An experimental investigation of the nonlinear transient electric field response induced in thin-walled cylindrical ferromagnetic shields by short-duration surface current pulses

Abstract

The paper presents results of an experimental investigation of the transient electric field induced at the interior surface of long, thin-walled, cylindrical, electrically-conductive ferromagnetic shields by axially-directed, unipolar, short-duration current pulses along the exterior surface. For an applied pulse having a duration that was sufficiently short compared to the shield response, the transient electric field response approached a result that depended on the total charge transported along the surface of the cylinder during the applied current pulse but was essentially independent of the particular time variation of the applied pulse. For practical purposes, such pulses can be regarded as impulses, and the resultant electric field response can be regarded as an impulse response for that charge level. Experimental results for a wide range of injected charge levels on a mildly ferromagnetic specimen are presented. Unlike the impulse response for the linear problem with a constant permeability, the impulse response exhibits nonlinear variation with applied charge level.