Open-ended cylindrical type magnetic shield apparatus

摘要

The magnetic shield device including a plurality of concentrically arranged open-ended cylinders having a magnetic shaking applied thereto. A rectangular magnetic ribbon is fixed on the innermost cylinder such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with a circumferential direction of the cylinder to obtain a large magnetic shielding enhancement on a transverse direction, and a coil is wound around the innermost cylinder for supplying a magnetic shaking current. A rectangular magnetic ribbon is fixed on at least one cylinder except for the innermost one such that a longitudinal direction of the ribbon is in parallel with or substantially in parallel with an axial direction of the cylinder to obtain a large magnetic shielding enhancement on the axial direction, and a coil is wound around the cylinder for supplying a magnetic shaking current. A leakage of the magnetic shaking fields can be minimized and a high magnetic shielding enhancement on both the axial and circumferential directions can be attained. At least one cylinder is made of a magnetic material, and axial length and diameter of cylinders are suitably adjusted to attain a uniformity of a leakage magnetic field within the cylinder can be improved while a sufficiently high shielding factor is remained.