Convection-caused symmetry breaking of azimuthal magnetorotational instability in a liquid metal Taylor--Couette flow

M. Seilmayer - J. Ogbonna - F. Stefani

Helmholtz-Zentrum Dresden--Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany

Abstract
We report the results of a liquid metal Taylor--Couette experiment in the centrifugally stable (Rayleigh stable) regime under the influence of an azimuthal magnetic field. In the present experimental setup, the azimuthal magnetorotational instability (AMRI) occurs as a travelling wave in a rotational shear flow. The observed symmetry breaking and a systematic deviation of the characteristic properties of the AMRI wave from theoretical prediction are caused by thermal convection. The central current-carrying rod was identified to be responsible for driving the radial heat flux. Preliminary numerical investigations point towards an interaction between AMRI and thermal convection, which supports our experimental findings. Tables 2, Figs 4, Refs 14.