bello, M. Battistella, P. Tinti, G. Kouzmenko, D. Boilson, Piergiorgio Sonato, Marco Cavenago, C. Wimmer, M. J. Singh, M. Rutigliano, P. Jain, Pierluigi Zaccaria, M. Ugoletti, Marco Boldrin, D. Rigamonti, Katsuyoshi Tsumori, S. Manfrin, D. Wünderlich, Gwenael Fubiani, Muriel Simon, G. Martini, G. Agarici, Mieko Kashiwagi, D. Terranova, Marco Barbisan, S. Martini, M. Urbani, Luca Grando, Roberto Pasqualotto, J. Zacks, A. Tonti, M. Recchia, C. Labate, Matteo Agostini, P.B. Krastev, V. Pilard, G. Gomez, A. Shepherd, Toigo, V, Marcuzzi, D, Serianni, G, Boldrin, M, Chitarin, G, Bello, S, Grando, L, Luchetta, A, Pasqualotto, R, Zaccaria, P, Zanotto, L, Agnello, R, Agostinetti, P, Agostini, M, Antoni, V, Aprile, D, Barbisan, M, Battistella, M, Berton, G, Bigi, M, Brombin, M, Candeloro, V, Canton, A, Casagrande, R, Cavallini, C, Cavazzana, R, Cordaro, L, Cruz, N, Palma, M, Dan, M, De Lorenzi, A, Delogu, R, De Muri, M, Denizeau, S, Fadone, M, Fellin, F, Ferro, A, Gaio, E, Gasparini, F, Gasparrini, C, Gnesotto, F, Jain, P, Krastev, P, Lopez-Bruna, D, Lorenzini, R, Maistrello, A, Manduchi, G, Manfrin, S, Marconato, N, Martines, E, Martini, G, Martini, S, Milazzo, R, Patton, T, Pavei, M, Peruzzo, S, Pilan, N, Pimazzoni, A, Poggi, C, Pomaro, N, Pouradier-Duteil, B, Recchia, M, Rigoni-Garola, A, Rizzolo, A, Sartori, E, Shepherd, A, Siragusa, M, Sonato, P, Sottocornola, A, Spada, E, Spagnolo, S, Spolaore, M, Taliercio, C, Terranova, D, Tinti, P, Tomsic, P, Trevisan, L, Ugoletti, M, Valente, M, Vignando, M, Zagorski, R, Zamengo, A, Zaniol, B, Zaupa, M, Zuin, M, Cavenago, M, Boilson, D, Rotti, C, Veltri, P, Decamps, H, Dremel, M, Graceffa, J, Geli, F, Urbani, M, Zacks, J, Bonicelli, T, Paolucci, F, Garbuglia, A, Agarici, G, Gomez, G, Gutierrez, D, Kouzmenko, G, Labate, C, Masiello, A, Mico, G, Moreno, J, Pilard, V, Rousseau, A, Simon, M, Kashiwagi, M, Tobari, H, Watanabe, K, Maejima, T, Kojima, A, Oshita, E, Yamashita, Y, Konno, S, Singh, M, Chakraborty, A, Patel, H, Singh, N, Fantz, U, Bonomo, F, Cristofaro, S, Heinemann, B, Kraus, W, Wimmer, C, Wunderlich, D, Fubiani, G, Tsumori, K, Croci, G, Gorini, G, Mccormack, O, Muraro, A, Rebai, M, Tardocchi, M, Giacomelli, L, Rigamonti, D, Taccogna, F, Bruno, D, Rutigliano, M, D'Arienzo, M, Tonti, A, and Panin, F

Subjects
Tokamak, Nuclear engineering, design, 7. Clean energy, 01 natural sciences, negative ion source, 010305 fluids & plasmas, law.invention, ITER neutral beam injector, ITER neutral beam injectors, Negative ion beam, Negative ion source, law, iter neutral beam injectors, 0103 physical sciences, General Materials Science, 010306 general physics, Civil and Structural Engineering, Dummy load, Magnetic filter, negative ion beam, Mechanical Engineering, Injector, Beam optics, Power (physics), Nuclear Energy and Engineering, Environmental science, Beam (structure), Voltage
Abstract

To reach fusion conditions and control the plasma configuration in ITER, the next step in tokamak fusion research, two neutral beam injectors (NBIs) will supply 16.5 MW each, by neutralizing accelerated negative hydrogen or deuterium ions. The requirements of ITER NBIs (40A/1 MeV D- ions for ≤1 h, 46A/870 keV H- ions for ≤1000 s) have never been simultaneously attained. So in the Neutral Beam Test Facility (NBTF, Consorzio RFX, Italy) the operation of the full-scale ITER NBI prototype (MITICA) will be tested and optimised up to full performances, focussing on accelerator (including voltage holding), beam optics, neutralisation, residual ion removal. The NBTF includes also the full-scale prototype of the ITER NBI source with 100 keV particle energy (SPIDER), for early investigation of: negative ion production and extraction, source uniformity, negative ion current density and beam optics. This paper will describe the main results of the first two years of SPIDER operation, devoted to characterizing plasma and beam parameters, including investigation of RF-plasma coupling efficiency and magnetic filter field effectiveness in reducing co-extracted electrons. SPIDER is progressing towards the first caesium injection, which aims at increasing the negative ion density. A major shutdown, planned for 2021, to solve the issues identified during the operation and to carry out programmed modifications, will be outlined. The installation of each MITICA power supply and auxiliary system is completed; in-vessel mechanical components are under procurement by Fusion for Energy (F4E). Integration, commissioning and test of the power supplies, procured by F4E and QST, as the Japanese Domestic Agency (JADA), will be presented. In particular, 1.0MV insulating tests were carried out step-by-step and successfully completed. In 2020 integrated tests of the power supplies on the accelerator dummy load started, including the assessment of their resilience to accelerator grid breakdowns using a short-circuit device located in vacuum. The aggressive programme, to validate the NBI design at NBTF and to meet ITER schedule (requiring NBIs in operation in 2032), will be outlined. Unfortunately, in 2020 the coronavirus disease infection affected the NBTF activities. A solution to proceed with integrated power tests despite the coronavirus is presented.

Published
2021

34. Turbulent filament properties in L and H-mode regime in the RFX-mod operating as a tokamak

Author

L. Carraro, B. Momo, L. Cordaro, Roberto Cavazzana, M. Veranda, I. Predebon, Silvia Spagnolo, C. Hidalgo, P. Scarin, M. Zuin, Lionello Marrelli, Emilio Martines, B. Zaniol, N. Vianello, G. De Masi, M. E. Puiatti, Paolo Franz, Davide Abate, RFX-mod Team, Monica Spolaore, B. Ph. van Milligen, G. Grenfell, Matteo Agostini, Grenfell, G, Spolaore, M, Abate, D, Carraro, L, Marrelli, L, Predebon, I, Spagnolo, S, Veranda, M, Agostini, M, van Milligen, B, Cavazzana, R, Cordaro, L, De Masi, G, Franz, P, Hidalgo, C, Martines, E, Momo, B, Puiatti, M, Scarin, P, Vianello, N, Zaniol, B, Zuin, M, and RFX-mod Team

Subjects
Nuclear and High Energy Physics, Tokamak, blobs, 01 natural sciences, biasing, 010305 fluids & plasmas, law.invention, Protein filament, Physics::Plasma Physics, law, Mod, 0103 physical sciences, magnetic fluctuations, 010306 general physics, filaments, vorticity, Physics, Turbulence, blob, turbulence, Mode (statistics), Biasing, Mechanics, Vorticity, Condensed Matter Physics, H-mode, filament, magnetic fluctuation
Abstract

The dynamics of turbulent filaments in L and ELM-free H-mode in the RFX-mod device operating as a tokamak is discussed in the present work. L-H transition and sustained H-mode have been achieved in the RFX-mod with the aid of an external electrode biasing (Spolaore et al 2017 Nucl. Fusion 57 116039). Through advanced statistical techniques, turbulent filaments are detected and tracked from the edge to the scrape-off layer (SOL) in a two-dimension floating potential map (measured with a 2D array of Langmuir probes) related with extreme events of a fixed ion saturation current signal in the SOL. While in L-mode filaments travel almost freely, their motion becomes restricted to the near SOL during the induced biasing H-mode. In this region, the background shear decorrelation time becomes shorter than the convective filament time, favouring its suppression. However, the experimental observation of a nearly 'trapped' monopole potential points out the possible role of the vortex selection mechanism. The sign and magnitude of the turbulent parallel vorticity are consistent with the E × B background vorticity in the SOL in this regime, while in L-mode, the inferred turbulent vorticity is always above the background one. The sparse filamentary transport in the far SOL during H-mode is further confirmed from the measurements of a poloidally symmetric array of electrostatic sensors on the wall. Lastly, the radial velocity of filaments in both regimes was discussed in the framework of analytical scalings. Filaments in L-mode exhibit a reasonable agreement with the sheath-limited regime in the cold ion approximation, with a non-negligible associated parallel current density measured with a set of 3-axial pick-up coils installed in the probe head. In H-mode, the collisionality increases near the separatrix while filaments seem to follow the inertial regime before become trapped.

Published
2020
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35. Design of embedded electrostatic sensors for the RFX-mod2 device

Author

Roberto Cavazzana, Simone Peruzzo, B. Momo, Nicola Vianello, Nicolò Marconato, M. Bernardi, M. Spolaore, G. De Masi, G. Grenfell, Silvia Spagnolo, Matteo Zuin, Emilio Martines, M. Dalla Palma, Spagnolo, S, Spolaore, M, Bernardi, M, Cavazzana, R, Peruzzo, S, Dalla Palma, M, De Masi, G, Grenfell, G, Marconato, N, Martines, E, Momo, B, Vianello, N, and Zuin, M

Subjects
Tokamak, Plasma diagnostic, probe, 01 natural sciences, Plasma diagnostics, 030218 nuclear medicine & medical imaging, law.invention, 03 medical and health sciences, symbols.namesake, 0302 clinical medicine, Optics, law, 0103 physical sciences, Langmuir probe, Instrumentation, Mathematical Physics, Physics, Toroid, 010308 nuclear & particles physics, business.industry, Plasma, Analysis and statistical methods, probes, Electrostatics, Magnetic Confinement Fusion, Pinch, symbols, Plasma diagnostics - probes, Electric potential, business, Analysis and statistical method
Abstract

RFX-mod experiment is currently under a challenging upgrade of the machine assembly. One of the main purpose of RFX-mod2, the upgraded device, is the achievement of better performances by decreasing the tearing modes amplitude in Reversed-Field Pinch (RFP) configuration thanks to a higher plasma-shell proximity [1, 2]. Moreover, most of the innovations characterizing the device and its diagnostics are conceived with the aim to operate in both RFP and tokamak configurations. This attention on the different configurations is taken into account in the electrostatic sensors design and layout. RFX-mod2 will be equipped with poloidal and toroidal arrays of electrostatic sensors, measuring plasma density and temperature, plasma potential, particle and energy fluxes and floating potential fluctuations. Two toroidal arrays of 72 sensors each (one on the high field side and one on the low field side) are foreseen. Moreover, four poloidal arrays of 28 elements will be housed. A such large amount of sensors is due to the requirement of a better characterization of the numerous instabilities observed in RFP plasma edge, along with the possibility to study the plasma shape in different tokamak configurations (circular, single null, double null). Two different kinds of Langmuir probes configurations will be installed: the so-called single probe and 5-pin balanced triple probe. The conceptual design of the sensors takes inspiration from the model successfully installed on RFX-mod [3], that allows to remove tiles in case of damage, by means of a remote handling manipulator. Each sensor is composed by two parts: the tile side houses pins directly faced to the plasma and connected by springs to the shell side, where specific contacts, conveniently isolated, carry the signals to the cables.

Published
2019

36. Design constraints on new vacuum components of RFX-mod2 upgrade using electrical modeling of reversed field pinch plasma

Author

Monica Spolaore, Matteo Zuin, Simone Peruzzo, Lionello Marrelli, Francesco Gnesotto, Laura Marsango, Emilio Martines, Roberto Cavazzana, Cavazzana, R, Marsango, L, Peruzzo, S, Zuin, M, Gnesotto, F, Marrelli, L, Spolaore, M, and Martines, E

Subjects
Tokamak, Materials science, Arc formation, Reversed field pinch, Mechanical Engineering, Divertor, Mechanics, Plasma, Halo current, Civil and Structural Engineering, Nuclear Energy and Engineering, Materials Science (all), 01 natural sciences, Arc suppression, 010305 fluids & plasmas, law.invention, law, 0103 physical sciences, Limiter, General Materials Science, Electric potential, 010306 general physics, Voltage
Abstract

The externally applied loop voltage, required to drive current carrying magnetic configurations, such as tokamaks or reversed field pinches (RFP), can induce currents between the plasma and the surrounding conducting components, such as limiters, divertor sections, stabilizing plates or enclosing stabilizing shells with insulated electrical gaps. An appropriate modeling of this problem can quantify these currents and give constraints for the design of new devices. In this paper a methodology based on lumped element circuit is used to evaluate this problem for the case of in vessel components of the RFX-mod2, which led to a redesign of the electrical connections of plasma facing components. In the new design some parts, having applied potential in the kV range, are still exposed to the weakly ionized scrape off plasma. The process of arc formation between them and their prevention had been experimentally investigated and possible arc suppression strategies identified.

Published
2018

37. H-mode achievement and edge features in RFX-mod tokamak operation

Author

N. Vianello, Roberto Paccagnella, Barbara Zaniol, Paolo Scarin, Emilio Martines, Paolo Franz, G. De Masi, C. Taliercio, C. Piron, Giuseppe Marchiori, S. Dal Bello, L. Zanotto, Roberto Cavazzana, Matteo Zuin, Luca Grando, C. Finotti, Lionello Marrelli, B. Momo, M. E. Puiatti, G. Grenfell, Alberto Ferro, M. Spolaore, Paolo Innocente, P. Piovesan, Lorella Carraro, L. Cordaro, Silvia Spagnolo, M. Recchia, O. Kudlacek, Spolaore, M, Cavazzana, R, Marrelli, L, Carraro, L, Franz, P, Spagnolo, S, Zaniol, B, Zuin, M, Cordaro, L, Dal Bello, S, De Masi, G, Ferro, A, Finotti, C, Grando, L, Grenfell, G, Innocente, P, Kudlacek, O, Marchiori, G, Martines, E, Momo, B, Paccagnella, R, Piovesan, P, Piron, C, Puiatti, M, Recchia, M, Scarin, P, Taliercio, C, Vianello, N, and Zanotto, L

Subjects
ELM filament, Nuclear and High Energy Physics, Tokamak, Edge (geometry), 01 natural sciences, 010305 fluids & plasmas, law.invention, Physics::Plasma Physics, law, 0103 physical sciences, 010306 general physics, SN shape, ELM filaments, Physics, Reversed field pinch, electrode biasing, Biasing, Radius, Plasma, Condensed Matter Physics, Computational physics, electromagnetic measure, H-mode, electromagnetic measures, Magnetohydrodynamics, Current density
Abstract

The RFX-mod experiment is a fusion device designed to operate as a reversed field pinch (RFP), with a major radius R = 2 m and a minor radius a = 0.459 m. Its high versatility recently allowed operating it also as an ohmic tokamak, allowing comparative studies between the two configurations in the same device. The device is equipped with a state of the art MHD mode feedback control system providing a magnetic boundary effective control, by applying resonant or non-resonant magnetic perturbations (MP), both in RFP and in tokamak configurations. In the fusion community the application of MPs is widely studied as a promising tool to limit the impact of plasma filaments and ELMs (edge localized modes) on plasma facing components. An important new research line is the exploitation of the RFX-mod active control system for ELM mitigation studies. As a first step in this direction, this paper presents the most recent achievements in term of RFX-mod tokamak explored scenarios, which allowed the first investigation of the ohmic and edge biasing induced H-mode. The production of D-shaped tokamak discharges and the design and deployment of an insertable polarized electrode were accomplished. Reproducible H-mode phases were obtained with insertable electrode negative biasing in single null discharges, representing an unexplored scenario with this technique. Important modifications of the edge plasma density and flow properties are observed. During the achieved H-mode ELM-like electromagnetic composite filamentary structures are observed. They are characterized by clear vorticity and parallel current density patterns.

Published
2017

38. Novel Technique for Direct Measurement of the Plasma Diffusion Coefficient in Magnetized Plasma

Author

J. Adamek, G. Van Oost, Codrina Ionita, C. Costin, Roman Schrittwieser, J. Stöckel, Emilio Martines, J. Brotankova, G. Popa, Brotankova, J, Martines, E, Adamek, J, Stockel, J, Popa, G, Costin, C, Ionita, C, Schrittwieser, R, and Van Oost, G

Subjects
Tokamak, Materials science, Physics::Instrumentation and Detectors, Plasma diffusion, Plasma, Condensed Matter Physics, law.invention, Ion, Nuclear magnetic resonance, Physics::Plasma Physics, law, Electrode, Tube (fluid conveyance), Exponential decay, Diffusion (business), Atomic physics, Diffusion coefficient, Probe diagnostic
Abstract

The diffusion coefficient in the edge plasma of fusion devices is measured by a new technique. The method is based on studying the decay of the plasma fluctuation spectrum inside the so-called “Ball-pen probe”: a small ceramic tube having its mouth flush with a magnetic surface and a movable electrode inside the tube. When the electrode protrudes from the tube, the measured signal shows the floating potential fluctuations of the plasma or the ion saturation current outside the tube. Retracting the electrode into the tube, the power spectrum of the signal displays an exponential decay that is different for different frequencies. Assuming a mainly diffusive behaviour of the plasma inside the tube, the spectrum decay length can be used to derive the value of the diffusion coefficient. The measurements were performed at several radial positions in the CASTOR edge region for three different values of Btor. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Published
2008

39. Density limit studies in the tokamak and the reversed-field pinch

Author

Matteo Zuin, G. De Masi, Roberto Cavazzana, Fulvio Auriemma, O. Tudisco, William Bin, P. Buratti, Lorella Carraro, N. Vianello, Gustavo Granucci, Cristian Galperti, Emilio Martines, G. Ciaccio, L. Marrelli, Roscoe White, Oliver Schmitz, M. Spolaore, G. Pucella, Saul Garavaglia, M. Marinucci, Matteo Agostini, M. E. Puiatti, Paolo Scarin, Gianluca Spizzo, B. Esposito, Carlo Sozzi, E. Alessi, C. Mazzotta, A. Moro, D. Minelli, Spizzo, G, Pucella, G, Tudisco, O, Zuin, M, Agostini, M, Alessi, E, Auriemma, F, Bin, W, Buratti, P, Carraro, L, Cavazzana, R, Ciaccio, G, Masi, G, Esposito, B, Galperti, C, Garavaglia, S, Granucci, G, Marinucci, M, Marrelli, L, Martines, E, Mazzotta, C, Minelli, D, Moro, A, Puiatti, M, Scarin, P, Sozzi, C, Spolaore, M, Schmitz, O, Vianello, N, and White, R

Subjects
Nuclear and High Energy Physics, RADIAL ELECTRIC-FIELD, Tokamak, particle orbits, design, CONFINEMENT, plasmamaterial interactions, law.invention, plasmamaterial interaction, PARTICLE-TRANSPORT, law, Electric field, Thermal, and computerized simulation, Limit (mathematics), theory, MARFE, particle orbit and trajectory, Physics, boundary layer effects, two-fluid and multi-fluid plasmas, Condensed Matter Physics, DISCHARGES, RFX-MOD, PLASMA, Reversed field pinch, Mechanics, Plasma, particle orbit, ASDEX UPGRADE, plasma-material interactions, boundary layer effect, two-fluid and multi-fluid plasma, Pinch, TURBULENCE, Atomic physics, Stellarator
Abstract

The ITER scenarios and the project of DEMO involve stable operation above the Greenwald density, which justifies efforts to understand and overcome the density limit, this last observed as a disruptive termination of tokamak discharges and a thermal crash (with no disruption) of stellarator and reversed-field pinch (RFP) ones. Both in the tokamak and the RFP, new findings show that the high density limit is not governed by a unique, theoretically well-determined physical phenomenon, but by a combination of complex mechanisms involving two-fluid effects, electrostatic plasma response to magnetic islands and plasma-wall interaction. In this paper we will show new evidence challenging the traditional picture of the 'Greenwald limit', in particular with reference to the role of thermal instabilities and the edge radial electric field Er in the development of this limit. © 2015 EURATOM.

Published
2015
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40. Turbulent electromagnetic filaments in actively modulated toroidal plasma edge

Author

D. Terranova, G. De Masi, Matteo Zuin, Gianluca Spizzo, Cristina Rea, Paolo Zanca, Paolo Scarin, Silvia Spagnolo, L. Marrelli, M. E. Puiatti, Matteo Agostini, N. Vianello, A. Mazzi, Roberto Cavazzana, B. Momo, Emilio Martines, M. Spolaore, Paolo Innocente, Spolaore, M, Agostini, M, Momo, B, Rea, C, Vianello, N, Zuin, M, Cavazzana, R, De Masi, G, Innocente, P, Marrelli, L, Martines, E, Mazzi, A, Puiatti, M, Spagnolo, S, Spizzo, G, Scarin, P, Terranova, D, and Zanca, P

Subjects
Physics, Nuclear and High Energy Physics, Tokamak, Toroid, magnetic perturbation, Reversed field pinch, Boundary (topology), Mechanics, reversed field pinch, Edge (geometry), Condensed Matter Physics, law.invention, Protein filament, electromagnetic turbulence, law, Physics::Plasma Physics, Beta (plasma physics), magnetic perturbations, plasma vorticity, Atomic physics, tokamak, Topology (chemistry)
Abstract

Filament or blob structures have been observed in all magnetic configurations with very similar features despite the difference in the magnetic geometry, and are believed to play an important role in convecting particles and energy towards the wall. Despite their different generation mechanism, turbulent structures and edge-localized mode (ELM) filaments share some common physical features. The electromagnetic effects on filament structures deserve particular interest, among others reasons for the implication they could have for ELM, related for instance to their dynamics in the transition region between closed and open field lines or to the possibility, at high beta regimes, of causing line bending which could enhance the interaction of blobs with the first wall. A direct characterization of the effects of active modification of the edge topology on EM turbulent filament structures is presented, comparing reversed field pinch and tokamak configurations. Measurements are obtained in the RFX-mod device, which allows operation in both configurations and with different equilibria. The RFX-mod experiment versatility is exploited also from the point of view of the active control of the edge magnetic topology, equipped with an advanced system for edge boundary feedback control. Three different case studies of actively controlled magnetic perturbations are shown, focusing on the filament interaction with local magnetic islands. High-frequency fluctuations, characterizing electrostatic and magnetic filament features, and the associated transport coefficients have been observed to be strongly affected by the island proximity and topology.

Published
2015
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41. Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

Author

Silvia Spagnolo, N. Vianello, Emilio Martines, Ambrogio Fasoli, Roberto Cavazzana, Ivo Furno, Christian Theiler, Matteo Agostini, J. A. Alonso, A. Scaggion, D. Carralero, G. De Masi, F. Avino, M. Spolaore, Gianluca Spizzo, B. Momo, Paolo Scarin, Matteo Zuin, C. Hidalgo, Spolaore, M, Vianello, N, Furno, I, Carralero, D, Agostini, M, Alonso, J, Avino, F, Cavazzana, R, De Masi, G, Fasoli, A, Hidalgo, C, Martines, E, Momo, B, Scaggion, A, Scarin, P, Spagnolo, S, Spizzo, G, Theiler, C, and Zuin, M

Subjects
Physics, Tokamak, Toroid, Reversed field pinch, WAVES, current filament, Vorticity, Condensed Matter Physics, TRANSPORT, Computational physics, law.invention, Vortex, Physics::Fluid Dynamics, law, Beta (plasma physics), plasma turbulence, electromagnetic structure, Torpex, Atomic physics, PROGRESS, Stellarator
Abstract

Electromagnetic features of turbulent filaments, emerging from a turbulent plasma background, have been studied in four different magnetic configurations: the stellarator TJ-II, the Reversed Field Pinch RFX-mod, a device that can be operated also as a ohmic tokamak, and the Simple Magnetized Torus, TORPEX. By applying an analogous diagnostic concept in all cases, direct measurements of both field-aligned current density and vorticity were performed inside the filament. The inter-machine comparison reveals a clear dependence of the filament vorticity upon the local time-averaged E × B flow shear. Furthermore, a wide range of local beta was explored allowing concluding that this parameter plays a fundamental role in the appearance of filament electromagnetic features.

Published
2015

42. Direct measurements of the plasma potential by katsumata-type probes

Author

Emilio Martines, J. Stöckel, J. Adamek, G. Popa, J. Brotankova, Codrina Ionita, Roman Schrittwieser, C. Costin, G. Van Oost, L. van de Peppel, Schrittwieser, R, Ionita, C, Adamek, J, Stockel, J, Brotankova, J, Martines, E, Popa, G, Costin, C, Van de Peppel, L, Van Oost, G, van de Peppel, L, and Stöckel, J

Subjects
Materials science, Tokamak, Measure (physics), General Physics and Astronomy, Toroidal plasma system, Electron, Plasma, Edge (geometry), CASTOR, Katsumata probe, Ion, law.invention, Electron flux, law, Plasma potential, Plasma diagnostics, Atomic physics, Probe diagnostic
Abstract

By taking advantage of the inherent difference between the gyro-radii of ions and electrons in a magnetised plasma, we developed a method to measure the plasma potential directly. The principle is based on the concept of the Katsumata probe. The probe collector is hidden inside a tube which screens an adjustable fraction of the electron flux whereas it lets pass most of the ions. In this paper an arrangement of three Katsumata-type probes with different diameters is used in the edge plasma region of the CASTOR tokamak to investigate the influence of the dimension of the probe. The results show almost no influence of the probe diameter on the values of the plasma potential. © Institute of Physics, Academy of Sciences of Czech Republic 2006.

Published
2006

43. High frequency MHD activity related to type I ELMs in ASDEX Upgrade

Author

T Bolzonella, H Zohm, M Maraschek, E Martines, S Saarelma, S Günter, ASDEX Upgrade Team, Bolzonella, T, Zohm, H, Maraschek, M, Martines, E, Saarelma, S, and Gunter, S

Subjects
Physics, Magnetic confinement fusion, Collisionality, Low frequency, Condensed Matter Physics, Nuclear Energy and Engineering, ASDEX Upgrade, Physics::Plasma Physics, Electron temperature, ELM, Atomic physics, Magnetohydrodynamics, Edge-localized mode, tokamak, Saturation (magnetic)
Abstract

High frequency coherent magnetic fluctuations related to the type I edge localized mode (ELM) cycle have been found in ASDEX Upgrade. Typical frequencies are in the range 300-500 kHz, and the poloidal mode number, m, measured at the outboard midplane, is estimated to be 10-15. These MHD modes are present in many low density (low collisionality) discharges, while they have not been found in high density ones yet. New findings on already known low frequency type I ELM precursors confirm that in ASDEX Upgrade type I ELM mode precursors are normally phase locked to the wall in discharges with NBI heating parallel to and in the direction of the plasma current (co-injection) and can be seen with a non-zero rotation frequency only in shots with anti-parallel NBI (counter-injection). Additional information is given by ECE data. The existence of low and high frequency MHD events suggests an interpretation in the framework of the peeling-ballooning model. The high frequency magnetic activity seems to be related strictly to the increase in (and eventual saturation of) edge electron temperature, while low frequency modes are related directly to the ELM crash itself.

Published
2004

44. A novel approach to direct measurement of the plasma potential

Author

Milan Tichý, Codrina Ionita, Emilio Martines, Martin Hron, J. Adamek, R. Schrittwieser, P. Balan, G. Van Oost, J. Stöckel, J. Ryszawy, Adamek, J, Stockel, J, Hron, M, Ryszawy, J, Tichy, M, Schrittwieser, R, Ionita, C, Balan, P, Martines, E, and Van Oost, G

Subjects
Tokamak, Materials science, Langmuir probe, General Physics and Astronomy, Electron, Plasma, law.invention, Ion, Magnetic field, symbols.namesake, Edge plasma, Physics::Plasma Physics, Saturation current, law, Plasma potential, symbols, Plasma diagnostics, Atomic physics
Abstract

A novel probe and approach to the direct measurements of the plasma potential in a strong magnetic field is suggested. The principle of this method is to reduce the electron saturation current to the same magnitude as that of the ion saturation current. In this case, the floating potential of the probe becomes indentical to the plasma potential. This goal is attained by a shield, which screens off an adjustable part of the electron current from the probe collector due to the much smaller gyro-radius of the electrons. First systematic measurements have been perfomred in the CASTOR tokamak.

Published
2004

45. Emissive probe measurements of plasma potential fluctuations in the edge plasma regions of tokamaks

Author

C. A. F. Varandas, Milan Tichý, Horacio Fernandes, J. Stöckel, G. Van Oost, J. A. C. Cabral, H. F. C. Figueiredo, C. Ioniţă, J. Adamek, Martin Hron, Emilio Martines, P. Balan, Roman Schrittwieser, Balan, P, Schrittwieser, R, Ionita, C, Cabral, J, Figueiredo, H, Fernandes, H, Varandas, C, Adamek, J, Hron, M, Stockel, J, Martines, E, Tichy, M, and Van Oost, G

Subjects
Tokamak, Materials science, Flux, Torus, Electron, Plasma, Edge (geometry), emissive probe, law.invention, law, Electron temperature, Atomic physics, tokamak, Instrumentation, ISTTOK
Abstract

The plasma potential Φpl and its fluctuations Φpl were measured by electron emissive probes in the edge plasma regions of two fusion experiments: the Instituto Superior Tecnico Tokamak (ISTTOK) (Lisbon, Portugal), and the Czech Academy of Sciences Torus (CASTOR) tokamak (Prague, Czech Republic). Into ISTTOK, three emissive probes were inserted outside the last closed flux surface (LCFS) on different minor radii. In CASTOR, two emissive probes, poloidally separated, and two cold cylindrical probes, mounted on the same shaft, were used, which could be radially shifted outside and inside the LCFS. The advantages of a sufficiently emissive probe are that in principle Φpl and Φpl can be measured directly, without being affected by electron temperature fluctuations or drifting electrons.

Published
2003

46. Overview of the RFX-mod fusion science activity

Author

A. De Lorenzi, Rita Lorenzini, F. Belli, Andrea Rizzolo, Luca Stevanato, O. McCormack, Paolo Scarin, D. F. Escande, J. S. Sarff, M. Bigi, Y. Zhang, Alessandro Fassina, L. Piron, N. Vianello, M. E. Puiatti, Roberto Paccagnella, Fabio Villone, Piergiorgio Sonato, Nicola Pilan, Emilio Martines, James D. Hanson, C. Taliercio, A. Zamengo, M. Recchia, L. Giudicotti, M. Vallar, J.Q. Dong, M. Dalla Palma, Daniele Bonfiglio, Paolo Franz, Matthias Komm, Luis Chacon, Satoru Kiyama, N. Visona, M. Siragusa, L. Zanotto, Paolo Bettini, D. Terranova, Raul Sanchez, Roscoe White, S. Dal Bello, M. Brombin, Enrico Zilli, Francesco Gnesotto, Yueqiang Liu, S.P. Hirshman, L. Pigatto, S. Martini, Piero Martin, M. Pavei, Nisarg Patel, Alessandra Canton, Lorenzo Frassinetti, Matteo Zuin, T. Bolzonella, G. Urso, Chenguang Li, Oliver Schmitz, C. Finotti, Paolo Zanca, Chiara Bustreo, Silvia Spagnolo, M. Veranda, M. Baruzzo, V. Antoni, T. Barbui, Hajime Sakakita, Pavlos Xanthopoulos, Wolf-Dieter Schneider, Nicolò Marconato, Yoshiro Narushima, W. A. Cooper, G. Pucella, Piero Agostinetti, Lionello Marrelli, B. Liu, B. Momo, Simone Peruzzo, X. Y. Xu, Elena Gaio, M. Moresco, Francesco Ghezzi, Y. Suzuki, C. Piron, O. Tudisco, Susanna Cappello, P. Piovesan, Adriano Luchetta, A. Maistrello, F. Sattin, M. Boldrin, Donald A. Spong, A. Buffa, L. Cordaro, V. Yanovskiy, R. Cavazzana, Cristina Rea, W. Gonzalez, Matteo Agostini, R. Piovan, Songfen Liu, Giuseppe Chitarin, G. Rostagni, S. M. Deambrosis, Alberto Ferro, O. Kudlacek, M. Spolaore, Gianluca Spizzo, Paolo Innocente, Italo Predebon, G. Mazzitelli, Marco Gobbin, D. Cester, J. L. Jackson, Laszlo Sajo-Bohus, M. Valente, T.C. Luce, L. Laguardia, Diego Marcuzzi, Fulvio Auriemma, Giuseppe Marchiori, P. Vincenzi, D.K. Mansfield, E. Spada, M. Valisa, G. De Masi, Gabriele Manduchi, Lorella Carraro, E. Miorin, M. Okabayashi, S. C. Guo, Barbara Zaniol, R. Delogu, D. Lopez-Bruna, Marco Barbisan, Faa Federico Felici, Cristian Ruset, Luca Grando, R. Bilel, Mazzitelli, G., Tudisco, O., Pucella, G., Zuin, M, DAL BELLO, S, Marrelli, L, Puiatti, M, Agostinetti, P, Agostini, M, Antoni, V, Auriemma, F, Barbisan, M, Barbui, T, Baruzzo, M, Belli, F, Bettini, P, Bigi, M, Bilel, R, Boldrin, M, Bolzonella, T, Bonfiglio, D, Brombin, M, Buffa, A, Bustreo, C, Canton, A, Cappello, S, Carraro, L, Cavazzana, R, Cester, D, Chacon, L, Chitarin, G, Cooper, W, Cordaro, L, DALLA PALMA, M, Deambrosis, S, Delogu, R, De Lorenzi, A, DE MASI, G, Dong, J, Escande, D, Fassina, A, Felici, F, Ferro, A, Finotti, C, Franz, P, Frassinetti, L, Gaio, E, Ghezzi, F, Giudicotti, L, Gnesotto, F, Gobbin, M, Gonzalez, W, Grando, L, Guo, S, Hanson, J, Hirshman, S, Innocente, P, Jackson, J, Kiyama, S, Komm, M, Kudlacek, O, Laguardia, A, Li, C, Liu, B, Liu, S, Liu, Y, López Bruna, D, Lorenzini, R, Luce, T, Luchetta, A, Maistrello, A, Manduchi, G, Mansfield, D, Marchiori, G, Marconato, N, Marcuzzi, D, Martin, P, Martines, E, Martini, S, Mazzitelli, G, Mccormack, O, Miorin, E, Momo, B, Moresco, M, Narushima, Y, Okabayashi, M, Paccagnella, R, Patel, N, Pavei, M, Peruzzo, S, Pilan, N, Pigatto, L, Piovan, R, Piovesan, P, Piron, C, Piron, L, Predebon, I, Pucella, G, Rea, C, Recchia, M, Rizzolo, A, Rostagni, G, Ruset, C, Sajò Bohus, L, Sakakita, H, Sanchez, R, Sarff, J, Sattin, F, Scarin, P, Schmitz, O, Schneider, W, Siragusa, M, Sonato, P, Spada, E, Spagnolo, S, Spolaore, M, Spong, D, Spizzo, G, Stevanato, L, Suzuki, Y, Taliercio, C, Terranova, D, Tudisco, O, Urso, G, Valente, M, Valisa, M, Vallar, M, Veranda, M, Vianello, N, Villone, F, Vincenzi, P, Visonà, N, White, R, Xanthopoulos, P, Xu, X, Yanovskiy, V, Zamengo, A, Zanca, P, Zaniol, B, Zanotto, L, Zhang, Y, and Zilli, E

Subjects
Nuclear and High Energy Physics, Guiding center, Tokamak, MHD, single helicity, reversed field pinch, runaway electron, 01 natural sciences, 010305 fluids & plasmas, law.invention, 3D boundary, Physics::Plasma Physics, law, Electric field, 0103 physical sciences, 010306 general physics, PWI, tokamak, reversed field pinch, tokamak, single helicity, 3D boundary, runaway electrons, MHD, PWI, Physics, Reversed field pinch, runaway electrons, Plasma, Condensed Matter Physics, Computational physics, Magnet, ingle helicity, Pinch, Atomic physics, Magnetohydrodynamics
Abstract

This paper reports the main recent results of the RFX-mod fusion science activity. The RFX-mod device is characterized by a unique flexibility in terms of accessible magnetic configurations. Axisymmetric and helically shaped reversed-field pinch equilibria have been studied, along with tokamak plasmas in a wide range of q(a) regimes (spanning from 4 down to 1.2 values). The full range of magnetic configurations in between the two, the so-called ultra-low q ones, has been explored, with the aim of studying specific physical issues common to all equilibria, such as, for example, the density limit phenomenon. The powerful RFX-mod feedback control system has been exploited for MHD control, which allowed us to extend the range of experimental parameters, as well as to induce specific magnetic perturbations for the study of 3D effects. In particular, transport, edge and isotope effects in 3D equilibria have been investigated, along with runaway mitigations through induced magnetic perturbations. The first transitions to an improved confinement scenario in circular and D-shaped tokamak plasmas have been obtained thanks to an active modification of the edge electric field through a polarized electrode. The experiments are supported by intense modeling with 3D MHD, gyrokinetic, guiding center and transport codes. Proposed modifications to the RFX-mod device, which will enable further contributions to the solution of key issues in the roadmap to ITER and DEMO, are also briefly presented. © 2017 IAEA, Vienna.

Published
2017

47. Effects of pulsed poloidal current drive on the edge region of a reversed field pinch plasma

Author

V. Antoni, L. Fattorini, N. Vianello, Roberto Cavazzana, M. Spolaore, L. Tramontin, G. Serianni, Emilio Martines, Antoni, V, Cavazzana, R, Fattorini, L, Martines, E, Serianni, G, Spolaore, M, Tramontin, L, and Vianello, N

Subjects
VELOCITY SHEAR-LAYER, Tokamak, Drift velocity, Materials science, Reversed field pinch, Phase (waves), reversed field pinch, Plasma, FLUCTUATIONS, Condensed Matter Physics, pulsed poloidal current drive, TRANSPORT, Magnetic field, law.invention, Nuclear magnetic resonance, Nuclear Energy and Engineering, Physics::Plasma Physics, law, RFP, ELECTROSTATIC TURBULENCE, Cathode ray, Atomic physics, Current (fluid), PPCD, RFX
Abstract

The plasma edge region of the RFX reversed field pinch experiment has been studied during pulsed poloidal current drive (PPCD) operation at low plasma current. The edge region is largely affected during PPCD, and evidence of important modifications of electric and magnetic field and of E × B drift velocity are reported. A substantial decrease of electrostatic transport has been observed during the PPCD phase and this effect is ascribed to a combination of displacement and plasma column shrinking.

Published
2000

48. Dependence of the density limit on the toroidal magnetic field on FTU

Author

S. Nowak, Gustavo Granucci, Emilio Martines, C. Mazzotta, Luca Boncagni, Angelo A. Tuccillo, M.L. Apicella, M. Marinucci, D. Frigione, A. Botrugno, Daniele Marocco, A. Romano, G. Calabrò, C. Cianfarani, F. Belli, V. Cocilovo, L. Gabellieri, G. Apruzzese, William Bin, L. Dimatteo, C. Castaldo, G. Pucella, G. Ramogida, E. Giovannozzi, Long Zeng, Matteo Zuin, P. Buratti, Basilio Esposito, G. Mazzitelli, O. Tudisco, G. Artaserse, Pucella, G, Tudisco, O, Apicella, M, Apruzzese, G, Artaserse, G, Belli, F, Bin, W, Boncagni, L, Botrugno, A, Buratti, P, Calabro, G, Castaldo, C, Cianfarani, C, Cocilovo, V, Dimatteo, L, Esposito, B, Frigione, D, Gabellieri, L, Giovannozzi, E, Granucci, G, Marinucci, M, Marocco, D, Martines, E, Mazzitelli, G, Mazzotta, C, Nowak, S, Ramogida, G, Romano, A, Tuccillo, A, Zeng, L, Zuin, M, Tuccillo, A. A., Romano, A., Ramogida, G., Mazzotta, C., Marocco, D., Marinucci, M., Giovannozzi, E., Gabellieri, L., Frigione, D., Esposito, B., Dimatteo, L., Cocilovo, V., Cianfarani, C., Castaldo, C., Calabrò, G., Buratti, P., Botrugno, A., Boncagni, L., Belli, F., Artaserse, G., Apruzzese, G., Apicella, M. L., Tudisco, O., and Pucella, G.

Subjects
Physics, FRASCATI TOKAMAK UPGRADE, toakamak, Nuclear and High Energy Physics, DISCHARGES, Tokamak, DIII-D, Frascati Tokamak Upgrade, Plasma, density limit, Fusion power, Condensed Matter Physics, law.invention, Magnetic field, law, Physics::Plasma Physics, PARTICLE PINCH, JET, Limiter, FTU, Atomic physics, Scaling, Current density
Abstract

The capability of predicting the density limit of a magnetically confined burning plasma is of crucial importance to establish the ultimate performance of a fusion power plant. The Greenwald density limit, commonly used as an empirical scaling law, predicts that the maximum achievable central line-averaged density is given by the relation (n) over bar (G) = k (J) over bar, where (J) over bar is the average plasma current density and k is the plasma elongation. However, several experiments have pointed out that such a limit can be overcome in the presence of peaked density profiles. This paper proposes a new empirical scaling law for a limiter tokamak operating in the low-energy confinement mode (L-mode) concerning the case of peaked density profiles associated with the presence of multifaceted asymmetric radiation from the edges. This result is based on dedicated experiments performed on the Frascati Tokamak Upgrade (FTU) under extremely clean machine conditions (Z(eff) = 1.0-1.5), in which the high-density domain is explored in a wide range of values of plasma current (I-p = 500-900 kA) and toroidal magnetic field (B-T = 4-8 T). It is found that the maximum achievable central line-averaged density essentially depends on the toroidal magnetic field only and does not depend on the average plasma current density: the behaviour is explained in terms of density profile peaking in the high-density domain. As a confirmation that the limit is an edge limit, it is also shown that a Greenwald-like scaling (i.e. depending on the current density) actually holds for the edge line-averaged density (at r/a similar or equal to 4/5).

Published
2013

49. Experimental observation of microtearing modes in a toroidal fusion plasma

Author

Silvia Spagnolo, Emilio Martines, Italo Predebon, M. Spolaore, Nicola Vianello, Matteo Zuin, Fulvio Auriemma, Fabio Sattin, Roberto Cavazzana, Roberto Paccagnella, Alessandro Fassina, Zuin, M, Spagnolo, S, Predebon, I, Sattin, F, Auriemma, F, Cavazzana, R, Fassina, A, Martines, E, Paccagnella, R, Spolaore, M, and Vianello, N

Subjects
Physics, RFX-mod, Toroid, Fusion plasma, General Physics and Astronomy, reversed field pinch, Plasma, Gradient strength, Core (optical fiber), Wavelength, INSTABILITIES, Amplitude, microtearing mode, Physics::Plasma Physics, TOKAMAK, RFP, Electron temperature, Atomic physics
Abstract

Experimental evidences of short wavelength electromagnetic modes are found in the reversed-field-pinch configuration device RFX-mod by means of in-vessel magnetic probes. The modes are revealed during the helical states of the plasma. Their amplitude is well correlated to the electron temperature gradient strength in the core. On the basis of linear gyrokinetic calculations we interpret these instabilities as microtearing modes.

Published
2013

50. RFX-mod: A multi-configuration fusion facility for three-dimensional physics studies

Author

Alessandra Canton, Matteo Zuin, D. F. Escande, Roberto Paccagnella, Federica Bonomo, E. Martines, Anton Soppelsa, L. Zanotto, Rita Lorenzini, Alessandro Fassina, M. Baruzzo, Paolo Scarin, Daniele Bonfiglio, Roberto Cavazzana, Barbara Zaniol, M. Veranda, D. Terranova, G. De Masi, Piero Martin, L. Piron, M. E. Puiatti, P. Piovesan, Luis Chacon, N. Vianello, G. Ciaccio, L. Marrelli, Lorella Carraro, Susanna Cappello, Gianluca Spizzo, Marco Gobbin, Paolo Zanca, Paolo Franz, M. Valisa, M. Spolaore, Paolo Innocente, Fulvio Auriemma, Matteo Agostini, B. Momo, Tommaso Bolzonella, Piovesan, P, Bonfiglio, D, Auriemma, F, Bonomo, F, Carraro, L, Cavazzana, R, De Masi, G, Fassina, A, Franz, P, Gobbin, M, Marrelli, L, Martin, P, Martines, E, Momo, B, Piron, L, Valisa, M, Veranda, M, Vianello, N, Zaniol, B, Agostini, M, Baruzzo, M, Bolzonella, T, Canton, A, Cappello, S, Chacon, L, Ciaccio, G, Escande, D, Innocente, P, Lorenzini, R, Paccagnella, R, Puiatti, M, Scarin, P, Soppelsa, A, Spizzo, G, Spolaore, M, Terranova, D, Zanca, P, Zanotto, L, and Zuin, M

Subjects
Physics, RFX-mod, Tokamak, Reversed field pinch, PLASMAS, reversed field pinch, Plasma, Condensed Matter Physics, Helicity, PERTURBATIONS, law.invention, Computational physics, Nonlinear system, law, RFP, Pinch, Magnetohydrodynamic drive, Atomic physics, FIELD, Stellarator
Abstract

RFX-mod [Sonato et al., Fusion Eng. Des. 66, 161 (2003)] exploits its 192 active coils in both reversed-field pinch (RFP) and tokamak configurations with varying degrees of 3D shaping, providing also a test bed for validating stellarator codes and 3D nonlinear magnetohydrodynamic codes. This makes RFX-mod a unique and flexible facility for comparative studies on 3D shaping and control. The paper discusses how 3D fields allow access to RFP and tokamak advanced regimes. 3D fields are used to feedback control Single Helicity (SH) RFP equilibria with 1/7 helicity up to similar to 2 MA. They also allow accessing SH regimes with higher density (Greenwald fraction up to 0.5), presently inaccessible in spontaneous SH regimes. Feedback on the 2/1 resistive-wall mode in RFX-mod tokamak plasmas allows for safe operation at q(a) < 2, an almost unexplored promising regime. Forcing the 2/1 mode to saturate at finite but small level, a helical tokamak equilibrium with significant n=1 modulation is produced and a new way to tailor sawteeth is found. The effects of different levels of 3D shaping on momentum transport in both RFP and tokamak helical states are discussed.

Published
2013

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