Pulse shielding by nonferrous and ferromagnetic materials

The problems encountered in pulse shielding by ferromagnetic materials are discussed. A limiting nonlinear shielding theory for magnetic materials based on the classic switching theory of ferromagnetism is established and verified experimentally. The limiting nonlinear theory includes the influence of saturation induction, coercive force, electrical conductivity, and pulse charge. The pulse shielding effectiveness of many different shielding materials, both ferrous and nonferrous, is analyzed. The material costs and weights are compared. It is shown that below a certain pulse current level, nickel-iron alloys produce the lightest shields. Above that current level, nonferrous materials become lighter because they are less dense. Suggestions for the improvement of ferrous alloys are included.