Prototype Multipole Magnets for the KEK Main Ring

Two types of multipole magnets were made and tested. They can generate multipole fields up to fourth order, both normal and skew, at the same time by one magnet. One has a twelve pole configuration, that is, a dodecapole magnet, the other is a "cos n??" magnet. They have an aperture of 160 mm in diameterand a 150 mm long core. The shape and the number of poles, and the number of coils were determined by the demand of the uniformity of multipole fields which was investigated numerically using the computer program LINDA. Multipole components of the magnets were analyzed by the rotating coils and a spectrum analyzer. The results well agree with numerical calculations.