DYNAMICS AND STATISTICS OF INVERSE CASCADE PROCESSES IN 2D MAGNETOHYDRODYNAMIC TURBULENCE

The inverse cascade of the mean square potential A in a 2D magnetofluid randomly forced at small scales is studied by numerical simulations. One finds the spectrum A(k) congruent-to 2.6 is-an-element-of A2/3 k-7/3. The cascade proceeds by coalescence of current filaments, which is a fast reconnection process owing to high turbulent resistivity. Statistics of deltaupsilon(l), and deltaB(l) are strictly Gaussian, also in the condensation phase of A(k) at k = 1. Only when the coherent magnetic field intensity exceeds that of the fluctuations, non-Gaussian statistics in deltaB(l) occur, which are, however, entirely due to the static magnetic structure and not associated with intermittency of the small-scale turbulence, the latter remaining Gaussian.