NONDIFFUSIVE CORRECTIONS TO THE LONG-SCALE BEHAVIOR OF ENSEMBLES OF TURBULENT MAGNETIC LINES - APPLICATION OF THE FUNCTIONAL METHOD

The transverse spreading of magnetic field lines in a turbulent plasma is investigated analytically in order to obtain a statistical charact erization at large spatial scales. We develop a functional-integral me thod that allows us to calculate in a systematic way statistical avera ges of physical quantities that depend on the fluctuating field. The k nown magnetic diffusion coefficient for the shear-free case is correct ed with a term arising from the assumption of a finite transverse corr elation length. For the case with magnetic shear the functional method provides the appropriate framework for a perturbative approach based on diagram series.