Superconducting quantum magnetic gradiometer and magnetic field gradient value measuring method

Abstract

The invention discloses a superconducting quantum magnetic gradiometer and a magnetic field gradient value measuring method. The magnetic gradiometer comprises a magnetic gradient coil, a superconducting quantum interference device (SQUID), a superconducting shielding cylinder and a position adjusting mechanism. The magnetic gradient coil is used for being coupled with a measured magnetic field, converting a magnetic field signal into a magnetic flux signal and coupling the magnetic flux signal into the SQUID; the SQUID is used for accurately measuring a coupled magnetic flux signal; the superconductive shielding cylinder has double functions, the SQUID is protected from interference according to complete diamagnetism of a superconductor, and the surrounding magnetic field of the magnetic gradient coil can be changed. The position adjusting mechanism is used for adjusting the relative position of the magnetic gradient coil and the superconducting shielding cylinder in a low-temperature environment, so that the effective area of a single coil in the magnetic field gradient coil is equivalently adjusted, and the balance degree of the magnetic gradient coil is improved. Through theoretical calculation, the common-mode noise introduced into the SQUID loop can be effectively reduced, and the common-mode rejection ratio of the magnetic gradiometer is improved.

Description

technical field [0001] The invention belongs to the technical field of magnetic field gradient measurement, and more specifically relates to a superconducting quantum magnetic force gradiometer with real-time common-mode balance adjustment capability and a magnetic field gradient value measurement method, which are mainly used to measure weak magnetic field gradients in an unshielded environment. Background technique [0002] The magnetic detector based on the Superconducting Quantum Interference Device (SQUID) is currently the magnetic detector with the lowest noise level and the highest sensitivity, and it is widely used in medicine, geophysics, military equipment and other fields. It works according to the flux quantization and the Josephson effect of superconductors. It is divided into low-temperature SQUID and high-temperature SQUID according to whether the cooling medium is liquid helium (4.2K) or liquid nitrogen (77K). According to the form of the readout circuit and t...

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Problems solved by technology

[0008] In view of the defects of the prior art, the purpose of the present invention is to further improve the common mode rejection ratio of the superconducting magnetic gradiometer, aiming to solve the problem that the unbalance degree of the coil is limited by the processing accuracy and it is difficult to improve, which causes the superconducting magnetic gradiometer to work in an unshielded environment It is not stable enough and the resolution is difficult to further improve

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