Transitions in a Magnetized Quasi-laminar Spherical Couette Flow

First results from a new magnetized spherical Couette experiment are presented.
For a line in the Re-Ha instability diagram with constant Reynolds Number Re = 1000 and increasing Hartmann number Ha we study the liquid metal movement in a spherical gap under the influence of a vertical magnetic field.
The resulting flow structures are inspected with comprehensive ultrasound technique.
Increasing the magnetic field strength until Ha = 60, we observe the equatorially anti-symmetric jet instability with azimuthal wave number m = 3 at low Ha.
At intermediate Ha, no dominant m is identifiable.
At high Ha, an unstable, equatorially symmetric state with various transitions between different azimuthal modes becomes visible.
Our observations are in agreement with numerical linear instability analysis.