Observation of coherent sheared turbulence flows in the DIII-D Tokamak.

University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706-1687, USA.
Physical Review Letters (Impact Factor: 7.73). 12/2002; 89(26):265003. DOI: 10.1103/PhysRevLett.89.265003
Source: PubMed

ABSTRACT Time-resolved measurements of the turbulent density flow field in a tokamak plasma reveal low-frequency ( approximately 15 KHz), coherent oscillations in the poloidal flow, v(theta). These flow oscillations have a long poloidal wavelength (m<3) and narrow radial extent (k(r)rho(i) approximately 0.2). The estimated flow-shearing rate is of the same order of magnitude as the turbulence decorrelation rate and may thus regulate the turbulence amplitude. These features are consistent with theoretically predicted axisymmetric, self-regulating, sheared flows recognized as geodesic acoustic modes.

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