Magnetising and magnet-calibrating power supplies

In the last few years, the rare-earth permanent-magnet materials have found increasing application, as they have become avaliable economically, because of their high coercivity and energy product (BH max). However, these very desirable characteristics create additional difficulties in processing the magnets. One of the rare earths, samarium cobalt, is now becoming well established in a number of applications. One of these is in microwave tubes, in particular travelling-wave tubes. The equipment now used to magnetise, calibrate and measure permanent magnets is described with particular reference to rare-earth samarium cobalt as used in travelling-wave tubes