- Fujisawa, A;
- Itoh, K;
- Iguchi, H;
- Matsuoka, K;
- Okamura, S;
- Shimizu, A;
- Minami, T;
- Yoshimura, Y;
- Nagaoka, K;
- Takahashi, C;
- Kojima, M;
- Nakano, H;
- Ohsima, S;
- Nishimura, S;
- Isobe, M;
- Suzuki, C;
- Akiyama, T;
- Ida, K;
- Toi, K;
- Itoh, S-I;
- Diamond, PH
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.