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

• Formation of intermediate shocks in Alfvénic turbulence, both within Cohen–Kulsrud–Burgers and one-dimensional MHD equations.
• Evidence of viscous gradient collapse of instable intermediate shocks and of the resulting dissipation intermittency.
• Breaking of universal inertial turbulence due to viscous dissipation of stable intermediate shocks.

The randomly driven Cohen–Kulsrud–Burgers equation is used to study the influence of viscous intermediate shocks (IS) on Alfvénic 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.