Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range

T. Shinya, Y. Takase, T. Wakatsuki, A. Ejiri, H. Furui, J. Hiratsuka, K. Imamura, T. Inada, H. Kakuda, H. Kasahara, R. Kumazawa, C. Moeller, T. Mutoh, Y. Nagashima, K. Nakamura, A. Nakanishi, T. Oosako, K. Saito, T. Seki, M. SoneharaH. Togashi, S. Tsuda, N. Tsujii, T. Yamaguchi

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R0 ≤ 0.38 m, a ≤ 0.25 m, Bt0 ≤ 0.3 T, Ip ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit ηCD ≡ n¯eIpR/PRF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.

    Original languageEnglish
    Article number073003
    JournalNuclear Fusion
    Volume55
    Issue number7
    DOIs
    Publication statusPublished - Jul 1 2015

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    plasma currents
    antennas
    frequency ranges
    orbits
    antenna arrays
    figure of merit
    high energy electrons
    high current
    waveguides
    magnetic fields
    electrons

    All Science Journal Classification (ASJC) codes

    • Nuclear and High Energy Physics
    • Condensed Matter Physics

    Cite this

    Shinya, T., Takase, Y., Wakatsuki, T., Ejiri, A., Furui, H., Hiratsuka, J., ... Yamaguchi, T. (2015). Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range. Nuclear Fusion, 55(7), [073003]. https://doi.org/10.1088/0029-5515/55/7/073003

    Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range. / Shinya, T.; Takase, Y.; Wakatsuki, T.; Ejiri, A.; Furui, H.; Hiratsuka, J.; Imamura, K.; Inada, T.; Kakuda, H.; Kasahara, H.; Kumazawa, R.; Moeller, C.; Mutoh, T.; Nagashima, Y.; Nakamura, K.; Nakanishi, A.; Oosako, T.; Saito, K.; Seki, T.; Sonehara, M.; Togashi, H.; Tsuda, S.; Tsujii, N.; Yamaguchi, T.

    In: Nuclear Fusion, Vol. 55, No. 7, 073003, 01.07.2015.

    Research output: Contribution to journalArticle

    Shinya, T, Takase, Y, Wakatsuki, T, Ejiri, A, Furui, H, Hiratsuka, J, Imamura, K, Inada, T, Kakuda, H, Kasahara, H, Kumazawa, R, Moeller, C, Mutoh, T, Nagashima, Y, Nakamura, K, Nakanishi, A, Oosako, T, Saito, K, Seki, T, Sonehara, M, Togashi, H, Tsuda, S, Tsujii, N & Yamaguchi, T 2015, 'Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range', Nuclear Fusion, vol. 55, no. 7, 073003. https://doi.org/10.1088/0029-5515/55/7/073003
    Shinya, T. ; Takase, Y. ; Wakatsuki, T. ; Ejiri, A. ; Furui, H. ; Hiratsuka, J. ; Imamura, K. ; Inada, T. ; Kakuda, H. ; Kasahara, H. ; Kumazawa, R. ; Moeller, C. ; Mutoh, T. ; Nagashima, Y. ; Nakamura, K. ; Nakanishi, A. ; Oosako, T. ; Saito, K. ; Seki, T. ; Sonehara, M. ; Togashi, H. ; Tsuda, S. ; Tsujii, N. ; Yamaguchi, T. / Non-inductive plasma start-up experiments on the TST-2 spherical tokamak using waves in the lower-hybrid frequency range. In: Nuclear Fusion. 2015 ; Vol. 55, No. 7.
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    AU - Shinya, T.

    AU - Takase, Y.

    AU - Wakatsuki, T.

    AU - Ejiri, A.

    AU - Furui, H.

    AU - Hiratsuka, J.

    AU - Imamura, K.

    AU - Inada, T.

    AU - Kakuda, H.

    AU - Kasahara, H.

    AU - Kumazawa, R.

    AU - Moeller, C.

    AU - Mutoh, T.

    AU - Nagashima, Y.

    AU - Nakamura, K.

    AU - Nakanishi, A.

    AU - Oosako, T.

    AU - Saito, K.

    AU - Seki, T.

    AU - Sonehara, M.

    AU - Togashi, H.

    AU - Tsuda, S.

    AU - Tsujii, N.

    AU - Yamaguchi, T.

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    N2 - Non-inductive plasma current start-up and sustainment by waves in the lower-hybrid frequency range (200 MHz) have been studied on the TST-2 spherical tokamak (R0 ≤ 0.38 m, a ≤ 0.25 m, Bt0 ≤ 0.3 T, Ip ≤ 0.14 MA) using three types of antenna: the 11-element inductively-coupled combline antenna, the dielectric loaded 4-waveguide array antenna, and the 13-element capacitively-coupled combline (CCC) antenna. The maximum plasma currents of 15 kA, 10 kA and 16 kA were achieved, respectively. The highest current drive figure of merit ηCD ≡ n¯eIpR/PRF was achieved by the CCC antenna. The efficiency of current drive should improve by reducing prompt orbit losses of high energy electrons by operating at higher plasma current (to improve orbit confinement) and higher toroidal magnetic field (to improve wave accessibility to the plasma core), while keeping the density high enough (to avoid excessive acceleration of electrons), but under the 'density limit'.

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