Can a disc dynamo work in the laboratory?

K.-H. Rädler - M. Rheinhardt

Astrophysical Institute Potsdam An der Sternwarte 16, D-14482 Potsdam, Germany

Abstract
The paper deals with the disc dynamo as often referred to in introductions to dynamo theory. Conditions under which a device of this kind can indeed work as a self-exciting dynamo are derived and discussed with a view to its realization in the laboratory. In any case the radius and the rotation rate of the disc have to be rather large. An estimate using very optimistic assumptions concerning the mechanical stability of the rotating disc and the electric resistance of the relevant parts of the device shows that, as long as no magnetizable material is used, a self-exciting dynamo might be possible, e.g., with a radius of 0.6 m and a rotation rate of 40 s⁻¹. A proper arrangement of magnetizable material clearly improves the conditions for the dynamo. Tables 4, Figs 1, Refs 3.