Self-similar hydromagnetic dynamo.

A simple axisymmetric dynamo mechanism is proposed. It may have bearing on the problem of the generation of magnetic fields in stars and on the sun spot phenomenon. The dynamo is realized in jet-like flows for which the velocity and induction are inversely proportional to the distance from the origin. There is no contradiction with the well known Cowling result, since the conditions of the antidynamo theorem require stronger damping at infinity. It is shown that when the circulation is large, an inverse bifurcation of the MHD regime occurs, whereas supercritical bifurcation occurs when the swirling is small. It is also found that self-generation of the magnetic field may cause lamination of an initially turbulent regime.