title: Identification of zonal flows in a toroidal plasma.
abstract: This Letter presents experimental confirmation of the presence of zonal flows in magnetically confined toroidal plasma using an advanced diagnostic system--dual heavy ion beam probes. The simultaneous observation of an electric field at two distant toroidal locations (approximately 1.5 m apart) in the high temperature (approximately 1 keV) plasma provides a fluctuation spectrum of electric field (or flow), a spatiotemporal structure of the zonal flows (characteristic radial length of approximately 1.5 cm and lifetime of approximately 1.5 ms), their long-range correlation with toroidal symmetry (n=0), and the difference in the zonal flow amplitude with and without a transport barrier. These constitute essential elements of turbulence-zonal flow systems, and illustrate one of the fundamental processes of structure formation in nature.
authors.affiliation: National Institute for Fusion Science, Oroshi-cho, Toki-shi, 509-52 Japan.
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authors.lastname: Fujisawa
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authors.lastname: Takahashi
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authors.lastname: Akiyama
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authors.lastname: Ida
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authors.lastname: Toi
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authors.lastname: Diamond