Incompressible MHD turbulence (Q1597424)

The inertial range of incompressible MHD turbulence is described in terms of counter-propagating waves. The cascade dynamics is controlled by shear Alfvén waves. The shear Alfvén waves determine the spectrum, and slow waves play a passive role. Cascades composed entirely of shear Alfvén waves do not generate a sufficient measure of slow waves. The MHD turbulence is shown to be anisotropic: the energy cascades are more rapidly along \(k_\perp\) than along \(k_\|\). An opening angle can be determined to define the scale-dependent anisotropy. The MHD turbulence is strong in the sense that waves which comprise it are critically damped. Inside the inertial range the turbulent fluctuations are small, and wave packets suffer distorsions as they move along magnetic field lines perturbed by counter-propagating wave packets. Basing of these results, the behaviour of MHD cascades may be understood geometrically.