Magnetic Field Diffusion in Fast Discharging Homopolar Machines

The unusually high mechanical and thermal stresses occuring in fast discharging homopolar machines require accurate prediction of high magnetic fields accompanying their operation. Linear methods and ideal configurations are no longer acceptable as simplifying assumptions in designing such devices used in controlled thermonuclear fusion experiments, laser applications, etc. A finite element method - Galerkin technique is used for solution of Maxwell's equations for a moving medium. The transient skin effect in the system is described in terms of a magnetic vector potential and an electric scalar potential. Lagrange multipliers are used to impose the necessary constraint on the vector potential Ā. The formulation for the steady-state magnetic fields in nonlinear media results as a particular case of the method. This approach was used for predicting the parameters for the very fast discharging homopolar machine (FDX) designed by the Center for Electromechanics at The University of Texas at Austin. FDX is in an advanced state of fabrication.