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926 results on '"Umeda, N."'

202. Development of 1 MeV H- Accelerator at JAEA for ITER NB.

Author

Taniguchi, M., de Esch, H. P. L., Svensson, L., Umeda, N., Kashiwagi, M., Watanabe, K., Tobari, H., Dairaku, M., Sakamoto, K., and Inoue, T.

Subjects
ELECTRON accelerators, ION bombardment, ION sources, CATIONS, PHYSICS research
Abstract

This paper reports the recent activities at JAEA for the development of 1 MeV H- ion accelerator toward the ITER NBI. For the development of MAMuG accelerator, a 320 mA H- ion beam was successfully accelerated as the highest record in the world at the MeV class energy (796 keV). This was achieved by protecting the H- ion source from the high heat load by the backstream positive ions, which was produced during the high current H- ion acceleration. The SINGAP accelerator was tested at JAEA to compare the performance of the SINGAP and the MAMuG. This paper also reports the results of the SINGAP test and the comparison between the SINGAP and the MAMuG is discussed. [ABSTRACT FROM AUTHOR]

Published
2009
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206. Operation and Development of the 500-keV Negative-Ion-Based Neutral Beam Injection System for JT-60U

Author

Kuriyama, M., primary, Akino, N., additional, Ebisawa, N., additional, Grisham, L., additional, Honda, A., additional, Itoh, T., additional, Kawai, M., additional, Kazawa, M., additional, Mogaki, K., additional, Ohara, Y., additional, Ohga, T., additional, Okumura, Y., additional, Oohara, H., additional, Umeda, N., additional, Usui, K., additional, Watanabe, K., additional, Yamamoto, M., additional, and Yamamoto, T., additional

Published
2002
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208. Noninductive Current Drive and Steady-State Operation in JT-60U

Author

Ushigusa, K., primary, Ide, S., additional, Oikawa, T., additional, Suzuki, T., additional, Kamada, Y., additional, Fujita, T., additional, Ikeda, Y., additional, Naito, O., additional, Matsuoka, M., additional, Kondoh, T., additional, Isayama, A., additional, Seki, M., additional, Imai, T., additional, Sakamoto, K., additional, Umeda, N., additional, Hamamatsu, K., additional, Fujii, T., additional, Uehara, K., additional, Yamamoto, T., additional, Miura, Y., additional, Kikuchi, M., additional, Kuriyama, M., additional, and Ninomiy, H., additional

Published
2002
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217. Present status of the negative ion based neutral beam injector for JT-60U

Author

Ohga, T., primary, Umeda, N., additional, Akino, N., additional, Ebisawa, N., additional, Grisham, L., additional, Hikita, S., additional, Honda, A., additional, Itoh, T., additional, Kawai, M., additional, Kazawa, M., additional, Kuriyama, M., additional, Kusaka, M., additional, Mogaki, K., additional, Oohara, H., additional, Pengyuan, L., additional, Satoh, F., additional, Seki, H., additional, Tanai, Y., additional, Toyokawa, Y., additional, Usui, K., additional, Yamamoto, T., additional, and Yamazaki, H., additional

Published
2002
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219. Progress of Negative Ions in Fusion Research.

Author

Grisham, L.R., Umeda, N., Kawai, M., Kuriyama, M., Ohga, T., and Yamamoto, T.

Subjects
*ANIONS, *NUCLEAR fusion, *CONTROLLED fusion, *ION bombardment
Abstract

Negative ion beams are assuming increasing significance in the field of controlled fusion research. The first generation of large high current negative ion sources has now operated successfully on the JT-60U tokamak for some years, producing negative ions of hydrogen or deuterium at energies up to 400 keV for conversion to several megawatts of neutrals which are used for plasma heating and current drive. We report an unexpected intensification phenomenon, and some of the improvements made or planned. In the realm of inertial confinement fusion, interest has grown in the use of heavy negative ion driver beams formed from halogens such as bromine, iodine, or chlorine. We discuss the advantages of negative ions as heavy ion fusion drivers, and assess the technical feasibility of a halogen negative beam system. We also discuss the potential for photodetaching the negative ions to produce atomically neutral beams and reduce beam space charge effects within the target chamber. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2003
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220. Reactor relevant current drive and heating by N-NBI on JT-60U

Author

Oikawa, T, primary, Kamada, Y, additional, Isayama, A, additional, Fujita, T, additional, Suzuki, T, additional, Umeda, N, additional, Kawai, M, additional, Kuriyama, M, additional, Grisham, L.R, additional, Ikeda, Y, additional, Kajiwara, K, additional, Ushigusa, K, additional, Tobita, K, additional, Morioka, A, additional, Takechi, M, additional, Itoh, T, additional, and Team, JT-60, additional

Published
2001
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225. Development of Negative ION Based NBI System for JT-60U

Author

Umeda, N., primary, Akino, N., additional, Ebisawa, N., additional, Grisham, L., additional, Hikita, S., additional, Honda, A., additional, Itoh, T., additional, Kawai, M., additional, Kazawa, M., additional, Kusaka, M., additional, Kusanagi, N., additional, Kuriyama, M., additional, Lee, P., additional, Mogaki, K., additional, Ohga, T., additional, Oohara, H., additional, Satoh, F., additional, Seki, H., additional, Seki, N., additional, Tanai, Y., additional, Toyokawa, R., additional, Usui, K., additional, and Yamazaki, H., additional

Published
2001
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226. Operation of the Positive-ION Based NBI System for JT-60U

Author

Oohara, H., primary, Akino, N., additional, Ebisawa, N., additional, Hikita, S., additional, Honda, A., additional, Itoh, T., additional, Kawai, M., additional, Kazawa, M., additional, Kusaka, M., additional, Kuriyama, M., additional, Mogaki, K., additional, Ohga, T., additional, Satoh, F., additional, Seki, H., additional, Tanai, Y., additional, Toyokawa, R., additional, Umeda, N., additional, Usui, K., additional, and Yamazaki, H., additional

Published
2001
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229. Spatial control of nanoparticle structures using dynamic processes under high flux Cu[sup -] implantation.

Author

Kishimoto, N., Takeda, Y., Umeda, N., Okubo, N., and Lee, C. G.

Subjects
ION implantation, COPPER ions, ANIONS, NANOPARTICLES
Abstract

Negative Cu ions of 60 keV, at high dose rates, have been applied for nanoparticle fabrication in insulators, using both conventional implantation and dynamic negative ion mixing (DNIM). Intense ion beams cause significant inbeam rearrangements of implants, i.e., spontaneous precipitation and depth-directional atomic migration. These dynamic processes are applicable for spatial control of nanoparticle structures. The spatial control is also possible by changing substrates, i.e., amorphous and crystalline SiO[sub 2] and a spinel crystal of MgAl[sub 2]O[sub 4]. The other approach for the spatial control is to use a DNIM method with dynamic growth, which presents a thick uniform structure of nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2001

230. Performance enhancement of negative ion sources for the JT-60U tokamak.

Author

Grisham, L. R., Kuriyama, M., Kawai, M., Itoh, T., and Umeda, N.

Subjects
ANIONS, TOKAMAKS
Abstract

The negative ion based neutral beam system now operating for plasma heating and current drive on the large JT-60U tokamak marked the first application of negative ion source technology to the production of high current, high voltage beams for conversion to neutral atomic beams. This pioneering system has demonstrated the technical feasibility of negative ion based neutral beams for future fusion devices. Because this was a very large advance in the state of the art with respect to all system parameters, the principal physical processes governing the performance of the ion source and accelerator were somewhat different than had been the case with earlier much smaller negative ion sources. We have explored the physical mechanisms limiting the power and pulse length capability of these large sources, and have implemented ameliorating changes to reduce power loading on the accelerator grids and increase the transmitted power fraction. [ABSTRACT FROM AUTHOR]

Published
2001

232. High-current heavy-ion accelerator system and its application to material modification.

Author

Kishimoto, N., Takeda, Y., Lee, C.G., Umeda, N., Okubo, N., and Iwamoto, E.

Abstract

A high-current heavy-ion accelerator system has been developed to realize intense particle fluxes for material modification. The facility of a tandem accelerator attained 1 mA-class ion current both for negative low-energy ions and positive high-energy ions. A negative ion source of the key device is of plasma-sputter type, equipped with multi-cusp magnets and Cs supply. The intense negative ions are either directly used for material irradiation at 60 keV or further accelerated up to 6 MeV after charge transformation. Application of negative ions, alleviating surface charging, enables us to conduct low-energy high-current irradiation to insulating substrates. Since positive ions over MeV are irrelevant to the Coulomb repulsion, the facility as a whole meets high-current irradiation into insulators over a wide energy range. Application of high flux ions provides technological merits not only in efficient implantation but also in different material kinetics. Other characteristics of the system are co-irradiation of intense laser and in-situ detection of kinetic processes. For the material modification, we present nanoparticle fabrication in insulators, and synergistic phenomena by co-irradiation of ions and photons. [ABSTRACT FROM PUBLISHER]

Published
2000

233. Performance of the Negative ion source for JT-60U.

Author

Kuriyama, M., Grisham, L., Itoh, T., Kawai, M., Ohga, T., and Umeda, N.

Abstract

The 500keV Negative-ion based neutral beam injector for JT-60U started the operation in 1996 and has injected so far a neutral beam power of 5.2MW at 350keV for 0.7sec. However there are some issues to be conquered for increasing furthermore the beam power and beam pulse duration time. One of those is source plasma non-uniformity in the arc chamber. Improving the issue, three countermeasures have been conducted. The first is to change an arc discharge distribution through changing arc current resistors which connects in series to each of eight filament cathode groups. The second is masking both ends of the plasma grid with thin molybdenum plates to block beam extraction at the edges. The third is changing arc discharge mode from space charge limited discharge to emission limited which is relatively independent on the plasma condition in the arc chamber. The first two countermeasures have been determined to be effective against the source plasma non-uniformity, and the third is being examined. [ABSTRACT FROM PUBLISHER]

Published
2000

239. Power flow in the negative-ion based neutral beam injection for JT-60

Author

Kuriyama, M., primary, Akino, N., additional, Ebisawa, N., additional, Grisham, L., additional, Hikita, S., additional, Honda, A., additional, Itoh, T., additional, Kawai, M., additional, Kazawa, M., additional, Kusaka, M., additional, Mogaki, K., additional, Ohga, T., additional, Okumura, Y., additional, Oohara, H., additional, Satoh, F., additional, Seki, H., additional, Tanai, Y., additional, Toyokawa, Y., additional, Umeda, N., additional, Usui, K., additional, Watanabe, K., additional, Yamaguchi, M., additional, and Yamazaki, H., additional

Published
2000
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241. Antigen-specific over-expression of human cartilage glycoprotein 39 on CD4+ CD25+ forkhead box protein 3+ regulatory T cells in the generation of glucose-6-phosphate isomerase-induced arthritis.

Author

Tanaka, Y., Matsumoto, I., Inoue, A., Umeda, N., Takai, C., and Sumida, T.

Subjects
ANTIGENS, GENE expression, CARTILAGE, GLYCOPROTEINS, CD4 antigen, FORKHEAD transcription factors, T cells, ARTHRITIS
Abstract

Human cartilage gp-39 ( HC gp-39) is a well-known autoantigen in rheumatoid arthritis ( RA). However, the exact localization, fluctuation and function of HC gp-39 in RA are unknown. Therefore, using a glucose-6-phosphate isomerase ( GPI)-induced model of arthritis, we investigated these aspects of HC gp-39 in arthritis. The rise in serum HC gp-39 levels was detected on the early phase of GPI-induced arthritis (day 7) and the HC gp-39 mRNA was increased significantly on splenic CD4+ T cells on day7, but not on CD11b+cells. Moreover, to identify the characterization of HC gp-39+ CD4+ T cells, we assessed the analysis of T helper ( Th) subsets. As a result, HC gp-39 was expressed dominantly in CD4+ CD25+ forkhead box protein 3 (FoxP3)+ refulatory T cells ( Treg), but not in Th1, Th2 or Th17 cells. Furthermore, to investigate the effect of HC gp-39 to CD4+ T cells, T cell proliferation assay and cytokine production from CD4+ T cells using recombinant HC gp-39 was assessed. We found that GPI-specific T cell proliferation and interferon ( IFN)-γ or interleukin ( IL)-17 production were clearly suppressed by addition of recombinant HC gp-39. Antigen-specific over-expression of HC gp-39 in splenic CD4+ CD25+ FoxP3+ Treg cells occurs in the induction phase of GPI-induced arthritis, and addition of recombinant HC gp-39 suppresses antigen-specific T-cell proliferation and cytokine production, suggesting that HC gp-39 in CD4+ T cells might play a regulatory role in arthritis. [ABSTRACT FROM AUTHOR]

Published
2014
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245. Sequential change of esophageal nitric oxide level in experimental esophagitis in rats

Author

Yamato, S., primary, Matsueda, K., additional, Uchida, M., additional, Shoda, R., additional, Muraoka, A., additional, Matsukawa, M., additional, Sekigawa, K., additional, Akiyama, J., additional, Fukushima, S., additional, Ohara, H., additional, Niihata, A., additional, Masaki, N., additional, Hayashi, S., additional, Shimojo, E., additional, and Umeda, N., additional

Published
1998
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246. Nobel experimental system to induce colonic peristaltic contractions and to monitor its intraluminal flow in rats

Author

Yamato, S., primary, Matsueda, K., additional, Hara, K., additional, Shoda, R., additional, Muraoka, A., additional, Matsukawa, M., additional, Sekigawa, K., additional, Akiyama, J., additional, Fukushima, S., additional, Ohara, H., additional, Niihata, A., additional, Uchida, M., additional, Shimojo, E., additional, and Umeda, N., additional

Published
1998
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248. Is Helicobacter pylori infection an age-dependent risk factor for Nepalese patients with peptic ulcer disease? A case control study

Author

Shoda, R., primary, Shrestha, P.K., additional, Hayashi, S., additional, Matsueda, K., additional, Fukushima, S., additional, Akiyama, J., additional, Sekigawa, K., additional, Ohara, H., additional, Niihata, A., additional, Matsukawa, M., additional, Yamato, S., additional, Masaki, N., additional, Muraoka, A., additional, Shimojo, E., additional, and Umeda, N., additional

Published
1998
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