Two-Dimensional Distribution of Electron Temperature in Ergodic Layer of LHD Measured from Line Intensity Ratio of CIV and NeVIII

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Author(s)

    • WANG Erhui
    • Department of Fusion Science, Graduate University for Advanced Studies
    • MORITA Shigeru
    • Department of Fusion Science, Graduate University for Advanced Studies|National Institute for Fusion Science
    • GOTO Motoshi
    • Department of Fusion Science, Graduate University for Advanced Studies|National Institute for Fusion Science
    • MURAKAMI Izumi
    • Department of Fusion Science, Graduate University for Advanced Studies|National Institute for Fusion Science
    • OISHI Tetsutarou
    • Department of Fusion Science, Graduate University for Advanced Studies|National Institute for Fusion Science

Abstract

Two-dimensional distribution of impurity lines emitted from ergodic layer with stochastic magnetic field lines in Large Helical Device (LHD) has been observed using a space-resolved extreme ultraviolet (EUV) spectrometer. The two-dimensional electron temperature distribution in the ergodic layer is successfully measured using the line intensity ratio of Li-like NeVIII 2s-3p (<sup>2</sup>S<sub>1/2</sub>-<sup>2</sup>P<sub>3/2</sub>: 88.09 Å, <sup>2</sup>S<sub>1/2</sub>-<sup>2</sup>P<sub>1/2</sub>: 88.13 Å) to 2p-3s (<sup>2</sup>P<sub>1/2</sub>-<sup>2</sup>S<sub>1/2</sub>: 102.91 Å, <sup>2</sup>P<sub>3/2</sub>-<sup>2</sup>S<sub>1/2</sub>: 103.09 Å) transitions emitted from radial location near Last Closed Flux Surface (LCFS). The intensity ratio analyzed with ADAS code shows no dependence on the electron density below 10<sup>14 </sup>cm<sup>−3</sup>. The result indicates a little higher temperature, i.e., 220 eV, in the poloidal location at high-field side near helical coils called O-point compared to the temperature near X-point, i.e., 170 eV. The electron temperature profile is also measured at the edge boundary of ergodic layer using the line intensity ratio of Li-like CIV 2p-3d (<sup>2</sup>P<sub>1/2</sub>-<sup>2</sup>D<sub>3/2</sub>: 384.03 Å, <sup>2</sup>P<sub>3/2</sub>-<sup>2</sup>D<sub>5/2</sub>: 384.18 Å) to 2p-3s (<sup>2</sup>P<sub>1/2</sub>-<sup>2</sup>S<sub>1/2</sub>: 419.53 Å, <sup>2</sup>P<sub>3/2</sub>-<sup>2</sup>S<sub>1/2</sub>: 419.71 Å) transitions. The intensity ratios analyzed with CHIANTI, ADAS and T.Kawachi codes show a slightly higher temperature near O-point, i.e., 25 eV for CHIANTI, 21 eV for ADAS and 11 eV for T.Kawachi's codes, compared to the temperature at X-point, i.e., 15 - 21 eV for CHIANTI, 9 - 15 eV for ADAS and 6 - 9 eV for T.Kawachi codes. It suggests that the transport coefficient in the ergodic layer is varied with three-dimensional structure.

Journal

  • Plasma and Fusion Research

    Plasma and Fusion Research 8(0), 2402176-2402176, 2013

    The Japan Society of Plasma Science and Nuclear Fusion Research

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