Transient convection experiments in internally-heated systems.

Radioactive decay of unstable isotopes is one of the main heat sources in the early stages of planetary formation as well as in the mantle of terrestrial planets. Laboratory studies characterized by Rayleigh and Prandtl numbers in the range relevant for planetary bodies had remained beyond the ability of the experimental approach until the development of a new technique based on microwave heating. Using this technique, we performed a series of experiments focused on the thermal evolution of an internally heated viscous fluid cooled from above.