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Journal Articles

Vacuum insulation and achievement of 980 keV, 185 A/m$$^{2}$$ H$$^{-}$$ ion beam acceleration at JAEA for the ITER neutral beam injector

Tobari, Hiroyuki; Taniguchi, Masaki; Kashiwagi, Mieko; Dairaku, Masayuki; Umeda, Naotaka; Yamanaka, Haruhiko; Tsuchida, Kazuki; Takemoto, Jumpei; Watanabe, Kazuhiro; Inoue, Takashi; et al.

Plasma Science and Technology, 15(2), p.179 - 183, 2013/02

 Times Cited Count:1 Percentile:5.25(Physics, Fluids & Plasmas)

Vacuum insulation is a common issue for the accelerator and the HV bushing for the ITER NBI. The HV bushing has five-stage structure and each stage consists of double-layered insulators. Hence, several triple points exist around the insulators. To reduce electric field at those points simultaneously, three types of stress ring were developed. In voltage holding test of a full-scale mockup equipped with those stress rings, 120% of rated voltage was sustained and the voltage holding capability required in ITER was verified. In the MeV accelerator, voltage holding capability was not sufficient due to breakdown triggered by electric field concentration at edge and corner on grid components. By extending gap length, 1 MV was sustained in vacuum. Furthermore, with new accelerator grids which compensates beam deflection due to magnetic field and space charge repulsion between beamlets, 980 keV, 185 A/m$$^{2}$$ H$$^{-}$$ ion beam acceleration was demonstrated, which was close to ITER requirement.

JAEA Reports

Density of Bunsen reaction solution and viscosity of poly-hydriodic acid

Kubo, Shinji; Yoshino, Koji*; Takemoto, Jumpei*; Kasahara, Seiji; Imai, Yoshiyuki; Onuki, Kaoru

JAEA-Technology 2012-037, 20 Pages, 2013/01

JAEA-Technology-2012-037.pdf:17.29MB

Densities of Bunsen reaction solutions in the iodine-sulfur process were measured with an oscillating U-tube density meter. Two types of the solutions were prepared to simulate sulfuric acid solutions and hydriodic acid solutions of the Bunsen reaction step. The former solution ranged in concentration from 0 to 45 wt% of sulfuric acid containing HI and I$$_{2}$$ of 0-2 mole%; the latter solution contained 0-17 mole% I$$_{2}$$, 1-15 mole% HI and 0-2 mole% H$$_{2}$$SO$$_{4}$$. The temperature of the measured solution were 10-60 $$^{circ}$$C. It was found that, in both solutions, the effect of HI and I$$_{2}$$ concentration on the density could well be represented by using a kind of mole fraction of iodine atom. Based on the finding, a set of correlation equations between the densities and the compositions were derived. Additionally, viscosities of ploy-hydriodic acid were measured using an oscillating viscosity meter in temperature range of 5-40 $$^{circ}$$C, and in the composition range of 0-17 mole% I$$_{2}$$ and 1-15 mole% HI; a empirical equation to calculate viscosity from the composition and the temperature are obtained.

Journal Articles

Voltage holding study of 1 MeV accelerator for ITER neutral beam injector

Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Dairaku, Masayuki; Takemoto, Jumpei; Tobari, Hiroyuki; Tsuchida, Kazuki; Yamanaka, Haruhiko; Watanabe, Kazuhiro; Kojima, Atsushi; et al.

Review of Scientific Instruments, 83(2), p.02B121_1 - 02B121_3, 2012/02

 Times Cited Count:11 Percentile:51.68(Instruments & Instrumentation)

JAEA has developed the MeV accelerator to demonstrate 1 MeV, 200 A/m$$^{2}$$ H$$^{-}$$ ion beam acceleration required for ITER NBI. A key to realize such a high power accelerator is improvement of voltage holding capability. Based on detailed investigation of the voltage holding characteristics, MeV accelerator was modified to reduce electric field concentration by extending gaps between the grid supports and increasing curvature radiuses at the support corners. After the modifications, accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. Moreover, beam deflection due to the magnetic field for electron suppression and space charge repulsion was compensated by aperture displacement technique. As the result, beam deflection was compensated and voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A/m$$^{2}$$, which is close to the requirement of ITER accelerator.

Journal Articles

Study of beamlet deflection and its compensations in a MeV accelerator

Kashiwagi, Mieko; Inoue, Takashi; Taniguchi, Masaki; Umeda, Naotaka; Grisham, L. R.*; Dairaku, Masayuki; Takemoto, Jumpei; Tobari, Hiroyuki; Tsuchida, Kazuki; Watanabe, Kazuhiro; et al.

AIP Conference Proceedings 1390, p.457 - 465, 2011/09

 Times Cited Count:8 Percentile:88.45

In a five stage multi-aperture and multi-grid (MAMuG) accelerator in JAEA, beam acceleration tests are in progress toward 1 MeV, 200 A/m$$^{2}$$ H$$^{-}$$ ion beams for ITER. The 1 MV voltage holding has been successfully demonstrated for 4000 s with the accelerator of expanded gap length that lowered local electric field concentrations. The led to increase of the beam energy up to 900 keV-level. However, it was found that beamlets were deflected more in long gaps and direct interceptions of the deflected beamlet caused breakdowns. The beamlet deflection and its compensation methods were studied utilizing a three-dimensional multi beamlet analysis. The analysis showed that the 1 MeV beam can be compensated by a combination of the aperture offset of 0.8 mm applied in the electron suppression (ESG) and the metal bar called a field shaping plate with a thickness of 1 mm attached beneath the ESG. The paper reports analytical predictions and experimental results of the MAMuG accelerator.

Journal Articles

Development of high voltage power supply system for ITER neutral beam injector

Tsuchida, Kazuki; Watanabe, Kazuhiro; Tobari, Hiroyuki; Takemoto, Jumpei; Yamanaka, Haruhiko; Inoue, Takashi

Denki Gakkai Kenkyukai Shiryo, Genshiryoku Kenkyukai (NE-11-001$$sim$$004 $$cdot$$ 006$$sim$$010), p.17 - 22, 2011/09

A 1 MeV high-energy neutral beam injector is under developing for heating and current drive of ITER plasma in collaboration with EUDA. JADA will provide ultra-high voltage DC power supply components. Design of the 1 MV power supply, R&Ds on a HV bushing and a water choke will be presented. These results satisfy the requirements for the NBI system.

Journal Articles

Development of full-size mockup bushing for 1 MeV ITER NB system

Tobari, Hiroyuki; Inoue, Takashi; Hanada, Masaya; Dairaku, Masayuki; Watanabe, Kazuhiro; Umeda, Naotaka; Taniguchi, Masaki; Kashiwagi, Mieko; Yamanaka, Haruhiko; Takemoto, Jumpei; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

High voltage (HV) bushing in the ITER NBI is one of critical components, which acts as a feedthrough for electric power and cooling water from the -1 MV power supply in SF$$_{6}$$ gas to beam source inside vacuum. JAEA has overcome a longstanding issue on manufacturing of a large bore ceramic ring with 1.56 m in diameter as the insulator of the five-stage HV bushing. Joining method of the ceramic and metal flange with thick Kovar plate to form vacuum boundary was also developed. By assembling components, a full-size mockup bushing simulating one stage of the HV bushing was successfully manufactured. In the voltage holding test, the high voltage of 240 kV including the margin of 20 % of a rated voltage was sustained for 3600 s without breakdown, and the voltage holding capability required in ITER was successfully verified.

Journal Articles

1 MV holding and beam optics in a multi-aperture multi-grid accelerator for ITER NBI

Kashiwagi, Mieko; Taniguchi, Masaki; Kojima, Atsushi; Dairaku, Masayuki; Hanada, Masaya; Hemsworth, R. S.*; Mizuno, Takatoshi*; Takemoto, Jumpei; Tanaka, Masanobu*; Tanaka, Yutaka*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

At JAEA, a multi-aperture multi-grid accelerator has been developed for the ITER neutral beam system. A target is H$$^{-}$$ ion beam acceleration of 0.5 A (200 A/m$$^{2}$$) at 1 MeV. In real accelerators, it was found that the voltage holding was about a half of that obtained in an ideal small electrode. After applying necessary gap length and radii of edges of grid supports to lower local electric field concentrations, the accelerator succeeded in sustaining 1 MV for 4000 s. As a result, beam parameters were increased to 879 keV, 0.36 A (157 A/m$$^{2}$$) at perveance matched condition from 796 kV, 0.32 A (140 A/m$$^{2}$$) reported in FEC2008. In the beam acceleration, the beamlet deflections due to magnetic field and space charge repulsion caused direct interceptions, that resulted in limitations in the beam energy and current. Compensation of these beamlet deflections has been tested applying aperture offset and field shaping plate, which were examined in a three-dimensional beam analysis.

JAEA Reports

Transient phenomena analysis of a DC -1MV power supply for the ITER NBI

Yamamoto, Masanori; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Takemoto, Jumpei; Yamashita, Yasuo*; Inoue, Takashi

JAEA-Technology 2010-029, 60 Pages, 2010/08

JAEA-Technology-2010-029.pdf:10.49MB

A power supply for the ITER Neutral Beam Injector (NBI) is a DC ultra-high voltage (UHV) power supply to accelerate negative ion beams of 40 A up to an energy of 1 MeV. Japan Atomic Energy Agency as the Japan Domestic Agency for ITER contributes procurement of dc -1 MV main components such as step-up -1 MV transformers rectifiers, a high voltage deck 2, a -1 MV insulating transformer, a transmission line, a surge reduction system and equipments for site test. Design of the surge suppression in the NBI power supply is one of the key issues to obtain the stable injector performance. This report describes the design study using EMTDC code on the surge suppression by optimizing the core snubber and additional elements in the -1 MV power supply. The results show that the input energy from the stray capacitance to the accelerator at the breakdown can be reduced to about 25 J that is smaller than the design criteria of 50 J for the ITER NBI.

Journal Articles

Design of a -1 MV dc UHV power supply for ITER NBI

Watanabe, Kazuhiro; Yamamoto, Masanori; Takemoto, Jumpei; Yamashita, Yasuo*; Dairaku, Masayuki; Kashiwagi, Mieko; Taniguchi, Masaki; Tobari, Hiroyuki; Umeda, Naotaka; Sakamoto, Keishi; et al.

Nuclear Fusion, 49(5), p.055022_1 - 055022_5, 2009/05

 Times Cited Count:23 Percentile:68.72(Physics, Fluids & Plasmas)

Japan Atomic Energy Agency as the Japan Domestic Agency (JADA) for ITER contributes procurement of dc -1 MV ultra-high voltage (UHV) components such as a dc -1 MV generator, a transmission line and a -1 MV insulating transformer for the ITER NBI power supply. Inverter frequency of 150 Hz in the -1 MV power supply and major circuit parameters have been proposed and adopted in the ITER NBI. The dc UHV insulation at the multi-layer insulation structure of the transformer for a long pulse up to 3600 s has been designed with electric field simulation. Based on the simulation overall dimensions of the dc UHV components have been finalized. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J which satisfies the design criteria of the total 50 J at -1 MV breakdown.

Journal Articles

-1 MV DC UHV power supply for ITER NBI

Watanabe, Kazuhiro; Yamamoto, Masanori; Takemoto, Jumpei; Yamashita, Yasuo*; Dairaku, Masayuki; Kashiwagi, Mieko; Taniguchi, Masaki; Tobari, Hiroyuki; Umeda, Naotaka; Sakamoto, Keishi; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 7 Pages, 2008/10

The JADA contributes procurement of DC -1 MV ultra-high voltage (UHV) components such as a -1 MV DC generator, a transmission line and a -1 MV insulating transformer. The DC UHV insulation has been carefully analyzed since DC long pulse insulation is quite different from conventional AC insulation. The insulation structure has been designed and the overall dimensions of the DC UHV components have been finalized. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J which satisfies the design criteria of the total 50 J at -1 MV breakdown. From these studies, major technical issues were considered and the functional technical specifications of the UHV components have been developed for the procurement by the JADA.

Oral presentation

Hydrogen production with high-temperature gas-cooled reactors, 9; R&D on on-line measuring instruments for IS process

Takemoto, Jumpei; Yoshino, Koji; Kubo, Shinji; Kasahara, Seiji; Takahashi, Toshio*; Hino, Ryutaro

no journal, , 

no abstracts in English

Oral presentation

Hydrogen production with high-temperature gas-cooled reactors, 4; R&D on on-line measuring instruments for IS process

Takemoto, Jumpei; Yoshino, Koji*; Imai, Yoshiyuki; Kubo, Shinji; Kasahara, Seiji; Takahashi, Toshio*; Hino, Ryutaro

no journal, , 

no abstracts in English

Oral presentation

Preparation of Broader Approach Rokkasho Site

Okumura, Yoshikazu; Ohira, Shigeru; Ejiri, Shintaro; Takemoto, Jumpei; Utsumi, Shigeo*; Kimura, Ai*

no journal, , 

JAEA, which is the Japanese Implementation Agency under the Broader Approach Agreement, plan to carried out the projects of International Fusion Energy Research Centre and International Fusion Material Irradiation Facility-Engineering Validation and Engineering Design Activity at the Rokkasho Site. For implementation of the projects, site preparation including construction of research facilities will be initiated in Japanese fiscal year 2008. In this presentation, outlines of site and buildings are presented and current status and future plans are also described.

Oral presentation

Design of -1 MV UHV power supply for the ITER NBI

Takemoto, Jumpei; Watanabe, Kazuhiro; Yamamoto, Masanori; Inoue, Takashi; Sakamoto, Keishi; Yamashita, Yasuo*

no journal, , 

no abstracts in English

Oral presentation

Voltage holding test of full-size mockup bushing for ITER NBI

Tobari, Hiroyuki; Inoue, Takashi; Dairaku, Masayuki; Yamanaka, Haruhiko; Umeda, Naotaka; Taniguchi, Masaki; Kashiwagi, Mieko; Takemoto, Jumpei; Watanabe, Kazuhiro; Sakamoto, Keishi

no journal, , 

The high voltage bushing in the ITER NBI has a five-stage structure composed of large bore ceramic rings. The ceramic ring must be 1.56 m in diameter because many conductors are located keeping insulation inside the ceramic ring. However, in conventional technique, the diameter has been limited less than 1 m. The joining technique of the brazing between the large ceramic ring with metal has not been established. Then, new forming method of the large ceramic ring and the brazing technique were developed. As a result, the large ceramic of 1.56 m in diameter was successfully manufactured and the ceramic ring was brazed to Kovar rings with vacuum tightness. To enhance voltage holding capability of the manufactured insulator, stress ring to suppress the breakdown staring from the joining point of the ceramic and metal was also developed. In the high voltage test of the insulator, 240 kV was sustained stably over 1 hour, and the voltage holding capability required in ITER was verified.

Oral presentation

Voltage holding test of a full-size mockup bushing for ITER NBI

Tobari, Hiroyuki; Inoue, Takashi; Dairaku, Masayuki; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Takemoto, Jumpei; Sakamoto, Keishi

no journal, , 

The HV bushing in the ITER NBI is a feedthrough for electric power and cooling water located between gas-insulated transmission line and a beam source in vacuum. The bushing has five-stage structure composed of large ceramic rings of which diameter must be 1.56 m to sustain electric insulation between conductors inside the ceramic. However, in conventional technique, the diameter has been limited less than 1 m. The brazing to form vacuum boundary for such a large ceramic ring with metal has not been established. Then, new forming method of the large ceramic ring and the brazing technique were developed. As a result, manufacturing of the ceramic ring and the brazing with to Kovar rings were accomplished. To enhance voltage holding capability of the insulator, stress ring to suppress the breakdown staring from the triple point was also developed. In the high voltage test of the insulator, 240 kV was sustained over 1 hour, and the voltage holding capability required in ITER was verified.

Oral presentation

Development and procurement of the ITER NB power supplies

Watanabe, Kazuhiro; Takemoto, Jumpei; Yamanaka, Haruhiko; Tsuchida, Kazuki; Dairaku, Masayuki; Kashiwagi, Mieko; Taniguchi, Masaki; Tobari, Hiroyuki; Umeda, Naotaka; Inoue, Takashi; et al.

no journal, , 

no abstracts in English

Oral presentation

Development of water choke model for high-voltage deck of ITER neutral beam

Tsuchida, Kazuki; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Takemoto, Jumpei; Inoue, Takashi; Tanaka, Shigeru*; Yamashita, Yasuo*

no journal, , 

In ITER Neutral Beam (NB) injection system, the negative ion source and the accelerator should be cooled to generate high energy and high power beam for the prolonged operation. Those devices will be settled at high electric potential of -1 MV and an water choke is needed in the cooling water line to insulate the high voltage. The water choke for ITER should meet the following specifications; high water pressure (2 MPa) and high leak current (several ten mA) due to the reduction of resistivity in hot water (65 $$^{circ}$$C), etc. So, we developed a ceramic insulation tube for the water choke of ITER NB system and it's performance was confirmed by mechanical and withstand voltage tests. From the test results, it was confirmed the developed ceramic tube has sufficient performance ($$>$$110 kV/tube) as a part of ITER water choke. The anti-corrosion and anti-dissolution of the sealing materials in the ceramic tube was also confirmed under the high leak current condition.

Oral presentation

Development of negative ion based neutral beam injector for ITER

Watanabe, Kazuhiro; Umeda, Naotaka; Kashiwagi, Mieko; Dairaku, Masayuki; Takemoto, Jumpei; Taniguchi, Masaki; Tsuchida, Kazuki; Tobari, Hiroyuki; Yamanaka, Haruhiko; Inoue, Takashi; et al.

no journal, , 

In the ITER project, negative-ion-based neutral beam injectors (NBI) which can inject deuterium neutral beams of 1 MeV, 16.5 MW per one injector are planned. The authors will report the subjects of the system and present status of the development for the major components of Japanese procurements for the ITER NBI and the ITER NBI test facility.

Oral presentation

Progress of procurement on the ITER NB ultra-high voltage power supplies

Yamanaka, Haruhiko; Watanabe, Kazuhiro; Tsuchida, Kazuki; Tobari, Hiroyuki; Takemoto, Jumpei; Inoue, Takashi

no journal, , 

JAEA, as a domestic agency of Japan (JADA) for ITER, is carrying out a research and development of a high-energy neutral beam injector for heating and current drive of ITER plasma in collaboration with European Domestic Agency. JADA will provide ultra-high voltage DC power supplies which can generate -1 MV DC power for the negative ion beam source. Present status of the design and manufacturing technology R&D on the power supply is reported as a part of contribution by JADA for the ITER Neutral Beam Injector. In particular, the current presentation highlights R&D status regarding the ceramic insulation tubes for water choke and the DC -1 MV insulating transformer.

23 (Records 1-20 displayed on this page)