Intermittent characteristics of turbulence induced by coherent structures (blobs)was clearly observed in the ion saturation current signal, density fluctuation, particle flux andheat flux in HT-7. It is obvious that ion saturation current signal has deviated from Gaussiandistribution and the skewness (S) and flatness (K) of signal increase radially outwards in thescrape-off layer (SOL). Using conditional analysis (CA), asymmetric character of the intermittentbursts are demonstrated. Owing to the radial propagation of the coherent structures, the particledensity profile in SOL is non-exponential and flat outwards from the last close flux surface (LCFS).It is found around LCFS that the large burst fluctuations (above 2.5 rms) are responsible for about50% of the total particle transport. Burst events move radially outwards with E_θ× B velocity, andthe blob size can be calculated as δΥ～V_rΤ_c. Our experiment shows that the blob size, life time anddrift velocity experienced a pronounced decorrelation in the shear layer. The electrostatic Reynoldsstress components become very strong and show a radially steep gradient in the proximity of theshear layer. These experimental findings may imply that the coherent structures are titled by thedeveloped shear flow in the E× B shear layer.
