Unified Theory of Edge Turbulence in High- and Low- Density Tokamaks

A new theoretical model, which includes density and temperature gradients and impurity radiation effects, for the edge turbulence in high- and low-density tokamaks is established on the magnetohydrodynamics. The different drive effects in the turbulent evolution are discussed and the mechanism of nonlinear saturation is investigated. The fluctuation levels and the associated diffusion coefficients at the turbulent saturation state are analytically given. The theoretical results are in agreement with the experimental observations on both high- and low-density tokamaks.