CN118409255B - Magnetization measuring sensor used under pulse strong magnetic field - Google Patents

Abstract

The present application belongs to the field of electromagnetic measurement, and specifically discloses a magnetization measurement sensor for use in a pulsed strong magnetic field, including four planar structure coils with uniform turn spacing and consistent size, the four coils are evenly distributed along the circumference, the two centrally symmetrical coils are wound in the same direction, and the central ends of the two centrally symmetrical coils are connected by a connecting line to form a group of coils; the lead-out ends of the two coils in each group of coils constitute the output ends of the group of coils, and the output ends of the two groups of coils are connected in series to form the output end of the magnetization measurement sensor. The present application can effectively eliminate the influence of uneven background magnetic field in magnetization measurement and improve the accuracy of magnetization measurement.

Description

A magnetization measurement sensor for pulsed strong magnetic field

Technical Field

The present application belongs to the field of electromagnetic measurement, and more specifically, relates to a magnetization measurement sensor for use in a pulsed strong magnetic field.

Background Art

Magnetization measurement is one of the main methods to study the properties of materials. Pulsed strong magnetic fields can induce the spin of the atomic nuclei of materials and the energy level transition of the electrons outside the nucleus. In this process, the quantum oscillation inside the material produces a weak magnetic field. Detecting this weak magnetic field can reflect the magnetization process of the material and characterize the properties of the material. However, the weak magnetic field generated by quantum oscillation is only on the order of ^10-6 , while the background magnetic field (pulsed strong magnetic field) that excites the material to produce quantum oscillations is as high as tens of Tesla (T). How to eliminate the influence of the background magnetic field and the spatial inhomogeneity of the background magnetic field is the key to magnetization measurement sensors.

The basic idea of the current common method in this field is: use a coaxially wound magnetic field induction coil, place the material sample to be tested at the center of the coil, the inner coil can sense the background magnetic field and the weak magnetic field generated by the quantum oscillation of the material at the same time, the outer coil has a larger radius and can only sense the background magnetic field, and the two are wound in opposite directions. When the product of the number of turns (N1) and the cross-sectional area (S1) of the outer coil (N1×S1) is equal to the product of the number of turns (N2) and the cross-sectional area (S2) of the inner coil (N2×S2), the background magnetic field can be offset after series connection, and the weak magnetic field generated by the quantum oscillation of the material can be extracted. However, this method cannot eliminate the influence of the inhomogeneity of the background magnetic field for the following reasons: (1) The wire diameter of the magnetization detection coil is thin and the volume is small. It can only be wound manually under a microscope, and it is difficult to control the condition of N1×S1=N2×S2. Therefore, it is necessary to design an additional zeroing circuit and perform repeated experiments to perform zeroing calibration. It usually takes hundreds of man-hours to process a sensor; (2) Since the magnetic field inside the pulse magnet is usually not strictly uniform, after zeroing at a specific position, if the placement position is offset, it needs to be zeroed again.

Therefore, it is urgent to study how to solve the problem that traditional magnetization measurement sensors cannot eliminate the influence of background magnetic field uniformity.

Summary of the invention

In view of the defects of the prior art, the purpose of the present application is to provide a magnetization measurement sensor for use in a pulsed strong magnetic field, aiming to solve the problem that the traditional magnetization detection coil cannot eliminate the influence of the uneven background magnetic field.

To achieve the above-mentioned purpose, in a first aspect, the present application provides a magnetization measurement sensor for use in a pulsed strong magnetic field, comprising four planar structure coils with uniform turn spacing and consistent sizes, the four coils are evenly distributed along the circumference, the two centrally symmetrical coils are wound in the same direction, and the center ends of the two centrally symmetrical coils are connected by a connecting wire to form a group of coils; the lead ends of the two coils in each group of coils constitute the output ends of the group of coils, and the output ends of the two groups of coils are connected in series to form the output end of the magnetization measurement sensor.

The magnetization measurement sensor for use in a pulsed strong magnetic field provided by the present application adopts four coils of a planar structure, the four coils are evenly distributed along the circumference, the two centrally symmetrical coils have the same winding direction, and the central ends of the coils are connected to form the same group of coils, so that the magnetization measurement sensor provided by the present application can be at any position of the pulsed strong magnetic field distribution. The induced electromotive force of the two groups of coils under the background magnetic field is the same. According to the winding direction of the two groups of coils and the series connection mode of the output ends, the induced electromotive force of the two groups of coils is subtracted or summed, which can effectively eliminate the influence of the uneven background magnetic field.

As a further preferred embodiment, when the coils in the two groups of coils are wound in opposite directions, the output ends of the two groups of coils are connected in series in the same direction to form the output end of the magnetization measurement sensor.

As a further preferred embodiment, when the coils in the two groups of coils are wound in the same direction, the output ends of the two groups of coils are connected in reverse series to form the output end of the magnetization measurement sensor.

As a further preference, the two connecting wires in the two groups of coils are insulated and arranged perpendicular to each other.

As a further preference, the four coils are arranged in a double-layer substrate, and the two connecting wires are arranged in different layers of the substrate.

As a further preference, the spacing between the coils and the turn spacing inside the coils are set according to the insulation level of the substrate material, so as to ensure that the magnetic field generated by the quantum oscillation of the material sample under test breaks through the substrate and is sensed by the coil.

As further preferred, the substrate is a double-layer printed circuit board.

As a further preference, the coil is made of copper wire material.

In a second aspect, the present application provides a magnetization measurement system, including an acquisition card, a host computer, and the magnetization measurement sensor for use in a pulsed strong magnetic field as described above;

The magnetization measurement sensor is used to sense the magnetic field generated by the quantum oscillation of the material sample under test, and output a signal representing the magnetization of the material sample under test; the acquisition card is used to acquire the signal representing the magnetization of the material sample under test; the host computer is used to obtain the signal representing the magnetization of the material sample under test, and obtain the magnetic flux reflecting the magnetization signal of the material sample under test through integration processing.

The magnetization measurement system provided by the present application adopts a magnetization measurement sensor including four coils of planar structure, wherein the four coils are evenly distributed along the circumference, and the two centrally symmetrical coils have the same winding direction, and the central ends of the coils are connected to form the same group of coils, so that the magnetization measurement sensor can be placed at any position of the pulsed strong magnetic field distribution, and the induced electromotive force of the two groups of coils under the background magnetic field is the same. According to the winding direction of the two groups of coils and the series connection mode of the output ends, the induced electromotive force of the two groups of coils is subtracted or summed, which can effectively eliminate the influence of the uneven background magnetic field, thereby effectively improving the magnetization measurement accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a magnetization measurement sensor for use in a pulsed strong magnetic field according to an embodiment of the present application;

2 is a schematic diagram of equipotential lines of a pulsed high magnetic field generated by a magnet in a pulsed high magnetic field system provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of placement of a sample of a material to be tested provided in an embodiment of the present application.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

It should be understood that, in the description of the present application, the term "several" means at least one, such as one, two, etc., unless otherwise clearly and specifically defined; the term "plurality" means two or more, unless otherwise clearly and specifically defined; the terms "first" and "second" etc. are used to distinguish different objects rather than to describe a specific order of objects; the term "and/or" includes any and all combinations of one or more related listed items.

In addition, references throughout this specification to "one embodiment," "one embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment," "in one embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

It should be noted that in magnetization measurement, the pulsed strong magnetic field used to induce quantum oscillations inside the material sample to generate a weak magnetic field is mainly generated by a pulsed strong magnetic field system composed of a pulse power supply and a magnet. Its working principle is: the pulse power supply discharges to the magnet, causing the magnet to generate a pulsed strong magnetic field under the action of a huge pulse current, as shown in Figure 2.

FIG1 is a schematic diagram of the structure of a magnetization measurement sensor for use in a pulsed strong magnetic field provided by an embodiment of the present application. As shown in FIG1 , the magnetization measurement sensor includes four coils (coil a, coil b, coil c, and coil d), the four coils are planar structure coils with uniform turn spacing and consistent size, the center ends of coils a to d are o ₁ , o ₂ , o ₃ , and o ₄ , respectively, and the lead ends of coils a to d are T1 , T2 , T3 , and T4 , respectively. Specifically, the four coils can be planar coils made of copper wire material.

The four coils are evenly distributed along the circumference, that is, the central ends o ₁ , o ₂ , o ₃ , and o ₄ of coils a to d are on the same circumference with o as the center, and are 90 degrees apart from each other.

Coil a and coil d are wound in the same direction, and the center ends _o1 and _o4 of coil a and coil d are connected by a first connecting wire 10 to form a first group of coils. Coil b and coil c are wound in the same direction, and the center ends _o2 and _o3 of coil b and coil c are connected by a second connecting wire 20 to form a second group of coils.

Furthermore, the first connecting wire 10 and the second connecting wire 20 provided in this embodiment can be insulated to ensure that there is no electrical connection between them; the first connecting wire 10 and the second connecting wire 20 can be arranged perpendicular to each other in a geometric structure to ensure that the mutual inductance of the first group of coils and the second group of coils is zero, so that the first group of coils and the second group of coils do not interfere with each other.

Specifically, to ensure that the first connecting wire 10 and the second connecting wire 20 are insulated, four coils can be arranged in a double-layer substrate 30, and two connecting wires are arranged in different layers of the substrate 30. In addition, considering that the coil is arranged in the substrate 30, it will be difficult for it to sense the weak magnetic field generated by the quantum oscillation of the sample of the material being tested, in order to ensure that the weak magnetic field can break through the substrate, the spacing between the coils and the turn spacing inside the coil can be adjusted according to the insulation level of the selected substrate material to ensure that the weak magnetic field generated by the quantum oscillation of the sample of the material being tested breaks through the substrate. Preferably, the substrate provided in this embodiment can adopt a double-layer printed circuit board with a plane size of 6mm×6mm, the size of a single coil is 2×2mm, the turn width is 5μm, the turn spacing is 5μm, and the spacing between adjacent coils is 2mm.

The output end of the first set of coils is composed of the lead-out terminal T1 of coil a and the lead-out terminal T2 of coil d, and the output end of the second set of coils is composed of the lead-out terminal T3 of coil b and the lead-out terminal T4 of coil c. The output end of the magnetization measurement sensor is composed of the output end of the first set of coils and the output end of the second set of coils connected in series, and the series connection mode is related to the winding direction of the coils in the two sets of coils.

When the coils in the two groups of coils are wound in opposite directions, that is, coil a and coil d in the first group of coils are wound counterclockwise, and coil b and coil c in the second group of coils are wound clockwise, or coil a and coil d in the first group of coils are wound clockwise, and coil b and coil c in the second group of coils are wound counterclockwise, then the output ends of the two groups of coils are connected in series in the same direction to form the output end of the magnetization measurement sensor, that is, the sum of the voltages at the output ends of the two groups of coils is the characteristic signal of the sample magnetization measured by the magnetization measurement sensor.

Specifically, when the coils in the two groups of coils are wound in opposite directions, the working principle of the magnetization measurement sensor provided in this embodiment is:

When the magnetization measurement sensor provided in this embodiment is placed under the pulsed strong magnetic field in FIG. 2 without placing the material sample to be measured, if the geometric center o of the distribution of coils a to d coincides with the geometric center O1 of the magnetic field distribution generated by the magnet in the pulsed strong magnetic field system, since coil a and coil d are located on the equipotential lines of the magnetic field of the magnet, the induced electromotive force of coil a and coil d under the background magnetic field is the same. In addition, according to the right-hand rule, the induced current directions of coil a and coil d under the background magnetic field are opposite, so the induced electromotive force directions of coil a and coil d are opposite. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vd of coil d is: Va=-Vd, so that the voltage V1 at the output end of the first group of coils (the signal between T1 and T2) is: V1=Va+ Vd=0. Similarly, the induced electromotive force of coil b and coil c in the background magnetic field is equal in magnitude and opposite in direction, that is, the relationship between the induced electromotive force Vb of coil b and the induced electromotive force Vc of coil c is: Vb=-Vc, so that the voltage V2 at the output end of the second coil (signal between T3 and T4) is: V2=Vb+Vc=0. Therefore, the total voltage V=V1+V2=0 is obtained by adding the voltage at the output end of the first group of coils and the voltage at the output end of the second group of coils.

If the geometric center o of the distribution of coils a~d is offset to the right or left relative to the geometric center O1 of the magnetic field distribution generated by the magnet, that is, the geometric center o of the distribution of coils a~d moves along the x-axis in the plane coordinates defined in Figure 2, since coils a and coils c are symmetrical along the x-axis and are located on the same equipotential line, the induced electromotive force of coils a and coils c under the background magnetic field is the same. In addition, since coils a and coils c are wound in opposite directions, the induced electromotive force of coils a and coils c is in opposite directions. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vc of coil c is: Va = -Vc. Similarly, the induced electromotive force of coils b and coils d under the background magnetic field is the same in magnitude but opposite in direction, that is, the relationship between the induced electromotive force Vb of coil b and the induced electromotive force Vd of coil d is: Vb=-Vd. Therefore, the total voltage V obtained by adding the voltage at the output end of the first group of coils and the voltage at the output end of the second group of coils is V1+V2=Va+Vd+Vb+Vc= 0.

If the centers o of the coils a to d are shifted upward or downward relative to the geometric center of the magnetic field generated by the magnet, that is, the geometric center o of the coils a to d moves along the y-axis in the plane coordinates defined in Figure 2, since coils a and b are symmetrical along the y-axis and are located on the same equipotential line, the induced electromotive force of coils a and coils b under the background magnetic field is the same. In addition, since coils a and coils b are wound in opposite directions, the induced electromotive force of coils a and coils b are in opposite directions. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vb of coil b is: Va=-Vb. Similarly, the induced electromotive force of coils c and coils d under the background magnetic field is the same in magnitude and opposite in direction, that is, the relationship between the induced electromotive force Vc of coil c and the induced electromotive force Vd of coil d is: Vc=-Vd. Therefore, the total voltage V obtained by adding the voltage at the output end of the first group of coils and the voltage at the output end of the second group of coils is V=V1+V2=Va+Vd+Vb+Vc=0.

When the winding directions of the coils in the two groups of coils are the same, that is, the winding directions of the coils in the first group of coils and the coils in the second group of coils are both counterclockwise or clockwise, the output ends of the two groups of coils are connected in series in reverse order to form the output end of the magnetization measurement sensor. In other words, the voltage difference between the output ends of the two groups of coils is the characteristic signal of the sample magnetization measured by the magnetization measurement sensor.

Specifically, when the coils in the two groups of coils are wound in opposite directions, the working principle of the magnetization measurement sensor provided in this embodiment is:

When the magnetization measurement sensor provided in this embodiment is placed under the pulsed strong magnetic field in FIG. 2 without placing the material sample to be measured, if the geometric center o of the distribution of coils a to d coincides with the geometric center O1 of the magnetic field distribution generated by the magnet in the pulsed strong magnetic field system, since coil a and coil d are located on the equipotential lines of the magnetic field of the magnet, the induced electromotive force of coil a and coil d under the background magnetic field is the same, and according to the right-hand rule, the induced current directions of coil a and coil d under the background magnetic field are opposite, so the induced electromotive force directions of coil a and coil d are opposite. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vd of coil d is: Va=-Vd, so that the voltage V1 at the output end of the first group of coils (the signal between T1 and T2) is: V1=Va+Vd=0. Similarly, the induced electromotive force of coil b and coil c in the background magnetic field is equal in magnitude and opposite in direction, that is, the relationship between the induced electromotive force Vb of coil b and the induced electromotive force Vc of coil c is: Vb=-Vc, so that the voltage V2 at the output end of the second coil (signal between T3 and T4) is: V2=Vb+Vc=0. Therefore, the total voltage V=V1-V2=0 is obtained by subtracting the voltage at the output end of the first group of coils from the voltage at the output end of the second group of coils.

If the geometric center o of the distribution of coils a~d is offset to the right or left relative to the geometric center O1 of the magnetic field distribution generated by the magnet, that is, the geometric center o of the distribution of coils a~d moves along the x-axis in the plane coordinates defined in Figure 2, since coils a and coils c are symmetrical along the x-axis and are located on the same equipotential line, the induced electromotive force of coils a and coils c under the background magnetic field is the same. In addition, since coils a and coils c have the same winding direction, the induced electromotive force of coils a and coils c has the same direction. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vc of coil c is: Va = Vc. Similarly, the background magnetic fields induced by coils b and coils d are of the same magnitude and direction, that is, the relationship between the induced electromotive force Vb of coil b and the induced electromotive force Vd of coil d is: Vb=Vd. Therefore, the total voltage V obtained by subtracting the voltage at the output end of the first group of coils from the voltage at the output end of the second group of coils is V1-V2=Va+Vd-(Vb+Vc)=0.

If the centers o of the coils a to d are shifted upward or downward relative to the geometric center of the magnetic field generated by the magnet, that is, the geometric center o of the coils a to d moves along the y-axis in the plane coordinates defined in Figure 2, since coils a and b are symmetrical along the y-axis and are located on the same equipotential line, the induced electromotive force of coils a and b under the background magnetic field is the same. In addition, since coils a and b have the same winding direction, the induced electromotive force of coils a and b has the same direction. Therefore, the relationship between the induced electromotive force Va of coil a and the induced electromotive force Vb of coil b is: Va = Vb. Similarly, the background magnetic fields induced by coils c and d are the same in magnitude and direction, that is, the relationship between the induced electromotive force Vc of coil c and the induced electromotive force Vd of coil d is: Vc = Vd. Therefore, the total voltage V obtained by adding the voltage at the output end of the first group of coils and the voltage at the output end of the second group of coils is V1-V2=Va+Vd-(Vb+Vc)=0.

According to the vector characteristics of the magnetic field and position, when the magnetization measurement sensor provided in this embodiment is placed at any position in the pulsed strong magnetic field and the measured sample is not placed, if the winding directions of the two groups of coils are opposite, the output end of the magnetization measurement sensor is composed of the output ends of the group coils connected in series in the same direction, and the voltage at the output end of the magnetization measurement sensor (the total voltage obtained by adding the voltage V1 at the output end of the first group coil and the voltage V2 at the output end of the second group coil) is always zero; if the winding directions of the two groups of coils are the same, the output end of the magnetization measurement sensor is composed of the output ends of the group coils connected in series in reverse direction, and the voltage at the output end of the magnetization measurement sensor (the total voltage obtained by subtracting the voltage V1 at the output end of the first group coil and the voltage V2 at the output end of the second group coil) is always zero. Therefore, the magnetization measurement sensor provided in this embodiment can effectively eliminate the influence of the background magnetic field inhomogeneity, so that the measured material sample is placed on any coil in the magnetization measurement sensor, as shown in Figure 3, and only the coil below the sample can sense the weak magnetic field generated by the quantum oscillation of the sample. At this time, the voltage output by the output end of the magnetization measurement sensor is the characteristic signal of the sample magnetization.

The magnetization measurement sensor for pulsed strong magnetic field provided in this embodiment has the following effects: (1) four planar structure coils are used, and the four coils are evenly distributed along the circumference. The two centrally symmetrical coils have the same winding direction and are connected at the center ends to form the same group of coils. This can make the magnetization measurement sensor provided in this embodiment have the same induced electromotive force under the background magnetic field at any position of the pulsed strong magnetic field distribution. According to the winding direction of the two groups of coils and the series connection mode of the output ends, the induced electromotive force of the two groups of coils can be subtracted or summed to effectively eliminate the influence of the uneven background magnetic field. (2) The planar structure coils can be machined using micro-electromechanical system (MEMS) technology to accurately control the number of turns and cross-sectional area of the coils. The control accuracy can reach sub-micron, solving the problem that the product of the number of turns and cross-sectional area of the coils is difficult to control under manual winding. (3) Based on (1) and (2), it is not necessary to perform zero compensation on the sensor.

In addition, the present application also provides a magnetization measurement system, including an acquisition card, a host computer and the magnetization measurement sensor under the above-mentioned pulsed strong magnetic field.

Among them, the magnetization measurement sensor is used to sense the magnetic field generated by the quantum oscillation of the material sample under test, and output the characteristic signal of the magnetization of the material sample under test. The acquisition card is used to collect the characteristic signal of the magnetization of the material sample under test. The host computer is used to obtain the characteristic signal of the magnetization of the material sample under test, and obtain the magnetic flux reflecting the magnetization signal of the material sample under test through integration processing.

The magnetization measurement system provided in this embodiment adopts a magnetization measurement sensor including four coils of planar structure, the four coils are evenly distributed along the circumference, the two centrally symmetrical coils have the same winding direction, and the central ends of the coils are connected to form the same group of coils, so that the magnetization measurement sensor can be placed at any position of the pulsed strong magnetic field distribution, and the induced electromotive force of the two groups of coils under the background magnetic field is the same. According to the winding direction of the two groups of coils and the series connection mode of the output ends, the induced electromotive force of the two groups of coils is subtracted or summed, which can effectively eliminate the influence of the uneven background magnetic field, thereby effectively improving the magnetization measurement accuracy.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims (9)

1. A magnetization measurement sensor for use in a pulsed strong magnetic field, characterized in that it comprises four planar structure coils with uniform turn spacing and consistent size, the four coils are evenly distributed along the circumference, the two centrally symmetrical coils are wound in the same direction, and the central ends of the two centrally symmetrical coils are connected by a connecting wire to form a group of coils; the lead ends of the two coils in each group of coils constitute the output ends of the group of coils, and the output ends of the two groups of coils are connected in series to form the output end of the magnetization measurement sensor. 2. The magnetization measurement sensor for use in a pulsed strong magnetic field as claimed in claim 1, characterized in that when the coils in the two groups of coils are wound in opposite directions, the output ends of the two groups of coils are connected in series in the same direction to form the output end of the magnetization measurement sensor. 3. The magnetization measurement sensor for use in a pulsed strong magnetic field as claimed in claim 1, characterized in that when the coils in the two groups of coils are wound in the same direction, the output ends of the two groups of coils are connected in reverse series to form the output end of the magnetization measurement sensor. 4. The magnetization measurement sensor for use in a pulsed strong magnetic field as claimed in claim 1, characterized in that the two connecting wires in the two sets of coils are insulated and arranged perpendicular to each other. 5. The magnetization measurement sensor for use in a pulsed strong magnetic field as claimed in claim 4, characterized in that the four coils are arranged in a double-layer substrate, and the two connecting wires are arranged in different layers of the substrate. 6. The magnetization measurement sensor for use in a pulsed strong magnetic field as described in claim 5 is characterized in that the spacing between the coils and the turn spacing inside the coils are set according to the insulation level of the substrate material to ensure that the magnetic field generated by the quantum oscillation of the measured material sample breaks through the substrate and is sensed by the coil. 7. The magnetization measurement sensor for use in a pulsed strong magnetic field according to claim 5 or 6, characterized in that the substrate is a double-layer printed circuit board. 8. The magnetization measurement sensor for use in a pulsed strong magnetic field according to claim 1, wherein the coil is made of copper wire material. 9. A magnetization measurement system, characterized by comprising an acquisition card, a host computer and a magnetization measurement sensor for use in a pulsed strong magnetic field according to any one of claims 1 to 8; The magnetization measurement sensor is used to sense the magnetic field generated by the quantum oscillation of the material sample under test, and output a signal representing the magnetization of the material sample under test; the acquisition card is used to acquire the signal representing the magnetization of the material sample under test; the host computer is used to obtain the signal representing the magnetization of the material sample under test, and obtain the magnetic flux reflecting the magnetization signal of the material sample under test through integration processing.