Effect of Neoclassical Transport Optimization on Energetic Ion Confinement in LHD

Murakami, Hitoshi; Yamada, H.; Sasao, M.; Isobe, M.; Ozaki, T.; Saida, T.; Goncharov, Pavel; Lyon, J. F.; Seki, T.; Takeiri, Y.; Oka, Y.; Tumori, K.; Ikeda, K.; Mutoh, T.; Saito, Kenji; Torii, Y.; Watari, T.; Wasaksa, A.; Watanabe, K. Y.; Funaba, H.; Yokoyama, M.; Maaßberg, H.; Beidler, C. D.; Fukuyama, A.; Itoh, K.; Ohkubo, Κ.; Kaneko, O.; Komori, A.; Motojima, O.

doi:10.13182/fst04-a561

Cited by 41 publications

(42 citation statements)

References 4 publications

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“…In order to investigate the beam fueling of the P-NB, the beam current scan was performed by changing the number of operating ion sources with the same gas condition in the inward-shifted magnetic configuration of R ax = 3.60 m, in which the confinement of fast ions is better than that of outward-shifted configurations of LHD [13]. The target plasma has a low density of 0.7 × 10 19 m −3 and is sustained by a tangential NB with a low portthrough power of 3.7 MW in the present experiment.…”

Section: Resultsmentioning

confidence: 99%

“…The ion heating experiments using P-NB were performed with the inward-shifted magnetic configuration of 3.55 m ≤ R ax ≤ 3.70 m, because the heating efficiency of P-NB of inward-shifted configurations is better than that of outward-shifted ones [13]. The P-NB power dependence of T i was investigated in the plasmas heated by P- NB alone.…”

Section: Resultsmentioning

confidence: 99%

“…The major and averaged minor radii are 3.9 m and 0.6 m, respectively. The toroidal and poloidal periods are n = 10 and m = 2, respectively [13]. The plasmas are heated by electron cyclotron resonance heating (ECH) of 2 MW, ion cyclotron heating (ICH) of 2 MW, and three tangential negative-ion-based NBIs with a total port-through power of 14 MW (BL1-3).…”

Section: Experimental Conditionsmentioning

confidence: 99%

See 2 more Smart Citations

Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

Nagaoka

Yokoyama

Takeiri

et al. 2008

Plasma and Fusion Research

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A perpendicular neutral beam (P-NB) injector was installed in the Large Helical Device (LHD) and utilized for high-power ion heating and measurement of the ion temperature (T i ) profile by charge exchange spectroscopy. Significant progress was achieved in ion heating experiments using P-NB, and a high T i of 5.2 keV was achieved at the plasma center. A T i peak profile with a steep gradient in the core region was observed, indicating an improved mode of ion transport. The enhancement of toroidal flow in the core region was observed with the T i rise. Transport analysis shows improvement in anomalous transport in the core region, and the neoclassical transport remains unchanged when the high T i is realized.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Experimental Conditionsmentioning

confidence: 99%

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Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

Nagaoka

Yokoyama

Takeiri

et al. 2008

Plasma and Fusion Research

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“…It is a reduced-version of the GNET code. 17,18 The GNET code can evaluate the accurate deposition profile and distribution in the velocity space of injected beam particles based on the Monte Carlo approach in 5D phase space. For the purpose of the application of this time-consuming GNET code to the experimental analysis, it has been reduced to the FIT code by considering that the full-orbit effect during the slowing-down process on the deposition profile evaluation is not necessary, and that the prompt orbit loss effect is a sufficient approximation for such a purpose.…”

Section: B Ion Heat Confinement Propertiesmentioning

confidence: 99%

Extension of the high-ion-temperature regime in the Large Helical Device

Yokoyama¹,

Nagaoka²,

Yoshinuma³

et al. 2008

Physics of Plasmas

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High-ion-temperature ͑exceeding 5 keV͒ hydrogen plasmas have been successfully produced in the Large Helical Device ͓Iiyoshi et al., Nucl. Fusion 39, 1245 ͑1999͒; Motojima et al., Nucl. Fusion 47, S668 ͑2007͔͒ with the ion heat confinement improvement in the core region. The experimental ion heat diffusivity at the core region is found to be almost independent of the ion temperature, T i ͑even decreasing as T i increases͒. The neoclassical ͑NC͒ ripple transport is suppressed by the ambipolar radial electric field, E r ͑Ͻ0͒ predicted by NC transport fluxes. The temperature ratio, T i / T e , is one of the key parameters to reduce the NC ambipolar particle and heat fluxes. Thus, it is suggested that the selective ion heating ͑making T i / T e larger͒ is a plausible approach to further increase T i . Spontaneous rotation is evaluated in these high-T i plasmas, in which a co-directed component is recognized at the radial location with a large T i gradient, in addition to the tokamak-like counter-directed component expected for E r Ͻ 0.

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“…Also, in this configuration, the deviation of trapped particle orbit from magnetic surfaces is very small and a good confinement of energetic particle is obtained [3]. The effect of neoclassical transport optimization on the energetic ion confinement has been shown experimentally in LHD [4].…”

Section: Introductionmentioning

confidence: 99%

Effect of Neoclassical Transport Optimization on Electron Heat Transport in Low-Collisionality LHD Plasmas

Murakami

Yamada

Wakasa

et al. 2007

Fusion Science and Technology

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Abstract.Electron heat transport in the low-collisonality ECH plasma is investigated to clarify the effect of neoclassical transport optimization on the thermal plasma transport in LHD. Five configurations are realized by shifting the magnetic axis position in major radius: 3.45m, 3.53m, 3.6m, 3.75m and 3.9m. A clear effective helical ripple (which is a quantitative measure of the neoclassical transport optimization) dependency on the enhancement factor of the global energy confinement relative to ISS95 is observed.Local heat transport analyses show a higher electron temperature and a lower heat transport in the neoclassical transport optimized configuration at half the minor radius. The comparisons of the experimental total heat fluxes with that of the neoclassical transport by DCOM/NNW suggests that the neoclassical transport plays a significant role in the heat transport and that the neoclassical transport optimization is effective in improving the plasma confinement in the low-collisionality LHD plasma.3

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Effect of Neoclassical Transport Optimization on Energetic Ion Confinement in LHD

Cited by 41 publications

References 4 publications

Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

Ion Heating Experiments Using Perpendicular Neutral Beam Injection in the Large Helical Device

Extension of the high-ion-temperature regime in the Large Helical Device

Effect of Neoclassical Transport Optimization on Electron Heat Transport in Low-Collisionality LHD Plasmas

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