Self-Organized Criticality Properties of the Turbulence-InducedParticle Flux at the Plasma Edge of the HT-6M Tokamak

Power spectrum and the probability distribution function (PDF) of the turbulence-induced particle flux Γ in the velocity shear layer of the HT-6M edge region have been measured and analysed. Three regions of frequency dependence (f⁰, f^-1, f^-4) have been observed in the spectrum of the flux. The PDF of the flux displays a Γ^-1 scaling over one decade in Γ. Using the rescaled-range statistical technique, we find that the degree of the self-similarity (Hurst exponent) of the particle flux in the measured region ranges from 0.64 to 0.83. All of these results may mean that the plasma transport is in a state characterized by the self-organized criticality.