Helium transport in the core and stochastic edge layer in LHD

K. Ida, M. Yoshinuma, M. Goto, O. Schmitz, S. Dai, A. Bader, M. Kobayashi, G. Kawamura, C. Moon, Y. Nakamura

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Abstract

Radial profiles of the density ratio of helium to hydrogen ions are measured using charge exchange spectroscopy with a two-wavelength spectrometer in the large helical device. Helium transport at the last closed flux surface (LCFS) and stochastic magnetic field layer outside the LCFS as well as in the core plasma is studied for a wide range of helium fractions, i.e. from hydrogen-dominated plasmas up to helium-dominated plasmas. The helium density profile becomes more peaked and inward convection velocity increases in the hydrogen-dominant plasma, while it becomes flat or hollow and the convection velocity is in the outward direction in the helium-dominant plasmas. The density gradient of helium at the LCFS is twice that of hydrogen and becomes steeper as the hydrogen becomes more dominant.

Original languageEnglish
Article number074010
JournalPlasma Physics and Controlled Fusion
Volume58
Issue number7
DOIs
Publication statusPublished - Jun 15 2016
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Ida, K., Yoshinuma, M., Goto, M., Schmitz, O., Dai, S., Bader, A., ... Nakamura, Y. (2016). Helium transport in the core and stochastic edge layer in LHD. Plasma Physics and Controlled Fusion, 58(7), [074010]. https://doi.org/10.1088/0741-3335/58/7/074010