Configuration method for a low-temperature three-axis resonant electromagnetic detection coil and detection system

Abstract

The present invention provides a configuration method for a low-temperature triaxial resonant electromagnetic detection coil, and the detection system at least includes: configuring a triaxial coil skeleton and winding coils on the triaxial coil skeleton; performing capacitance matching on the coils in each direction to obtain the resonant frequency of the coils; placing the coils in a test environment and performing radio frequency protection on the coils; placing the coils in the area to be measured and connecting test equipment, measuring the magnetic signals of the coils, and calibrating the parameters of the measured magnetic signals. Compared with traditional coils, it has higher sensitivity. In the frequency band range of the resonant frequency, the magnetic field noise can be limited to the order of magnitude of 10 fT / Hz 1 / 2 . Moreover, it has a simple structure, is easy to operate, and has wide applicability.

Description

Technical Field

[0001] The present invention relates to the field of magnetic exploration, and particularly to a configuration method and a detection system for a low-temperature three-axis resonant electromagnetic detection coil. Background Art

[0002] An induction coil sensor (also known as a search coil sensor, a pick-up coil sensor, a magnetic antenna, etc., hereinafter referred to as a coil) is one of the most typical and well-known magnetic sensors. The output signal V of the coil depends on the change rate dB / dt of the magnetic flux density. According to the working principle of the coil, it can be divided into two categories: an air-core coil and a magnetic-core coil. Among them, the magnetic-core coil uses a magnetic core with a high magnetic permeability placed in the center of the coil to concentrate the magnetic field lines in the environment into the interior of the magnetic core, playing a role of magnetic flux focusing, thereby improving the sensitivity of the coil. However, this type of coil is also prone to generating large errors, and has defects such as difficulty in reducing the volume and the coils in three axial directions cannot be concentric.

[0003] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a configuration method and a detection system for a low-temperature three-axis resonant electromagnetic detection coil, which are used to solve the problem of large errors generated when a coil with high sensitivity is used for magnetic signal detection in the prior art.

[0005] To achieve the above object and other related objects, the present invention provides a configuration method for a low-temperature three-axis resonant electromagnetic detection coil, and the configuration method for the low-temperature three-axis resonant electromagnetic detection coil at least includes:

[0006] Configuring a three-axis coil skeleton and winding coils on the three-axis coil skeleton;

[0007] Performing capacitance matching on the coils in each direction to obtain the resonant frequency of the coils;

[0008] Placing the coils in a test environment and performing radio frequency protection on the coils;

[0009] Placing the coils in a region to be measured and connecting test equipment, measuring the magnetic signals of the coils, and calibrating the parameters of the measured magnetic signals.

[0010] Optionally, the method of configuring the three-axis coil skeleton includes: enabling the coils wound on the three-axis coil skeleton to generate electromagnetic fields orthogonal to each other in three directions.

[0011] Optionally, the method for obtaining the resonance frequency of the coil includes: obtaining the resonance frequency of the coil by using an LC resonance circuit.

[0012] Optionally, the test environment is a non-magnetic environment, and the temperature of the test environment is between 64.15 Kelvin and 77.15 Kelvin.

[0013] Optionally, the parameter calibration of the measured magnetic signal includes: recording the noise signal of each frequency; applying the magnetic signal corresponding to the frequency, and calculating the signal-to-noise ratio of each frequency; calculating the sensitivity of the coil by characterizing the magnetic signal and the signal-to-noise ratio of each frequency.

[0014] To achieve the above and other related objectives, the present invention provides a detection system for implementing a configuration method of a cryogenic three-axis resonant electromagnetic detection coil. The detection system at least includes: a three-axis coil skeleton, a coil, a dewar, and a test device, where:

[0015] The three-axis coil skeleton is used for winding the coil;

[0016] The dewar is used to provide a test environment;

[0017] The test device is connected to the coil, measures the magnetic signal of the coil, and calibrates the parameters of the measured magnetic signal.

[0018] Optionally, the centers of the coils in three directions coincide.

[0019] Optionally, the material of the coil is a non-magnetic material, including a copper enameled wire coil.

[0020] Optionally, the liquid in the dewar includes liquid nitrogen.

[0021] Optionally, the test device includes a readout module and a data acquisition module, where: the readout module is connected to the coil and performs low-noise amplification on the signal output by the coil; the data acquisition module is connected to the readout module and acquires the output signal of the readout module.

[0022] As described above, a configuration method and a detection system of a cryogenic three-axis resonant electromagnetic detection coil of the present invention have the following

[0023] Beneficial effects:

[0024] 1) The configuration method and the detection system of the cryogenic three-axis resonant electromagnetic detection coil of the present invention have higher sensitivity than traditional coils, and within the frequency band range of the resonance frequency, the magnetic field noise can be limited to the order of 10 fT / Hz 1 / 2 of magnitude.

[0025] 2) The configuration method and detection system of the low-temperature three-axis resonant electromagnetic detection coil of the present invention have a simple structure, are easy to operate, and have wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It shows a functional flowchart of the configuration method of the low-temperature three-axis resonant electromagnetic detection coil of the present invention.

[0027] Figure 2 It shows a schematic structural diagram of the three-axis coil skeleton of the present invention.

[0028] Figure 3 It shows a schematic structural diagram of the detection system of the present invention.

[0029] Figure 4 It shows a schematic diagram of the signal sensitivity effect when the detection system of the present invention performs detection.

[0030] DESCRIPTION OF THE REFERENCE NUMERALS

[0031] 1 Detection system

[0032] 11 Three-axis coil skeleton

[0033] 12 Dewar

[0034] 13 Test equipment

[0035] 131 Readout module

[0036] 132 Data acquisition module

[0037] Steps S1 to S4 DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] Please refer to Figures 1 to 4 . It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. The drawings only show the components related to the present invention, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0040] Such as Figure 1As shown in the figure, this embodiment provides a configuration method for a low-temperature three-axis resonant electromagnetic detection coil. The configuration method for the low-temperature three-axis resonant electromagnetic detection coil includes:

[0041] Step S1: Configure a three-axis coil skeleton and wind a coil on the three-axis coil skeleton. It should be noted that a coil skeleton is a common component in electronic and electrical equipment. It is a bracket used for winding coils and providing support. In this embodiment, the three-axis coil skeleton can ensure that the wound coil generates electromagnetic fields orthogonal to each other in three directions (i.e., the X-axis, Y-axis, and Z-axis), and at the same time, the volume occupied by the coil wound on the three-axis coil skeleton is small, so as to meet the requirements of miniaturization and micro-miniaturization of magnetic signal detection on the premise of ensuring sensitivity.

[0042] Specifically, as an example, the method of configuring the three-axis coil skeleton includes: making the coil wound on the three-axis coil skeleton generate electromagnetic fields orthogonal to each other in three directions. It should be noted that orthogonality in direction is used to measure correlation in a vector space. Orthogonality represents a special case: non-correlation. The intuitive understanding in a vector space includes: the same direction indicates positive correlation; the opposite direction indicates negative correlation; orthogonal directions indicate non-correlation. More specifically, how to describe correlation in a function space is that the change in each unit is the same. Therefore, the physical meaning of orthogonality is that the sum of the changes in each unit is 0. In this embodiment, the three directions being orthogonal to each other means that the unit vector sum of the electromagnetic fields on the X-axis, Y-axis, and Z-axis is 0, that is, the way to configure the three-axis coil skeleton is to configure the three-axis coil into a Cartesian rectangular coordinate system for magnetic signal detection. It should be further noted that the method of configuring the three-axis coil skeleton includes, but is not limited to, making the coil wound on the three-axis coil skeleton generate electromagnetic fields orthogonal to each other in three directions. It is also possible to configure the three-axis coil into a plane polar coordinate system, a cylindrical coordinate system, a spherical coordinate system, etc. As long as magnetic signal detection can be performed, any method of configuring the three-axis coil skeleton is applicable and is not limited to this embodiment.

[0043] Step S2: Perform capacitance matching on the coils in each direction to obtain the resonant frequency of the coils. It should be noted that the sensitivity of the coil is the highest near the resonant frequency, and the resonant frequency can be adjusted by adjusting the value of the capacitance. The value of the capacitance can be adjusted by the method of capacitance parallel connection. It is also possible to increase the magnetic field sensitivity of the coil by reducing the coil impedance near the resonant point.

[0044] Specifically, as an example, the method for obtaining the resonance frequency of the coil includes: obtaining the resonance frequency of the coil by adopting an LC resonance circuit. Specifically, the coil and the inductor can be combined to be equivalent to a circuit containing a capacitor and an inductor. When the capacitor and the inductor are connected in series, within a very short period of time, the voltage of the capacitor gradually increases while the current gradually decreases; at the same time, the current in the inductor gradually increases while the voltage of the inductor gradually decreases. Similarly, when the voltage of the capacitor gradually decreases, the current gradually increases; at the same time, the current in the inductor gradually decreases while the voltage of the inductor gradually increases. The increase in voltage can reach a positive maximum value, and the decrease in voltage can also reach a negative maximum value. Similarly, the direction of the current also changes between the positive and negative directions during this process. At this time, it is said that the circuit oscillates.

[0045] When the capacitor and the inductor are connected in series, the capacitor discharges, and the inductor starts to have a reverse recoil current, and the inductor charges; when the voltage of the inductor reaches the maximum, the capacitor finishes discharging, and then the inductor starts to discharge while the capacitor starts to charge. Such a reciprocating process is called resonance. Since the equivalent circuit includes a capacitor C and an inductor L, this resonance is also called an LC resonance circuit. At the same time, because the inductor continuously charges and discharges, electromagnetic waves are generated. The phenomenon of the circuit oscillation may gradually disappear or may remain unchanged. This process is called equal-amplitude oscillation and also belongs to resonance. The period of resonance is determined by one period of the voltage change across the capacitor or the inductor. The reciprocal of the resonance period is called the resonance frequency.

[0046] It should be further noted that the methods for obtaining the resonance frequency of the coil include but are not limited to adopting an LC resonance circuit, and an RLC resonance circuit can also be used. As long as the resonance frequency of the coil can be obtained, any method for obtaining the resonance frequency of the coil is applicable and is not limited to this embodiment.

[0047] Step S3: Place the coil in a test environment and perform radio frequency protection on the coil. Specifically, as an example, the test environment is a magnetic-free environment, and the temperature of the test environment is between 64.15 Kelvin and 77.15 Kelvin. It should be noted that the test environment includes a liquid nitrogen environment, and the temperature of the liquid nitrogen is between 64.15 Kelvin and 77.15 Kelvin. Due to the low temperature, the resistance of the coil is usually between one-seventh and one-sixth of that at room temperature. For the coil in each direction (including the X direction, Y direction, and Z direction), the magnetic field noise V sys The expression is:

[0048]

[0049] where Vn is the voltage noise of the previous stage, In is the current noise in the coil, Z is the impedance of the coil, Q is the quality factor of the coil, k Bis a constant, T is the temperature, and Rs is the resistance of the coil.

[0050] According to Expression (1), it can be seen that by reducing the operating temperature T of the coil, as the temperature T decreases, the impedance of the coil decreases, thereby reducing the magnetic field noise V of the coil sys and improving the magnetic field sensitivity of the coil. On the other hand, liquid nitrogen is usually placed in a Dewar, and the Dewar can provide radio frequency protection for the coil.

[0051] It should be further noted that the test environment includes but is not limited to a non-magnetic environment, and the temperature of the test environment includes but is not limited to being between 64.15 Kelvin and 77.15 Kelvin. As long as radio frequency protection can be provided for the coil, and thus the magnetic field noise V sys is minimized, any test environment is applicable and is not limited to this embodiment.

[0052] Step S4: Place the coil in the area to be measured and connect it to the test equipment, measure the magnetic signal of the coil, and calibrate the parameters of the measured magnetic signal.

[0053] Specifically, as an example, calibrating the parameters of the measured magnetic signal includes: recording the noise signal at each frequency; applying a magnetic signal corresponding to the frequency and calculating the signal-to-noise ratio at each frequency; calculating the sensitivity of the coil by characterizing the magnetic signal and the signal-to-noise ratio at each frequency.

[0054] Specifically, as Figure 4 shown, the resonant frequency of the coil is 10 kHz. Connect the test equipment to the coil, set different frequencies on the test equipment, measure the coil, and based on the amplitude of the magnetic signal and the noise amplitude at each frequency, calculate the signal-to-noise ratio corresponding to each frequency through calculation. Then, obtain the sensitivity information of the coil by calculating the magnetic field noise V sys In the frequency band from 0 to 10 kHz, as the frequency increases, the amplitude of the signal and the amplitude of the noise increase synchronously, and the signal-to-noise ratio of the magnetic signal gradually increases. When the frequency exceeds the resonant frequency, the signal-to-noise ratio of the coil gradually decreases; at the same time, there is a negative correlation between the magnetic field noise of the coil and the signal-to-noise ratio, that is, when the coil is close to the resonant frequency, the signal-to-noise ratio of the coil is the largest, so the magnetic field noise of the coil is the smallest, and at this time the sensitivity of the coil is the highest.

[0055] As Figure 2 and Figure 3 shown, this embodiment also provides a detection system 1 for implementing the configuration method of the cryogenic triaxial resonant electromagnetic detection coil described in this embodiment. The detection system 1 includes: a triaxial coil skeleton 11, a coil, a Dewar 12, and a test equipment 3, where:

[0056] As Figure 2 and Figure 3As shown, the three-axis coil skeleton 11 is used for winding the coil. Specifically, as an example, the winding method of the coil includes: the centers of the coils in three directions coincide; the material of the coil is a non-magnetic material, including a copper enameled coil. It should be noted that when the centers of the coils in three directions coincide, the magnetic signals measured are of the same physical point, and the magnetic signals of this physical point are orthogonal to each other in the X-axis, Y-axis, and Z-axis directions. The copper enameled coil is a hollow coil, which can be arranged more compactly on the three-axis coil skeleton 11, greatly saving space and meeting the requirements of system miniaturization and microminiaturization. It should be further noted that the winding method of the coil includes, but is not limited to, the coincidence of the centers of the coils in three directions. As long as magnetic signal detection can be performed and the coil can maintain high sensitivity, any winding method of the coil is applicable and is not limited to this embodiment.

[0057] As Figure 3 shown, the Dewar 12 is used to provide a test environment. Specifically, as an example, the liquid in the Dewar 12 includes liquid nitrogen. It should be noted that the Dewar 12 can store liquid gases and is an ideal container and tool for low-temperature research and component protection. In this embodiment, the liquid stored in the Dewar 12 is liquid nitrogen to provide a low-temperature environment, so that the impedance of the coil reaches the lowest. It should be further noted that as long as the impedance of the coil can reach the lowest, any setting form of the Dewar is applicable and is not limited to this embodiment.

[0058] As Figure 3 shown, the test device 13 is connected to the coil to measure the magnetic signal of the coil and calibrate the parameters of the measured magnetic signal. Specifically, the test device 13 includes a readout module 131 and a data acquisition module 132, where: the readout module 131 is connected to the coil to perform low-noise amplification on the signal output by the coil; the data acquisition module 132 is connected to the readout module 131 to acquire the output signal of the readout module. It can be obtained through measurement that when the resonance frequency of the coil is 10 kHz, the magnetic field noise of the coil is limited to the order of 10 fT / Hz 1 / 2 , thus having wide applicability. It should be noted that the test device 13 stores the data of the coil collected for data analysis and processing, and the specific analysis and processing process will not be elaborated here one by one.

[0059] In summary, a configuration method and a detection system for a low-temperature three-axis resonant electromagnetic detection coil according to the present invention at least include: configuring a three-axis coil skeleton and winding coils on the three-axis coil skeleton; performing capacitance matching on the coils in each direction to obtain the resonant frequencies of the coils; placing the coils in a test environment and performing radio frequency protection on the coils; placing the coils in a region to be measured and connecting test equipment, measuring magnetic signals of the coils, and calibrating parameters of the measured magnetic signals. The configuration method and the detection system for the low-temperature three-axis resonant electromagnetic detection coil according to the present invention have higher sensitivity compared with traditional coils, and within the frequency band range of the resonant frequency, the magnetic field noise can be limited to the order of magnitude of 10 fT / Hz 1 / 2 . The configuration method and the detection system for the low-temperature three-axis resonant electromagnetic detection coil according to the present invention have a simple structure and are easy to operate, and have wide applicability. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0060] The above embodiments are only used to illustrate the principle and its effects of the present invention by way of example, rather than to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A configuration method for a low-temperature triaxial resonant electromagnetic detection coil, characterized in that The configuration method of the low-temperature three-axis resonant electromagnetic detection coil at least includes: Configuring a three-axis coil skeleton and winding coils on the three-axis coil skeleton; Performing capacitance matching on the coils in each direction to obtain the resonant frequency of the coils; Placing the coils in a test environment and performing radio frequency protection on the coils; Placing the coils in the area to be measured and connecting them to the test equipment, measuring the magnetic signals of the coils, and calibrating the parameters of the measured magnetic signals; The method of configuring the three-axis coil skeleton includes: enabling the coils wound on the three-axis coil skeleton to generate electromagnetic fields with three mutually orthogonal directions; Calibrating the parameters of the measured magnetic signals includes: recording the noise signals at each frequency; applying magnetic signals corresponding to the frequencies and calculating the signal-to-noise ratio at each frequency; calculating the sensitivity of the coils by characterizing the magnetic signals and signal-to-noise ratio at each frequency; The winding method of the coils includes: the centers of the coils in three directions coincide; The configuration method of the low-temperature three-axis resonant electromagnetic detection coil uses a Dewar to provide a low-temperature environment; the liquid in the Dewar includes liquid nitrogen.

2. The configuration method of the low-temperature triaxial resonant electromagnetic detection coil according to claim 1, characterized in that: The method of obtaining the resonant frequency of the coils includes: obtaining the resonant frequency of the coils by adopting the LC resonant circuit method.

3. The configuration method of the low-temperature triaxial resonant electromagnetic detection coil according to claim 1, characterized in that: The test environment is a non-magnetic environment, and the temperature of the test environment is between 64.15 Kelvin and 77.15 Kelvin.

4. A detection system for implementing the configuration method of the cryogenic triaxial resonant electromagnetic detection coil as described in any one of claims 1-3, characterized in that: The detection system at least includes: a three-axis coil skeleton, coils, a Dewar, and test equipment, where: The three-axis coil skeleton is used for winding the coils; The Dewar is used to provide a test environment; The test equipment is connected to the coils, measures the magnetic signals of the coils, and calibrates the parameters of the measured magnetic signals.

5. The detection system according to claim 4, wherein: The winding method of the coils includes: the centers of the coils in three directions coincide.

6. The detection system according to claim 4, wherein: The material of the coils is a non-magnetic material, including copper enameled coils.

7. The detection system according to claim 4, wherein: The liquid in the Dewar includes liquid nitrogen.

8. The detection system according to claim 4, wherein: The test equipment includes a readout module and a data acquisition module, where: the readout module is connected to the coils and performs low-noise amplification on the signals output by the coils; the data acquisition module is connected to the readout module and acquires the output signals of the readout module.

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