Effects of the radial electric field on the confinement of fast ions in ITER

Tani, K.; Honda, M.; Oikawa, T.; Shinohara, K.; Kusama, Y.; Sugie, Toshiharu

doi:10.1088/0029-5515/55/5/053010

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…The differences in the fast-ion population and the impurity profile may affect the radial electric field. The fast-ion confinement may be changed through the change of the radial electric field [41,42]. The difference in the fast-ion population affects to the pressure anisotropy and the plasma flow.…”

Section: Difference To the Short-pulse Injection Experimentmentioning

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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Section: Difference To the Short-pulse Injection Experimentmentioning

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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show abstract

“…Meanwhile, the fishbone instability can be excited by the interaction of fast ions with the internal kink mode [22]. The relevant simulation works have been extensively carried out, for instance, the investigations of NBI transport and loss in ITER by radial electric field [23] and RMPs [24,25]. Redistribution of alpha particles by internal kink and sawtooth is studied with circular cross section and ITER-like parameters [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Effect of ideal internal MHD instabilities on NBI fast ion redistribution in ITER 15 MA scenario

Yang¹,

Liu²,

Wang³

et al. 2023

Plasma Sci. Technol.

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Transport of fast ions is a crucial issue during the operation of ITER. Redistribution of neutral beam injection (NBI) fast ions by the ideal internal magneto-hydrodynamic (MHD) instabilities in ITER is studied utilizing the guiding-center code ORBIT (R.B. White et al 1984 Phys. Fluids 27 2455). Effects of the perturbation amplitude A of the internal kink, the perturbation frequency f of the fishbone instability, and the toroidal mode number n of the internal kink are investigated, respectively, in this work. The n = 1 internal kink mode can cause NBI fast ions transporting in real space from regions of 0 < s ≤ 0.32 to 0.32 < s ≤ 0.53, where s labels the normalized plasma radial coordinate. The transport of fast ions is greater as the perturbation amplitude increases. The maximum relative change of the number of fast ions approaches 5% when the perturbation amplitude rises to 500 G. A strong transport is generated between the regions of 0 < s ≤ 0.05 and 0.05 < s ≤ 0.12 in the presence of the fishbone instability. Higher frequency results in greater transport, and the number of fast ions in 0 < s ≤ 0.05 is reduced by 30% at the fishbone frequency of 100 kHz. Perturbations with higher n will lead to excursion of fast ion transport regions outward along the radial direction. The loss of fast ions, however, is not affected by the internal MHD perturbation. Strong transport from 0 < s ≤ 0.05 to 0.05 < s ≤ 0.12 does not influence the plasma heating power of ITER, since the NBI fast ions are still located in the plasma core. On the other hand, the influence of fast ion transport from 0 < s ≤ 0.32 to 0.32 < s ≤ 0.53 needs a further study.

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“…The standard method and formulas can be found nowadays in textbooks and monographs [1,2]. In some circumstances, an equilibrium electric field perpendicular to the background magnetic field may be present, e. g. near the edge region of magnetic confinement devices [3][4][5][6][7], where a transport barrier may be induced due to the radial electric field. In future larger devices like the International Thermonuclear Experimental Reactor (ITER), the electric field may be present in a wider region near the edge due to its scaling with the major radius.…”

Section: Introductionmentioning

confidence: 99%

The electromagnetic waves propagating parallel to the magnetic field in a uniform magnetized plasma with a transverse electric field

Zhou¹,

Yue²,

Wang³

et al. 2021

Phys. Scr.

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In natural and laboratory magnetized plasmas, an equilibrium electric field may exist perpendicular to the background magnetic field. In such a situation all the plasma species experience a common drift and the equilibrium distribution functions have a common shift in velocity space. The susceptibility tensor is derived for such a situation using the characteristics and then the Lorentz transformation method is adopted to verify the results. As an application we give an analysis of the waves propagating parallel to the background magnetic field for a simple electron plus single charged ion plasma. It is predicted that the presence of a transverse equilibrium electric field can drastically change the wave propagation only if the wave frequency is close to the plasma Langmuir frequency.

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Effects of the radial electric field on the confinement of fast ions in ITER

Cited by 5 publications

References 24 publications

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

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

Effect of ideal internal MHD instabilities on NBI fast ion redistribution in ITER 15 MA scenario

The electromagnetic waves propagating parallel to the magnetic field in a uniform magnetized plasma with a transverse electric field

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