Causal relationship between zonal flow and turbulence in a toroidal plasma

Akihide Fujisawa, Akihiro Shimizu, Haruhisa Nakano, Shinsuke Ohshima, Kimitaka Itoh, Yoshihiko Nagashima, Sanae I. Itoh, Harukazu Iguchi, Yasuo Yoshimura, Takashi Minami, Keiichi Nagaoka, Chihiro Takahashi, Mamoru Kojima, Shin Nishimura, Mitsutaka Isobe, Chihiro Suzuki, Tsuyoshi Akiyama, Takeshi Ido, Keisuke Matsuoka, Shoichi OkamuraPatrick H. Diamond

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


Electric field fluctuations are directly measured using twin heavy-ion-beam probes in Compact Helical System. The spectrum of the electric field fluctuation reveals the existence of a zonal flow at a frequency of less than 1 kHz, coherent modes with a long correlation length (conjectured as geodesic acoustic modes), and background turbulence. Analyses using a wavelet elucidate nonlinear interactions between these fluctuation components in disparate scales. The highlighted findings are that the turbulent fluctuations should be modulated in response to the direction of zonal flow, and should be suppressed, on average, by the zonal flow. This is the first observation that demonstrates the causal linkage between zonal flow and turbulence in toroidal plasmas at a high temperature.

Original languageEnglish
Article number033501
Journaljournal of the physical society of japan
Issue number3
Publication statusPublished - Mar 2007

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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