Extended self-similarity of intermittent turbulence in edge magnetized plasmas

We investigate the intermittency of the edge plasma turbulence in the T-10 tokamak, the Large Helical Device, the linear machine NAGDIS-II and the HYBTOK-II tokamak. The higher order structure functions are analysed to characterize the self-similarity of the plasma intermittency. The generalized scale invariance over three decades of time scales is observed by involving the extended self-similarity hypothesis. Turbulent fluctuations demonstrate multifractal statistics. The structure function scalings deviate strongly from Kolmogorov's K41 model prediction. The high-order structure functions have a nonlinear scaling being a nonlinear function of the order index. The nonlinear scaling is interpreted within the framework of the log-Poisson model considering ‘hidden’ statistical symmetry (dilatation group), hierarchy of moments, a generalized scale covariance and an underlying multifractal multiplicative cascading process.