Comparison of electron internal transport barriers in the large helical device and JT-60U plasmas

K. Ida, T. Fujita, T. Fukuda, Y. Sakamoto, S. Ide, K. Toi, S. Inagakl, T. Shimozuma, S. Kubo, H. Idei, A. Fujisawa, S. Ohdachi, M. Yoshinuma, H. Funaba, K. Narihara, S. Murakami, A. Wakasa, M. Yokoyama, Y. Takeiri, K. Y. WatanabeK. Tanaka, Y. Liang, N. Ohyabu

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    Abstract

    Plasmas with an electron internal transport barrier (ITB), which is characterized by peaked electron temperature profiles, are obtained in the JT-60U tokamak and in the large helical device (LHD) when the electron cyclotron heating (ECH) is focused on the magnetic axis. The maximum values of R/L Te, where R is the major radius and LTe is the scale length of the electron temperature gradient, are similar for the LHD and JT-60U ITB plasmas. However, there is a clear jump of R/LTe observed in LHD but not in JT-60U in the ECH power scan. This result is consistent with the fact that the trigger mechanism of the electron ITB is the fast transition of the radial electric field from a small negative Er to a large positive Er in LHD and a change of the magnetic shear from positive to negative is required for the formation of the electron ITB in JT-60U. There are also differences in the electron temperature profiles inside the ITB. The flattening of the electron temperature profile inside the strong ITB could be explained by the sharp increase of q values observed in JT-60U, while no flattening of the electron temperature profile is observed in LHD, where the central q values stay low.

    Original languageEnglish
    Pages (from-to)A45-A50
    JournalPlasma Physics and Controlled Fusion
    Volume46
    Issue number5 SUPPL. A
    DOIs
    Publication statusPublished - May 2004

    All Science Journal Classification (ASJC) codes

    • Nuclear Energy and Engineering
    • Condensed Matter Physics

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    Ida, K., Fujita, T., Fukuda, T., Sakamoto, Y., Ide, S., Toi, K., Inagakl, S., Shimozuma, T., Kubo, S., Idei, H., Fujisawa, A., Ohdachi, S., Yoshinuma, M., Funaba, H., Narihara, K., Murakami, S., Wakasa, A., Yokoyama, M., Takeiri, Y., ... Ohyabu, N. (2004). Comparison of electron internal transport barriers in the large helical device and JT-60U plasmas. Plasma Physics and Controlled Fusion, 46(5 SUPPL. A), A45-A50. https://doi.org/10.1088/0741-3335/46/5A/004