A Sector Magnet for a 10-50 MeV Soc

A full-scale prototype magnet sector of a 12-sector, 10-50 MeV separated orbit cyclotron has been built and tested. Eleven pairs of alternating-gradient pole tips are mounted on a yoke structure which provides a common magnetic return path. The pole tips are all excited by a single pair of coils which surround the pole tip mounting bases at the upper and lower yoke faces. The pole tips combine both the negative- and positive-gradient sections in a single unit; the magnetic field gradients are about 800 gauss/in. The pole tips are 4.5 in. wide and have a mean gap of 1.75 in. They were machined by the numeric controlled milling process. Special edge contours were developed to achieve a useful radial aperture of 3 inches. Experience with the prototype magnet demonstrates that magnets for separated orbit cyclotrons present no special difficulty in design, construction, or alignment.