Nonlinear skin-effect in the discharge resistor fabricated from tape of low-carbon steel

The paper considers penetration of a pulsed magnetic field into a resistive element fabricated from tape of low-carbon steel. The numerical model developed for the purpose showed that the process of magnetic field diffusion into a steel tape at the pulse leading edge can be conventionally divided into three stages: an initial stage extending up to saturation of the metal surface layers, stage of saturation in which the current wave propagates into the bulk of the tape, and stage of conduction, in which the current is distributed practically uniformly in the tape. Approximate analytical relations describing the voltage drop across the resistive element have been derived for each of the three stages, which permit estimation of the effect of the ferromagnetic properties of steel on transients in electrical circuits with a discharge resistor. Experiments with pulsed current of 60 kA have corroborated the validity of the results obtained.