高性能磁気シールド・ルームの試作
1983 年 52 巻 1 号 p. 59-68
詳細
1983 年 52 巻 1 号 p. 59-68
A magnetically shielded room has been constructed. It has three composite walls of permalloy and aluminum plates. The most crucial point for the characteristics of the shielded room is the connections of these plates. Residual DC magnetic field inside the room is below 1×10-7 T, and the value can be decreased down to 7×10-9 T within the space of one meter cube at the center of the shielded room by using three pairs of cancellation coils placed perpendicularly with each other pair close to the outside surface of the shielded room. Shielding factor for 50 Hz AC magnetic field is larger than 80 dB, and increases with increasing frequency up to a value larger than 135 dB at 18 MHz.
