Critical-current density analysis of force and stability in maglev systems

The levitation force and stability in a superconductor-magnet system with maglev geometry are studied as function of the critical-current density of the superconductor, from a realistic model based on minimizing the magnetic energy. Results show that although the force is an increasing function of the critical-current density Jc, an overhigh Jc may result in instability. Therefore, the optimum critical-current density in the superconductor for a given levitation system should be an intermediate value which depends on the system dimensions and the magnetic field of the magnet.