Rotating thermal convection at very large Rayleigh numbers

The large scale thermal convection systems in geo- and astrophysics are usually influenced by Coriolis forces caused by the rotation of their celestial bodies. To better understand the influence of rotation on the convective flow field and the heat transport at these conditions, we study Rayleigh-B\'enard convection, using pressurized sulfur hexaflouride (SF$_6$) at up to 19\,bars in a cylinder of diameter D=1.12\,m and a height of L=2.24\,m. The gas is heated from below and cooled from above and the convection cell sits on a rotating table inside a large pressure vessel (the ``Uboot of G\"ottingen''). With this setup Rayleigh numbers of up to $Ra=10^{15}$ can be reached, while Ekman numbers as low as $Ek=10^{-8}$ are possible. The Prandtl number in these experiment is kept constant at $Pr\simeq 0.8$. We report on heat flux measurements (expressed by the Nusselt number Nu) as well as measurements from more than 150 temperature probes inside the flow.