The effect of Silk damping on primordial magnetic fields

We study the effects of plasma viscosity on the dynamics of primordial magnetic fields by simulating magnetohydro-dynamics in the early universe by appropriate non-linear cascade models. We find numerically that even in the presence of large kinetic viscosity, magnetic energy is transferred to large length scales. There are indications, however, that the inverse cascade stops at a given time which depends on the magnitude of viscosity. For realistic viscosities we do not find equipartition between magnetic and kinetic energies.