Stability of a magnetically levitated diamagnetic fluid column

The stability of a magnetically levitated nonmagnetic liquid column in a ma gnetic fluid and a nonuniform magnetic field is studied theoretically and e xperimentally. The angular velocity equation of the interfacial wave is der ived by assuming that (1) the fluids are inviscid, (2) the undisturbed inte rface between the levitated fluid and the surrounding fluid is an infinitel y long cylindrical surface, (3) the amplitudes of the disturbances are very small, and (4) the magnetic susceptibility of each fluid is much smaller t han 1. The stable conditions of different modes are discussed. The experime ntal study is performed with two very long magnetic north poles set face to face to form the nonuniform magnetic field, using water as the levitated f luid and a diluted oil-base magnetic fluid as the surrounding fluid.