Observation of non-locality of parametric decay during rf injection experiments on TST-2

POSTER

Abstract

Investigation of linear/nonlinear wave energy transfer in spectral and real spaces of plasma is important for understanding complex plasma structural formation. We present an experimental observation of non-locality of parametric decay instability (PDI) during rf injection experiments in the TST-2 spherical tokamak. The PDI is considered to be mainly associated with pump wave (high harmonic fast wave, HHFW), lower-sideband (HHFW or ion Bernstein wave), and ion cyclotron quasi-mode (ICQM). PDI is a nonlinear and local phenomenon. However, the PDI is widely observed in various locations inside the vessel, and the same frequency matching condition is satisfied beyond difference of local ion cyclotron frequencies at observation locations. We discuss origin of the non-locality in term of wave propagation and coupling phase.

Authors

  • Yoshihiko Nagashima

    University of Tokyo, Univ. Tokyo, The University of Tokyo

  • Takuya Oosako

    Univ. Tokyo, The University of Tokyo, University of Tokyo

  • Yuichi Takase

    University of Tokyo, The University of Tokyo, Univ. Tokyo

  • Akira Ejiri

    University of Tokyo, Univ. Tokyo, The University of Tokyo

  • Osamu Watanabe

    University of Tokyo, The University of Tokyo

  • Hiroaki Kobayashi

    University of Tokyo, Univ. Tokyo, The University of Tokyo

  • Takashi Yamaguchi

    University of Tokyo, The University of Tokyo

  • Bung Il An

    University of Tokyo, Univ. Tokyo, The University of Tokyo, MIT

  • Hiroki Kurashina

    University of Tokyo, The University of Tokyo

  • Kotaro Yamada

    University of Tokyo, The University of Tokyo

  • Hiroyuki Hayashi

    University of Tokyo, The University of Tokyo

  • Hazuki Matsuzawa

    The University of Tokyo, University of Tokyo

  • Kentaro Hanashima

    University of Tokyo, The University of Tokyo

  • Junichi Hiratsuka

    University of Tokyo, The University of Tokyo

  • Hidetoshi Kakuda

    University of Tokyo, The University of Tokyo

  • Takuya Sakamoto

    University of Tokyo, The University of Tokyo

  • Takuma Wakatsuki

    University of Tokyo, Univ. Tokyo, The University of Tokyo