  This paper considers magnetic field generation by a fluid flow in a system
referred to as the Archontis dynamo: a steady nonlinear magnetohydrodynamic
(MHD) state is driven by a prescribed body force. The field and flow become
almost equal and dissipation is concentrated in cigar-like structures centred
on straight-line separatrices. Numerical scaling laws for energy and
dissipation are given that extend previous calculations to smaller
diffusivities. The symmetries of the dynamo are set out, together with their
implications for the structure of field and flow along the separatrices. The
scaling of the cigar-like dissipative regions, as the square root of the
diffusivities, is explained by approximations near the separatrices. Rigorous
results on the existence and smoothness of solutions to the steady, forced MHD
equations are given.
