Negative-ion-based neutral beam injector for Large Helical Device

Kaneko, O.; Oka, Y.; Osakabe, M.; Takeiri, Y.; Tsumori, K.; Akiyama, R.; Asano, E.; Kawamoto, T.; Andõ, Akira; Kuroda, T.

doi:10.1109/fusion.1995.534414

Cited by 3 publications

(2 citation statements)

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“…NBI consists of usually positive/negative ion source and neutralizer. Negative ion based NBIs have been developed and been utilized in the Large Helical Device (LHD) [1], JT-60U [2], and ITER [3]. The production of hydrogen negative ions is considered to be a competitive production between so called "volume" and "surface" production in a negative ion source.…”

Section: 1752'8and721mentioning

confidence: 99%

Vibrational States of Hydrogen Molecules in One Third LHD Negative Ion Source

Nishiura

Matsumoto²,

Tsumori³

et al. 2011

AIP Conference Proceedings

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EVWUDFW The effect of the cesium on hydrogen negative ions is discussed using the vacuum ultraviolet emissions (VUV) from vibrational states of hydrogen molecules. The VUV spectrum from 90 to 165 nm is related to the H -production from the dissociative attachment of electrons to hydrogen molecules. The VUV spectra in hydrogen plasmas are measured in the extraction region of a negative ion source for neutral beam injector. Under the pure hydrogen discharge, the cesium vapor is introduced into the ion source to enhance the hydrogen negative ion density. When the same arc power of ~99kW is applied in both with and without cesium admixture cases, the ratio of the observed VUV spectrum without to with cesium is not changed clearly. Therefore the production process of H -related to the wall/electrode surface would be enhanced rather than the volume production process..H\ZRUGV negative ions, vibrational states, VUV spectrum, ion source, hydrogen molecules

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Section: 1752'8and721mentioning

confidence: 99%

Vibrational States of Hydrogen Molecules in One Third LHD Negative Ion Source

Nishiura

Matsumoto²,

Tsumori³

et al. 2011

AIP Conference Proceedings

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“…This negative ion source had been developed at NIFS [3]. The construction of the injection system began in 1996 [4], and the injection experiments started in 1998.…”

Section: Introductionmentioning

confidence: 99%

Status of Negative-Ion-Based Neutral Beam Injectors in LHD

Kaneko¹,

Takeiri²,

Oka³

et al. 2005

AIP Conference Proceedings

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Recent progress in LHD N-NBI system is described. The system was designed to provide 15 MW of port-through beam power by three beam lines (BL-1 to BL-3) with 180 keV hydrogen for 10 sec. However, starting from 3.2 MW injection by two beam lines, the performance has not satisfied all its specifications at the same time yet. This is because several difficulties were found in large negative ion sources although the specifications were determined based on the R&D results of small ion sources. Hence, the continuous efforts have been done to improve the performance of negative ion source, and the injection power has been increased year by year, and in the latest LHD experimental campaign total port-through power of 13.1 MW was achieved, where R&D on the ion source of BL-1 has been succeeded. Two improvements have been done on the ion source of BL-1. One is the optimization of magnetic cusp structure by modifying the shape of plasma source, which increased the negative ion current. The other is the adoption of multi-slot aperture for the grounded grid, which reduces the conditioning time of the accelerator dramatically. As a result, the specifications of beam energy and port-through power were satisfied in BL-1. The remaining problem is a pulse length which is still limited due to high heat load on the grounded grid.

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