環境磁気ノイズと磁気シールド技術I : 電車に起因する磁界変動

概要

論文の詳細を見る
Magnetically shielded rooms for biomagnetism should be designed to take account of the S/N ratio of the biomagnetic signal to the environmental magnetic noise generated mainly by dc electric railcars and moving automobiles in the vicinity. In Japanese urban areas, there is a considerable difference between the fluctuation of magnetic fields during the day, when trains are running, and at night, when there is no train traffic. This paper describes the characteristics of the fluctuation of magnetic noise (FMN) due to dc electric railcars and a method for predicting its amplitude. Firstly, the relationship between the FMN and the electric current supplied to streetcars using parallel tracks, which is supposed to be the main urban noise source at low frequency, is analyzed in the time domain. Next, the characteristics of the FMN at three locations are compared and the relationship between the amplitude of the FMN and the distance from a railroad using personal tracks is investigated. The decay factor of the magnetic noise in relation to the distance from a railroad can be obtained from such a measurement. The amplitude of the FMN at any distance from the railroad can be easily predicted if the decay factor is measured. Finally, the characteristics of FMN due to dc electric railcars using parallel tracks and personal tracks are compared.
社団法人日本磁気学会の論文
2005-04-01