Laborexperimente zur Entstehung und Wirkung kosmischer Magnetfelder

Magnetic fields of cosmic bodies are generated by the hydromagnetic dynamo effect in moving electrically conducting fluids, such as liquid metals or plasmas. Once produced, cosmic magnetic fields are able to act back on moving fluids. This back-reaction may have dramatic consequences for cosmic structure formation, with the magnetorotational instability (MRI) in accretions disks as the most prominent example. Considerable theoretical and computational progress has been made in understanding both the dynamo effect as well as magnetically triggered flow instabilities. Complementary to this, the last fifteen years have seen much effort in studying both effects in liquid metal experiments. We summarize the history of these experiments, discuss their main results and their limitations, and give an outlook on future activities.