Intermittent dissipation and lack of universality in one-dimensional Alfvenic turbulence

The randomly driven Cohen-Kulsrud-Burgers equation is used to study the influence of viscous intermediate shocks (IS) on Alfvenic turbulence. Some of these structures are unstable and undergo gradient collapse leading, as the viscosity is reduced, to increasingly intermittent dissipation bursts. The slow decay at intermediate scales of stable IS prevents the existence of a usual inertial range. Furthermore, the dissipation is unable to adiabatically compensate for the energy injection, making the total energy sensitive to the viscosity parameter. Turbulence thus looses its universal character. Preliminary simulations extend these conclusions to magnetohydrodynamic equations with anisotropic viscosity, typical of strongly magnetized plasmas. (C) 2013 Elsevier B.V. All rights reserved.