First operation in SPIDER and the path to complete MITICA

Serianni, G.; Toigo, V.; Bigi, M.; Boldrin, M.; Chitarin, G.; Bello, S. Dal; 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.; Canton, A.; Cavazzana, R.; Palma, M. Dalla; Dan, M.; Delogu, R.; Lorenzi, A. De; Muri, M. De; Denizeau, S.; Fadone, M.; Fellin, F.; Ferro, A.; Gaio, E.; Gambetta, G.; Gasparini, F.; Gnesotto, F.; Jain, Palak; 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.; Rigoni, A.; 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.; Cavenago, M.; Boilson, D.; Rotti, C.; Veltri, P.; Chareyre, J.; Decamps, Hans; Dremel, M.; Graceffa, J.; Geli, F.; Schunke, B.; Svensson, Lennart; Urbani, M.; Bonicelli, T.; Agarici, G.; Garbuglia, A.; Masiello, A.; Paolucci, Francesco; Simon, M.; Bailly-Maitre, L.; Bragulat, E.; Gomez, G.; Gutiérrez, Daniel; Labate, C.; Mico, G.; Moreno, J.F.; Pilard, V.; Kouzmenko, G.; Rousseau, Anthony; Chakraborty, Arun; Baruah, U.; Patel, Hitesh; Singh, Narinder; Patel, Amee B.; Dhola, H.; Raval, B.; Cristofaro, S.; Fantz, U.; Heinemann, B.; Kraus, Werner; Kashiwagi, M.; Tobari, H.

doi:10.1063/1.5133076

Cited by 48 publications

(30 citation statements)

References 39 publications

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“…At present, the measured RF power transfer efficiencies are in the range of 55-60%, which reveals a high optimization potential. Increasing the RF power transfer efficiency would relax the demands on the generators and the RF circuit, reducing the probability of RF breakdowns, which is for example currently an issue at the SPIDER test bed of the NBTF [13].…”

Section: Discussionmentioning

confidence: 99%

“…The full-size source will be commissioned and operated at the European Neutral Beam Test Facility (NBTF) in Padua, Italy [11]. The NBTF hosts a test facility for the ITER NBI ion source (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma, SPIDER), which went into operation in 2018 [12,13]. The second test facility that represents the full prototype beamline of the HNB of ITER (Megavolt ITER Injector and Concept Advancement, MITICA) is currently planned to go into full operation in 2024 [14].…”

Section: Introductionmentioning

confidence: 99%

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Negative Hydrogen Ion Sources for Fusion: From Plasma Generation to Beam Properties

et al. 2021

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The neutral beam injection systems for the international fusion experiment ITER used for heating, current drive, and diagnostic purposes are based on RF-driven negative hydrogen ion sources with a source area of roughly 0.9 m × 1.9 m. The sources operate at 0.3 Pa in hydrogen and in deuterium using a total available RF generator power of 800 kW per source at a frequency of 1 MHz. In order to fulfill the challenging requirements for ITER and beyond (like a DEMOnstration power plant, DEMO), worldwide developments are underway addressing the topics of plasma generation, ion extraction together with the issue of reducing and stabilizing the co-extracted electron current, and the beam properties. At the example of the activities at the ITER prototype source and the size scaling experiment ELISE, the present status and its challenges are summarized. The RF power transfer efficiency of these sources is only about 65% in maximum, giving significant room for improvements to relax the demands on the RF generator and ensure reliable operation. The plasma uniformity in front of the large extraction system is the result of plasma drifts. They have a huge impact on the nonuniformity of the co-extracted electrons and influence the ions and thus the beam properties as well. Understanding the optics of such large beams composed of hundreds of beamlets is a crucial task and is under continuous improvement. The main challenge, however, is still the fulfillment of the ITER requirements for deuterium, in particular, for long pulses. The management of caesium, which is evaporated into the source to generate sufficient negative ions by the surface conversion process, is one of the keys for stable and reliable operation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Negative Hydrogen Ion Sources for Fusion: From Plasma Generation to Beam Properties

et al. 2021

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“…The full-scale prototype of ITER HNB ion sources is currently in operation in the SPIDER experiment, which is part of the Neutral Beam Test Facility (NBTF) located at Consorzio RFX (Padua, Italy). The ITER HNB ion sources and their prototype, together with their respective acceleration system, are required to deliver a beam current density of 355 A/m 2 (H)/285 A/m 2 (D) from a total extraction area of 0.2 m 2 , and with a ratio between co-extracted electrons and negative ions lower than 0.5 (H)/1 (D) [ [1]- [4]]. To meet these requirements, caesium (Cs) is evaporated into the source to lower the surface work function and produce negative ions by impact of H/D and positive ions on the surfaces, especially those close to the apertures of the acceleration system [ [5], [6]].…”

Section: Introductionmentioning

confidence: 99%

Negative ion density in the ion source SPIDER in Cs free conditions

Barbisan¹,

Agnello²,

Casati³

et al. 2022

Plasma Phys. Control. Fusion

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The SPIDER experiment, operated at the Neutral Beam Test Facility of Consorzio RFX, Padua, hosts the prototype of the H-/D- ion source for the ITER neutral beam injectors. The maximization of the ion current extracted from the source and the minimization of the amount of co-extracted electrons are among the most relevant targets to accomplish. The Cavity Ring-Down Spectroscopy diagnostic measures the negative ion density in the source close to the plasma grid (the plasma-facing grid of the ion acceleration system), so to identify the source operational parameters that maximize the amount of negative ions which can be extracted. In this study SPIDER was operated in hydrogen and deuterium in Cs-free conditions, therefore negative ions were mostly produced by reactions in the plasma volume. This work shows how the magnetic filter field and the bias currents, present in SPIDER to limit the amount of co-extracted electrons, affect the density of negative ions available for extraction. The results indicate that the magnetic filter field in front of the acceleration system should be set between about 1.6 mT, condition that maximizes the density of available negative ions, and about 3.2 mT, condition that minimizes the ratio of electron current to ion current. The negative ion density also resulted to be maximized when the plasma grid and its surrounding bias plate was positively biased against the source body with a total current in the range 0 A÷100 A. The paper shows also how much, in Cs-free conditions, the electric fields in the acceleration system can affect the density of negative ions in the source, close to the plasma grid apertures.

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“…S PIDER is the full-scale prototype of the negative ion source (IS) of the ITER neutral beam injector (NBI). It is currently in the experimental phase at the Neutral Beam Test Facility (NBTF) hosted in Padua, Italy [1], [2]. During experimental campaigns, the circulation of radio frequency (RF) stray currents in the electrical circuits of Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER) was observed.…”

Section: Introductionmentioning

confidence: 99%

RF Stray Currents in SPIDER Power Circuits: Model Assessment and Experimental Results

Nardi

Casagrande

Maistrello

et al. 2022

IEEE Trans. Plasma Sci.

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The ITER Neutral Beam Test Facility (NBTF), Padua, Italy, hosts two different experiments: Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER), the prototype of the ion source (IS) of ITER neutral beam injector (NBI), and Megavolt ITER Injector and Concept Advancement (MITICA), the prototype of the ITER NBI. The ISs of SPIDER and MITICA are driven by radio frequency (RF) power, for a total of 800 kW at 1 MHz. The RF power is delivered to the inductively coupled plasma drivers of the IS by four tetrode oscillators. Operation of SPIDER at high power pointed out the presence of RF stray currents circulating in the electric system. These currents hinder the correct operation of the system, causing damage to its components. To improve the comprehension of the issue, after an overall circuital investigation and the identification of a possible reclosing path for the RF stray currents, a simplified model of SPIDER electric system was developed, initially focusing on a single RF circuit. The aim of the work presented in this article is to extend the model to four RF circuits, to study the impact of their mutual coupling and of the common potential references on RF stray currents magnitude, with a view to improve the comprehension of the issue and the effect of the provisions to mitigate it. The results obtained with this model are compared to SPIDER experimental measurements for validation.

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First operation in SPIDER and the path to complete MITICA

Cited by 48 publications

References 39 publications

Negative Hydrogen Ion Sources for Fusion: From Plasma Generation to Beam Properties

Negative Hydrogen Ion Sources for Fusion: From Plasma Generation to Beam Properties

Negative ion density in the ion source SPIDER in Cs free conditions

RF Stray Currents in SPIDER Power Circuits: Model Assessment and Experimental Results

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