Inverse Problems in MHD

We consider inverse problems in MHD that are related to the reconstruction of velocity fields from external measurements of electromagnetic fields. Possible applications are contactless flow measurements in metallurgical and crystal growth facilities as well as velocity reconstructions for cosmic and laboratory hydromagnetic dynamos. In the case of small magnetic Reynolds numbers it is necessary to apply external magnetic field and to measure the flow induced electromagnetic fields. Analytical results concernig the uniqueness problem of velocity reconstruction and the need for regularization are discussed. First results for inverse dynamo theory, i.e. the region of high magnetic Reynolds number, are also presented.