Numerical simulation of the aα-effect and turbulent magnetic diffusion with molecular diffusivity

We extend the numerical methods of a previous paper to the study of the α-effect in a turbulent plasma. In the frozen-turbulence case the α-effect vanishes for zero molecular diffusivity. The value of α is, however, found to depend very sensitively on the molecular diffusivity. The same is true for the turbulent magnetic diffusivity β. The theoretical predictions of the first-order smoothing and the Markovian approximations are well satisfied in the appropriate limits, for both α and β.