Book Review: Permanent Magnets in Theory and Practice, 2nd Ed.

Abstract

magnetic fields include treatments of magnetic flux density and field strength, the Biot-Savart law, vector potential, Ampere's circuital law, magnetic materials, magnetic susceptibility, relative permeability, ferromagnetism, magnetic circuits, magnetic forces on charges and currents, Faraday's and Lenz's laws, eddy currents and magnetic energy. By this time Maxwell's equations have been deduced and applied extensively. The next chapter groups these equations and provides a general discussion. Five chapters are then devoted to the propagation of plane electromagnetic waves in various media and across interfaces, four on guided waves, two of which concern the optical waveguides, and three on radiation of electromagnetic waves.135 examples and 423 problems form important parts of the book. Many of the problems are new and their function is not only to illustrate the basic principles but also to show a variety of applications. The problems often require the demonstration of a given result; about half of the remaining answers are given at the end of the book. For convenience, the problems are classified by section, are approximately in order of increasing difficulty and proceed in short steps. Teachers will find further, and easier, problems in a companion book Electromagnetism: Principles and Applications by the first two authors and by the same publisher. There are useful lists, tables and appendices giving vector definitions, identities and theorems, physical constants, Sl prefixes, units conversions and Maxwell's equations. Other attractive features are that each chapter begins with a clearly-stated aim and ends with a useful summary.It is a pleasure to read this lucid, well-illustrated and attractively-presented book which gives a very thorough coverage of the subject. It is an ideal text for, and can be highly recommended to undergraduates in electronic and electrical engineering and physics. It should also be in all university and polytechnic libraries.

A Novel Augmented Railgun Using Permanent Magnets

“…Let us assume that the permanent magnet operates in the state represented by the maximum value of ^_`. Therefore, the minimum permanent magnet volume ( bc ) for generating a flux density ( d_e ) in the volume of the barrel air gap ( d_e ), is obtained by [18]: (9) Where d_e and ^_` are the magnetic flux density of the air gap and the maximum amount of the permanent magnet, respectively. Equation (9) indicates that large flux density in the air-gap can be obtained by reducing the air-gap volume.…”

“…Like the Open magnetic circuit of augmented railguns, the 2-D planar model has been used instead of the 3-D circuit to simplify and reduces the huge numbers of meshes required for the Maxwell ANSYS program.Let us assume that the permanent magnet operates in the state represented by the maximum value of ^_`. Therefore, the minimum permanent magnet volume ( bc ) for generating a flux density ( d_e ) in the volume of the barrel air gap ( d_e ), is obtained by[18]:…”