Nonlinear saturation of the turbulentαeffect

We study the saturation of the turbulent $\alpha$ effect in the nonlinear regime. A numerical experiment is constructed based on the full nonlinear magnetohydrodynamics equations that allows the $\alpha$ effect to be measured for different values of the mean magnetic field. The object is to distinguish between two possible theories of nonlinear saturation. It is found that the results are in close agreement with the theories that predict strong suppression and are incompatible with those that predict that the turbulent $\alpha$ effect persists up to mean fields of order of the equipartition energy.