Princeton MagnetoRotational Instability (MRI) Experiment: Recent Progress in the Search for the MRI

The Princeton MRI Experiment investigates the MRI in a magnetized cylindrical liquid Gallium Couette flow with inner and outer radii of 7cm and 21cm, and height 28cm. At Reynolds Number of $10^7$ we expect to destabilize several modes of the MRI in the presence of a 0.5T axial magnetic field. Ekman effects are reduced via a pair of differentially rotating rings at the end caps. After flow characterization with water, the apparatus was filled with Gallium to search for signatures of the MRI: an amplified radial magnetic field, and enhanced turbulent viscosity coupling the cylinders. Initial diagnostics measure torque and external radial B fields. In the future internal magnetic field and flow diagnostics will be added. Our main objectives are to (1) clearly demonstrate MRI; (2) study its nonlinear behavior and angular momentum transport; (3) compare with simulations similar to those used in astrophysical disks. This work is supported by the US DOE, NSF, and NASA.