Results of a modified PROMISE experiment

Key words magnetic fields – magnetohydrodynamics (MHD) The PROMISE experiment relies on the fact that the critical Reynolds number for the appearance of the magnetorotational instability (MRI) in liquid metal flows drastically decreases when the purely axial magnetic field is replaced by a helical one. We report the results of a modified version of this experiments in which the radial electrical boundary conditions are changed. Special focus is laid on the role of the radial jet region where the two Ekman vortices from the top and the bottom meet each other. c ○ 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim