Magnetic-field dynamic compensation system and methods based on spatial correlation

Abstract

The invention relates to a magnetic-field dynamic compensation system and methods based on spatial correlation, wherein the system can realize the dynamic compensation of environment magnetic fields at the directions of three axles through a large set and a small set of Helmholtz coil racks and two fluxgate meters based on the spatial correlation of a PID (Proportion Integration Differentiation) negative feedback electronic circuit and the fluctuation of the environment magnetic fields. The invention further discloses three methods using the system, including (1) a proportioning type magnetic-field dynamic compensation method, (2) a series type integral magnetic-field dynamic compensation method, and (3) a parallel integral type magnetic-field dynamic compensation method. The system of the invention is easy to construct, has low cost and simple operation, and can achieve excellent dynamic compensation effect, and simultaneously, the methods can maximally eliminate the affects of the fluxgate meters to other magnetic detectors at the centers of coils, and have great application prospect in extremely-low field nuclear magnetic resonance, imaging thereof and other biological magnetic researches based on an SQUID (Superconducting Quantum Interference Device).

Description

technical field [0001] The invention relates to the technical field of magnetic field compensation, in particular to a system and method for dynamic magnetic field compensation based on spatial correlation. Background technique [0002] Normally, the earth's environmental magnetic field is 30~50μT. Due to external interference, such as the movement of vehicles, power frequency and its multiplier, etc., the environmental magnetic field has time fluctuations. Especially for laboratories located in urban areas, the fluctuation of the environmental magnetic field during working hours is very large. The fluctuation in the vertical direction reaches the order of micro Tesla (μT), and the fluctuation in the horizontal direction also exceeds 100nT. Many experimental equipment, such as scanning electron microscopes, neutron scattering testers, and biomagnetic detectors (magnetocardiography, magnetoencephalography), etc., have relatively high requirements on the environmental magneti...

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Problems solved by technology

[0004] The current magnetic field dynamic compensation method usually places the magnetic sensor in the center of the coil. Although this method can obtain a good compensation effect, it is difficult for some experiments that are sensitive to magnetic materials or devices, such as superconducting quantum interference devices ( Superconducting Quantum Interference Device, SQUID) biomagnetism and extremely low-field magnetic resonance experiments require the magnetic sensor to be far away from the center of the coil, making the above dynamic compensation method no longer applicable

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