CN116400271A - Portable low-frequency weak magnetic calibration device - Google Patents

Abstract

The invention discloses a portable low-frequency weak magnetic calibration device, which comprises a magnetic shielding shell, wherein the volume of the magnetic shielding shell is less than 1dm ³ The invention has the characteristic of small volume, is convenient for handheld calibration of low-frequency weak magnetic noise, and can solve the problems that the current high-performance magnetic shielding device is difficult to move and cannot evaluate the environmental magnetic noise level rapidly.

Description

A Portable Low Frequency Magnetic Weakening Calibration Device

technical field

The invention belongs to the technical field of calibration of low-frequency magnetic field weakening environment, and in particular relates to a portable low-frequency magnetic field weakening calibration device.

Background technique

Ultra-high sensitivity magnetometers have been extensively studied and applied in the detection of biomagnetic signals such as human brain magnetism, heart magnetism, and neuromagnetism. At the same time, it also has great application potential in space exploration and cutting-edge physics research. Low-frequency weak magnetic signals such as biomagnetic signals often have the characteristics of frequency less than 100Hz and amplitude less than 250pT. However, there is a 50000nT geomagnetic field on the earth, and the low-frequency weak magnetic signal will be directly submerged in the geomagnetic noise. In order to obtain a weak magnetic signal with a high signal-to-noise ratio, a high-performance magnetic shielding room is often used to shield the magnetic noise, so that the optical pump magnetometer, the atomic magnetometer based on the spin-exchange-free relaxation (SERF) effect, and other ultra-sensitive magnetometers The strong gauge works in a uniform weak magnetic environment.

However, the magnetic field in the non-laboratory environment is more complex, and the external magnetic noise is not limited to the geomagnetic noise. The high-performance magnetic shielding device may not guarantee the high accuracy of the ultra-high sensitivity magnetometer in such a complex magnetic environment. At the same time, high-performance magnetic shielding devices often have the characteristics of large mass and difficulty in moving, making it difficult to quickly detect the current weak magnetic noise level.

Therefore, in order to quickly judge the field-weakening noise level of the current magnetic environment, a portable field-weakening calibration device is urgently needed.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a portable low-frequency field weakening calibration device, aiming at solving or improving at least one of the above technical problems.

In order to achieve the above object, the present invention provides a portable low-frequency magnetic field weakening calibration device, which includes a magnetic shielding shell, the volume of the magnetic shielding shell is less than 1dm ³ , and an installation A magnetic induction component is fixedly installed in the installation cavity, and through holes are opened symmetrically on both sides of the installation cavity, and the through holes communicate with the outside world.

Preferably, the magnetic sensing component includes a sensor bracket, the sensor bracket is fixedly installed in the installation cavity, and a magnetometer is fixedly installed in the sensor bracket.

Preferably, the sensor holder is made of non-magnetic material.

Preferably, the sensitivity δB of the magnetometer is ≤10pT/Hz ^1/2 .

Preferably, the magnetic shielding shell is composed of several shielding layers and supporting layers that are alternately covered.

Preferably, the shielding layer is a soft magnetic material with high magnetic permeability.

Preferably, a degaussing coil is wound around the inner and outer walls of the magnetic shielding shell.

Preferably, a compensation coil is provided inside the magnetic shielding shell, and the compensation coil extends into the sensor bracket.

Compared with the prior art, the present invention has the following advantages and technical effects:

In the present invention, the overall volume of the magnetic shielding shell is set to be less than 1dm ³ , so that it has the characteristics of small size, which is convenient for hand-held calibration of low-frequency weak magnetic noise, and quickly judges the level of weak magnetic noise in the current magnetic environment through the magnetic induction component, which can solve the current High-performance magnetic shields are difficult to move and cannot quickly assess the level of magnetic noise in the environment.

Description of drawings

The drawings constituting a part of the application are used to provide further understanding of the application, and the schematic embodiments and descriptions of the application are used to explain the application, and do not constitute an improper limitation to the application. In the attached picture:

Fig. 1 is the sectional view of overall structure of the present invention;

Fig. 2 is a sectional view of Embodiment 2 of the present invention;

Fig. 3 is the sectional view of embodiment three of the present invention;

Fig. 4 is the sectional view of embodiment four of the present invention;

Fig. 5 is a usage scenario of the present invention.

In the figure: 1. Magnetometer; 2. Magnetic shielding shell; 3. Through hole; 4. Sensor bracket; 5. Shielding layer; 6. Supporting layer; 7. Degaussing coil; 8. Compensating coil.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1, as shown in Figure 1, this embodiment provides a portable low-frequency magnetic field weakening calibration device, including a magnetic shielding shell 2, the volume of the magnetic shielding shell 2 is less than 1dm ³ , and the inner shielding coefficient of the magnetic shielding shell 2 is close to a fixed value An installation cavity is opened at the center, and a magnetic induction component is fixedly installed in the installation cavity. Through holes 3 are symmetrically opened on both sides of the installation cavity, and the through holes 3 communicate with the outside world.

Specifically, the sum of the volume of the magnetic shielding shell 2 and the volume of its surrounding part is less than 1dm ³ . Under this volume, not only the shielding coefficient of the magnetic shielding shell 2 can meet the requirements, but also the overall weight of the device can be reduced, which is convenient for hand-held Low frequency field weakening signal calibration.

Further, the shielding coefficient of the magnetic shielding shell 2 is greater than 500.

In a further optimized solution, the magnetic induction component includes a sensor bracket 4 fixedly installed in the installation cavity, and a magnetometer 1 is fixedly installed in the sensor bracket 4 .

The position of the magnetometer 1 is fixed by the sensor bracket 4 to improve the overall stability of the device, and the magnetometer 1 is used to measure the magnitude and direction of the earth's magnetic field.

In a further optimization solution, the sensor bracket 4 is made of non-magnetic material.

It can effectively reduce the influence of the magnetic field of the bracket material itself on the calibration accuracy of the device.

Further optimizing the scheme, the sensitivity δB of the magnetometer 1 is ≤10pT/Hz ^1/2 .

Under this sensitivity, the magnetometer 1 can detect most of the low frequency magnetic field weakening signals.

Embodiment 2, referring to FIG. 2 , the difference between this embodiment and Embodiment 1 is that the magnetic shielding shell 2 is composed of several shielding layers 5 and supporting layers 6 that are arranged alternately.

The supporting layer 6 can strengthen the rigidity of the shielding layer 5 and form a multi-layer shielding structure, effectively improving the shielding factor of the magnetic shielding shell 2 .

In a further optimization scheme, the shielding layer 5 is a soft magnetic material with high magnetic permeability.

The shielding layer 5 is made of soft magnetic material with an initial relative permeability greater than 100,000, and a maximum relative permeability greater than 300,000.

Further, the shielding layer 5 and the supporting layer 6 are bonded with a 10 μm double-sided adhesive, and there are preferably 3 pairs of the shielding layer 5 and the supporting layer 6 to form a 3-layer nested magnetic shielding shell 2 .

Embodiment 3, referring to FIG. 3 , the difference between this embodiment and Embodiments 1 and 2 is that a degaussing coil 7 is wound around the inner and outer walls of the magnetic shielding shell 2 .

The degaussing coil 7 can lead out the magnetic field in the soft magnetic material with high magnetic permeability, so as to avoid magnetic saturation and affect the shielding coefficient.

Embodiment 4, referring to FIG. 4 , the difference between this embodiment and Embodiments 1, 2 and 3 is that a compensation coil 8 is provided in the magnetic shielding shell 2, and the compensation coil 8 extends into the sensor bracket 4

The compensation coil 8 can further compensate the bias and gradient of the magnetic noise inside the magnetic shielding shell 2, provide a more uniform uniform magnetic field for the magnetometer 1, and improve the calibration accuracy of the device.

The processing method of the single-point calibration data of the present invention is as follows: the measurement result H=H ₀ +H ₂ of the magnetometer 1, H ₀ is inherent magnetic noise, and this parameter can be measured in the high-performance magnetic shielding device; H ₂ is the external The remanence of the magnetic field H ₁ after being shielded by the magnetic shielding shell 2 is considered to be a constant value S because the shielding coefficient inside the magnetic shielding shell 2 is considered to be H ₁ =SH ₂ . The calibration result H ₁ =S(HH ₀ ) is obtained.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or It should not be construed as limiting the invention by implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (8)

1. A portable low frequency field weakening calibration device is characterized in that: comprises a magnetic shielding shell (2), wherein the volume of the magnetic shielding shell (2) is less than 1dm ³ The magnetic shielding device is characterized in that an installation cavity is formed in the position, close to a fixed value, of the inner shielding coefficient of the magnetic shielding shell (2), a magnetic induction assembly is fixedly installed in the installation cavity, through holes (3) are symmetrically formed in two sides of the installation cavity, and the through holes (3) are communicated with the outside.

2. The portable low-frequency weak magnetic calibration device according to claim 1, wherein: the magnetic induction assembly comprises a sensor support (4), the sensor support (4) is fixedly installed in the installation cavity, and a magnetometer (1) is fixedly installed in the sensor support (4).

3. The portable low-frequency weak magnetic calibration device according to claim 2, wherein: the sensor support (4) is made of nonmagnetic materials.

4. The portable low-frequency weak magnetic calibration device according to claim 2, wherein: the sensitivity delta B of the magnetometer (1) is less than or equal to 10pT/Hz ^1/2 。

5. The portable low-frequency weak magnetic calibration device according to claim 1, wherein: the magnetic shielding shell (2) consists of a plurality of shielding layers (5) and supporting layers (6) which are alternately coated.

6. The portable low-frequency weak magnetic calibration device according to claim 5, wherein: the shielding layer (5) is made of a soft magnetic material with high magnetic conductivity.

7. The portable low-frequency weak magnetic calibration device according to claim 1, wherein: and demagnetizing coils (7) are circumferentially wound on the inner wall and the outer wall of the magnetic shielding shell (2).

8. The portable low-frequency weak magnetic calibration device according to claim 2, wherein: a compensation coil (8) is arranged in the magnetic shielding shell (2), and the compensation coil (8) extends into the sensor bracket (4).

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