Abstract
A set of reduced magnetohydrodynamic equations for mean and fluctuating fields is derived and applied to the dynamo effect in reversed field pinch (RFP) and tokamak plasmas. There are two dynamo effects, the first arising from mean field equilibrium, and the second from the fluctuations. The dynamo effect does not drive a net current in steady state. The quasilinear dynamo caused both by growing and stationary tearing modes is calculated and found to be consistent with field reversal in RFP’s. Numerical solutions of the equations are presented, which are in qualitative agreement with experiment and other computations.