An upper bound is determined for the turbulently generated axial electromotive force in reversed-field pinches, constrained solely by energy conservation in the approximation of incompressible magnetohydrodynamics. The field reversal is predicted and comparisons are made with the minimum-energy state with the invariant magnetic helicity.

• Received 20 October 1989

DOI:https://doi.org/10.1103/PhysRevA.42.7487