On evaluation of shielding factor for 60Hz power source component in two-fold shell type magnetic shielding device

Recently, importance of magnetic shielding in new material fields and biomagnetic fields has markedly increased for the necessity of realizing the space of magnetic field which unlimitedly approches zero. Particularly, shielding to 60Hz commercial power source component is troublesome. For this purpose, two things have to be considered. One is on developments of the magnetic field sensor which is easy to handle and has a sufficient sensitivity of being able to detect a faint magnetic field close to zero, instead of SQUID. The other is dependent on constructions of the shielding system.