A magnetic field strength-plane gradient composite planar magnetic detector

Abstract

The application provides a magnetic field strength-plane gradient composite plane magnetic detector, and relates to a magnetic detector, which comprises a superconducting layer, a magnetoresistance layer and a soft magnetic layer. The superconducting layer is composed of two identical closed superconducting loops connected together, the two closed superconducting loops have ring holes with the same size at the centers, the two closed superconducting loops and the common area connected together each comprise a current compression structure, the magnetoresistance layer is located above the current compression structure of the superconducting layer, the soft magnetic layer is a rectangular structure, two rectangular structures are located above the superconducting layer, one rectangular structure is located below the superconducting layer, and the one rectangular structure overlaps with the two rectangular structures above the superconducting layer at the position of the ring hole of the superconducting layer. The application overcomes the problem that the existing magnetic detector cannot simultaneously measure the magnetic field strength and the magnetic field gradient in different directions, and provides a new magnetic field strength-gradient composite magnetic detector.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of weak magnetic field detection, and particularly relates to a magnetic field intensity-plane gradient composite plane magnetic detector. BACKGROUND

[0002] Magnetic detectors play an important role in scientific research, national defense and military industry, industrial production, medical treatment and other fields. Commonly used magnetic detectors include vector magnetic field detectors, scalar magnetic field detectors and gradient magnetic field detectors. Almost all types of vector magnetic field detectors and scalar magnetic field detectors can only detect the magnetic field intensity scalar or vector at a certain position in space. Due to the existence of the geomagnetic field and the space environment magnetic field, the detection of weak space magnetic field signals needs to use the method of measuring the magnetic field gradient to remove the geomagnetic and environmental magnetic field noise. The conventional gradient magnetic field detector is composed of a vector magnetic field detector or a scalar magnetic field detector and a gradient coil. Among all types of gradient coils, the plane gradient coil is widely used due to the fact that the coil structure is located in the same plane and is easy to be processed by photolithography. However, the current plane magnetic field gradient detector only has the function of detecting the magnetic field gradient and does not have the function of detecting the magnetic field intensity vector in different directions. SUMMARY

[0003] In order to overcome the difficulty that the existing magnetic detector has single detection capability, can only detect the magnetic field intensity scalar, the magnetic field intensity vector in a certain direction or the gradient of the magnetic field intensity vector in a certain direction, and cannot simultaneously detect the magnetic field intensity vector and the magnetic field gradient, the application provides a magnetic field intensity-plane gradient composite plane magnetic detector, which is a new magnetic field intensity-plane gradient composite plane magnetic detector. The magnetic field intensity-plane gradient composite plane magnetic detector provided by the application can solve the problem that the existing magnetic detector cannot simultaneously measure the spatial magnetic field intensity vector and the magnetic field gradient. At the same time, the magnetic field intensity-plane gradient composite plane magnetic detector provided by the application has high sensitivity, and therefore can be used for the measurement of weak magnetic field intensity and gradient.

[0004] To achieve the above object, the technical scheme adopted by the application is as follows:

[0005] The magnetic field strength-gradient composite planar magnetic detector of the present application comprises a superconducting layer, magnetoresistance and soft magnetic layer. The superconducting layer is composed of two identical closed superconducting loops, and the two closed superconducting loops have a common area connected. Each closed superconducting loop has a ring hole with the same size in the center. The superconducting layer comprises three current compression structures, which are respectively located in the two closed superconducting loops and the common area connected thereto. The magnetoresistance has three, which are respectively located above the three current compression structures of the superconducting layer. The soft magnetic layer is a rectangular structure, two of which are located above the superconducting layer, and one of which is located below the superconducting layer and overlaps with the two rectangular structures above the superconducting layer at the position of the ring hole of the superconducting layer.

[0006] The soft magnetic layer is used to induce the horizontal magnetic field and convert the direction of the magnetic field into the direction perpendicular to the ring hole of the superconducting layer. The superconducting layer is used to induce the magnetic field perpendicular to the ring hole and generate superconducting shielding current in the closed loop. When the superconducting shielding current flows through the current compression structure of the superconducting layer, the superconducting shielding current density increases, and an enhanced induced magnetic field is generated above the current compression structure. The magnetoresistance is used to detect the magnetic field strength above the three current compression structures of the superconducting layer. According to the detected magnetic field strength above each current compression structure, the magnetic field strength perpendicular to the direction of the ring hole of the superconducting layer, the magnetic field strength along the connecting line of the two ring holes of the superconducting layer and the gradient can be obtained.

[0007] The superconducting layer is made of yttrium barium copper oxide high temperature superconducting material, the magnetoresistance is made of giant magnetoresistance or tunnel magnetoresistance, and the soft magnetic layer is made of permalloy.

[0008] Compared with the existing technology, the present application has the following advantages:

[0009] The present application utilizes the zero resistance effect and complete diamagnetism of superconductor, and the magnetic guiding property of soft magnetic material, realizes the multi-dimensional detection of spatial magnetic field vector, and has the ability of planar magnetic field gradient detection, so as to overcome the difficulty that the existing magnetic detector has single detection ability and can only detect the magnetic field strength scalar, the magnetic field strength vector in a certain direction or the gradient of the magnetic field strength vector in a certain direction, and cannot detect the magnetic field strength vector and the magnetic field gradient at the same time.

[0010] In addition, due to the compression structure of superconductor and the magnetic aggregation effect of soft magnetic material, the detection accuracy of magnetoresistance can be significantly improved, so that the magnetic field detection accuracy of the magnetic field strength-gradient composite magnetic detector proposed by the present application can reach or even exceed that of SQUID device and superconducting-giant magnetoresistance magnetic sensor. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a top view of the magnetic field strength-gradient composite planar magnetic detector of the present application;

[0012] Figure 2 This is a bottom view of the magnetic field strength-gradient composite planar magnetic detector of the present invention;

[0013] Figure 3 This is a side view of the magnetic field strength-gradient composite planar magnetic detector of the present invention.

[0014] Wherein: 1-superconducting layer, 2-magnetoresistance, 3-soft magnetic layer. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 , Figure 2 , Figure 3 As shown, the magnetic field strength-planar gradient composite planar magnetic detector of this embodiment includes a superconducting layer 1, a magnetoresistive layer 2, and a soft magnetic layer 3. The superconducting layer 1 consists of two identical closed superconducting loops, each with a ring hole of the same size at its center. The two closed superconducting loops share a common region and form a planar gradient coil structure. The superconducting layer 1 includes three current compression structures, located on both sides of the two closed superconducting loops and their common connection region, respectively. Three magnetoresistive layers 2 are placed above the three current compression structures. The soft magnetic layer 3 consists of three rectangular sheets, two of which are located above the superconducting layer 1 and symmetrically placed on both sides of the two closed superconducting loops, and one rectangular sheet is located below the superconducting layer 1, overlapping with the two rectangular sheets above it at the ring hole position of the superconducting layer 1.

[0017] like Figure 1 , 2 As shown, the soft magnetic layer 3 is used to sense the horizontal magnetic field (set as the x-direction) and convert the magnetic field direction into a direction perpendicular to the annular hole of the superconducting layer 1 (set as the z-direction). Under an external magnetic field, the magnetic field perpendicular to the annular hole of the superconducting layer 1 includes magnetic field components in the x and z directions. The superconducting layer 1 is used to sense the magnetic field perpendicular to the annular hole. When the superconducting layer 1 is in a superconducting state, the magnetic field perpendicular to the annular hole will generate a shielding current in the superconducting layer 1. When the shielding current flows through the current compression region, the superconducting shielding current density increases, and an enhanced induced magnetic field is generated near the current compression region, which is detected by the magnetoresistive resistors 2. The magnetic fields detected by the three magnetoresistive resistors 2 are as follows:

[0018] B1 = n m B x +n s B z1

[0019] B2 = -n m B x +n s Bz2

[0020] B3=2n m B x +n s B z1 -n s B z2

[0021] In the above formula, B1, B2 and B3 are the magnetic fields above the current compression structure on both sides of the two closed superconducting loops and the common connection area detected by the magnetic resistance, B x is the external magnetic field in the x direction, B z1 , B z2 are the external magnetic fields in the z direction at the two superconducting loop holes, n m is the x direction magnetic field amplification factor, n s is the z direction magnetic field amplification factor.

[0022] According to the magnetic field strength above each current compression structure detected by the three magnetic resistances, the magnetic field strength of the external magnetic field perpendicular to the superconducting layer loop hole direction, the magnetic field strength along the center line direction of the two superconducting layer loop holes and the gradient can be obtained.

[0023] As Figure 1 , 2 shown, the superconducting layer 1 can be prepared by using yttrium barium copper oxide high temperature superconducting material, the magnetic resistance 2 is made of tunnel magnetic resistance, and the soft magnetic layer 3 is made of permalloy.

[0024] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A magnetic field strength-plane gradient composite planar magnetic probe, characterized by: The magnetic field strength-plane gradient composite plane magnetic detector comprises a superconducting layer (1), a magnetoresistance (2) and a soft magnetic layer (3); the superconducting layer (1) is composed of two identical closed superconducting loops, the two closed superconducting loops have a common area connected, and each closed superconducting loop has a ring hole with the same size at the center; the superconducting layer (1) comprises three current compression structures, which are respectively located at the two closed superconducting loops and the common area connected therewith; the magnetoresistance (2) has three in total, which are respectively located above the three current compression structures of the superconducting layer (1), and the soft magnetic layer (3) has three rectangular structures, two of which are located above the superconducting layer (1), and one of which is located below the superconducting layer (1) and overlaps with the two rectangular structures above the superconducting layer (1) at the position of the ring hole of the superconducting layer (1).

2. The magnetic field strength-plane gradient composite planar magnetic probe of claim 1, wherein: The soft magnetic layer (3) is used for inducting the horizontal magnetic field and converting the direction of the magnetic field into the direction vertically penetrating the ring hole of the superconducting layer (1); the superconducting layer (1) is used for inducting the magnetic field vertically penetrating the ring hole and generating a superconducting shielding current in the closed superconducting loop; when the superconducting shielding current flows through the current compression structure of the superconducting layer (1), the superconducting shielding current density increases, and an enhanced induced magnetic field is generated above the current compression structure; the magnetoresistance (2) is used for detecting the magnetic field strength above the three current compression structures of the superconducting layer (1), and according to the detected magnetic field strength above each current compression structure, the magnetic field strength of the external magnetic field in the direction perpendicular to the ring hole of the superconducting layer (1), the magnetic field strength and gradient along the connecting line direction of the two ring holes of the superconducting layer (1) can be obtained.

3. The magnetic field strength-plane gradient compound planar magnetic probe of claim 1, wherein: The superconducting layer (1) is prepared by using yttrium barium copper oxide high-temperature superconducting material; the magnetoresistance (2) is made by using giant magnetoresistance or tunnel magnetoresistance; and the soft magnetic layer (3) is made by using permalloy.

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