Modern high-energy magnetic materials such as samarium-cobalt and neodymium-iron-boron require very large magnetizing fields to achieve full saturation. In some cases the recommended magnetizing field is as high as 40 kOe. Such a field is readily achievable in a large solenoid, and unidirectional magnetization is easily accomplished. Many applications, such as motors and linear actuators, however, require multipole magnets. The problem of designing custom fixtures for multipole magnetization has often been considered more of an art than a science. This paper shows that by mathematically modeling the capacitor discharge magnetizer and the fixture the problem can be solved with reasonable predictability. Two different multipole fixture designs are presented along with the experimental results. The basic equations are presented and used to predict the magnetic-field intensity inside the fixtures. It is shown that optimum performance is achieved when the resistance of the fixture is equal to the parasitic resistance of the magnetizer. Finite-element analysis is also used as part of the design process. The experimental results have been achieved using a high-voltage, low-energy capacitor-discharge magnetizer and air core fixtures. The magnetization patterns that are produced are very sharp and well defined.
