Simulation of shock waves in ferrite-loaded coaxial transmission lines with axial bias

Abstract

A novel model is presented for shock wave development in axially-biased ferrite-loaded coaxial lines. The one-dimensional transverse electromagnetic plane wave equations for the coaxial line are linked to the three-dimensional Landau-Gilbert gyromagnetic equation describing the coherent ferrite magnetization process. The effects of demagnetization field terms imposed by the ferrite and coaxial line geometry are identified. Numerical time-stepping solution gives the predicted transmission line waveforms directly in the time domain. Simulated and experimental waveforms are compared for a nickel-zinc ferrite-loaded coaxial pulse-sharpening line. The model is shown to give generally good results for the shock front waveform, rise time and propagation characteristics, except that predicted and measured rise times diverge increasingly at very low pulse amplitudes.