Evaluation of Conduction Property to Improve Performance of Conductive Shield Layer Installed in Magnetically Shielded Rooms

To improve the shielding performance of magnetically shielded rooms (MSRs) used in biomagnetism measurements and to ensure their stability, we evaluated the electrical conduction properties at contact parts of conductor plates. These conductor plates are used as the conductive shield layer and form an integral part of the MSRs along with the magnetic shield layer. Although the conductive shield layer prevents magnetic noises with wide frequencies using the eddy current effect, poor electrical contact between the conductor plates causes increased electric resistance at that particular part. Consequently, this diminishes the effectiveness of the eddy current, thus lowering the shielding performance of the conductive shield layer. Therefore, cases of poor electrical contact should be detected and rectified to ensure high shielding performance and maintain stability. In this study, we develop resistance sensors to detect areas of poor contact. By establishing a quantitative relationship between poor contact and shielding performance, we can better understand the significance of these processes in improving and maintaining optimal performance. Moreover, we describe an application example of these resistance sensors on an actual construction site of an MSR.