Phase-space characterization of negative ion beams for fusion
Multi-grid, multi-aperture accelerators are used in ion sources of neutral beam injectors (NBIs) for fusion. Accelerators are typically optimized by numerical tools, usually taking the e-fold divergence as a valuable global indicator of the single beamlet optics. Nonetheless the velocity distributio...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | Nuclear Fusion |
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| Online Access: | https://doi.org/10.1088/1741-4326/adabf9 |
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| author | Carlo Poggi Antonio Pimazzoni Emanuele Sartori Gianluigi Serianni |
| author_facet | Carlo Poggi Antonio Pimazzoni Emanuele Sartori Gianluigi Serianni |
| author_sort | Carlo Poggi |
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| description | Multi-grid, multi-aperture accelerators are used in ion sources of neutral beam injectors (NBIs) for fusion. Accelerators are typically optimized by numerical tools, usually taking the e-fold divergence as a valuable global indicator of the single beamlet optics. Nonetheless the velocity distribution of accelerated beamlets often deviates from ideal Gaussian profiles. Therefore an accurate characterization of the beamlets optics is essential, particularly for negative ion sources within the context of developing ITER NBIs, which pose challenging requirements on single beamlet optics. For this purpose, an Allison-type emittance scanner was installed in SPIDER, the prototype radio-frequency ion source of ITER heating neutral beams, and utilized to characterize the vertical phase-space of isolated beamlets. In this paper we present the characterization of the beamlets around perveance-match conditions using the Allison type emittance scanner, showing that the minimum divergence obtained is larger than the design value. The discrepancy is investigated using numerical simulations, which highlight the presence of a non-negligible temperature of the extracted negative ions, and of non Gaussian tails, which cannot be reproduced by a uniform thermal distribution of negative ions. |
| format | Article |
| id | doaj-art-b8c40922819d48efb5defdae7c0d8621 |
| institution | Kabale University |
| issn | 0029-5515 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Nuclear Fusion |
| spelling | doaj-art-b8c40922819d48efb5defdae7c0d86212025-01-31T10:35:07ZengIOP PublishingNuclear Fusion0029-55152025-01-0165202606410.1088/1741-4326/adabf9Phase-space characterization of negative ion beams for fusionCarlo Poggi0https://orcid.org/0000-0001-8482-803XAntonio Pimazzoni1https://orcid.org/0000-0003-2650-3944Emanuele Sartori2https://orcid.org/0000-0002-5651-1825Gianluigi Serianni3ITER Organization, Route de Vinon-sur-Verdon , CS 90 046, F-13067 St. Paul-lez-Durance Cedex, FranceConsorzio RFX , Corso Stati Uniti 4, 35127 Padova, ItalyConsorzio RFX , Corso Stati Uniti 4, 35127 Padova, Italy; Universitá degli Studi di Padova , Via 8 Febbraio 1848, 2, 35122 Padova, PD, ItalyConsorzio RFX , Corso Stati Uniti 4, 35127 Padova, ItalyMulti-grid, multi-aperture accelerators are used in ion sources of neutral beam injectors (NBIs) for fusion. Accelerators are typically optimized by numerical tools, usually taking the e-fold divergence as a valuable global indicator of the single beamlet optics. Nonetheless the velocity distribution of accelerated beamlets often deviates from ideal Gaussian profiles. Therefore an accurate characterization of the beamlets optics is essential, particularly for negative ion sources within the context of developing ITER NBIs, which pose challenging requirements on single beamlet optics. For this purpose, an Allison-type emittance scanner was installed in SPIDER, the prototype radio-frequency ion source of ITER heating neutral beams, and utilized to characterize the vertical phase-space of isolated beamlets. In this paper we present the characterization of the beamlets around perveance-match conditions using the Allison type emittance scanner, showing that the minimum divergence obtained is larger than the design value. The discrepancy is investigated using numerical simulations, which highlight the presence of a non-negligible temperature of the extracted negative ions, and of non Gaussian tails, which cannot be reproduced by a uniform thermal distribution of negative ions.https://doi.org/10.1088/1741-4326/adabf9neutral beamsITER HNBSPIDERdiagnostics |
| spellingShingle | Carlo Poggi Antonio Pimazzoni Emanuele Sartori Gianluigi Serianni Phase-space characterization of negative ion beams for fusion Nuclear Fusion neutral beams ITER HNB SPIDER diagnostics |
| title | Phase-space characterization of negative ion beams for fusion |
| title_full | Phase-space characterization of negative ion beams for fusion |
| title_fullStr | Phase-space characterization of negative ion beams for fusion |
| title_full_unstemmed | Phase-space characterization of negative ion beams for fusion |
| title_short | Phase-space characterization of negative ion beams for fusion |
| title_sort | phase space characterization of negative ion beams for fusion |
| topic | neutral beams ITER HNB SPIDER diagnostics |
| url | https://doi.org/10.1088/1741-4326/adabf9 |
| work_keys_str_mv | AT carlopoggi phasespacecharacterizationofnegativeionbeamsforfusion AT antoniopimazzoni phasespacecharacterizationofnegativeionbeamsforfusion AT emanuelesartori phasespacecharacterizationofnegativeionbeamsforfusion AT gianluigiserianni phasespacecharacterizationofnegativeionbeamsforfusion |