SUPPRESSION OF CROSS-FIELD TURBULENT TRANSPORT OF PASSIVE SCALAR CONCENTRATION IN 2-DIMENSIONAL MAGNETOHYDRODYNAMICS

A theory of the cross-field turbulent transport of a passive scalar in a magnetized, two dimensional, electrically conducting fluid is prese nted. Both a renormalized quasilinear calculation and analyses of an e xactly solvable simple model demonstrate that weak magnetic fields in a highly conducting medium are capable of strongly suppressing the tur bulent cross-field transport by alteration of the Lagrangian correlati on time of a scalar fluid element, without effect on the turbulence in tensity, Passive scalar transport along the magnetic field is unchange d. An explicit expression for the effective cross-field diffusivity is given.