重イオン・シンクロトロンの加速器技術と物理・その2―HIMAC電磁石の設計と製作：ヒステリシス特性との格闘―

抄録

Physical quantities of coersive force, permeability and saturation magnetization of such ferromagnetic materials as laminations for magnets supposedly correlate to each other in physics viewpoint of ferromagnetism. The correlation affects magnetic field distribution depending on excitation levels because the maximum of permeability appears at a middle excitation level between coersive force and saturation magnetization; so that the correlation is helpful for producing magnets with a wide good field region for a broad excitation range in practice of finishing magnets. Dipole and quadrupole magnets of HIMAC synchrotron had demountable pole end pieces of which thickness and shape were adjustable. The adjustments were based on filed measurements and provided high-quality magnets. Taking the correlation into account, such an excitation curve as I (excitation current) vs BL (integrated filed) was proposed to be a sum of two independent fractional expressions so as to reproduce measurements well.