Overview of LHD Plasma Diagnostics

Kawahata, K.; Peterson, B.J.; Akiyama, Tsuyoshi; Ashikawa, N.; Emoto, M.; Funaba, H.; Hamada, Y.; Ida, K.; Inagaki, S.; Ido, T.; Isobe, M.; Goto, M.; Mase, A.; Masuzaki, S.; Michael, C.; Morisaki, T.; Morita, S.; Muto, S.; Nagayama, Y.; Nakamura, Yukio; Nakanishi, Hiroyuki; Sakamoto, R.; Narihara, K.; Nishiura, M.; Ohdachi, S.; Okajima, S.; Osakabe, M.; Sakakibara, S.; Sanin, A.; Sasao, M.; Sato, K.; Shimizu, A.; Shoji, M.; Sudo, S.; Tamura, N.; Tanaka, Kaoru; Toi, K.; Tokuzawa, T.; Veshchev, E.; Vyacheslavov, L. N.; Yamada, I.; Yoshinuma, M.

doi:10.13182/fst10-a10819

Cited by 2 publications

(2 citation statements)

References 61 publications

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“…LHD is equipped with several diagnostic systems (Kawahata et al 2010). In this paper, we have mainly used electron temperature and density profiles, the ion ratio among protons, deuterons and helium ions, and the time evolution of the neutron emission rate.…”

Section: Experiments Apparatusmentioning

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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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: Experiments Apparatusmentioning

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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“…The LHD includes several diagnostic systems [21]. The following measurements are used in this paper.…”

Section: Experimental Apparatusmentioning

confidence: 99%

Degradation of fast-ion confinement depending on the neutral beam power in MHD quiescent LHD plasmas

Nuga,

Seki,

Ogawa

et al. 2024

Nucl. Fusion

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We investigated the degradation of neutral beam (NB) fast-ion confinement depending on the NB power without magnetohydrodynamics (MHD) instabilities in the Large Helical Device (LHD). In the LHD deuterium experiment, the neutron emission rate per NB power decreased by up to 20% with increasing injected NBs during a single discharge. Because there were no significant variations in the electron temperature and density, the NB shine-through rate, or the magnetic fluctuation due to the change in NB power, the reduction in the neutron emission rate indicates the degradation of the fast-ion confinement. In this paper, we formulated this degradation depending on the NB power and quantitatively estimated the degraded effective confinement time. In addition, we performed neutron emission rate simulations using the obtained effective confinement time. The simulation and experimental results were in good agreement, suggesting that the degraded effective confinement time is valid.

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Overview of LHD Plasma Diagnostics

Cited by 2 publications

References 61 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

Degradation of fast-ion confinement depending on the neutral beam power in MHD quiescent LHD plasmas

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