Homogeneous dynamos: Theory and practice

The magnetism of many naturally occurring bodies is attributed to the motion of conducting fluids in their interiors. Although the physical principles underlying such self-excited dynamos are identical to those governing an electric generator in a power station, they (unlike the commercial machine) operate in a simple homogeneous body of conductor, and are therefore less easily excited. The theory of such ''homogeneous dynamos'' is adumbrated here, and past attempts to construct working laboratory models are reviewed. Consideration is given to the possibility of conducting a turbulent homogeneous dynamo experiment in liquid sodium. The proposed configuration is a crude representation of the simplest of all theoretical dynamo models, that of Ponomarenko [J. Appl. Mech. Tech. Phys. 14, 755 (1972)]. In addition to demonstrating for the first time a homogeneous magnetohydrodynamic (MHD) dynamo in the laboratory, the experiment should enhance understanding of MHD turbulence, and provide insight into how the field generation process saturates