Control of the radial electric field shear by modification of the magnetic field configuration in LHD

Ida, K.; Yoshinuma, M.; Yokoyama, M.; Inagaki, S.; Tamura, N.; Peterson, B.J.; Morisaki, T.; Masuzaki, S.; Komori, A.; Nagayama, Y.; Tanaka, K.; Narihara, K.; Watanabe, K.Y.; Beidler, C. D.; Group, LHD Experimental

doi:10.1088/0029-5515/45/5/010

Cited by 53 publications

(66 citation statements)

References 33 publications

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“…The experimental observation of radial electric field or the poloidal rotation is difficult in the high-T i phase because of a hollow carbon impurity profile (discussed later). However, the neoclassical radial electric field is considered to be a good indication in LHD plasmas, as demonstrated in previous studies [17,18]. The neoclassical ion thermal diffusivity does not change in the core region, as shown in Fig.…”

Section: Resultssupporting

confidence: 64%

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: Resultssupporting

confidence: 64%

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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“…The ambipolarity of neoclassical particle fluxes has been demonstrated to well describe the bifurcation nature of the radial electric field (E r ) in LHD and also in other helical plasmas [3,4]. Thus, it is of a great importance to accurately calculate the neoclassical radial fluxes, and then ambipolar E r .…”

Section: Outlook and Present Status Of Task3d Developmentmentioning

confidence: 99%

Development of Integrated Transport Code, TASK3D, and Its Applications to LHD Experiment

Yokoyama

Wakasa

Seki

et al. 2012

Plasma and Fusion Research

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The integrated transport code for helical plasmas, TASK3D, has been developed both by modifying modules in TASK to be applicable to three-dimensional magnetic configurations, and by adding new modules for stellarator-heliotron specific physics and incorporating three-dimensional equilibria. In this paper, these module developments so far are collectively introduced, and recent progress on the applications of TASK3D to heat transport analyses of LHD plasmas is introduced.

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“…However, it is fair to think that the NC ambipolar E r gives a rather good indication for the experimentally observed E r in LHD as demonstrated in previous papers. 9,20 The estimated ambipolar E r at t = 0.75 s ͓T i ͑0͒ ϳ 1.6 keV͔ and 1.15 s ͑ϳ5.2 keV͒ are shown in Fig. 5͑a͒.…”

Section: -3mentioning

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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Control of the radial electric field shear by modification of the magnetic field configuration in LHD

Cited by 53 publications

References 33 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

Development of Integrated Transport Code, TASK3D, and Its Applications to LHD Experiment

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

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