Geo and astrophysically motivated liquid metal experiments at Helmholtz Zentrum Dresden Rossendorf

Thermal turbulence at low Prandtl numbers is important for understanding stars and planets. Experiments with the lowest Prandtl numbers can only be realized with liquid metals and represent a great challenge. In the department of magnetohydrodynamics at the Helmholtz Zentrum Dresden Rossendorf (HZDR) these liquid metal convection flows as well as their interaction with magnetic fields are investigated experimentally. With a targeted use of ultrasonic Doppler velocimetry (UDV) as well as non-contact CIFT measurement techniques, the complex velocity fields in the liquid metal can be reconstructed. The velocity measurements are complemented by high temporal resolution temperature measurements. This allows the global scaling for the heat transport (Nußelt number) as well as the flow intensity (Reynolds number) to be determined. In this talk I will give an overview of the different low Prandtl number experiments at HZDR. The focus will be on convection experiments. The experiments were performed with the alloy gallium indium tin, which is liquid at room temperature and has a Prandtl number of Pr ≈ 0.03. I will also give a short outlook on the upcoming dynamo experiments with liquid sodium and present ideas for future sodium convection experiments at a Prandtl number Pr = O(10^-3).