Anomalous Scaling of Impurity Transport in Drift Wave Turbulence

The statistical properties of impurity transport in the edge tokamak plasma modeled by the Hasegawa-Wakatani system are investigated using the structure function analysis. The impurities are considered as a passive scalar advected by the plasma flow. The use of extended self-similarity (ESS) enables us to show that in the quasiadiabatic regime, the impurity density and the vorticity of the electric drift velocity exhibit similar multifractal scaling. However, potential fluctuations are self-similar and exhibit a monofractal scaling in agreement with Kolmogorov-Kraichnan theory for two-dimensional turbulence. Long-range spatial correlations have also been studied using Hurst exponent. The latter has been calculated by structure function method. The values of Hurst exponents for impurity and vorticity show that spatial anti-persistency dominates these quantities. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)