Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2

T. Wakatsuki, A. Ejiri, T. Shinya, Y. Takase, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, H. Kasahara, Yoshihiko Nagashima, K. Nakamura, A. Nakanishi, T. Oosako, K. Saito, T. Seki, F. Shimpo, M. Sonehara, H. Togashi, S. TsudaN. Tsujii, T. Yamaguchi

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

    1 Citation (Scopus)

    Abstract

    Lower hybrid current drive experiments were performed on the TST-2 spherical tokamak (R = 0.38 m, a = 0.25 m, B t = 0.3 T, I p = 0.1 MA). A waveguide array antenna consisting of four dielectric (alumina, ε r = 10.0) loaded waveguides was used. The coupling characteristics were investigated over a wide range of input power (0.1 W - 40 kW). The reflection coefficient of this antenna increased when the input power exceeded approximately 1 kW. This result was compared with a numerical simulation based on the finite element method (FEM). The ponderomotive effect was calculated for the wave field calculated by COMSOL [1]. This calculation also showed variation of the reflection coefficient with the input power. Non-inductive plasma current start-up to 10 kA was demonstrated using 40 kW of lower hybrid wave (LHW) power. The current drive figure of merit (η CD =I p n e R/P RF ) of this antenna was higher than that obtained using the combline antenna, which is designed to excite a travelling fast wave. The best current drive efficiency was obtained in the case in which the n (= ck /ω) spectrum of the excited LHW was peaked around 9 and the toroidal field was higher than in previous experiments.

    Original languageEnglish
    Title of host publicationRadiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference
    PublisherAmerican Institute of Physics Inc.
    Pages422-425
    Number of pages4
    ISBN (Print)9780735412101
    DOIs
    Publication statusPublished - Jan 1 2014
    Event20th Topical Conference on Radiofrequency Power in Plasmas - Sorrento, Italy
    Duration: Jun 25 2013Jun 28 2013

    Publication series

    NameAIP Conference Proceedings
    Volume1580
    ISSN (Print)0094-243X
    ISSN (Electronic)1551-7616

    Other

    Other20th Topical Conference on Radiofrequency Power in Plasmas
    CountryItaly
    CitySorrento
    Period6/25/136/28/13

      Fingerprint

    All Science Journal Classification (ASJC) codes

    • Physics and Astronomy(all)

    Cite this

    Wakatsuki, T., Ejiri, A., Shinya, T., Takase, Y., Furui, H., Hiratsuka, J., ... Yamaguchi, T. (2014). Results of lower hybrid wave experiments using a dielectric loaded waveguide array antenna on TST-2. In Radiofrequency Power in Plasmas - Proceedings of the 20th Topical Conference (pp. 422-425). (AIP Conference Proceedings; Vol. 1580). American Institute of Physics Inc.. https://doi.org/10.1063/1.4864578