  Magnetic fields of planets, stars and galaxies are generated by
self-excitation in moving electrically conducting fluids. Once produced,
magnetic fields can play an active role in cosmic structure formation by
destabilizing rotational flows that would be otherwise hydrodynamically stable.
For a long time, both hydromagnetic dynamo action as well as magnetically
triggered flow instabilities had been the subject of purely theoretical
research. Meanwhile, however, the dynamo effect has been observed in
large-scale liquid sodium experiments in Riga, Karlsruhe and Cadarache. In this
paper, we summarize the results of liquid metal experiments devoted to the
dynamo effect and various magnetic instabilities such as the helical and the
azimuthal magnetorotational instability and the Tayler instability. We discuss
in detail our plans for a precession-driven dynamo experiment and a large-scale
Tayler-Couette experiment using liquid sodium, and on the prospects to observe
magnetically triggered instabilities of flows with positive shear.
