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1. Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

Author

Marcuzzi, D., Toigo, V., Boldrin, M., Chitarin, G., Bello, S. Dal, Grando, L., Luchetta, A., Pasqualotto, R., Pavei, M., Serianni, G., Zanotto, L., Agnello, R., Agostinetti, P., Agostini, M., Aprile, D., Barbisan, M., Battistella, M., Berton, G., Bigi, M., Brombin, M., Candela, V., Candeloro, V., Canton, A., Casagrande, R., Cavallini, C., Cavazzana, R., Cordaro, L., Cruz, N., Palma, M. Dalla, Dan, M., De Lorenzi, A., Delogu, R., De Muri, M., De Nardi, M., Denizeau, S., Fadone, M., Fellin, F., Ferro, A., Gaio, E., Gasparrini, C., Gnesotto, F., Jain, P., La Rosa, A., Lopez-Bruna, D., Lorenzini, R., Maistrello, A., Manduchi, G., Manfrin, S., Marconato, N., Mario, I., Martini, G., Milazzo, R., Patton, T., Peruzzo, S., Pilan, N., Pimazzoni, A., Poggi, C., Pomaro, N., Pouradier-Duteil, B., Recchia, M., Rigoni-Garola, A., Rizzetto, D., Rizzolo, A., Santoro, F., Sartori, E., Segalini, B., Shepherd, A., Siragusa, M., Sonato, P., Sottocornola, A., Spada, E., Spagnolo, S., Spolaore, M., Taliercio, C., Tinti, P., Tomsič, P., Trevisan, L., Ugoletti, M., Valente, M., Valisa, M., Veronese, F., Vignando, M., Zaccaria, P., Zagorski, R., Zaniol, B., Zaupa, M., Zuin, M., Cavenago, M., Boilson, D., Rotti, C., Decamps, H., Geli, F., Sharma, A., Veltri, P., Zacks, J., Simon, M., Paolucci, F., Garbuglia, A., Gutierrez, D., Masiello, A., Mico, G., Labate, C., Readman, P., Bragulat, E., Bailly-Maitre, L., Gomez, G., Kouzmenko, G., Albajar, F., Kashiwagi, M., Tobari, H., Kojima, A., Murayama, M., Hatakeyama, S., Oshita, E., Maejima, T., Shibata, N., Yamashita, Y., Watanabe, K., Singh, N. P., Singh, M. J., Dhola, H., Fantz, U., Heinemann, B., Wimmer, C., Wünderlich, D., Tsumori, K., Croci, G., Gorini, G., Muraro, A., Rebai, M., Tardocchi, M., Giacomelli, L., Rigamonti, D., Taccogna, F., Bruno, D., Rutigliano, M., Longo, S., Deambrosis, S., Miorin, E., Montagner, F., Tonti, A., and Panin, F.

Subjects
Physics - Plasma Physics, Physics - Accelerator Physics
Abstract

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities. A Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, SPIDER and MITICA. SPIDER is dedicated to developing and characterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accelerator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full performances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign. Parallelly, developments on MITICA, the full-scale prototype of the ITER NBI featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of in-vessel components, while power supplies and auxiliary plants are already under final testing and commissioning. Integration, commissioning and tests of the 1MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. The integrated test to confirm 1MV output by combining invertor systems, DC generators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, solutions for the repair and the improvement of the system were developed. Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion.

Published
2023
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2. Influence of the magnetic filter field topology on the beam divergence at the ELISE test facility

Author

Barbisan, M., Fantz, U., and Wünderlich, D.

Subjects
Physics - Plasma Physics, Physics - Accelerator Physics
Abstract

The ELISE test facility hosts a RF negative ion source, equipped with an extraction system which should deliver half the current foreseen for the ITER Neutral Beam Injector, keeping the ratio of co-extracted electrons to ions below 1. An important tool for the suppression of the co-extracted electrons is the magnetic filter field, produced by a current flowing in the plasma grid, the first grid of the 3 stage extraction system. To boost the source performances new concepts for the production of the magnetic filter field have been tested, combining the existing system with permanent magnets attached on the source walls. The topologies of these new magnetic configurations influence the beam particles trajectories in the extraction region, with consequences for the overall beam optics. These effects will be characterized in this article by studying the angular distribution of the beam particles, as measured by the Beam Emission Spectroscopy (BES) diagnostic. The behavior of the beam will be studied also through the measurements of the currents flowing on the grounded grid (the third grid) and on the grid holder box surrounding its exit. The main finding is that the broader component of the beam increases when the magnetic field is strengthened by permanent magnets, i.e. in the cases in which most of the co-extracted electrons are suppressed., Comment: 7 pages, 4 figures. Contributed paper for the NIBS 2016 conference. Accepted manuscript

Published
2022
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3. Beam characterization by means of emission spectroscopy in the ELISE test facility

Author

Barbisan, M., Bonomo, F., Fantz, U., and Wünderlich, D.

Subjects
Physics - Plasma Physics, Physics - Accelerator Physics
Abstract

The ELISE test facility at IPP Garching hosts a RF H-/D- ion source and an acceleration system. Its target is to demonstrate the performance foreseen for the ITER NBI system in terms of extracted current density (H/D), fraction of co-extracted electrons and pulse duration. The size of the ELISE extraction area is half that foreseen for the ITER NBI. This paper presents a detailed study of the ELISE beam divergence and uniformity. In particular, it was possible to describe the beam as the sum of two components at very different divergence: about 2{\deg} vs. 5{\deg}{\div}7{\deg}. As test cases, the beam properties have been measured as function of two source parameters. The first one is the current flowing through the grid facing the plasma, the Plasma Grid, in order to generate the magnetic filter field. The second one is the bias current flowing between the Plasma Grid and the source walls. Both the filter field and the bias current influence the fraction of co-extracted electrons, but also the properties of the plasma just in front of the extraction system and the beam properties. The divergence and the uniformity of the beam have been measured by a Beam Emission Spectroscopy (BES) diagnostic; the detailed analysis of the raw spectra collected by BES led to describing the beam with two components of different divergence. This concept has been supported by the information given by thermal imaging of the diagnostic calorimeter. Further support to the proposed beam model has been found in the behavior of the currents flowing in the acceleration system and beamline components; these currents are given by the most divergent (charged) particles of the beam., Comment: 15 pages, 8 figures. Accepted manuscript (embargo expired)

Published
2022
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4. First hydrogen operation of NIO1: characterization of the source plasma by means of an optical emission spectroscopy diagnostic

Author

Barbisan, M., Baltador, C., Zaniol, B., Cavenago, M., Fantz, U., Pasqualotto, R., Serianni, G., Vialetto, L., and Wünderlich, D.

Subjects
Physics - Plasma Physics
Abstract

NIO1 is a compact and flexible radiofrequency H- ion source, developed by Consorzio RFX and INFN-LNL. Aim of the experimentation on NIO1 is the optimization of both the production of negative ions and their extraction and beam optics. In the initial phase of its commissioning, NIO1 was operated with nitrogen, but now the source is regularly operated also with hydrogen. To evaluate the source performances an optical emission spectroscopy diagnostic was installed. The system includes a low resolution spectrometer in the spectral range of 300-850 nm and a high resolution (50 pm) one, to study respectively the atomic and the molecular emissions in the visible range. The spectroscopic data have been interpreted also by means of a collisional-radiative model developed at IPP Garching. Besides the diagnostic hardware and the data analysis methods, the paper presents the first plasma measurements across a transition to the full H mode, in a hydrogen discharge. The characteristic signatures of this transition in the plasma parameters are described, in particular the sudden increase of the light emitted from the plasma above a certain power threshold., Comment: 3 pages, 2 figures. Contributed paper for the ICIS 2015 conference. Accepted manuscript

Published
2022
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5. Helicon wave-generated plasmas for negative ion beams for fusion

Author

Furno Ivo, Agnello Riccardo, Fantz U., Howling Alan, Jacquier Remy, Marini Claudio, Plyushchev Gennady, Guittienne Philippe, and Simonin Alain

Subjects
Physics, QC1-999
Abstract

In the next generation of fusion reactors, such as DEMO, neutral beam injectors (NBIs) of high energy (0.8-1 MeV) deuterium atoms with high wall-plug efficiency (>50%) will be required to reach burning plasma conditions and to provide a significant amount of current drive. The present NBI system for DEMO assumes that 50 MW is delivered to the plasma by 3 NBIs. In the Siphore NBI concept, negative deuterium ions are extracted from a long, thin ion source 3 m high and 15 cm wide, accelerated and subsequently photo-neutralized. This requires the development of a new generation of negative ion sources. At the Swiss Plasma Center, a novel radio frequency helicon plasma source, based on a resonant network antenna source delivering up to 10 kW at 13.56 MHz, has been developed and is presently under study on the Resonant Antenna Ion Device (RAID). RAID is a linear device (1.9 m total length, 0.4 m diameter) and is equipped with an extensive set of diagnostics for full plasma characterization. In this work, the principles of operation of resonant antennas as helicon sources are introduced. We present absolute spectroscopy, Langmuir probe, and interferometry measurements on helicon plasmas. We characterize the performance of the source in terms of hydrogen/deuterium dissociation and negative ion production as a function of the input power. Furthermore, first results with the helicon birdcage antenna installed on the Cybele negative ion source at CEA-IRFM are presented, as a first step towards the validation of the Siphore concept.

Published
2017
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8. A novel hydrogenic spectroscopic technique for inferring the role of plasma-molecule interaction on power and particle balance during detached conditions

Author

Verhaegh, K, Lipschultz, B, Bowman, C, Duval, B P, Fantz, U, Fil, A, Harrison, J R, Moulton, D, Myatra, O, Wünderlich, D, Federici, F, Gahle, D S, Perek, A, Wensing, M, team, the TCV, and team, the EuroFusion MST1

Subjects
Physics - Plasma Physics
Abstract

Detachment, an important mechanism for reducing target heat deposition, is achieved through reductions in power, particle and momentum; which are induced through plasma-atom and plasma-molecule interactions. Experimental research in how those reactions precisely contribute to detachment is limited. In this work, we investigate a new spectroscopic technique to utilise Hydrogen Balmer line measurements to 1) disentangle the Balmer line emission from the various plasma-atom and plasma-molecule interactions; and 2) quantify their contributions to ionisation, recombination and radiative power losses. During detachment, the observed $H\alpha$ emission often strongly increases, which could be an indicator for plasma-molecule interactions involving $H_2^+$ and/or $H^-$. Our analysis technique quantifies the $H\alpha$ emission due to plasma-molecule interactions and uses this to 1) quantify the Balmer line emission contribution due to $H_2^+$ and/or $H^-$; 2) subsequently estimate its resulting particle sinks/sources and radiative power losses. Its performance is verified using synthetic diagnostic techniques of both detached TCV and MAST-U SOLPS-ITER simulations. Experimental results of this technique on TCV data show a bifurcation occurs between the measured total $H\alpha$ and the atomic estimate of $H\alpha$ emission, indicative of the presence of additional $H\alpha$ due to plasma-molecule interactions with $H_2^+$ (and/or $H^-$). An example analysis shows that the hydrogenic line series, even $Ly\alpha$ as well as the medium-n Balmer lines can be significantly influenced by plasma-molecule interactions by tens of percent during which significant Molecular Activated Recombination (MAR) is expected.

Published
2020
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9. Performance analysis of a 2.45 GHz microwave plasma torch for CO$_2$ decomposition in gas swirl configuration

Author

D'Isa, F. A., Carbone, E. A. D., Hecimovic, A., and Fantz, U.

Subjects
Physics - Plasma Physics
Abstract

Microwave plasmas are a promising technology for energy-efficient CO$_{2}$ valorization via conversion of CO$_{2}$ into CO and O$_2$ using renewable energies. A 2.45 GHz microwave plasma torch with swirling CO$_{2}$ gas flow is studied in a large pressure (60-1000~mbar) and flow (5-100~slm) range. Two different modes of the plasma torch, depending on the operating pressure and microwave input power, are described: at pressures below 120~mbar the plasma fills most of the plasma torch volume whereas at pressures of about 120~mbar an abrupt contraction of the plasma in the center of the resonator is observed along with an increase of the gas temperature from 3000~K to 6000~K. The CO outflow is found to be proportional to the plasma effective surface and exhibits no significant dependence on the actual CO$_{2}$ flow injected into the reactor but only on the input power at certain pressure. Thermal dissociation calculations show that, even at the lowest pressures of this study, the observed conversion and energy efficiency are compatible with a thermal dissociation mechanism.

Published
2019
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13. Status and future development of Heating and Current Drive for the EU DEMO

Author

Tran, M.Q., Agostinetti, P., Aiello, G., Avramidis, K., Baiocchi, B., Barbisan, M., Bobkov, V., Briefi, S., Bruschi, A., Chavan, R., Chelis, I., Day, Ch., Delogu, R., Ell, B., Fanale, F., Fassina, A., Fantz, U., Faugel, H., Figini, L., Fiorucci, D., Friedl, R., Franke, Th., Gantenbein, G., Garavaglia, S., Granucci, G., Hanke, S., Hogge, J.-P., Hopf, C., Kostic, A., Illy, S., Ioannidis, Z., Jelonnek, J., Jin, J., Latsas, G., Louche, F., Maquet, V., Maggiora, R., Messiaen, A., Milanesio, D., Mimo, A., Moro, A., Ochoukov, R., Ongena, J., Pagonakis, I.G., Peponis, D., Pimazzoni, A., Ragona, R., Rispoli, N., Ruess, T., Rzesnicki, T., Scherer, T., Spaeh, P., Starnella, G., Strauss, D., Thumm, M., Tierens, W., Tigelis, I., Tsironis, C., Usoltceva, M., Van Eester, D., Veronese, F., Vincenzi, P., Wagner, F., Wu, C., Zeus, F., and Zhang, W.

Published
2022
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14. EUROfusion contributions to ITER nuclear operation.

Author

Litaudon, X., Fantz, U., Villari, R., Toigo, V., Aumeunier, M.-H., Autran, J.-L., Batistoni, P., Belonohy, E., Bradnam, S., Cecchetto, M., Colangeli, A., Dacquait, F., Dal Bello, S., Dentan, M., De Pietri, M., Eriksson, J., Fabbri, M., Falchetto, G., Figini, L., and Figueiredo, J.

Subjects
*TRITIUM, *NEUTRON irradiation, *RESEARCH reactors, *NEUTRAL beams, *NEUTRON flux, *BLOOD volume, *ARTIFICIAL intelligence, *HYDROGEN ions
Abstract

ITER is of key importance in the European fusion roadmap as it aims to prove the scientific and technological feasibility of fusion as a future energy source. The EUROfusion consortium of labs within Europe is contributing to the preparation of ITER scientific exploitation and operation and aspires to exploit ITER outcomes in view of DEMO. The paper provides an overview of the major progress obtained recently, carried out in the frame of the new (initiated in 2021) EUROfusion work-package called ' Pr eparation of I TER O peration' (PrIO). The overview paper is directly supported by the eleven EUROfusion PrIO contributions given at the 29th Fusion Energy Conference (16–21 October 2023) London, UK [www.iaea.org/events/fec2023]. The paper covers the following topics: (i) development and validation of tools in support to ITER operation (plasma breakdown/burn-through with evolving plasma volume, new infra-red synthetic diagnostic for off-line analysis and wall monitoring using Artificial Intelligence techniques, synthetic diagnostics development, development and exploitation of multi-machine databases); (ii) R&D for the radio-frequency ITER neutral beam sources leading to long duration of negative deuterium/hydrogen ions current extraction at ELISE and participation in the neutral beam test facility with progress on the ITER source SPIDER, and, the commissioning of the 1 MV high voltage accelerator (MITICA) with lessons learned for ITER; (iii) validation of neutronic tools for ITER nuclear operation following the second JET deuterium–tritium experimental campaigns carried out in 2021 and in 2023 (neutron streaming and shutdown dose rate calculation, water activation and activated corrosion products with advanced fluid dynamic simulation; irradiation of several materials under 14.1 MeV neutron flux etc). [ABSTRACT FROM AUTHOR]

Published
2024
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16. Beam divergence of RF negative hydrogen ion sources for fusion

Author

Wimmer, C., primary, Barnes, M., additional, den Harder, N., additional, Navarro, A., additional, Nocentini, R., additional, Orozco, G., additional, Wünderlich, D., additional, Heinemann, B., additional, Fantz, U., additional, Serianni, G., additional, and Veltri, P., additional

Published
2024
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17. On the road to ITER NBIs: SPIDER improvement after first operation and MITICA construction progress

Author

Toigo, V., Marcuzzi, D., Serianni, G., Boldrin, M., Chitarin, G., Bello, S. Dal, 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. Dalla, 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., Tomsič, 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-F, 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.P., Fantz, U., Bonomo, F., Cristofaro, S., Heinemann, B., Kraus, W., Wimmer, C., Wünderlich, 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.

Published
2021
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18. ITER-relevant 600 s steady-state extraction of negative hydrogen ions at the test facility ELISE.

Author

Wünderlich, D., Riedl, R., Fröschle, M., Heiler, A., Navarro, A., Yordanov, D., Döring, A., and Fantz, U.

Subjects
ANIONS, ION sources, HYDROGEN ions, NEUTRAL beams, DEUTERIUM ions, PLASMA beam injection heating
Abstract

The neutral beam heating system for the future international fusion experiment ITER will be based on radio-frequency driven ion sources delivering a large (≈1 × 2 m2) and homogeneous negative hydrogen or deuterium ion beam of several ten Amperes for several hundred seconds. The size scaling experiment ELISE (Extraction from a Large Ion Source Experiment) is an integral part of the R&D road-map towards the ITER neutral beam heating system. Recently, 90% of the ITER target for the extracted current density was achieved in hydrogen for 600 s, increasing the pulse length over which such current densities can be achieved by a factor of more than ten. For ten second beam pulses the ITER target current density was achieved. These breakthrough results are made possible by using a steady-state capable high-voltage power supply together with an improved version of internal potential rods and a modified topology of the magnetic filter field. [ABSTRACT FROM AUTHOR]

Published
2025
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24. Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

Author

Marcuzzi, D, Toigo, V, Boldrin, M, Chitarin, G, Dal Bello, S, Grando, L, Luchetta, A, Pasqualotto, R, Pavei, M, Serianni, G, Zanotto, L, Agnello, R, Agostinetti, P, Agostini, M, Aprile, D, Barbisan, M, Battistella, M, Berton, G, Bigi, M, Brombin, M, Candela, V, Candeloro, V, Canton, A, Casagrande, R, Cavallini, C, Cavazzana, R, Cordaro, L, Cruz, N, Dalla Palma, M, Dan, M, De Lorenzi, A, Delogu, R, De Muri, M, De Nardi, M, Denizeau, S, Fadone, M, Fellin, F, Ferro, A, Gaio, E, Gasparrini, C, Gnesotto, F, Jain, P, La Rosa, A, Lopez-Bruna, D, Lorenzini, R, Maistrello, A, Manduchi, G, Manfrin, S, Marconato, N, Mario, I, Martini, G, Milazzo, R, Patton, T, Peruzzo, S, Pilan, N, Pimazzoni, A, Poggi, C, Pomaro, N, Pouradier-Duteil, B, Recchia, M, Rigoni-Garola, A, Rizzetto, D, Rizzolo, A, Santoro, F, Sartori, E, Segalini, B, Shepherd, A, Siragusa, M, Sonato, P, Sottocornola, A, Spada, E, Spagnolo, S, Spolaore, M, Taliercio, C, Tinti, P, Tomsic, P, Trevisan, L, Ugoletti, M, Valente, M, Valisa, M, Veronese, F, Vignando, M, Zaccaria, P, Zagorski, R, Zaniol, B, Zaupa, M, Zuin, M, Cavenago, M, Boilson, D, Rotti, C, Decamps, H, Geli, F, Sharma, A, Veltri, P, Zacks, J, Simon, M, Paolucci, F, Garbuglia, A, Gutierrez, D, Masiello, A, Mico, G, Labate, C, Readman, P, Bragulat, E, Bailly-Maitre, L, Gomez, G, Kouzmenko, G, Albajar, F, Kashiwagi, M, Tobari, H, Kojima, A, Murayama, M, Hatakeyama, S, Oshita, E, Maejima, T, Shibata, N, Yamashita, Y, Watanabe, K, Singh, N, Singh, M, Dhola, H, Fantz, U, Heinemann, B, Wimmer, C, Wunderlich, D, Tsumori, K, Croci, G, Gorini, G, Muraro, A, Rebai, M, Tardocchi, M, Giacomelli, L, Rigamonti, D, Taccogna, F, Bruno, D, Rutigliano, M, Longo, S, Deambrosis, S, Miorin, E, Montagner, F, Tonti, A, Panin, F, Marcuzzi D., Toigo V., Boldrin M., Chitarin G., Dal Bello S., Grando L., Luchetta A., Pasqualotto R., Pavei M., Serianni G., Zanotto L., Agnello R., Agostinetti P., Agostini M., Aprile D., Barbisan M., Battistella M., Berton G., Bigi M., Brombin M., Candela V., Candeloro V., Canton A., Casagrande R., Cavallini C., Cavazzana R., Cordaro L., Cruz N., Dalla Palma M., Dan M., De Lorenzi A., Delogu R., De Muri M., De Nardi M., Denizeau S., Fadone M., Fellin F., Ferro A., Gaio E., Gasparrini C., Gnesotto F., Jain P., La Rosa A., Lopez-Bruna D., Lorenzini R., Maistrello A., Manduchi G., Manfrin S., Marconato N., Mario I., Martini G., Milazzo R., Patton T., Peruzzo S., Pilan N., Pimazzoni A., Poggi C., Pomaro N., Pouradier-Duteil B., Recchia M., Rigoni-Garola A., Rizzetto D., Rizzolo A., Santoro F., Sartori E., Segalini B., Shepherd A., Siragusa M., Sonato P., Sottocornola A., Spada E., Spagnolo S., Spolaore M., Taliercio C., Tinti P., Tomsic P., Trevisan L., Ugoletti M., Valente M., Valisa M., Veronese F., Vignando M., Zaccaria P., Zagorski R., Zaniol B., Zaupa M., Zuin M., Cavenago M., Boilson D., Rotti C., Decamps H., Geli F., Sharma A., Veltri P., Zacks J., Simon M., Paolucci F., Garbuglia A., Gutierrez D., Masiello A., Mico G., Labate C., Readman P., Bragulat E., Bailly-Maitre L., Gomez G., Kouzmenko G., Albajar F., Kashiwagi M., Tobari H., Kojima A., Murayama M., Hatakeyama S., Oshita E., Maejima T., Shibata N., Yamashita Y., Watanabe K., Singh N. P., Singh M. J., Dhola H., Fantz U., Heinemann B., Wimmer C., Wunderlich D., Tsumori K., Croci G., Gorini G., Muraro A., Rebai M., Tardocchi M., Giacomelli L., Rigamonti D., Taccogna F., Bruno D., Rutigliano M., Longo S., Deambrosis S., Miorin E., Montagner F., Tonti A., Panin F., Marcuzzi, D, Toigo, V, Boldrin, M, Chitarin, G, Dal Bello, S, Grando, L, Luchetta, A, Pasqualotto, R, Pavei, M, Serianni, G, Zanotto, L, Agnello, R, Agostinetti, P, Agostini, M, Aprile, D, Barbisan, M, Battistella, M, Berton, G, Bigi, M, Brombin, M, Candela, V, Candeloro, V, Canton, A, Casagrande, R, Cavallini, C, Cavazzana, R, Cordaro, L, Cruz, N, Dalla Palma, M, Dan, M, De Lorenzi, A, Delogu, R, De Muri, M, De Nardi, M, Denizeau, S, Fadone, M, Fellin, F, Ferro, A, Gaio, E, Gasparrini, C, Gnesotto, F, Jain, P, La Rosa, A, Lopez-Bruna, D, Lorenzini, R, Maistrello, A, Manduchi, G, Manfrin, S, Marconato, N, Mario, I, Martini, G, Milazzo, R, Patton, T, Peruzzo, S, Pilan, N, Pimazzoni, A, Poggi, C, Pomaro, N, Pouradier-Duteil, B, Recchia, M, Rigoni-Garola, A, Rizzetto, D, Rizzolo, A, Santoro, F, Sartori, E, Segalini, B, Shepherd, A, Siragusa, M, Sonato, P, Sottocornola, A, Spada, E, Spagnolo, S, Spolaore, M, Taliercio, C, Tinti, P, Tomsic, P, Trevisan, L, Ugoletti, M, Valente, M, Valisa, M, Veronese, F, Vignando, M, Zaccaria, P, Zagorski, R, Zaniol, B, Zaupa, M, Zuin, M, Cavenago, M, Boilson, D, Rotti, C, Decamps, H, Geli, F, Sharma, A, Veltri, P, Zacks, J, Simon, M, Paolucci, F, Garbuglia, A, Gutierrez, D, Masiello, A, Mico, G, Labate, C, Readman, P, Bragulat, E, Bailly-Maitre, L, Gomez, G, Kouzmenko, G, Albajar, F, Kashiwagi, M, Tobari, H, Kojima, A, Murayama, M, Hatakeyama, S, Oshita, E, Maejima, T, Shibata, N, Yamashita, Y, Watanabe, K, Singh, N, Singh, M, Dhola, H, Fantz, U, Heinemann, B, Wimmer, C, Wunderlich, D, Tsumori, K, Croci, G, Gorini, G, Muraro, A, Rebai, M, Tardocchi, M, Giacomelli, L, Rigamonti, D, Taccogna, F, Bruno, D, Rutigliano, M, Longo, S, Deambrosis, S, Miorin, E, Montagner, F, Tonti, A, Panin, F, Marcuzzi D., Toigo V., Boldrin M., Chitarin G., Dal Bello S., Grando L., Luchetta A., Pasqualotto R., Pavei M., Serianni G., Zanotto L., Agnello R., Agostinetti P., Agostini M., Aprile D., Barbisan M., Battistella M., Berton G., Bigi M., Brombin M., Candela V., Candeloro V., Canton A., Casagrande R., Cavallini C., Cavazzana R., Cordaro L., Cruz N., Dalla Palma M., Dan M., De Lorenzi A., Delogu R., De Muri M., De Nardi M., Denizeau S., Fadone M., Fellin F., Ferro A., Gaio E., Gasparrini C., Gnesotto F., Jain P., La Rosa A., Lopez-Bruna D., Lorenzini R., Maistrello A., Manduchi G., Manfrin S., Marconato N., Mario I., Martini G., Milazzo R., Patton T., Peruzzo S., Pilan N., Pimazzoni A., Poggi C., Pomaro N., Pouradier-Duteil B., Recchia M., Rigoni-Garola A., Rizzetto D., Rizzolo A., Santoro F., Sartori E., Segalini B., Shepherd A., Siragusa M., Sonato P., Sottocornola A., Spada E., Spagnolo S., Spolaore M., Taliercio C., Tinti P., Tomsic P., Trevisan L., Ugoletti M., Valente M., Valisa M., Veronese F., Vignando M., Zaccaria P., Zagorski R., Zaniol B., Zaupa M., Zuin M., Cavenago M., Boilson D., Rotti C., Decamps H., Geli F., Sharma A., Veltri P., Zacks J., Simon M., Paolucci F., Garbuglia A., Gutierrez D., Masiello A., Mico G., Labate C., Readman P., Bragulat E., Bailly-Maitre L., Gomez G., Kouzmenko G., Albajar F., Kashiwagi M., Tobari H., Kojima A., Murayama M., Hatakeyama S., Oshita E., Maejima T., Shibata N., Yamashita Y., Watanabe K., Singh N. P., Singh M. J., Dhola H., Fantz U., Heinemann B., Wimmer C., Wunderlich D., Tsumori K., Croci G., Gorini G., Muraro A., Rebai M., Tardocchi M., Giacomelli L., Rigamonti D., Taccogna F., Bruno D., Rutigliano M., Longo S., Deambrosis S., Miorin E., Montagner F., Tonti A., and Panin F.

Abstract

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities. In order to enable such development, a Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, called SPIDER and MITICA. SPIDER is dedicated developing and characterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accelerator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full performances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign, in particular events/issues occurred during operation, which led to the identification of improvement opportunities/necessities (e.g. RF discharges, local burns, water leaks, other damages, configuration/design upgrades to maximize chances/margin to quest target parameters). Parallelly, developments on MITICA, the full-scale prototype of the ITER Neutral Beam Injector (NBI) featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of the beam source, accelerator and the beam line components, while power supplies and auxiliary plants, already installed, are under final testing and commissioning. Integration, commissioning and tests of the 1 MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. 1.2 MV dc insulating tests of high voltage components were successfully completed. The integrated test to confir

Published
2023

25. SPIDER in the roadmap of the ITER neutral beams

Author

Serianni, G., Toigo, V., Bigi, M., Boldrin, M., Chitarin, G., Dal Bello, S., Grando, L., Luchetta, A., Marcuzzi, D., Pasqualotto, R., Pomaro, N., Zaccaria, P., Zanotto, L., Agostinetti, P., Agostini, M., Antoni, V., Aprile, D., Barbisan, M., Battistella, M., Brombin, M., Cavazzana, R., Dalla Palma, M., Dan, M., De Lorenzi, A., Delogu, R., De Muri, M., Denizeau, S., Fadone, M., Fellin, F., Ferbel, L., Ferro, A., Gaio, E., Gambetta, G., Gasparini, F., Gnesotto, F., Jain, P., Maistrello, A., Manduchi, G., Manfrin, S., Marchiori, G., Marconato, N., Moresco, M., Patton, T., Pavei, M., Peruzzo, S., Pilan, N., Pimazzoni, A., Piovan, R., Poggi, C., Recchia, M., Rizzolo, A., Rostagni, G., Sartori, E., Siragusa, M., Sonato, P., Spada, E., Spagnolo, S., Spolaore, M., Taliercio, C., Tinti, P., Ugoletti, M., Valente, M., Zamengo, A., Zaniol, B., Zaupa, M., Baltador, C., Cavenago, M., Boilson, D., Rotti, C., Veltri, P., Bonicelli, T., Paolucci, F., Muriel, S., Masiello, A., Chakraborty, A., Patel, H., Singh, N.P., Fantz, U., Heinemann, B., Kraus, W., Kashiwagi, M., and Tsumori, K.

Published
2019
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32. Ion flux measurements using a Mach-Langmuir probe in the ITER prototype neutral beam injection ion source.

Author

Zielke, D, Wimmer, C, and Fantz, U

Subjects
PLASMA beam injection heating, ION sources, NEUTRAL beams, CATIONS, HYDROGEN ions, ANIONS
Abstract

Neutral beam injection systems as foreseen for ITER use radio-frequency (RF) ion sources at low pressure, where negative hydrogen ions are mainly produced via surface conversion of neutral atoms and positive ions at a plasma facing grid (PG). Up to now there is only limited knowledge about how fluxes and directed velocities of the positive ions are affected by external parameters such as power, pressure and the horizontal magnetic filter field which causes plasma drifts and vertical asymmetries in the vicinity of the PG. For this reason a combined Mach-Langmuir-probe diagnostic is used at multiple positions in the expansion and close to the extraction system in the prototype RF ion source (1/8 of the full ITER ion source size) to measure the positive ions directed velocity and flux as well as the plasma parameters simultaneously. With increasing RF power the flux towards the PG is found to increase linearly, its magnitude being controlled by the plasma density. Towards ITER-relevant pressures the ion flux decreases, in contrast to the directed velocity, which increases non-linearly, reaching around 5 km s−1 at a pressure of 0.3 Pa. The magnetic filter field is discovered to strongly bent down the ion flow in front of the PG. As a result, the ions at the lower half of the PG flow almost exclusively parallel to it, wherefore the flux which impinges onto the lower PG half is reduced by around one order of magnitude. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Particle injection methods in 3D-PIC MCC simulations applied to plasma grid biasing.

Author

Lindqvist, M., Wünderlich, D., Mochalskyy, S., den Harder, Niek, Revel, A., Minea, T., and Fantz, U.

Subjects
NEUTRAL beams, ION sources, PLASMA beam injection heating, ANIONS, FUSION reactor divertors, ELECTRONS
Abstract

In negative ion sources for the ITER Neutral Beam Injection system, the co-extraction of electrons is one of the main limiting factors. The current of co-extracted electrons can be decreased by applying a positive bias voltage to the Plasma Grid (PG) with respect to its source walls. Simulations using three-dimensional Particle-in-Cell Monte Carlo Collision (3D-PIC MCC) model are a powerful tool for studying the extraction region of such ion sources. However, the inclusion of both PG and source walls in the simulation domain is difficult due to numerical constraints. This study uses the 3D-PIC MCC code ONIX to explore the effects of particle injection models on plasma characteristics, using a flux injection model to regulate particle influx for a flat transition in potential from the bulk plasma to the simulation domain. Biasing of the PG above floating potential is possible using the flux injection scheme and results in a notable reduction in co-extracted electrons, corroborating with established experimental observations. [ABSTRACT FROM AUTHOR]

Published
2024
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39. Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

Author

Marcuzzi, D., primary, Toigo, V., additional, Boldrin, M., additional, Chitarin, G., additional, Dal Bello, S., additional, Grando, L., additional, Luchetta, A., additional, Pasqualotto, R., additional, Pavei, M., additional, Serianni, G., additional, Zanotto, L., additional, Agnello, R., additional, Agostinetti, P., additional, Agostini, M., additional, Aprile, D., additional, Barbisan, M., additional, Battistella, M., additional, Berton, G., additional, Bigi, M., additional, Brombin, M., additional, Candela, V., additional, Candeloro, V., additional, Canton, A., additional, Casagrande, R., additional, Cavallini, C., additional, Cavazzana, R., additional, Cordaro, L., additional, Cruz, N., additional, Dalla Palma, M., additional, Dan, M., additional, De Lorenzi, A., additional, Delogu, R., additional, De Muri, M., additional, De Nardi, M., additional, Denizeau, S., additional, Fadone, M., additional, Fellin, F., additional, Ferro, A., additional, Gaio, E., additional, Gasparrini, C., additional, Gnesotto, F., additional, Jain, P., additional, La Rosa, A., additional, Lopez-Bruna, D., additional, Lorenzini, R., additional, Maistrello, A., additional, Manduchi, G., additional, Manfrin, S., additional, Marconato, N., additional, Mario, I., additional, Martini, G., additional, Milazzo, R., additional, Patton, T., additional, Peruzzo, S., additional, Pilan, N., additional, Pimazzoni, A., additional, Poggi, C., additional, Pomaro, N., additional, Pouradier-Duteil, B., additional, Recchia, M., additional, Rigoni-Garola, A., additional, Rizzetto, D., additional, Rizzolo, A., additional, Santoro, F., additional, Sartori, E., additional, Segalini, B., additional, Shepherd, A., additional, Siragusa, M., additional, Sonato, P., additional, Sottocornola, A., additional, Spada, E., additional, Spagnolo, S., additional, Spolaore, M., additional, Taliercio, C., additional, Tinti, P., additional, Tomsič, P., additional, Trevisan, L., additional, Ugoletti, M., additional, Valente, M., additional, Valisa, M., additional, Veronese, F., additional, Vignando, M., additional, Zaccaria, P., additional, Zagorski, R., additional, Zaniol, B., additional, Zaupa, M., additional, Zuin, M., additional, Cavenago, M., additional, Boilson, D., additional, Rotti, C., additional, Decamps, H., additional, Geli, F., additional, Sharma, A., additional, Veltri, P., additional, Zacks, J., additional, Simon, M., additional, Paolucci, F., additional, Garbuglia, A., additional, Gutierrez, D., additional, Masiello, A., additional, Mico, G., additional, Labate, C., additional, Readman, P., additional, Bragulat, E., additional, Bailly-Maitre, L., additional, Gomez, G., additional, Kouzmenko, G., additional, Albajar, F., additional, Kashiwagi, M., additional, Tobari, H., additional, Kojima, A., additional, Murayama, M., additional, Hatakeyama, S., additional, Oshita, E., additional, Maejima, T., additional, Shibata, N., additional, Yamashita, Y., additional, Watanabe, K., additional, Singh, N.P., additional, Singh, M.J., additional, Dhola, H., additional, Fantz, U., additional, Heinemann, B., additional, Wimmer, C., additional, Wünderlich, D., additional, Tsumori, K., additional, Croci, G., additional, Gorini, G., additional, Muraro, A., additional, Rebai, M., additional, Tardocchi, M., additional, Giacomelli, L., additional, Rigamonti, D., additional, Taccogna, F., additional, Bruno, D., additional, Rutigliano, M., additional, Longo, S., additional, Deambrosis, S., additional, Miorin, E., additional, Montagner, F., additional, Tonti, A., additional, and Panin, F., additional

Published
2023
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42. A substantial step forward in the realization of the ITER HNB system: The ITER NBI Test Facility

Author

Toigo, V., Piovan, R., Dal Bello, S., Gaio, E., Luchetta, A., Pasqualotto, R., Zaccaria, P., Bigi, M., Chitarin, G., Marcuzzi, D., Pomaro, N., Serianni, G., Agostinetti, P., Agostini, M., Antoni, V., Aprile, D., Baltador, C., Barbisan, M., Battistella, M., Boldrin, M., Brombin, M., Dalla Palma, M., De Lorenzi, A., Delogu, R., De Muri, M., Fellin, F., Ferro, A., Finotti, C., Fiorentin, A., Gambetta, G., Gnesotto, F., Grando, L., Jain, P., Maistrello, A., Manduchi, G., Marconato, N., Moresco, M., Ocello, E., Pavei, M., Peruzzo, S., Pilan, N., Pimazzoni, A., Recchia, M., Rizzolo, A., Rostagni, G., Sartori, E., Siragusa, M., Sonato, P., Sottocornola, A., Spada, E., Spagnolo, S., Spolaore, M., Taliercio, C., Valente, M., Veltri, P., Zamengo, A., Zaniol, B., Zanotto, L., Zaupa, M., Boilson, D., Graceffa, J., Svensson, L., Schunke, B, Decamps, H., Urbani, M., Kushwah, M, Chareyre, J, Singh, M., Bonicelli, T., Agarici, G., Masiello, A., Paolucci, F., Simon, M., Bailly-Maitre, L, Bragulat, E., Gomez, G., Gutierrez, D., Mico, G., Moreno, J.-F., Pilard, V., Kashiwagi, M., Hanada, M., Tobari, H., Watanabe, K., Maeshima, T., Kojima, A., Umeda, N., Yamanaka, H., Chakraborty, A., Baruah, U., Rotti, C., Patel, H., Nagaraju, M.V., Singh, N.P., Patel, A., Dhola, H., Raval, B., Fantz, U., Heinemann, B., Kraus, W., Hanke, S., Hauer, V., Ochoa, S., Blatchford, P., Chuilon, B., Xue, Y., De Esch, H.P.L., Hemsworth, R., Croci, G., Gorini, G., Rebai, M., Muraro, A., Cavenago, M., D'Arienzo, M., and Sandri, S.

Published
2017
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45. Effects of the magnetic field topology on the co-extracted electron current in a negative ion source for fusion.

Author

Wünderlich, D., Montellano, I. M., Lindqvist, M., Mimo, A., Mochalskyy, S., and Fantz, U.

Subjects
MAGNETIC field effects, ANIONS, ION sources, PLASMA beam injection heating, ELECTRONS, ELECTRON configuration
Abstract

The negative hydrogen ion current that can be extracted from ion sources for neutral beam heating in fusion experiments can be strongly restricted by the amount of co-extracted electrons and their increase over time, particularly during long pulses (up to 1 h). Models describing the underlying physics of particle extraction from a low-temperature plasma with a high amount of negative ions are essential for identifying measures for reducing and stabilizing the co-extracted electrons. In this work, the 3D PIC-MCC code ONIX (Orsay Negative Ion eXtraction) for the plasma volume around one extraction aperture in the first grid of the extraction system is used for analyzing the effect of the magnetic field configuration on the co-extracted electrons and the extracted negative ions. The magnetic field topology is the result of superimposing two different fields that are perpendicular to each other, the filter field (dominant in the ion source volume) and the electron deflection field (dominant in the extraction system). A parametric study changing the relative intensity of these two fields is performed. It is demonstrated that on the local scale of the simulation, the strength of the filter field does not affect the amount of co-extracted electrons, while a significant reduction of the co-extracted electron current is observed when strengthening the electron deflection field. [ABSTRACT FROM AUTHOR]

Published
2021
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48. On the road to ITER NBIs: SPIDER improvement after first operation and MITICA construction progress

Author

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, Panin, F, Toigo V., Marcuzzi D., Serianni G., Boldrin M., Chitarin G., Bello S. D., 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. 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P., 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., Panin F., 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, Panin, F, Toigo V., Marcuzzi D., Serianni G., Boldrin M., Chitarin G., Bello S. D., 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. D., 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. -F., 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. P., 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.

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 usin

Published
2021

49. Application of a Langmuir probe AC technique for reliable access to the low energy range of electron energy distribution functions in low pressure plasmas.

Author

Heiler, A., Friedl, R., and Fantz, U.

Subjects
LANGMUIR probes, DISTRIBUTION (Probability theory), ENERGY function, PLASMA pressure, PLASMA potentials, HYDROGEN plasmas, ELECTRON distribution
Abstract

The electron energy distribution function (EEDF) in low pressure plasmas is typically evaluated by using the second derivative d 2 I / d V 2 of a Langmuir probe I – V characteristic (Druyvesteyn formula). Since measured probe characteristics are inherently noisy, two-time numerical differentiation requires data smoothing techniques. This leads to a dependence on the employed filtering technique, and information particularly in the region near the plasma potential can easily get lost. As an alternative to numerical differentiation of noisy probe data, a well-known AC probe technique is adopted to measure d 2 I / d V 2 directly. This is done by superimposing a sinusoidal AC voltage of 13 kHz on the probe DC bias and performing a Fourier analysis of the current response. Parameters such as the modulation amplitude (up to 1.5 V) and the number of applied sine oscillations per voltage step of the DC ramp are carefully chosen by systematic parameter variations. The AC system is successfully benchmarked in argon and applied to hydrogen plasmas at a laboratory inductively coupled plasma experiment (4– 10 Pa gas pressure, 300– 1000 W RF power). It is shown that the EEDF is reliably accessible with high accuracy and stability in the low energy range. Hence, a trustworthy determination of basic plasma parameters by integration of the EEDF can be provided. [ABSTRACT FROM AUTHOR]

Published
2020
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