Progress of ECRH by EBW in over-dense plasmas and controlling the confinement regime by ECCD with high power launching in LHD

H. Igami, Y. Yoshimura, H. Takahashi, T. Shimozuma, S. Kubo, H. Idei, M. Nishiura, S. Ogasawara, R. Makino, S. Ohdachi, K. Ida, M. Yoshinuma, T. Ido, A. Shimizu, N. Tamura, S. Inagaki, T. Mutoh

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    1 Citation (Scopus)

    Abstract

    In the large helical device (LHD), fundamental electron cyclotron resonance heating (ECRH) by the electron Bernstein wave (EBW) excited via the ordinary-extraordinary-EBW (O-X-B) mode conversion process was performed with high power (∼1MW) launching. Profiles of increase of the electron temperature (Te) and the soft X-ray signals during the power injection suggest power absorption in the core region. Effects of the local modification of the rotational transform ι/2π(=1/q) by electron cyclotron current drive (ECCD) on the formation and sustainment of the electron internal transport barrier (e-ITB) was investigated for the first time. Co ECCD raised ι/2π close to 0.5 in the core region and caused the flattening of the Te profile. Additional ECRH power is required to form the e-ITB. On the contrary, counter (cntr.) ECCD separates ι/2π from 0.5 in the core region and avoids the flattening of the Te profile. The e-ITB can be formed and sustained without additional ECRH. Analysis of the heat pulse transport with use of the modulation ECRH (MECH) shows the good confinement region extends to the ι/2π =0.5 rational surface in the case of cntr. ECCD.

    Original languageEnglish
    Article number02006
    JournalEPJ Web of Conferences
    Volume32
    DOIs
    Publication statusPublished - 2012
    Event17th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating, EC 2011 - Deurne, Netherlands
    Duration: May 7 2012May 10 2012

    All Science Journal Classification (ASJC) codes

    • Physics and Astronomy(all)

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