Flux pumping power storage devices, electric power transmission, electric motors (e.g. for vehicle propulsion, as in vactrains or maglev trains), magnetic levitation devices, and fault current limiters. Flux pumping Flux pumping is a method for magnetising superconductors to fields in excess of 15 teslas. The method can be applied to any type II superconductor and exploits a fundamental property of superconductors. That is their ability to support and maintain currents on the length scale of the superconductor. Conventional magnetic materials are magnetised on a molecular scale which means that superconductors can maintain a flux density orders of magnitude bigger than conventional materials.
Current density is the charge density (SI unit: coulombs per cubic metre), in which "n"(r, "t") is the number of particles per unit volume ("number density") (SI unit: m), "q" is the charge of the individual particles with density "n" (SI unit: coulombs). A common approximation to the current density assumes the current simply is proportional to the electric field, as expressed by: where E is the electric field and "σ" is the electrical conductivity. Conductivity "σ" is the reciprocal (inverse) of electrical resistivity and has the SI units of siemens per metre (S⋅m), and E has the SI units of newtons