Characterization of coherent structures in tokamak edge turbulence.

Abstract

A statistical test for extracting and identifying coherent structures in the scrape-off layer turbulence is used to analyze Langmuir probe data from the ADITYA and ASDEX tokamaks. This method, the biorthogonal decomposition, allows one to characterize large-scale coherent structures in plasma turbulence in an unambiguous manner. It is shown that such structures effectively contribute to radial transport and to intermittency. Results from numerical simulations of turbulence driven by the resistive interchange instability in the scrape-off layer are compared to the observed statistical properties.