Attenuation of low frequency fields by conducting ellipsoidal shells

Abstract

The diffusion rate (λ, s−1) of a spatially uniform, switched-on, field through a prolate spheroidal shell, has been related to the geometry of the shell, and orientation of the field with respect to it. The shell is assumed to be an isotropic ohmic conductor; the fields are described by Poisson's equation.For a spatially uniform alternating field (frequency ω), the attenuated field inside the shell is shown to be a function of λ/ω; the smaller this ratio, the lower the attenuation. The computed results have been verified experimentally and by checking them against exact solutions which are available for limiting cases of the general problem. The results are relevant to the properties of an electric field meter whose sensor is a gas-filled glass bulb. The breakdown frequency of the gas depends on the field within it.