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The enhancement of the fusion reaction rate coefficient induced by energetic protons, which is one of the typical nuclear elastic scattering (NES) effects, was observed in the large helical device (LHD) located at the National Institute for Fusion Science. An intense high purity hydrogen beam (the atomic ratio of the contained deuterium was less than 1 ppm) with ∼170 keV-energy and ∼10 MW-power was injected into a deuterium plasma with the electron temperature ∼9 keV and density ∼1019 m−3. After the hydrogen beam injection, the neutron generation rate by the D(d,n)3He fusion reaction immediately increased, and an increment of over one order of magnitude was observed, even though there was no meaningful ion temperature variation. The reasons for the increment in the neutron generation rate are discussed with reference to the Boltzmann–Fokker–Planck analysis along with LHD experimental data. It is concluded that the increment was induced by the production of energetic deuterons due to the NES of energetic protons. [ABSTRACT FROM AUTHOR]

A world's first 275kV gas cooled type gas insulated power transformer with a low sound level ideal for urban area, which depends on SF6 gas alone for both insulation and cooling, was developed and has been put into commercial service since 1990 in Hong Kong. This paper presents the design philosophy, the principal technical items, the rating and the feature of 275kV 30MVA transformer, the performance test results, and the long term energization test result of the transformer.

The fast deuteron (non-Maxwellian component) diagnostic method, which is based on the higher resolution optical spectroscopic measurement, has been developed as a powerful tool. Owing to a decrease in the D–H charge-exchange cross section, the diagnostic ability of conventional optical diagnostic methods should be improved for ∼MeV energy deuterons. Because the 3He–H charge-exchange cross section is much larger than that of D–H in the ∼MeV energy range, the visible light (VIS) spectrum of 3He produced by the dueteron–dueteron (DD) reaction may be a useful tool. Although the density of 3He is small because it is produced via the DD reaction, improvement of the emissivity of the VIS spectrum of 3He can be expected by using a high-energy beam. We evaluate the VIS spectrum of 3He for the cases when a fast deuteron tail is formed and not formed in the ITER-like beam injected deuterium plasma. Even when the beam energy is in the MeV energy range, a large change appears in the half width at half maximum of the VIS spectrum. The emissivity of the VIS spectrum of 3He and the emissivity of bremsstrahlung are compared, and the measurable VIS spectrum is obtained. It is shown that the VIS spectrum of 3He is a useful tool for the MeV beam deuteron tail diagnostics. [ABSTRACT FROM AUTHOR]

The neutral beam (NB) fast ion confinement in the Large Helical Device (LHD) is studied for several full field ($B_{t}\sim 2.75~\text{T}$) magnetic configurations by a combination of neutron measurement and simulations. To investigate the NB fast ion confinement, we have performed a series of short-pulse NB injection experiments. The experiment results are analysed by the integrated code TASK3D-a. From this investigation, the effective particle diffusion coefficients of the tangential and perpendicular NBs are approximately $D^{\text{eff}}\sim 0.1~\text{m}^{2}~\text{s}^{-1}$ and $D^{\text{eff}}\sim 1~\text{m}^{2}~\text{s}^{-1}$ in the standard configuration. It is clarified that the NB fast ion confinement improves when the plasmas are shifted inward. Moreover, it is also found that the simulation, which considers the deuteron dilution effect due to the presence of impurity ions, can describe a neutron emission rate consistent with the measurement. [ABSTRACT FROM AUTHOR]