Magnetic permeability of a diphasic flow, made of liquid gallium and iron beads

Magnetohydrodynamics studies in laboratory experiments have long been restricted to low magnetic netic Reynolds number hows, mainly as a result of the very high magnetic diffusivity lambda = 1/mu sigma of common conducting fluids (mu is the fluid's magnetic permeability and sigma its electrical conductivity). The best conductivities are found in liquid metals which have a unit magnetic permeability, relative to vacuum. We show experimentally that a suspension of solid particles with a high magnetic permeability in a liquid metal yields an effective medium that has a high electrical conductivity and an enhanced magnetic permeability. The dispersion of the beads results from the turbulent fluid motion. The range of accessible magnetic Reynolds number can be increased by a factor of as much as 4 in our experimental setup.