3-SCALE EXPANSION OF THE SOLUTION OF THE MAGNETOHYDRODYNAMIC EQUATIONS AND THE REYNOLDS-EQUATION FOR A TOKAMAK

An asymptotic solution of the equations of magnetohydrodynamics(MBD) a t large Reynolds numbers is constructed. The three-scale asymptotic so lution describes the evolution of small rapidly varying perturbations of the equilibrium state with allowance for nonlinear interaction. It is shown that in the linearly unstable situation there arises an aniso tropic coherent structure whose evolution leads to energy exchange bet ween the high- and low-frequency waves. A closed system of MHD Reynold s equations for the anisotropic structure that permits calculation of the Reynolds stresses is derived.