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Three-Dimensional Calculations of Electrical Parameters in Flux Compression Systems

The Finite Difference Time Domain (FDTD) method, adapted for magnetic field diffusion problems, has been applied for accurate calculation of the resistance and inductance of arbitrarily-wound helical coils of interest in flux-compression systems. These simulations have been performed using a locally-developed three-dimensional variable-mesh FDTD code that has been parallelized along three directions. The resistance calculations automatically take account of skin and proximity effects. The simulations also yield a detailed 3-D picture of magnetic field diffusion through a complex, multi-material coil in the presence of arbitrary time-dependent current waveforms. Hence they can provide critical insight into coil performance in real-life systems. We report on the critical issues that must be kept in mind for such simulations and the results of test problems with simple coil geometries.