Electron Bernstein wave heating and emission measurement through the very narrow O-X-B mode conversion window in the LHD

H. Igami, S. Kubo, T. Shimozuma, Y. Yoshimura, H. Takahashi, M. Nishiura, S. Ogasawara, R. Makino, H. Idei, K. Nagasaki, T. Seki, M. Osakabe, T. Mutoh

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    1 Citation (Scopus)


    In the large helical device (LHD), the theoretically predicted width of the ordinary-extraordinary-electron Bernstein wave (O-X-B) mode conversion (MC) window is comparable to the beam width and the power deposition is located in the off-axis region if the 77GHz fundamental electron cyclotron (EC) wave of is launched from an existing horizontal port antenna. In the experiment, the actual MC window location was looked for with changing the aiming. The effective aiming with that the increase of the stored energy was observed was two degrees apart from the location of the theoretical MC window at a maximum. Measurement of the waves originated from the thermally emitted EBW and radiated via the B-X-O mode conversion process is effective to improve the accuracy of the theoretical prediction with comparison between the theoretical and the experimental results. The theoretical prediction suggests that the width of the MC window of the fundamental 77GHz EC wave can be expanded if the lower port antenna is used. On the other hand, the MC window of the second harmonic 154GHz EC wave is blocked by horizontal port wall if another horizontal port antenna is used. It is required to move the final mirror of the quasi-optical antenna toward the plasma surface. Focusing of the beam at the plasma cutoff is (PC) also necessary for the effective mode conversion.

    Original languageEnglish
    Title of host publicationRadiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference
    PublisherAmerican Institute of Physics Inc.
    Number of pages4
    ISBN (Print)9780735412101
    Publication statusPublished - 2014
    Event20th Topical Conference on Radiofrequency Power in Plasmas - Sorrento, Italy
    Duration: Jun 25 2013Jun 28 2013

    Publication series

    NameAIP Conference Proceedings
    ISSN (Print)0094-243X
    ISSN (Electronic)1551-7616


    Other20th Topical Conference on Radiofrequency Power in Plasmas

    All Science Journal Classification (ASJC) codes

    • General Physics and Astronomy


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