Development of magnetic liquid metal suspensions for magnetohydrodynamics

Abstract: A new class of materials is developed that is a liquid with both high conductivity and magnetic susceptibility for magnetohydrodynamic (MHD) applications. We develop a general method for making such suspensions and demonstrate that various magnetic and non-magnetic metal particles, from 40 nm - 500 microns in diameter, can be suspended in liquid gallium and its alloys. The method uses an acid solution to prevent oxidation of the liquid metal and metallic particles, which allows wetting and thus suspending. We can increase the magnetic permeability by a factor of 5.0 by controlling the packing fraction of magnetic particles, which gives these materials the potential to exhibit strong MHD effects on the laboratory scale that are usually only observable in the cores of planets and stars. We can independently tune the viscosity by a factor of 230 by adding non-magnetic particles, which would allow independent control of MHD effects from turbulence.