Fluctuation of the ambipolar equilibrium in magnetic perturbations

We draw attention on the fast oscillatory deviations from the residual non-ambipolarity in the case where electrons are driven by strong magnetic perturbations.Comment: Latex 6 pages, one EPS figure include

Coherent structures in a turbulent environment

A systematic method is proposed for the determination of the statistical properties of a field consisting of a coherent structure interacting with turbulent linear waves. The explicit expression of the generating functional of the correlations is obtained, performing the functional integration on a neighbourhood in the function space around the soliton. The results show that the non-gaussian fluctuations observed in the tokamak plasma edge can be explained by the intermittent formation of nonlinear coherent structures.Comment: Revtex 21 pages includes 6 EPS figure