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

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, Valentina; Candeloro, V.; Canton, A.; Casagrande, Riccardo; Cavallini, C.; Cavazzana, R.; Cordaro, Luigi; Cruz, N.; Palma, M. Dalla; Dan, M.; Lorenzi, A. De; Delogu, R.; Muri, M. De; Nardi, Marco De; Denizeau, S.; Fadone, M.; Fellin, F.; Ferro, A.; Gaio, E.; Gasparrini, Claudia; Gnesotto, F.; Jain, Palak; Rosa, A. La; López‐Bruna, D.; Lorenzini, R.; Maistrello, A.; Manduchi, G.; Manfrin, S.; Marconato, N.; Mario, I.; Martini, Geórgia Ribeiro; Milazzo, Ruggero; Patton, T.; Peruzzo, S.; Pilan, N.; Pimazzoni, A.; Poggi, C.; Pomaro, N.; Duteil, Basile Pouradier; Recchia, M.; Garola, Andrea Rigoni; Rizzetto, D.; Rizzolo, A.; Santoro, Francesco; Sartori, E.; Segalini, B.; Shepherd, A.; Siragusa, M.; Sonato, P.; Sottocornola, Alessandro; 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.; Zagórski, R.; Zaniol, B.; Zaupa, M.; Zuin, M.; Cavenago, M.; Boilson, D.; Rotti, C.; Decamps, Hans; Geli, F.; Sharma, A.; Veltri, P.; Zacks, J.; Simon, M.; Paolucci, Francesco; Garbuglia, A.; Gutiérrez, Daniel; Masiello, A.; Mico, G.; Labate, C.; Readman, P.; Bragulat, E.; Bailly-Maitre, L.; Gomez, G.; Kouzmenko, G.; Albajar, F.; Kashiwagi, M.; Tobari, H.; Kojima, Akira; Murayama, Masamichi; Hatakeyama, S.; Oshita, E.; Maejima, Tetsuya; Shibata, N.; Yamashita, Yasuo; Watanabe, K.; Singh, Narinder; Singh, Manoj; Dhola, H.; Fantz, U.; Heinemann, B.; Wimmer, Christian; Wünderlich, D.; Tsumori, K.; Croci, G.; Gorini, G.; Muraro, A.; Rebaı̈, M.; Tardocchi, M.; Giacomelli, L.; Rigamonti, D.; Taccogna, F.; Bruno, D.; Rutigliano, M.; Longo, S.; Deambrosis, Silvia Maria; Miorin, Enrico; Montagner, F.; Tonti, Andrea; Panin, F.

doi:10.1016/j.fusengdes.2023.113590

Cited by 10 publications

(3 citation statements)

References 42 publications

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“…The CRAFT quarter-size negative ion source (shown in figure 1) adopts an inductively coupled plasma (ICP) mode like the ITER negative ion source [18][19][20]. The main parameters of the CRAFT quarter-size RF negative ion source are listed in table 1.…”

Section: Methodsmentioning

confidence: 99%

Study on stray electrons ejecting from a long-pulse negative ion source for fusion

Yang,

Wei,

et al. 2024

Plasma Phys. Control. Fusion

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The negative ion based neutral beam injection (NNBI) is a desirable plasma heating and current drive method for the large-scale magnetic fusion devices. Due to the strict requirements and difficult development of the negative ion source for fusion, a long-pulse negative ion source has been developed under the framework of the Comprehensive Research Facility for Fusion Technology (CRAFT) in China. This negative ion source consists of a single RF driver plasma source and a three-electrode accelerator. The typical extraction and acceleration voltage are 4~8 kV and 40~50 kV, respectively.During one shot of the long-pulse (~100 s) beam extraction, the gas pressure in the vacuum vessel increased sharply and the temperature of the cryopump rise from 8 K to 20 K. Moreover, the vessel wall appeared a high temperature after several long-pulse shots. A self-consistent simulation of beam-gas interaction revealed that the heat loads on the vessel wall should be caused by the stray electrons ejecting from the accelerator. Those stray electrons are mainly generated via the stripping or ionization collisions and strongly deflected by the downstream side of the deflection magnetic field for the co-extracted electron. The location of hot spots measured by infrared thermography is consistent with the simulation results. To solve this problem, a series of electron dumps are designed to avoid the direct impinging of the ejecting electrons on the cryopump and the vessel wall. And the results suggest that the hot spots are almost eliminated.

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Section: Methodsmentioning

confidence: 99%

Study on stray electrons ejecting from a long-pulse negative ion source for fusion

Yang,

Wei,

et al. 2024

Plasma Phys. Control. Fusion

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show abstract

“…As part of the R&D on NBI technology, INFN-E supports a specific activity on the optimization of negative ion sources that are the basis of NBIs. This research is aimed at performing measurements with the small source NIO1, installed in the premises of the RFX Consortium in Padua, Italy [31], and also at providing support to the ongoing commissioning of the prototype source SPIDER, installed in a test lab built on purpose in the CNR Research Area in Padua, near to and under the responsibility of RFX Consortium [32].…”

Section: The Magnetic Confinement Fusion Roadmapmentioning

confidence: 99%

Applications of nuclear physics to energy: the INFN-E project of the National Institute of Nuclear Physics (INFN)

Ripani

2024

J. Inst.

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In this talk, the main issues in radioactive waste management worldwide will be briefly introduced, as well as the world roadmap towards nuclear fusion. Then, an overview of the activities of the INFN-E (INFN Energia) strategic project will be given, showing how INFN's skills on basic theoretical aspects and on the design, construction and use of accelerators and radiation detectors can be applied to specific projects for the characterization and monitoring of radioactive waste as a means to increase nuclear safety and in the context of advanced plants for the study of nuclear fusion.

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“…The replacement of the four RF generators based on self-oscillators with solid-state RF generators [28][29][30] is expected to provide a large improvement, as the latter ones do not rely on internal resonance to set the frequency. In principle, this will avoid frequency instabilities (i.e.…”

Section: Vertical and Horizontal Homogeneity Among Rf Driversmentioning

confidence: 99%

Highlights of recent SPIDER results and improvements

Sartori,

Agnello,

Agostini

et al. 2023

J. Inst.

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Three years of experiments on SPIDER allowed characterization of the main features of the source plasma and of the negative ion beam, in the original design configuration. For the large dimensions of the source chamber, and of the extraction area, the investigation of the single-beamlet currents and of the source plasma uniformity had to be carried out to extend the knowledge gained in smaller prototype sources. The configuration of the multiple RF drivers and filter field topologies were found to cause a peculiar behavior in the plasma confinement in the drivers, creating left-right asymmetries which were also visible in the extracted negative ion currents, even after the early implementation of a new scheme of plasma-grid current send and return busbars that greatly improved performance at high filter fields. The plasma properties in the driver and expansion region as well as the positive ion energy at the extraction region were studied in different experimental conditions, and interpreted also with the support of numerical models, suggesting that an improved plasma confinement could contribute to the increase of the plasma density, and to a certain extent to a lowering of the plasma potential profile; both effects shall contribute to increase the presence of cold negative ions for the formation of low-divergence beamlets. Early results related to unwanted RF discharges on the back of the plasma source and the gas conductance of the beam source suggested the reduction of the vessel pressure as mitigation, leading to the definition of a new pumping system. The difficulties related to the simultaneous operation, stable control and high-power operation of multiple RF self-oscillating vacuum tube based RF generators were an unambiguous obstruction to the experimentation, calling for the implementation of RF solid-state amplifiers. The initial tests related to caesium management, the non-uniform plasma properties at different locations across the plasma grid, and the challenges in the measurement of the current and divergence of the accelerated beamlet, unambiguously resulted in the need of new diagnostic systems to investigate with better resolution the spatial uniformities. This contribution summarises how the main experimental findings in the previous experimental campaigns are driving modifications to the SPIDER experiment, during the present shut down, in view of future operations.

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

Cited by 10 publications

References 42 publications

Study on stray electrons ejecting from a long-pulse negative ion source for fusion

Study on stray electrons ejecting from a long-pulse negative ion source for fusion

Applications of nuclear physics to energy: the INFN-E project of the National Institute of Nuclear Physics (INFN)

Highlights of recent SPIDER results and improvements

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