Investigation of radial electric field in the edge region and magnetic field structure in the Large Helical Device

Y. Suzuki, K. Ida, K. Kamiya, M. Yoshinuma, H. Tsuchiya, Inagaki Shigeru, S. Sakakibara, K. Y. Watanabe, Y. Narushima, S. Ohdachi, I. Yamada, R. Yasuhara, K. Tanaka, T. Akiyama, H. Yamada

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

In the Large Helical Device experiments, a significant pressure gradient is observed in the edge region where the three-dimensional magnetohydrodynamics equilibrium analysis predicts the stochastization of magnetic field lines. Therefore, experimental investigation of this edge plasma behavior is attracting much interest to identify either the plasma response to stochastic magnetic fields or the topological change of magnetic fields due to the plasma. In this study, we have investigated the relation of the stochastization of magnetic field lines to the radial electric field, Er. When magnetic field lines become stochastic or open and connected to the vessel, electrons are lost along these field lines while ions are trapped. Then, a strong Er shear from negative to positive appears at the boundary. Two magnetic configurations with different widths of the stochastic layer in the vacuum are studied for low-β discharges. It has been found that the position of a strong Er shear appears outside of the last closed flux surface. When comparing the vacuum magnetic field, the positions of strong Er shear are observed in the edge of the stochastic layer. In the stochastic region, the scatter of stochastic field lines is studied. The position of a strong Er shear appears in the region where the outward scatter of the field lines increases. In that region, stochastic field lines intersect the regions with long and short connection lengths. Although the connection length is longer than the electron mean free path, the scatter of stochastic field lines with short connection lengths appear in the regions with positive E r. These results are compared with moderate-β discharges, where a large plasma response is expected. The prediction of the vacuum magnetic field qualitatively agree with the experimental observations but quantitative differences are found.

Original languageEnglish
Article number124042
JournalPlasma Physics and Controlled Fusion
Volume55
Issue number12
DOIs
Publication statusPublished - Dec 1 2013

Fingerprint

Electric fields
Magnetic fields
electric fields
magnetic fields
shear
Plasmas
Vacuum
vacuum
Trapped ions
Electrons
Magnetohydrodynamics
Pressure gradient
pressure gradients
mean free path
magnetohydrodynamics
vessels
electrons
Fluxes
configurations
predictions

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Investigation of radial electric field in the edge region and magnetic field structure in the Large Helical Device. / Suzuki, Y.; Ida, K.; Kamiya, K.; Yoshinuma, M.; Tsuchiya, H.; Shigeru, Inagaki; Sakakibara, S.; Watanabe, K. Y.; Narushima, Y.; Ohdachi, S.; Yamada, I.; Yasuhara, R.; Tanaka, K.; Akiyama, T.; Yamada, H.

In: Plasma Physics and Controlled Fusion, Vol. 55, No. 12, 124042, 01.12.2013.

Research output: Contribution to journalArticle

Suzuki, Y, Ida, K, Kamiya, K, Yoshinuma, M, Tsuchiya, H, Shigeru, I, Sakakibara, S, Watanabe, KY, Narushima, Y, Ohdachi, S, Yamada, I, Yasuhara, R, Tanaka, K, Akiyama, T & Yamada, H 2013, 'Investigation of radial electric field in the edge region and magnetic field structure in the Large Helical Device', Plasma Physics and Controlled Fusion, vol. 55, no. 12, 124042. https://doi.org/10.1088/0741-3335/55/12/124042
Suzuki, Y. ; Ida, K. ; Kamiya, K. ; Yoshinuma, M. ; Tsuchiya, H. ; Shigeru, Inagaki ; Sakakibara, S. ; Watanabe, K. Y. ; Narushima, Y. ; Ohdachi, S. ; Yamada, I. ; Yasuhara, R. ; Tanaka, K. ; Akiyama, T. ; Yamada, H. / Investigation of radial electric field in the edge region and magnetic field structure in the Large Helical Device. In: Plasma Physics and Controlled Fusion. 2013 ; Vol. 55, No. 12.
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AU - Tsuchiya, H.

AU - Shigeru, Inagaki

AU - Sakakibara, S.

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AU - Narushima, Y.

AU - Ohdachi, S.

AU - Yamada, I.

AU - Yasuhara, R.

AU - Tanaka, K.

AU - Akiyama, T.

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