Experimental investigation of magnetorotational instability in hydromagnetic Taylor-Couette flows

Magnetorotational instability (MRI) is believed to be largely responsible for the formation of protostars and black holes by introducing turbulence and facilitating an outward angular momentum transport in accretion disks. MRI is replicable in Taylor-Couette flows of electrically conducting fluids in the presence of externally applied magnetic fields. The Potsdam Rossendorf Magnetic Instability Experiment (PROMISE) at Helmholtz-Zentrum Dresden-Rossendorf is one of several existing facilities where an experimental approach towards understanding MRI takes place. PROMISE creates a magnetized Taylor-Couette flow of GaInSn alloy between concentric copper cylinders. Using PROMISE, the azimuthal MRI (AMRI), which is obtained when an azimuthal magnetic field is applied to the flow, have been demonstrated. The azimuthal magnetic field is induced by a strong central current along the cylinder axis. PROMISE has also shown evidence of the helical MRI (HMRI), which is obtained when an axial magnetic field is applied in addition to the azimuthal magnetic field. The axial magnetic field is induced by current through a coil wound around the outer cylinder. Recently, a symmetry breaking of AMRI due to thermal convection in the GaInSn alloy was discovered. In future, the transition from AMRI to HMRI will be investigated.