Identification of zonal flows in a toroidal plasma.
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.
Fujisawa
A
A
National Institute for Fusion Science, Oroshi-cho, Toki-shi, 509-52 Japan.
Itoh
K
K
Iguchi
H
H
Matsuoka
K
K
Okamura
S
S
Shimizu
A
A
Minami
T
T
Yoshimura
Y
Y
Nagaoka
K
K
Takahashi
C
C
Kojima
M
M
Nakano
H
H
Ohsima
S
S
Nishimura
S
S
Isobe
M
M
Suzuki
C
C
Akiyama
T
T
Ida
K
K
Toi
K
K
Itoh
S-I
SI
Diamond
P H
PH