Kubo number and magnetic field line diffusion coefficient for anisotropic magnetic turbulence - art. no. 066405

The magnetic line diffusion coefficients D-x and D-y are obtained by numeri cal simulations in the case that all the magnetic turbulence correlation le ngths l(x), l(y), and l(z) are different. We find that the variety of numer ical results can be organized in terms of the Kubo number, the definition o f which is extended from R = (deltaB/B-o) (l(parallel to)/l(perpendicular t o)) to R = (deltaB/B-o)(l(z)/l(x)), for l(x)greater than or equal tol(y). H ere, l(parallel to) (l(perpendicular to)) is the correlation length along ( perpendicular to) the average field B-o = B-o(e) over cap (z). We have anom alous, non-Gaussian transport for R less than or similar to0.1, in which ca se the mean square deviation scales nonlinearly with time. For R greater th an or similar to 1 we have several Gaussian regimes: an almost quasilinear regime for 0.1 less than or similar toR less than or similar to1. an interm ediate, transition regime for 1 less than or similar toR less than or simil ar to 10, and a percolative regime for R greater than or similar to 10. An analytical form of the diffusion coefficient is proposed. D-i = D(delta Bl( z)lB(o)l(x))(mu)(l(i)/l(x))(v)l(x)(2)/l(z), which well describes the numeri cal simulation results in the quasilinear, intermediate, and percolative re gimes.