Effect of poloidal sheared flow on the long-range correlation characters of edge plasma turbulent transport

Abstract

The long-range correlation characteristics of the turbulence-induced particle transport fluxes measured in the plasma edge region of the Chinese Tokamak-6B (CT-6B) [X. Yang et al., Nucl. Fusion 36, 1669 (1996)] have been investigated. The Hurst exponent calculations and the power spectra exhibit the self-similarity and long-range correlation character of the particle transport fluxes. The rescaled probability distribution functions (PDF’s) of the local fluxes are found to be self-similar, with the self-similarity parameter well above 0.5 in the range of time scales between the turbulence decorrelation and confinement time. The decorrelation effect of the E×B flow shear on the long-range correlation character of the flux has been identified by the changes in the radial dependences of the Hurst parameter, spectral decay index, and the outward flux tail of the PDF near the flow shear layer. This suggests that the mechanism for these changes is the simple decorrelation of the large-scale transport events by the shear flow.