Dynamical cancellation of the environmental magnetic disturbing fields

Abstract

A cubic Helmholtz-coil triaxial system, with a mean side of 2 m and a volume of uniform field of 0.2 m3, allows the compensation of both the main ambient magnetic field and the urban magnetic noise, in the frequency band of 0–10 Hz. The main ambient magnetic field can be cancelled, or controlled, by a stabilised power supply. The alternating disturbing fields are compensated by a triaxial magnetometric system. The triaxial sensor unit is placed near the homogenous volume of the Helmholtz system. The feed-back loops of the magnetometer channels are closed using special windings of the triaxial Helmholtz system. This configuration enables one to cancel out the simulated disturbances at a ratio of 1 × 102 − 5 × 102 and the industrial noise at a ratio of 1 × 102. Functional studies of the magnetometric sensors and magnetometric devices can be performed in the homogenous volume created by the triaxial Helmholtz system. A system of cylindrical multilayer shielding can be placed in the volume of the dynamically compensated field: thus the ratio of magnetid field cancellation becomes 104.