Response of plasma toroidal flow to the transition between nested and stochastic magnetic field in LHD

The LHD Experiment Group

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Response of the plasma toroidal flow to the forward and backward transition between the nested and the stochastic magnetic field is studied using the charge exchange spectroscopy in the large helical device (LHD). Abrupt damping of toroidal flow associated with a transition from nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 after the exchange of the neutral beam injection (NBI) direction from co- to counter-direction in LHD. The stochastization of magnetic field occurs only in a narrow range of magnetic shear near 0.5 and spontaneous back-transition from stochastic to nested magnetic field (healing) is observed in the steady-state phase of magnetic shear. When the NBI direction is changed from counter- to co-direction, the healing of magnetic field occurs associated with the increase of magnetic shear.

Original languageEnglish
Article number076032
JournalNuclear Fusion
Volume57
Issue number7
DOIs
Publication statusPublished - May 31 2017

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toroidal plasmas
shear
magnetic fields
beam injection
healing
neutral beams
counters
charge exchange
magnetic flux
damping
spectroscopy

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Response of plasma toroidal flow to the transition between nested and stochastic magnetic field in LHD. / The LHD Experiment Group.

In: Nuclear Fusion, Vol. 57, No. 7, 076032, 31.05.2017.

Research output: Contribution to journalArticle

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AU - The LHD Experiment Group

AU - Ida, K.

AU - Yoshinuma, M.

AU - Tsuchiya, H.

AU - Kobayashi, T.

AU - Suzuki, C.

AU - Yokoyama, M.

AU - Shimizu, A.

AU - Nagaoka, K.

AU - Shigeru, Inagaki

AU - Itoh, K.

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AB - Response of the plasma toroidal flow to the forward and backward transition between the nested and the stochastic magnetic field is studied using the charge exchange spectroscopy in the large helical device (LHD). Abrupt damping of toroidal flow associated with a transition from nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 after the exchange of the neutral beam injection (NBI) direction from co- to counter-direction in LHD. The stochastization of magnetic field occurs only in a narrow range of magnetic shear near 0.5 and spontaneous back-transition from stochastic to nested magnetic field (healing) is observed in the steady-state phase of magnetic shear. When the NBI direction is changed from counter- to co-direction, the healing of magnetic field occurs associated with the increase of magnetic shear.

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