<i>In situ</i> calibration of neutral beam port-through power and estimation of neutral beam deposition on LHD

Osakabe, M.; Takeiri, Y.; Tsumori, K.; Murakami, S.; Kaneko, O.; Ikeda, K.; Oka, Y.; Asano, E.; Kawamoto, T.; Akiyama, R.; Kawahata, K.; Komori, A.; Inoue, N.; Yonezu, Y.; Ohyabu, N.; Motojima, O.

doi:10.1063/1.1319867

Cited by 34 publications

(4 citation statements)

References 9 publications

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“…(The present analysis focuses on the discharges with high magnetic field, 2.75 T, and the tangential NBI). In the experiments, the NBI deposition power is evaluated by the NB shine-through measurement [29]. The calculated power agrees with the experimental one within the 7.7% standard deviation.…”

Section: Comparison Of Energy Transport Between Isotopic H-and D-domi...supporting

confidence: 68%

“…For the NBI heating, three tangentially injected neutral beam heating systems [28] have been utilized in the experiment. Although the NBI port-through powers in H and D plasmas is slightly different, the deposited power, which is evaluated by the NB shine-through measurement as shown in [29], is almost the same in compared discharges. In addition, a perpendicular NBI was employed for the Charge Exchange Spectroscopy (CXRS) to measure radial profiles of the ion temperature (T i ), radial electric field (E r ) and the poloidal rotation velocity (V E×B ) [30].…”

Section: Methodsmentioning

confidence: 96%

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Isotope effects on transport characteristics of edge and core plasmas heated by neutral beam injection (NBI) in an inward shifted configuration at the Large Helical Device

Zhou,

Xu,

Kobayashi

et al. 2024

Nucl. Fusion

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Isotope effects have been investigated in neutral beam injection (NBI) heated plasmas on the Large Helical Device (LHD) with similar operational parameters between hydrogen (H) and deuterium (D) plasmas. Experimental results show that the global energy confinement has no significant dependence on the isotope mass under similar discharge conditions with nearly the same heating power, line-averaged density (n ̅_e) and magnetic field. For both electron and ion energy transport, the transport coefficients, which are obtained based on local power balance analysis, have analogous profiles between H and D dominant plasmas. For neoclassical χ_e and χ_i values, they are almost equal between H and D dominant plasmas in low n ̅_e discharges, whereas in high n ̅_e cases they are lower in H plasmas than those in D ones. At low n ̅_e, the electron and ion thermal transport in both H and D plasmas are dominated by neoclassical transport at a certain zone (ρ≈0.6-0.85), while the anomalous transport process has primary effects in the remaining area, and the density fluctuations exhibit ion temperature gradient mode nature. With increase of n ̅_e, the anomalous transport becomes prevailing and the density fluctuations propagate along electron diamagnetic drift direction. Bispectral analysis reveals that the H plasma has stronger nonlinear coupling in edge density fluctuations in both low and high density discharges, which is probably due to that the D plasma has stronger damping rate for the nonlinear interaction of turbulence. For a comparative study, the present results have been compared with those observed in the ECRH discharges [1]. The reasons for the similarities and dissimilarities between these two different heating manners are not clear yet. To unravel the underlying physics, essential inputs from theories and simulations are required.

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Section: Comparison Of Energy Transport Between Isotopic H-and D-domi...supporting

confidence: 68%

Section: Methodsmentioning

confidence: 96%

Isotope effects on transport characteristics of edge and core plasmas heated by neutral beam injection (NBI) in an inward shifted configuration at the Large Helical Device

Zhou,

Xu,

Kobayashi

et al. 2024

Nucl. Fusion

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“…The size of the torus hall is W75 × L45 × H40 m 3 . As the main heating system, three tangential neutral beam injectors (t-NBI) and two radial neutral beam injectors (r-NBI) are connected to LHD [44,45]. Neutron yield during deuterium plasma experiments were measured by the neutron flux monitors, located at the top of LHD center axis (#1), near the large outside port on the mid plane (#2, #3), consisting of 235 U fission chamber, 10 B counter and 3 He counter as found in Fig.…”

Section: Location Of Radiation Monitors Around the Torus Hallmentioning

confidence: 99%

Radiation control in LHD and radiation shielding capability of the torus hall during first campaign of deuterium experiment

Kobayashi

Saze

Ogawa

et al. 2019

Fusion Engineering and Design

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“…Real time video is also used to monitor ICRF antennas and the Local Island Divertor head for arcing and hot spots. Also, IR thermography measurements monitor the temperature of the graphite armor tiles of the neutral beam injection (NBI) beam dumps [38]. Finally, for machine operation purposes numerous thermocouples are installed throughout LHD [36] and are sampled continuously and displayed at a 1-Hz sampling rate along with measurements of the vacuum tank and cryostat pressures.…”

Section: ) Real Time Monitoringmentioning

confidence: 99%

LHD Diagnostics Toward Steady-State Operation

Sudo

Peterson

Kawahata

et al. 2004

IEEE Trans. Plasma Sci.

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Abstract-The large helical device (LHD) is the world largest helical system having all superconducting coils. After completion of LHD in 1998, six experimental campaigns have been carried out successfully. The maximum stored energy, central electron temperature, and volume averaged beta value are 1.16 MJ, 10 keV, and 3.2%, respectively. The confinement time of the LHD plasma appears to be equivalent to that of tokamaks. One of the most important missions for LHD is to prove steady-state operation, which is also significant to international thermonuclear experimental reactor (ITER) and to future fusion reactors. LHD is quite appropriate for this purpose based upon the beneficial feature of a helical system, that is, no necessity of the plasma current. So far, the plasma discharge duration was achieved up to 150 s. The plasma density was kept constant by feedback control of gas puffing with real time information of the line density. The issue for demonstrating steady-state operation is whether divertor function to control particle and heat flux is effective enough. Relevant to this, LHD diagnostics should be consistent with the following: 1) continuous operation of main diagnostics during long-pulse operation for feedback control and physics understanding; 2) measurement of fraction of H, He, and impurities in the plasma; 3) heat removal and measure against possible damage or surface erosion of diagnostic components inside of the vacuum chamber; 4) data acquisition system for handling real time data display and a huge amount of data. Although there are already some achievements on the above subjects, there remain still several issues to be resolved.On the other hand, the long-pulse operation of the plasma gives benefits to the diagnostics. For example, the polarizing angle of ECE emission can be changed during the discharge, and the intensity dependence on the polarizing angle has been obtained. The spatial scanning of the neutral particle analyzer and the spectrometer can supply the spatial profiles of the fast neutral particle flux and the specific impurity lines.In this paper, the present status of these issues and future plans are described.

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In situ calibration of neutral beam port-through power and estimation of neutral beam deposition on LHD

Cited by 34 publications

References 9 publications

Isotope effects on transport characteristics of edge and core plasmas heated by neutral beam injection (NBI) in an inward shifted configuration at the Large Helical Device

Isotope effects on transport characteristics of edge and core plasmas heated by neutral beam injection (NBI) in an inward shifted configuration at the Large Helical Device

Radiation control in LHD and radiation shielding capability of the torus hall during first campaign of deuterium experiment

LHD Diagnostics Toward Steady-State Operation

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