Kann man das Erdmagnetfeld im Labor simulieren?

The transfer process of mechanical energy into electromagnetic energy is called the dynamo effect, which is believed to be the origin of the magnetic fields of many astrophysical bodies. First some phenomena of the Earth magnetic field are outlined. In planetary bodies, which consist of a homogeneous liquid interior, a dynamo action is produced by numerous interacting effects such as convection due to concentration and density gradients, coriolis forces, Eckmann pumping, local freezing processes etc. yielding a certain flow structure within these bodies. This flow field leads in terms of the induction equation to a production/conservation of magnetic fields. Since the physical effects producing a dynamo can not be simulated in a laboratory experiment, several simplifications are introduced. Therefore, an excursion in the field of magnetohydrodynamics is mades in order to show that shear flows owing a certain helicity are capable to produce magnetic fields. In the experiment a kinematic dynamo in a homogeneous non-ferromagnetic fluid domain will be investigated, which posseses a flow field likely occuring in astrophysical objects. The theoretical model delivering conditions for the self-excitation of a magnetic fields is based on the mean-field theory. Mean field dynamos are governed by an inverse cascade with magnetic energies being transferred from smaller scales to larger ones and therefore are requiring a scale separation. The main ideas of the mean field approach as well as the simplifications of the analytical and numerical models are outlined in this report and their impact on the design of experimental setup are addressed and discussed. Finally, the experimental program is described, which is mainly intended to verify the results obtained in the simulations. (orig.)SIGLEAvailable from TIB Hannover: ZA 5141(6223) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman