Magnetic shields

A. Mager

IEEE Transactions on Magnetics · 1970 · 162 citations · 9 references

Concepts

TL;DR

Magnetic shielding is relevant for static fields and alternating fields up to about 10 kHz, and texture materials exhibit anomalous frequency‑dependent shielding factors that have been modeled. The study derives shielding‑factor formulas for single‑ and double‑walled spherical and cylindrical shells, including longitudinal fields for static double‑walled shells, and provides expressions for open‑ended cylinders up to 1 kHz transverse and 10 kHz longitudinal, with practical application suggestions and a grid‑based model. Resonance effects are observed in alternating magnetic fields.

Abstract

Magnetic shielding is interesting in static fields and in alternating fields up to circa 10kHz. Formulas of the shielding factors for single- and double-walled spherical and cylindrical shells are given, in the latter case also for fields longitudinal to the axes (double-walled shells only for static fields). For cylinders with open ends the shielding factors are represented up to 1kHz for transverse and up to 10kHz for longitudinal fields. In alternating fields interesting resonance effects are observed. Suggestions for practical application are given. Texture materials show an anomalous frequency characteristic of the shielding factor; different models for this effect are discussed. In one of these models the shielding factors of grids are treated.

References

9