MAGNETIC SHIELD APPARATUS AND MAGNETIC SHIELDING METHOD

PROBLEM TO BE SOLVED: To obtain a magnetic shielding function which is equivalent to that using high permeability soft magnetic material such as permalloy by using low cost material, and to shield an outside magnetic field without affecting electron beam. SOLUTION: The magnetic shield apparatus is provided with a casing 3 composed of low permeability magnetic material such as iron or silicon steel storing an electron apparatus 1, and an exciting coil 4 wound around (a side wall of) the casing 3 and magnetizing the casing 3 by making current I flow through it. The exciting coil 4 generates the magnetic field along the electron beam EB of an electron beam apparatus 1. Furthermore, the casing 3 is magnetized so that the magnetism in the casing 3 is not saturated. COPYRIGHT: (C)2008,JPO&INPIT