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High Performance of Neutral Beam Injectors for Extension of LHD Operational Regime
Abstract High-power negative and positive ion-based neutral beam injectors (NBIs) are operated with high reliability in the Large Helical Device (LHD). The total injection power is >20 MW, and suchExpand
High-power and long-pulse injection with negative-ion-based neutral beam injectors in the Large Helical Device
A negative-ion-based neutral beam injection (NBI) system, in which large caesium-seeded negative-ion sources are utilized, has operated reliably in the Large Helical Device (LHD) since it wasExpand
Spatial distribution of the charged particles and potentials during beam extraction in a negative-ion source.
TLDR
The agreement of the charges is interpreted to indicate that the H(-) density decreasing at the beam extraction is compensated by the electrons diffusing from the driver region, and in the plasmas with very low electron density, the pre-sheath of the extraction field penetrates deeply inside the plAsmas. Expand
Neutral beam injection with an improved accelerator for LHD.
TLDR
The beam profiles, port-through, rates and injection powers obtained with an improved accelerator with the multislot grounded grid are described and the maximum injection power reaches 6 MW/187 keV. Expand
Beamlet characteristics in the accelerator with multislot grounded grid.
TLDR
Characteristics of multibeamlets are investigated by means of beamlet monitoring technique and the optimal horizontal and vertical divergence angles of single beamlet are estimated at 4.1 and 6.1 mrad, respectively. Expand
Cavity Ring‐Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source
A Cavity Ring‐Down (CRD) system was applied to measure the density of negative hydrogen ion (H−) in vicinity of extraction surface in the H− source for the development of neutral beam injector onExpand
High Power Neutral Beam Injection in LHD
The results on high power injection with the neutral beam injection (NBI) system for the Large Helical Device (LHD) are reported. The system consists of three beam-lines with two hydrogen negativeExpand
Research and Development Activities on Negative Ion Sources
Abstract The research and development (R&D) activity on the negative ion sources at the National Institute for Fusion Science is described. During the R&D period from 1989 to 1998, intensiveExpand
Measurement of Electron Density near Plasma Grid of Large-scaled Negative Ion Source by Means of Millimeter-Wave Interferometer
A millimeter‐wave interferometer with the frequency of 39 GHz (λ = 7.7 mm) was newly installed to a large‐scaled negative ion source. The measurable line‐integrated electron density (ne•l) is fromExpand
Recent Progress in the Negative‐Ion‐Based Neutral Beam Injectors in Large Helical Device
Negative‐ion‐based neutral beam injection (negative‐NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to theExpand
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