Liquid metal experiments on the magnetorotational instability in a Taylor-Couette flow

The magnetorotational instability (MRI) is known to play a key role in the formation of stars and black holes by triggering turbulence in hydrodynamically stable Keplerian accretion discs. As discussed recently, it might also play a role in the angular momentum transport in the Earth's outer core. We report the experimental demonstration of this instability in a Taylor-Couette flow under the influence of a helical magnetic field. Special focus is laid on a new version of this experiment in which the Ekman pumping is strongly reduced by using split end-caps.