The Riga dynamo experiment

Cosmic magnetic fields, including the magnetic field of the Earth, are produced by the homogeneous dynamo effect in moving electrically conducting fluids. We sketch the history of the underlying theory and comment on previous attempts to realize homogeneous dynamos in the laboratory. For the main part, we report on two series of experiments carried out at the Riga dynamo facility. In November 1999 a slowly growing magnetic field eigenmode was observed for the first time in a liquid metal experiment. In July 2000, the magnetic field saturation regime was studied and a number of interesting back-reaction effects were observed. A preliminary interpretation of the measured data is also presented.