Current Status of Large Helical Device and Its Prospect for Deuterium Experiment

Osakabe, M.; Takeiri, Y.; Morisaki, T.; Motojima, G.; Ogawa, K.; Isobe, M.; Tanaka, Masahiro; Murakami, S.; Shimizu, A.; Nagaoka, K.; Takahashi, H.; Nagasaki, K.; Fujita, T.; Oya, Yasuhisa; Sakamoto, M.; Ueda, Y.; Akiyama, Tsuyoshi; Kasahara, Hiroshi; Sakakibara, S.; Sakamoto, R.; Tokitani, M.; Yamada, H.; Yokoyama, M.; Yoshimura, Y.

doi:10.1080/15361055.2017.1335145

Cited by 48 publications

(61 citation statements)

References 49 publications

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“…There are several diagnostics systems to investigate the fast particle physics (Gorelenkov et al 2014), such as the neutral particle analyser (Medley & Roquemore 1998;Osakabe et al 2006;Kamio et al 2019), fast ion D α spectroscopy (FIDA) (Luo, Heidbrink & Burrell 2004;Heidbrink et al 2007), fast ion loss detector (Darrow et al 1995;Ogawa et al 2010) and neutron spectroscopy (Adams et al 1993;Ishikawa et al 2007). Because the deuterium plasma experiment campaign began in 2 H. Nuga and others the Large Helical Device (LHD) (Osakabe et al 2017(Osakabe et al , 2018Takeiri 2018a,b) from March 2017, the investigation of fast ion behaviour using neutron diagnostics (Isobe et al 2018; and FIDA (Fujiwara et al 2019) have been enabled in LHD.…”

Section: Introductionmentioning

confidence: 99%

“…In LHD deuterium plasmas, ∼2.45 MeV fast neutrons are yielded owing to the deuterium-deuterium (DD) fusion reaction. Because of the high injection energy of neutral beams of up to E b ∼ 180 keV, most of the neutrons are generated by the fusion reaction between fast deuteron and thermal deuteron instead of the reaction between thermal ions (Osakabe et al 2017). This is the so-called 'beam-thermal' fusion reaction.…”

Section: Introductionmentioning

confidence: 99%

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Studies of the fast ion confinement in the Large Helical Device by using neutron measurement and integrated codes

et al. 2020

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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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Studies of the fast ion confinement in the Large Helical Device by using neutron measurement and integrated codes

et al. 2020

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“…In Paper II [31] and Paper III [32], we apply this theory to perform quasioptical modeling of radiofrequency-wave beams in magnetized plasma as an example. In particular, we consider applications to mode conversion caused by magnetic shear in edge plasma [29], which, for example, is a known problem [33,34] in the Large Helical Device [35,36].…”

Section: B General Ideamentioning

confidence: 99%

Quasioptical modeling of wave beams with and without mode conversion. I. Basic theory

et al. 2019

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This work opens a series of papers where we develop a general quasioptical theory for modeconverting electromagnetic beams in plasma and implement it in a numerical algorithm. Here, the basic theory is introduced. We consider a general quasimonochromatic multi-component wave in a weakly inhomogeneous linear medium with no sources. For any given dispersion operator that governs the wave field, we explicitly calculate the approximate operator that governs the wave envelope ψ to the second order in the geometrical-optics parameter. Then, we further simplify this envelope operator by assuming that the gradient of ψ transverse to the local group velocity is much larger than the corresponding parallel gradient. This leads to a parabolic differential equation for ψ ("quasioptical equation") in the basis of the geometrical-optics polarization vectors. Scalar and mode-converting vector beams are described on the same footing. We also explain how to apply this model to electromagnetic waves in general. In the next papers of this series, we report successful quasioptical modeling of radiofrequency wave beams in magnetized plasma based on this theory.

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“…In the deuterium experiment performed in the large helical device (LHD) [14][15][16], energetic particle confinement studies are largely advanced using a variety of neutron diagnostics [17][18][19][20][21][22][23]. Sci-Fi detectors play a part in comprehensive neutron diagnostics.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved secondary triton burnup 14 MeV neutron measurement by a new scintillating fiber detector in middle total neutron emission ranges in deuterium large helical device plasma experiments

et al. 2021

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A middle-sensitivity scintillating fiber detector (hereafter middle Sci-Fi detector) that works at a deuterium-tritium neutron flux of ~105-107 cm−2s−1 was utilized to measure secondary deuterium-tritium neutron emission rates with high temporal resolution at a total neutron emission rate of 1013 to 1015 n/s, where strong magnetohydrodynamic (MHD) instabilities were observed in the large helical device deuterium plasma experiments. The gain and angular characteristics of the middle Sci-Fi detector were evaluated in an accelerator-based deuterium-tritium neutron source in the intense 14 MeV neutron source facility at Osaka University. Observation of 1 MeV triton transport due to MHD instability was performed by a middle Sci-Fi detector whose deuterium-tritium neutron counting rate was approximately 20 times higher than that of the conventional Sci-Fi detector. Fusion-born triton transport due to energetic-particle-driven MHD instability was observed using the middle Sci-Fi detector due to its high detection efficiency and high discrimination ability of deuterium-tritium neutrons from the sea of deuterium-deuterium neutrons.

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Current Status of Large Helical Device and Its Prospect for Deuterium Experiment

Cited by 48 publications

References 49 publications

Studies of the fast ion confinement in the Large Helical Device by using neutron measurement and integrated codes

Studies of the fast ion confinement in the Large Helical Device by using neutron measurement and integrated codes

Quasioptical modeling of wave beams with and without mode conversion. I. Basic theory

Time-resolved secondary triton burnup 14 MeV neutron measurement by a new scintillating fiber detector in middle total neutron emission ranges in deuterium large helical device plasma experiments

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