Title :
Ferromagnetic high-permeability alloy alone can provide sufficient low-frequency and eddy-current shieldings for biomagnetic measurements
Author :
Okada, Yoshio C. ; Shah, Bharat ; Huang, Jin-Chu
Author_Institution :
Dept. of Neurology and Physiol., New Mexico Univ., Albuquerque, NM, USA
fDate :
7/1/1994 12:00:00 AM
Abstract :
A low cost, two-shell ferromagnetic shielded room large enough for a person to enter and prepare experiments was constructed for biomagnetic measurements. No aluminium or copper shell was used for eddy-current shielding. A high-permeability nickel-iron-molybdenum alloy (1.57 mm thick) was used for both ferromagnetic and eddy-current shieldings. The shielding factor was 60 dB at DC and 40 dB between 0.1 Hz and about 3 Hz. The eddy-current shielding due to the alloy alone provided a shielding factor of 55 dB at 30 Hz and 66 dB at 60 Hz. The shielding factor was sufficiently high in all the frequency range for biomagnetic measurements with a first-order superconducting gradiometer.
Keywords :
biological techniques and instruments; biomagnetism; eddy currents; ferromagnetism; iron alloys; magnetic shielding; molybdenum alloys; nickel alloys; 0 to 60 Hz; 40 to 66 dB; NiFeMo; biomagnetic measurements; biomagnetism research; eddy-current shielding; ferromagnetic high-permeability alloy; first-order superconducting gradiometer; high-permeability Ni-Fe-Mo alloy; low-frequency shielding; shielded room; shielding factor; Aluminum; Biological materials; Biomagnetics; Costs; Frequency; Geophysical measurements; Iron alloys; Magnetic materials; Magnetic noise; Magnetic shielding; Alloys; Environment, Controlled; Equipment Design; Facility Design and Construction; Magnetics; Permeability;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
