Patent ID: 7271590

Claim:
A magnet apparatus comprising: a first static-magnetic-field generating source and a second static-magnetic-field generating source, each including superconductive coils and being disposed facing each other across a uniform static-magnetic-field region; the first static-magnetic-field generating source including: a first main coil in which current flows in a first circular direction; a first shield coil, disposed with its center axis identical to that of the first main coil, in which current flows in a second circular direction opposite to the first circular direction; a first auxiliary coil, disposed with its center axis identical to that of the first main coil, in which current flows in the first circular direction; and a first cooling container for containing the first main coil, the first shield coil, and the first auxiliary coil; the second static-magnetic-field generating source including: a second main coil, disposed with its center axis identical to that of the first main coil, in which current flows in the first circular direction; a second shield coil, disposed with its center axis identical to that of the first main coil, in which current flows in the second circular direction; a second auxiliary coil, disposed with its center axis identical to that of the first main coil, in which current flows in the first circular direction; and a second cooling container for containing the second main coil, the second shield coil, and the second auxiliary coil; wherein the radius of the first main coil is substantially equal to or smaller than the radius of the first shield coil; the radius of the second main coil is substantially equal to or smaller than the radius of the second shield coil; the radius of the first auxiliary coil is smaller than the radius of the first shield coil; the radius of the second auxiliary coil is smaller than the radius of the second shield coil; the distance between the first main coil and the second main coil is smaller than the distance between the first shield coil and the second shield coil; the distance between the first shield coil and the second shield coil is smaller than the distance between the first auxiliary coil and the second auxiliary coil; the upper and lower shield coils suppress an outward fringe field from a circular periphery of the magnetic apparatus; and the upper and lower auxiliary coils vertically suppress the outward fringe field from the magnetic apperatus.