DISTRIBUTION PROPERTIES OF THE FRINGING FIELD FROM A SEMIINFINITE RING HEAD WITH AN ARBITRARY POLE-ANGLE

General formulae for studying the distribution of the fringing field f rom a semi-infinite ring head with an arbitrary pole-angle, are derive d by the method of the Schwartz-Christoffel transformation. The mappin g functions can be calculated without any approximation. Based on thes e formulae, the distributive properties of the fringing field are stud ied in detail. It is found that the field intensity is monotonic with respect to the pole angle, while the optimum one does not exist. It is also found that the Karlquist's formula, which was obtained on the as sumption that the magnetic scalar potential has a constant gradient ac ross the top of the gap, can be applicable at the practical recording distance only for a rectangular head.