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Ikeda K, Tsumori K, Nagaoka K, Nakano H, Kisaki M, Fujiwara Y, Kamio S, Haba Y, Masaki S, Osakabe M. Extension of high power deuterium operation of negative ion based neutral beam injector in the large helical device. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:113322. [PMID: 31779449 DOI: 10.1063/1.5128529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Second deuterium operation of the negative ion based neutral beam injector was performed in 2018 in the large helical device. The electron and ion current ratio improves to Ie/Iacc(D) = 0.31 using the short extraction gap distance of 7 mm between the plasma grid (PG) and the extraction grid (EG). The strength of the magnetic field by the electron deflection magnet installed in the EG increases by 17% at the PG ingress surface, which effectively reduces the electron component in the negative ion rich plasma in the vicinity of PG apertures. The reduction of the electron current made it possible to operate at a high power arc discharge and beam extraction. Then, the deuterium negative ion current increases to 55.4 A with the averaged current density of 233 A/m2. The thermal load on the EG using 7 mm gap distance is 0.6 times smaller than the thermal load using a 8 mm gap caused by the reduction of coextracted electron current. The injection beam power increases to 2.9 MW in the beam line BL3, and the total beam injection power increases to 7 MW by three beam lines in the second deuterium campaign.
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Affiliation(s)
- K Ikeda
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - K Tsumori
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - K Nagaoka
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - H Nakano
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - M Kisaki
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - Y Fujiwara
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - S Kamio
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
| | - Y Haba
- Graduate School of Science, Nagoya University, Nagoya 464-8603, Japan
| | - S Masaki
- The Graduate University for Advanced Studies, SOKENDAI, 322-6 Oroshi, Toki 509-5292, Japan
| | - M Osakabe
- National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences, 322-6 Oroshi, Toki 509-5292, Japan
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Haba Y, Nagaoka K, Tsumori K, Kisaki M, Nakano H, Ikeda K, Fujiwara Y, Kamio S, Yoshimura S, Osakabe M. Development of a dual beamlet monitor system for negative ion beam measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123303. [PMID: 30599604 DOI: 10.1063/1.5056260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/25/2018] [Indexed: 06/09/2023]
Abstract
To evaluate negative ion beam properties, a dual beamlet monitor system has been developed. The dual beamlet monitor system has two diagnostics in one hexagonal box. One diagnostic is a "fast beamlet monitor" for measuring the time evolution of beamlet current profiles with the time resolution of up to 25 MHz. The other diagnostic is a "pepper-pot-type phase space analyzer," which is applied for the evaluation of a phase space structure of the negative ion beamlet. The dual beamlet monitor system is applied to the measurement of the beamlet in the Neutral Beam Test Stand at National Institute for Fusion Science (NIFS-NBTS), in which the beam accelerator is almost identical to those of working beam injectors in the large helical device. It is demonstrated that the overlapping components from the neighboring beamlet can be eliminated, and the phase space structure can be obtained for the single beamlet.
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Affiliation(s)
- Y Haba
- Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - K Nagaoka
- Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
| | - K Tsumori
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - M Kisaki
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - H Nakano
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - K Ikeda
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - Y Fujiwara
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - S Kamio
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - S Yoshimura
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
| | - M Osakabe
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki 509-5292, Japan
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Pilan N, Antoni V, De Lorenzi A, Chitarin G, Veltri P, Sartori E. A new deflection technique applied to an existing scheme of electrostatic accelerator for high energy neutral beam injection in fusion reactor devices. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:02B325. [PMID: 26932053 DOI: 10.1063/1.4939857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor. In order to solve these two issues, a magnetic deflector is proposed to screen the BS from direct exposure to radiation and neutrons so that the voltage insulation between the electrostatic accelerator and the grounded vessel can be enhanced by using compressed SF6 instead of vacuum so that the negative ions can be accelerated at energies higher than 1 MeV. By solving the beam transport with different magnetic deflector properties, an optimum scheme has been found which is shown to be effective to guarantee both the steering effect and the beam aiming.
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Affiliation(s)
- N Pilan
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
| | - V Antoni
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
| | - A De Lorenzi
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
| | - G Chitarin
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
| | - P Veltri
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
| | - E Sartori
- Consorzio RFX-Associazione EURATOM-ENEA per la Fusione, Corso Stati Uniti 4, 35127 Padova, Italy
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Chitarin G, Agostinetti P, Aprile D, Marconato N, Marcuzzi D, Serianni G, Veltri P, Zaccaria P. Off-normal and failure condition analysis of the MITICA negative-ion accelerator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:02B311. [PMID: 26932039 DOI: 10.1063/1.4933184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The negative-ion accelerator for the MITICA neutral beam injector has been designed and optimized in order to reduce the thermo-mechanical stresses in all components below limits compatible with the required fatigue life. However, deviation from the expected beam performances can be caused by "off-normal" operating conditions of the accelerator. The purpose of the present work is to identify and analyse all the "off-normal" operating conditions, which could possibly become critical in terms of thermo-mechanical stresses or of degradation of the optical performances of the beam.
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Affiliation(s)
- Giuseppe Chitarin
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Piero Agostinetti
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Daniele Aprile
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Nicolò Marconato
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Diego Marcuzzi
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Gianluigi Serianni
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Pierluigi Veltri
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
| | - Pierluigi Zaccaria
- Consorzio RFX, (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova, Italy
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Kojima A, Hanada M, Tobari H, Nishikiori R, Hiratsuka J, Kashiwagi M, Umeda N, Yoshida M, Ichikawa M, Watanabe K, Yamano Y, Grisham LR. Development of design technique for vacuum insulation in large size multi-aperture multi-grid accelerator for nuclear fusion. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:02B304. [PMID: 26932032 DOI: 10.1063/1.4931803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators for fusion application. In this method, the nested multi-stage configuration of the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages was based on the previous experimental results about the area effect and the multi-aperture effect. Since the multi-grid effect was found to be the extension of the area effect by the total facing area this time, the total voltage holding capability of the multi-stage can be estimated from that per single stage by assuming the stage with the highest electric field, the total facing area, and the total apertures. By applying these consideration, the analysis on the 3-stage MAMuG accelerator for JT-60SA agreed well with the past gap-scan experiments with an accuracy of less than 10% variation, which demonstrated the high reliability to design MAMuG accelerators and also multi-stage high voltage bushings.
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Affiliation(s)
- A Kojima
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - M Hanada
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - H Tobari
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - R Nishikiori
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - J Hiratsuka
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - M Kashiwagi
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - N Umeda
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - M Yoshida
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - M Ichikawa
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - K Watanabe
- Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
| | - Y Yamano
- Saitama University, Saitama, Saitama-ken 338-8570, Japan
| | - L R Grisham
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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Franzen P, Fantz U. On the NBI system for substantial current drive in a fusion power plant: Status and R&D needs for ion source and laser neutralizer. FUSION ENGINEERING AND DESIGN 2014. [DOI: 10.1016/j.fusengdes.2014.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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