Magnetic field generator having a plurality of coils for generating

Abstract

A magnetic field generator includes: a first coil group, including at least one coil, for generating a magnetic field upon energization; a second coil group, including at least one coil, and arranged such that a magnetic field is generated in substantially the same space as that of the magnetic field generated by the first coil group, a self-inductance of the second coil group being smaller than that of the first coil group; and a driving means for selectively energizing the first and second coil groups. The driving means energizes the second coil group first, and after the magnetic field is caused to rise by the second coil group, energizes the first coil group, thereby holding a constant magnetic field. A method of driving a magnetic field generator including a first coil group for generating a magnetic field and a second coil group for generating a magnetic field in substantially the same space as that of the magnetic field generated by the first coil group and having a self-inductance smaller than that of the first coil group, includes the steps of: energizing only the second coil group to generate a magnetic field; and energizing the first coil group after the magnetic field generated by the second coil group rises, thereby holding a constant magnetic field.