| 摘要 |
PURPOSE:To enable to check extension of a leakage magnetic field without providing a ferromagnetic cylinder body by a method wherein the leakage magnetic field is negated by providing ring type shield coils of a pair or the plural number of pairs having the same magnetic efficiency with main coils, and having the opposite directions of generated magnetic fluxes coaxially with the main coils on the outsides of the magnetic field coils. CONSTITUTION:A pair of shield coils 41, 42 are arranged coaxially with main coils 11, 12, and moreover at the positioning symmetrical in relation to a plane of symmetry 2. A pair of the shield coils 41, 42 thereof are constructed of themselved to satisfy the supreme uniformity of a magnetic field. Moreover the shield coils 41, 42 and the main coils 11, 12 are so formed as to generate magnetic fluxes in the opposite directions from each other, and moreover so constructed as to make magnetic efficiencies of a pair of the shield coils 41, 42, namely the sum of the products of the magnetically effective areas and the ampere-turns of the individual coils to be equalized with that of the main coils 11, 12. |
