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Your search keyword '"Kashiwagi, M."' showing total 4 results
Start Over Author "Kashiwagi, M." Topic ion sources Topic magnetic fields
4 results on '"Kashiwagi, M."'

1. Experimental Validation of an Innovative Deflection Compensation Method in a multi-Beamlet Negative-Ion Accelerator.

Author

Chitarin, G., Kojima, A., Agostinetti, P., Aprile, D., Baltador, C., Hiratsuka, J., Ichikawa, M., Marconato, N., Sartori, E., Serianni, G., Veltri, P., Yoshida, M., Kashiwagi, M., Hanada, M., and Antoni, V.

Subjects
ION accelerators, ANIONS, MAGNETIC fields, HYDROGEN ions, ION sources
Abstract

An innovative magnetic configuration called ADCM (Asymmetric Deflection Compensation Magnets) has been recently proposed for the cancellation of the "criss-cross" deflection of ion trajectories in multi-beamlet negative ion accelerators. Such undesired deflection occurs due to the transverse magnetic field, which is necessary for the suppression of co-extracted electrons. In view of the application of this concept to the ITER Heating Neutral Beam Injector, the new configuration has been experimentally tested for the first time in 2016, in the framework of a research collaboration between Consorzio RFX and QST. [ABSTRACT FROM AUTHOR]

Published
2017
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2. Compensation of beamlet repulsion in a large negative ion source with a multi aperture accelerator.

Author

Kashiwagi, M., Inoue, T., Grisham, L. R., Hanada, M., Kamada, M., Taniguchi, M., Umeda, N., and Watanabe, K.

Subjects
*ELECTRON accelerators, *PARTICLES (Nuclear physics), *CATHODE rays, *ION bombardment, *MAGNETIC fields, *ION sources, *PHYSICS research
Abstract

Excess heat loads to accelerator grids limit extension of pulse length in operation of the large negative ion sources with multi aperture accelerator. Part of the heat loads is caused by interception of deflected beamlets due to their space charge repulsion. In this paper, a beamlet steering technique using aperture offset was examined for compensation of the beamlet deflections utilizing a three dimensional beam analysis simulating the D- negative ion source of JT-60 U. The beamlet deflection was analyzed in detail using fifty beamlets, which were extracted from apertures arranged in a lattice pattern of 10×5. The simulation showed successful compensation of the beamlet deflection by aperture offsets defined according to the thin lens theory. Even if the beam energy was changed, the necessary aperture offset would not be changed maintaining the perveance and a ratio of extraction and acceleration voltage. In JT-60 U, it was shown that the aperture offset of less than 1.0 mm would be enough to compensate the repulsion of all beamlets. When the magnetic field was applied for suppression of co-extracted electrons, necessary aperture offset was estimated to be ±0.5 mm for 500 keV D- ion beam in JT-60 U, in addition to the offset for the space charge repulsion. This result showed good agreements with the previous experimental results and design study of the JT-60 U N-NBI. [ABSTRACT FROM AUTHOR]

Published
2009
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3. Uniform H- ion beam extraction in a large negative ion source with a tent-shaped magnetic filter.

Author

Tobari, H., Hanada, M., Kashiwagi, M., Taniguchi, M., Umeda, N., Watanabe, K., Inoue, T., Sakamoto, K., and Takado, N.

Subjects
MAGNETIC fields, ION sources, DISTRIBUTION (Probability theory), ANALYSIS of variance, MAGNETICS
Abstract

Based on previous studies on the spatial uniformity of the negative ion beam, the external magnetic filter was replaced to a novel tent-shaped magnetic filter in the JAEA 10 A negative ion source. The line-cusp field configuration on the source chamber was also changed to form a symmetric magnetic field like many of positive ion sources aiming at high proton yield. This magnetic field configuration allows fast electrons emitted from filament cathodes to rotate azimuthally inside the source chamber. The source configuration thus prevents localization of fast electrons due to their B×grad B drift in the filter field. As a result, the H- ion beam profile extracted from a wide region of 340×170 mm2 showed reduction of standard deviation from 16% in the original to 7.9% with the tent filter. The negative ion source with the tent filter satisfied the requirement of the beam uniformity for a large negative ion source in the ITER neutral beam injection. [ABSTRACT FROM AUTHOR]

Published
2008
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4. Improvement of beam uniformity by magnetic filter optimization in a Cs-seeded large negative-ion source.

Author

Hanada, M., Seki, T., Takado, N., Inoue, T., Tobari, H., Mizuno, T., Hatayama, A., Dairaku, M., Kashiwagi, M., Sakamoto, K., Taniguchi, M., and Watanabe, K.

Subjects
ION sources, ANIONS, CESIUM, PLASMA gases, ELECTRONS, MAGNETS, HYDROGEN ions, PROTONS, MAGNETIC fields
Abstract

The influence of magnetic filter configuration on the beam uniformity was examined to improve beam uniformity in a large Cs-seeded negative-ion source. By reducing the filter strength of the transverse magnetic field used in a typical negative-ion source, the beam uniformity was largely improved with the improvement of the plasma uniformity while the beam intensity was kept to be nearly constant. However, the coextracted electron current greatly increased. To suppress the coextracted electron current, a tent-shaped magnetic filter was applied together with modifications in the cusp magnets to form a typical multicusp positive-ion source arrangement. The uniformity in longitudinal beam profile was improved with the deviation of local beam intensity within 16% that was nearly equal to the deviation obtained at 50 G cm of the transverse filter strength. In the meantime, the coextracted electron current was kept to be the same as the H- ion current. The present result suggests that the uniformity of H- ion-beam profile is affected by the uniformity of atoms or protons in the source plasma, which are the primary species of negative ions under Cs-seeded surface production. [ABSTRACT FROM AUTHOR]

Published
2006
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